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  Subjects -> AGRICULTURE (Total: 719 journals)
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Journal Cover   European Journal of Agronomy
  [SJR: 1.381]   [H-I: 60]   [7 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1161-0301
   Published by Elsevier Homepage  [2812 journals]
  • Impact of conservation agriculture practices on energy use efficiency and
           global warming potential in rainfed pigeonpea–castor systems
    • Abstract: Publication date: May 2015
      Source:European Journal of Agronomy, Volume 66
      Author(s): G. Pratibha , I. Srinivas , K.V. Rao , B.M.K. Raju , C.R. Thyagaraj , G.R. Korwar , B. Venkateswarlu , Arun K. Shanker , Deepak K. Choudhary , K.Srinivas Rao , Ch. Srinivasarao
      Identification of agricultural practices which maximize crop productivity, energy use efficiency (EUE) and minimize greenhouse gas (GHG) emissions is essential. There is dearth of information in rainfed agriculture in general and conservation agriculture in particular, hence a study was conducted to assess the EUE and GHG emissions of different tillage practices like conventional tillage (CT), reduced tillage (RT) and zero tillage (ZT) and residue levels (harvesting heights resulting in 0, 10 and 30cm anchored residue) in pigeonpea–castor systems under semi-arid rainfed regions of India. CT recorded 30 and 31% higher energy inputs than ZT in pigeonpea and castor, respectively. The fuel consumption in ZT was 58 and 81% lower than CT in pigeonpea and castor, respectively. This lower fuel consumption in ZT reduced the GHG emissions by 21 and 23% in pigeonpea and castor, respectively, in comparison with CT. EUE and energy productivity were maximum in ZT with 10cm anchored residue. Further, castor grown on pigeonpea residue recorded 10 and 20% higher energy inputs and GHG emissions over pigeonpea grown on castor residues. Our results indicate that, reduction in one tillage operation with residue have a minimal impact on the crop yields but have a substantial environmental benefits.


      PubDate: 2015-05-26T19:30:09Z
       
  • Light interception, leaf nitrogen and yield prediction in almonds: A case
           study
    • Abstract: Publication date: May 2015
      Source:European Journal of Agronomy, Volume 66
      Author(s): Jose L. Zarate-Valdez , Saiful Muhammad , Sebastian Saa , Bruce D. Lampinen , Patrick H. Brown
      Crop yield prediction is important for the optimization of irrigation water, fertilizers, and other inputs and resources on the farm. In perennial crops, yield prediction is influenced by multiple factors regulated within the tree such as carry over effects from previous years, source-sink interactions and resource allocation and remobilization, but the bases for those regulation mechanisms are not well understood. This study reports the analysis of intensive sampling of light interception, leaf and nut nutrient concentration and yield of 768 almond trees subjected to fertilization and irrigation treatments within a mid-age commercial orchard. Nitrogen fertilization had a significant effect on individual tree fPAR, LAI, leaf nitrogen content and nut yield. While light interception and leaf area index (LAI) were poor predictors of kernel yield (R 2 =0.16–0.36 for light interception and 0.21–0.40 for LAI), leaf nitrogen pool (LNP) was able to predict 71–76% of the tree yield variability observed in two and three years. Near harvest, the LNP was highly correlated with fruit nitrogen pool (FNP) (R 2 =0.87). The results indicate that tree yield and nitrogen demand can be predicted based on leaf nitrogen content.


      PubDate: 2015-05-26T19:30:09Z
       
  • Modeling nitrous oxide emissions from organic and conventional
           cereal-based cropping systems under different management, soil and climate
           factors
    • Abstract: Publication date: May 2015
      Source:European Journal of Agronomy, Volume 66
      Author(s): Jordi Doltra , Jørgen E. Olesen , Dolores Báez , Aránzazu Louro , Ngonidzashe Chirinda
      Mitigation of greenhouse gas emissions from agriculture should be assessed across cropping systems and agroclimatic regions. In this study, we investigate the ability of the FASSET model to analyze differences in the magnitude of N2O emissions due to soil, climate and management factors in cereal-based cropping systems. Forage maize was grown in a conventional dairy system at Mabegondo (NW Spain) and wheat and barley in organic and conventional crop rotations at Foulum (NW Denmark). These two European sites represent agricultural areas with high and low to moderate emission levels, respectively. Field trials included plots with and without catch crops that were fertilized with either mineral N fertilizer, cattle slurry, pig slurry or digested manure. Non-fertilized treatments were also included. Measurements of N2O fluxes during the growing cycle of all the crops at both sites were performed with the static chamber method with more frequent measurements post-fertilization and biweekly measurements when high fluxes were not expected. All cropping systems were simulated with the FASSET version 2.5 simulation model. Cumulative soil seasonal N2O emissions were about ten-fold higher at Mabegondo than at Foulum when averaged across systems and treatments (8.99 and 0.71kgN2O-Nha−1, respectively). The average simulated cumulative soil N2O emissions were 9.03 and 1.71kgN2O-Nha−1 at Mabegondo and at Foulum, respectively. Fertilization, catch crops and cropping systems had lower influence on the seasonal soil N2O fluxes than the environmental factors. Overall, in its current version FASSET reproduced the effects of the different factors investigated on the cumulative seasonal soil N2O emissions but temporally it overestimated emissions from nitrification and denitrification on particular days when soil operations, ploughing or fertilization, took place. The errors associated with simulated daily soil N2O fluxes increased with the magnitude of the emissions. For resolving causes of differences in simulated and measured fluxes more intensive and temporally detailed measurements of N2O fluxes and soil C and N dynamics would be needed.


      PubDate: 2015-05-26T19:30:09Z
       
  • Bread wheat genetic variation for grain’s protein, iron and zinc
           concentrations as uptake by their genetic ability
    • Abstract: Publication date: July 2015
      Source:European Journal of Agronomy, Volume 67
      Author(s): Reza Amiri , Sohbat Bahraminejad , Shahryar Sasani , Saeid Jalali-Honarmand , Rosa Fakhri
      Genetic diversity among 80 irrigated bread wheat genotypes was studied for their grain’s protein, iron and zinc concentrations as well as agronomic traits. The trend of these traits over the 70 years of cultivar releasing was demonstrated. The experiment was conducted as a RCBD with three replicates under normal and terminal drought stress conditions in Kermanshah, Iran during 2011–2012 cropping season. The results of combined ANOVA revealed high significant genotypic differences for all traits, except grain iron and zinc yield. Terminal drought stress reduced all studied traits except grain iron concentration which it increased by 14.10%. The maximum effect of drought stress was on grain zinc yield, grain yield and thousand grain weight as much as 26.65, 23.48 and 18% reduction, respectively. In both conditions, there were negative correlations among grain yield and grain iron, zinc and protein concentrations. Moreover, it was found that grain yield was increased with a small improvement during 70 years while protein, iron and zinc concentrations were decreased over the years. A wide range of genetic diversity in micronutrients uptake, particularly iron and zinc within studied wheat genotypes was identified which suggesting that selection for improved micronutrients efficiency is possible. What was concluded from this study is breeders’ attention to enhancing grain production caused to neglect the quality of wheat production specially protein, iron and zinc concentrations during the last 70 years.


      PubDate: 2015-05-26T19:30:09Z
       
  • The effects of short-term waterlogging on the lint yield and yield
           components of cotton with respect to boll position
    • Abstract: Publication date: July 2015
      Source:European Journal of Agronomy, Volume 67
      Author(s): Jie Kuai , Zhiguo Zhou , Youhua Wang , Yali Meng , Binglin Chen , Wenqing Zhao
      The objectives of this study were to determine the influence of waterlogging on the lint yield and yield components, biomass accumulation and distribution in the cotton boll with respect to boll position. Cottons were subjected to waterlogging 66 days after the seedlings were transplanted into ponds created by maintaining 1–2cm of water on the soil surface for 0, 3, 6, 9 or 12d. The ponds were then drained to allow recovery. The tap root and main stem biomass were significantly reduced and the plant biomass decreased resulting from decreased biomass in fruiting branch 1–8 (FB1–8) after waterlogging. The vegetative and reproductive biomass of FB9–16 increased by altered fruiting dynamics resulted from previous waterlogging, and the highest biomass was measured in 6 days of waterlogging (WL6). Waterlogging of 3, 6, 9 and 12d resulted in a 16.0%, 24.1%, 39.5% and 50.2% reduction in lint yield, due to decreased boll number. Altered fruiting dynamics after waterlogging increased the contribution of bolls at position 3 on FB9–16 to the total yield due to an increase in boll number. The proportion of the boll wall and the seed biomass increased, while the proportion of the fiber biomass and the fiber/seed ratio decreased progressively with waterlogging duration. Insufficient assimilates were preferred compensation in boll number to boll biomass. These findings demonstrate that the bolls at various positions differed in their response to waterlogging and that even short periods (3d) of waterlogging can have considerable long-term effects on the growth of cotton.


      PubDate: 2015-05-26T19:30:09Z
       
  • Propensity for seed-mediated gene flow from potato crops and potential
           consequences for the coexistence of GM and non-GM potato systems
    • Abstract: Publication date: July 2015
      Source:European Journal of Agronomy, Volume 67
      Author(s): S. Phelan , T. Fitzgerald , J. Grant , S. Byrne , C. Meade , E. Mullins
      Potato is a critical crop to European growers, both economically and agronomically as a break crop in the standard cereal rotation. As studies investigating the agronomic performance and environmental impact of disease resistant, GM potatoes come to an end across several sites in Europe, past discussions on achieving the effective coexistence of GM and equivalent non-GM crops have too often focussed on the purported risk of excessive pollen-mediated gene flow. Dependent on the crop in question, the impact of seed loss pre- and/or post-harvest presents a greater challenge to securing efficient coexistence practises. To examine this issue for potato, a total of 51 fields that had been commercially cultivated with potatoes were surveyed in two separate cohorts for post-harvest tuber loss and/or volunteer emergence. Across 17 fields studied, the average post-harvest tuber loss was recorded at 141,758±911 tubers ha−1, with volunteer establishment in the following crop ranging from 400±59ha−1 to 55,698±47ha−1. In parallel, by surveying a separate cohort of 34 commercial fields an average of 30,789±2658 volunteer ha−1 was recorded in the subsequent cereal crop, with a repeat survey made after an additional year indicating an 87.2% reduction in this mean number of volunteers across the 34 fields (P <0.001). Of the additional variables studied only location (P <0.001), herbicide application (P =0.037) and potato variety used (P =0.045) significantly influenced volunteer proliferation. Volunteer fecundity was confirmed with upto 3 tubers produced per 1st generation volunteer, with tuber yield from the 2nd generation volunteers reduced significantly (P <0.001). Assessments of the tuber lots from these 2nd generation volunteers confirmed their ability to sprout post-dormancy, therefore, indicating the potential for 3rd generation volunteers to emerge. Combined, the datasets confirm the potential for significant seed-mediated gene flow from commercial potato systems; indicating that the regulated 0.9% coexistence threshold would in all probability be compromised if GM potatoes were grown in rotations of 1:4 years or less, in the absence of a comprehensive tuber loss and/or volunteer management system.


      PubDate: 2015-05-26T19:30:09Z
       
  • Productivity and resource use in intensified cropping systems in the
           Rolling Pampa, Argentina
    • Abstract: Publication date: July 2015
      Source:European Journal of Agronomy, Volume 67
      Author(s): J.F. Andrade , S.L. Poggio , M. Ermácora , E.H. Satorre
      Increasing cropland productivity is critical to meet future global demand of food, fibers and biofuels. Recent innovations in grain crop management are aimed at designing more ecologically complex cropping systems by growing doublecrop sequences comprising a great variety of crop species. The objectives of this study were to compare (i) the pattern of resource use and the productivity in cool-season crops and their influence on the following warm-season second crops, and (ii) the overall resource capture, resource use efficiency, and productivity of various single and double cropping systems. Hence, three field experiments under rainfed conditions and computer-simulated experiments were conducted in contrasting sites in the Rolling Pampa. Seven cropping systems were evaluated, which included five double crop sequences (rapeseed/soybean, wheat/soybean, barley/soybean, field pea/soybean, and field pea/maize) and maize and soybean as single crops. Cool-season crops differed in resource use, which therefore affected differently the following second crop. The highest and the lowest yields with double cropped soybean were produced after field pea and wheat, respectively. Soybean single crop was the least productive treatment because of low resource capture and moderate resource use efficiency. Double cropping systems including soybean as second crop outperformed soybean single crop productivity due to larger resource use. Comparatively, maize single crop used fewer resources but with higher efficiency than the cropping systems including soybean, which led to higher yields when water was not limiting. Field pea/maize double crop was the most productive system, since field pea allowed for long resource use periods, while maintaining similar resource use efficiency as maize single crops. Field experiment results were confirmed by crop yield simulations based on 39 years of environmental data from the same sites. Wheat/soybean double crops expanded and contributed to raise productivity in the Pampas with available farming technologies. However, novel crop type combinations appeared as feasible ways for improving resource use balance in the growing season among the component crops. This may raise the total annual productivity or, at least, increase the grain yield of soybean, the more profitable component at present. These findings have important implications regarding the ecological intensification of commodity grain cropping systems, which can be implemented by proactive farmers in the short-term in various regions of the world.


      PubDate: 2015-05-26T19:30:09Z
       
  • Strategies to optimize nitrogen efficiency when fertilizing with pig
           slurries in dryland agricultural systems
    • Abstract: Publication date: July 2015
      Source:European Journal of Agronomy, Volume 67
      Author(s): A.D. Bosch-Serra , C. Ortiz , M.R. Yagüe , J. Boixadera
      In dryland agricultural systems, pig slurry (PS) is usually applied to cereal crops only at sowing, and slurries accumulate for the rest of the year in pits. In this context, a four-year experiment was established in order to evaluate the feasibility of PS applications at the barley or wheat tillering stage. The main treatments were PS either applied at sowing (25Mgha−1) or not, but they alternated after a two-year period. Both were annually combined with eight side-dressing treatments at cereal tillering: mineral N as NH4NO3 (M; 60 or 120kgNha−1 yr−1), PS from fattening pigs (PSf; 17, 30, 54 Mgha−1 yr−1), PS from sows (PSs; 25, 45, 81 Mgha−1 yr−1) and a treatment without N. The combined fertilization treatments were 18 plus a control (no N applied). In the context of crop rotation, the biennial alternation of PS applied at sowing allowed the control of soil nitrate increments, while PS side-dressing improved N recovery compared with a unique application at sowing. The highest yields (>3.6 Mgha−1 yr−1) were obtained with an annual average (4-yr) N rate close to 173kg Nha−1 (±40kg Nha−1). The best overall strategies corresponded to PSs side-dressings of 50–90kg Nha−1. These PSs rates also recorded the highest values on the five calculated N-efficiency indexes, which were higher than or similar to results from M side-dressings or those recorded in the literature. These similarities (M vs. PSs) were also shown by the reduction of unaccounted-for N inside the overall N balance. Thus, split PS application during the crop cycle is a sound fertilization option in dryland systems.


      PubDate: 2015-05-26T19:30:09Z
       
  • Increased utilization of lengthening growing season and warming
           temperatures by adjusting sowing dates and cultivar selection for spring
           maize in Northeast China
    • Abstract: Publication date: July 2015
      Source:European Journal of Agronomy, Volume 67
      Author(s): Jin Zhao , Xiaoguang Yang , Shuwei Dai , Shuo Lv , Jing Wang
      Global warming has lengthened the theoretical growing season of spring maize in Northeast China (NEC), and the temperatures during the growing season have increased. In practise, crop producers adjust sowing dates and alternate crop cultivars to take advantage of the lengthening growing season and increasing temperatures. In this study, we used crop data and daily weather data for 1981–2007 at five locations in NEC to quantify the utilization of the lengthening growing season and increasing temperatures by adjusting sowing dates and cultivar selection for spring maize production. If these two positive factors are not fully utilized, then it is important to know the potential impacts of these climatic trends on spring maize grain yields. The results show that in NEC, both the actual and theoretical growing seasons are lengthening, i.e., the sowing dates have been advanced and the maturity dates have been delayed. The actual sowing dates are 1–8days later and the actual maturity dates are 6–22days earlier than the theoretical perspective. Advancing sowing dates and changing cultivars led to 0–5days and 6–26days extension of the growing season. For the potential thermal time (TT), adjusting the sowing dates decreased the unutilized TT before sowing, while the cultivar selection increased the utilized TT and decreased the unutilized TT after maturity. On average, the unutilized heating resource before sowing is less than that after the maturity date (0.3–1.9% vs. 2.1–7.8%). During 1981–2007, for per day extension of the growing season, the spring maize grain yield increased by 75.2kgha−1. The spring maize grain yields have increased by 7.1–57.2% when both early sowing and changing cultivars during 1981–2007. In particular, adjusting the sowing dates increased the grain yield by 1.1–7.3%, which was far less than the increase effect (6.5–43.7%) from switching to late maturing cultivars. Therefore, selecting late maturing cultivars is an important technique to improve maize grain yields in NEC under the global warming context. Nevertheless, if the currently unutilized TT were fully explored, the local spring maize grain yield would have increased by 12.0–38.4%.


      PubDate: 2015-05-26T19:30:09Z
       
  • Analyzing the impact of the farming context and environmental factors on
           cropping systems: A regional case study in Burgundy
    • Abstract: Publication date: May 2015
      Source:European Journal of Agronomy, Volume 66
      Author(s): N. Aouadi , J.N. Aubertot , J. Caneill , N. Munier-Jolain
      Developing cropping systems able to improve overall sustainability requires socio-economic drivers, farm features, environmental conditions and local constraints to be taken into account. The aim of this study was to analyze the relationship between the farming context and the cropping system (CS) and to identify the components of a production situation (PS) that drive the CS characteristics. Surveys on cropping practices in 2006 in the Burgundy region were analyzed using multivariate analysis including hierarchical clustering. Thirteen groups of CS were identified and their crop sequence and level of pesticide and fertilizer use were described. A multivariate analysis was used to study the diversity in PS according to their climate, soil, and farm features. Classification and the regression tree method (CART) identified the PS variables which were most influential on CS, and defined six groups of PS that minimized intra-group CS variability. However, this variability remained high, suggesting that differences in farmer’s objectives and knowledge also contributed to differentiate cropping systems in the region studied.


      PubDate: 2015-05-26T19:30:09Z
       
  • A simulation model for predicting canopy structure and light distribution
           in wheat
    • Abstract: Publication date: July 2015
      Source:European Journal of Agronomy, Volume 67
      Author(s): Wenyu Zhang , Liang Tang , Xue Yang , Leilei Liu , Weixing Cao , Yan Zhu
      Quantitative simulation of architectural structure and light distribution within a crop canopy is important for photosynthesis estimation and virtual construction. This study was undertaken to simulate the leaf curve, canopy structure and light distribution in winter wheat (Triticum aestivum L.). The field experiments with different plant types and sowing densities were carried out, and the time-course changes in canopy structure and light distribution were measured in winter wheat. The leaf curvature in wheat canopy increased with increasing sowing density and the leaf curve could be simulated with a quadratic function and its varied forms. The maximal value of leaf curvature was considered as a cultivar parameter reflecting the genetic characteristics, and the plant number per unit area was used to quantify the effects of sowing density on leaf curvature. Based on the simulated canopy structure, the leaf angle distribution function (f(θL )), extinction coefficient (K(θ)) and leaf area index (LAI) of the canopy were directly calculated by dividing leaf inclination angle into tiny units and accumulating the corresponding leaf areas. Then, the vertical distribution of photosynthetic photon flux density (PPFD) in a canopy could be simulated by using the Beer’s law. The models were validated with the independent dataset from the field experiment of different wheat cultivars. The average relative root mean square error (RRMSE) between the estimated and observed values were 17.44% for layered LAI and 19.35% for PPFD. These results indicated that the present model could effectively predict the growth dynamics of structure and of light distribution within wheat canopies, which would be useful for structural visualization or photosynthesis simulation.


      PubDate: 2015-05-26T19:30:09Z
       
  • Effects of increased day and night temperature with supplemental infrared
           heating on winter wheat growth in North China
    • Abstract: Publication date: March 2015
      Source:European Journal of Agronomy, Volume 64
      Author(s): Shibo Fang , Davide Cammarano , Guangsheng Zhou , Kaiyan Tan , Sanxue Ren
      The main future challenge is to feed 9 billion people under a changed climate, and the projected increase in global temperature will affect, negatively or positively, future wheat production depending on the geographical location. Temperature is a key factor in crop growth, development and yield. Global temperatures are rising asymmetrically with the daily minimum temperature rising faster than the daily maximum temperature. The objectives of this study are to evaluate wheat biomass growth, development, yield and harvest index under whole day and night time temperatures increased by 2.5°C in field conditions. The field experiment was carried out during three growing seasons (2008/09, 2009/10, and 2010/11) in Hebei Province, which is the main wheat region of the North China Plain. The experiment was carried out using a warming system with infrared radiation lamps suspended 2.3m above the ground which increased the mean air temperature by 2.0–2.5°C . The treatments were: (1) ambient control (CK: not warmed), (2) higher night temperature (HNT: warmed from 19:00 to 7:00), and (3) higher day–night temperature (HDNT: warmed from 9:00 to 17:00 and 19:00 to 7:00). Each treatment was replicated four times for a total of 12 plots (2×4m2 each) in a randomized complete block design for the growing season 2009/10 and 2010/11 and 5 times in 2008/09. Results of this study, showed that overall wheat biomass increased by 30% and yield by 20% under heating conditions with the highest relative increase for the cold year (2009/10). Grain yield under control treatments, for the cold year, decreased by 37% because the number of days of minimum temperature below 0°C increased by 14 days. Overall, the different warming timing (night-time only versus day–night) did not cause any significant difference in yield and biomass increase. However, as an overall pattern, warming increased aboveground biomass, grain yield, plant height and panicle numbers, but decreased harvest index. In conclusion, wheat growth and yield were significantly increased by artificial warming indicating that a warming in such area of China has potential benefits to current wheat cultivars. Higher temperatures changed the ratio of beginning/length of overwintering causing a significant change in stem numbers.


      PubDate: 2015-05-26T19:30:09Z
       
  • Morphological traits associated with vegetative growth of rice (Oryza
           sativa L.) during the recovery phase after early-season drought
    • Abstract: Publication date: March 2015
      Source:European Journal of Agronomy, Volume 64
      Author(s): Midori Okami , Yoichiro Kato , Nobuya Kobayashi , Junko Yamagishi
      Rapid leaf growth during the recovery period after a dry spell is essential for the adaptation of rice (Oryza sativa L.) to drought–prone environments. However, how rice plants resume growth when the drought stress ends is not well understood. The objective of this study was to determine the traits and mechanisms associated with the above-ground morphological response to rewatering after early-season drought, by comparing three rice lines with contrastive plant architectures. In the field, we measured the above-ground architecture, carbohydrate partitioning, and consumption of non-structural carbohydrates by IR64 (indica rice), a New Plant Type line (tropical japonica rice) and an IR64 introgression line (IL) with large leaves and reduced tillering under fully irrigated and drought+rewatered conditions. In an ancillary pot experiment, we monitored changes in tiller number and leaf growth under fully irrigated, droughted and drought+rewatered conditions. There were genotypic differences in recovery growth patterns upon rewatering after drought: the New Plant Type lines prioritized individual tiller growth, while IR64 and the IR64 IL prioritized the production of new tillers and concomitantly consumed much carbohydrate. The increase in tiller number during the recovery period was lower in the IR64 IL than in IR64 owing to the longer phyllochron and larger amount of assimilate required to produce new tillers in the IL. Rice development during the recovery period depends on the plant type (constitutive tiller number to size ratio) and tillering response to soil moisture regime, which would be mediated mainly by phyllochron and tiller production per assimilate. Rapid increase in tiller number upon rewatering in IR64 was associated with the low amount of assimilate required to produce new tillers rather than with the short phyllochron.


      PubDate: 2015-05-26T19:30:09Z
       
  • Physiological differences in yield related traits between flint and dent
           Argentinean commercial maize genotypes
    • Abstract: Publication date: August 2015
      Source:European Journal of Agronomy, Volume 68
      Author(s): Santiago Tamagno , Ignacio A. Greco , Helbert Almeida , Lucas Borrás
      Argentina is the worldwide single maize (Zea mays L.) exporter of non-GMO flint maize, also called plata maize. This grain is known for high dry-milling yields, the production of large endosperm grits and specific cooking functional properties. But, this special maize has lower yields at farmer fields when compared to regular dent germplasm, and studies describing the physiological characteristics behind this are scarce. Our objective was to understand differences in yield determination mechanisms between flint and dent commercial germplasm for the temperate area. We characterized 31 genotypes (24 dent and 7 flint) growing at five different environments for describing their yield differences, and also described specific physiological traits to unravel the mechanisms behind these yield differences. Grain yield, KNP, KW, plant growth rate and biomass partitioning around flowering, kernel set efficiency per unit of accumulated ear biomass at flowering and assimilate availability per kernel during flowering all showed significant kernel type (flints vs. dents) effects (p <0.05). And significant genotype differences within each kernel type were evident for all traits (p <0.01). Flint kernel type showed lower yields (ca. 80% of dents) due to reduced KNP and KW. This lower KNP in flints was mostly related to a lower plant growth rate around flowering, although they also showed a reduced biomass partitioning to the ear during this period. Flint genotypes, however, showed higher kernel set efficiency per unit of accumulated ear biomass when compared to dents (p <0.01). Lower KW in flints was related to a reduced assimilate availability per kernel around flowering (p <0.01), both kernel types showed similar assimilate availability per kernel during grain filling (p >0.05). This indicated flint and dent kernel types had the same amount of assimilates to fulfill their early established potential KW. Our results emphasize the importance of the flowering period for understanding yield differences between flints and dents, and biomass accumulation rate during this period was identified as a key trait for increasing flint yields.


      PubDate: 2015-05-26T19:30:09Z
       
  • Splitting the application of 3,4-dimethylpyrazole phosphate (DMPP):
           Influence on greenhouse gases emissions and wheat yield and quality under
           humid Mediterranean conditions
    • Abstract: Publication date: March 2015
      Source:European Journal of Agronomy, Volume 64
      Author(s): Ximena Huérfano , Teresa Fuertes-Mendizábal , Miren K. Duñabeitia , Carmen González-Murua , José María Estavillo , Sergio Menéndez
      Wheat is among the most widely grown cereals in the world. In order to enhance its production, its management is based on the addition of nitrogen (N) fertilizers. Nevertheless, its application could increase nitrous oxide (N2O) emissions, which effects are very pernicious to the environment, being a strong greenhouse gas (GHG). Regarding GHG, soil processes can also produce or consume carbon dioxide (CO2) and methane (CH4). Nitrification inhibitors (NI) have been developed with the aim of decreasing fertilizer-induced N losses and increase N efficiency. The fact that the application of a NI enhances N use efficiency is a good reason to think that more N should be also available for increasing the grain N concentration of wheat plants. If the application of NI means an increase in N use efficiency, it is plausible to consider that more N would be available, hence, increasing the grain N concentration of wheat. We present a two-year field-experiment to evaluate the influence of the NI 3,4-dimethylpyrazol phosphate (DMPP) on grain yield, grain quality and GHG emissions. Fertilizer dose, with and without DMPP, was 180kgNha−1 applied as ammonium sulfate nitrate (ASN) splitted in two applications of 60kgNha−1 and 120kgNha−1, respectively. A treatment with a non-splitted application of ASN with DMPP and an unfertilized treatment were also included. The splitted application of ASN with DMPP was able to reduce N2O emissions, without affecting yield and its components. The alternative management of a non-splitted application of DMPP was more efficient mitigating N2O emissions, whilst keeping yield and slightly reducing grain protein content. In consequence of the low N2O fluxes from our soils, the EF applied in our region should be lower than the default value of 1% proposed by IPCC.


      PubDate: 2015-05-26T19:30:09Z
       
  • Determining the effects of land consolidation on the multifunctionlity of
           the cropland production system in China using a SPA-fuzzy assessment model
           
    • Abstract: Publication date: February 2015
      Source:European Journal of Agronomy, Volume 63
      Author(s): Beibei Guo , Xiaobin Jin , Xuhong Yang , Xu Guan , Yinan Lin , Yinkang Zhou
      The purpose of this study was to identify and measure the effect of land consolidation (LC) on the multifunctionality of cropland ecosystems. LC can serve agriculture multifunctionality, but it can also have a huge impact on the individual functions within the sector. We took 2006–2012 as study period, based on an analysis of county scale land consolidation projects (LCP) in the 31 provinces of China, this study found that the wide range of LC implementation has comprehensively influenced the multifunctionality of agriculture. LCP have significantly improved the production function of cropland, driven investment in agriculture, promoted development of the rural agricultural economy, maintained food security and stability in the rural area, and increased crop supply in most provinces. However, it also slightly impaired rural ecological benefits in some provinces. During the study period, land consolidation influenced the agricultural supply function in 14 provinces, covering 43.97% of the LC affected area and producing an increase of 1.25 million ha in cropland; In five provinces it influenced the production function over 31.18% of the LC area, changing the supply function outcome most and the ecological function least. Thus, the widespread implementation of LCP can result in significant impacts on the crop production system.


      PubDate: 2015-05-26T19:30:09Z
       
  • Influence of temperature and solar radiation on grain yield and quality in
           irrigated rice system
    • Abstract: Publication date: March 2015
      Source:European Journal of Agronomy, Volume 64
      Author(s): Nanyan Deng , Xiaoxia Ling , Yang Sun , Congde Zhang , Shah Fahad , Shaobing Peng , Kehui Cui , Lixiao Nie , Jianliang Huang
      An insight into optimal temperature and radiation (T&R) in different rice phenological stages will contribute to rice cultivation management and crop modeling. This study was aimed to unravel the responses of various rice cultivars to different T&R conditions and to identify the optimal T&R for both yield and quality in the Yangtze River Valley in China. For this purpose, two Indica and three Japonica cultivars were grown under irrigation conditions, respectively, on three sowing dates (April 30, May 10 and May 30) in 2012 and 2013 to acquire different combinations of T&R conditions. Various morphological, yield- and quality-related traits were investigated. This study demonstrated that temperature in this region is a limiting factor compared with radiation. Besides, there was a smaller variation of the average T&R in reproductive stage than in vegetative and grain filling stages. Therefore, T&R in various phenological stages were classified into three major combinations, namely, HL, LH, MM mainly based on temperature in vegetative and grain filling stages. MM combination had similar average daily temperature in both vegetative and grain filling stages compared with the average temperature of rice growth season. HL combination was of higher (at least 1°C) average daily temperature in vegetative stage and lower (at least 1°C) in grain filling stage compared with MM. Opposite to HL, LH combination was of lower average daily temperature in vegetative stage and higher in grain filling stage compared with MM. Most of the cultivars harvested the highest grain yield with highest T&R use efficiency in HL combination compared to the other two combinations. When the average temperature in vegetative stage was estimated to be 26–28°C and 22–27°C in grain filling stage, higher grain yield can be gained. Moreover, highly significant correlation was found between temperature and LAI (leaf area index), CGR (crop growth rate), and TDW (total above ground biomass) in vegetative stage. HI (harvest index) and all grain-processing and appearance-quality-related traits was highly significantly correlated with temperature in grain filling stage. In conclusion, HL combination with average daily temperature ranges of 26–28°C in vegetative stage, and 22–27°C in grain filling stage are recommended to achieve high grain yield and quality for irrigated rice in the Yangtze River Valley in China by adjusting sowing date and crop establishment.


      PubDate: 2015-05-26T19:30:09Z
       
  • Seed yield prediction of sesame using artificial neural network
    • Abstract: Publication date: August 2015
      Source:European Journal of Agronomy, Volume 68
      Author(s): Samad Emamgholizadeh , M. Parsaeian , Mehdi Baradaran
      The prediction of seed yield is one of the most important breeding objectives in agricultural research. So, in this study, two methods namely artificial neural network (ANN) and multiple regression model (MLR) were employed to estimate the seed yield of sesame (SYS) from readily measurable plant characters (e.g., flowering time of 100% (days), the plant height (cm), the capsule number per plant, the 1000-seed weight (g) and the seed number per capsule). The ANN and MLR were tested using field data. Results showed that the ANN predicts the SYS accurately with a root-mean-square-error (RMSE) of 0.339t/ha and a determination coefficient (R 2) of 0.901. Also, it was found that the ANN model performed better than the MLR model with a RMSE of 0.346t/ha, and R 2 of 0.779. Finally, sensitivity analysis was conducted to determine the most and the least influential characters affecting SYS. It was found that the capsule number per plant and the flowering time of 100% had the most and least significant effects on SYS, respectively.


      PubDate: 2015-05-26T19:30:09Z
       
  • Selecting crop models for decision making in wheat insurance
    • Abstract: Publication date: August 2015
      Source:European Journal of Agronomy, Volume 68
      Author(s): A. Castañeda-Vera , P.A. Leffelaar , J. Álvaro-Fuentes , C. Cantero-Martínez , M.I. Mínguez
      In crop insurance, the accuracy with which the insurer quantifies the actual risk is highly dependent on the availability on actual yield data. Crop models might be valuable tools to generate data on expected yields for risk assessment when no historical records are available. However, selecting a crop model for a specific objective, location and implementation scale is a difficult task. A look inside the different crop and soil modules to understand how outputs are obtained might facilitate model choice. The objectives of this paper were (i) to assess the usefulness of crop models to be used within a crop insurance analysis and design and (ii) to select the most suitable crop model for drought risk assessment in semi-arid regions in Spain. For that purpose first, a pre-selection of crop models simulating wheat yield under rainfed growing conditions at the field scale was made, and second, four selected models (Aquacrop, CERES-Wheat, CropSyst and WOFOST) were compared in terms of modelling approaches, process descriptions and model outputs. Outputs of the four models for the simulation of winter wheat growth are comparable when water is not limiting, but differences are larger when simulating yields under rainfed conditions. These differences in rainfed yields are mainly related to the dissimilar simulated soil water availability and the assumed linkages with dry matter formation. We concluded that for the simulation of winter wheat growth at field scale in such semi-arid conditions, CERES-Wheat and CropSyst are preferred. WOFOST is a satisfactory compromise between data availability and complexity when detail data on soil is limited. Aquacrop integrates physiological processes in some representative parameters, thus diminishing the number of input parameters, what is seen as an advantage when observed data is scarce. However, the high sensitivity of this model to low water availability limits its use in the region considered. Contrary to the use of ensembles of crop models, we endorse that efforts be concentrated on selecting or rebuilding a model that includes approaches that better describe the agronomic conditions of the regions in which they will be applied. The use of such complex methodologies as crop models is associated with numerous sources of uncertainty, although these models are the best tools available to get insight in these complex agronomic systems.


      PubDate: 2015-05-26T19:30:09Z
       
  • Maize yields benefit from injected manure positioned in bands
    • Abstract: Publication date: March 2015
      Source:European Journal of Agronomy, Volume 64
      Author(s): J.J. Schröder , G.D. Vermeulen , J.R. van der Schoot , W. van Dijk , J.F.M. Huijsmans , G.J.H.M. Meuffels , D.A. van der Schans
      The use of positioned mineral fertilizer phosphorus (P) starters reduces the risk of yield penalties in maize production. However, it also increases the soil P surplus and attendant risk of P losses to the environment, in particular on farms with ample supplies of livestock manures. We examined whether routine applications of starter P can be refrained from if manure is injected in subsurface bands close to the anticipated position of the maize rows as an alternative to the conventional even injection at random lateral positions relative to the rows. Fourteen field experiments were executed on sandy soils in The Netherlands. In these experiments comparisons were made of the nitrogen (N) and P-concentrations in shoots and of dry matter (DM), N and P-yields over time, between evenly injected liquid manure (with and without starter P) and band-injected liquid manure. Silage yields of DM, N and P generally responded positively (P <0.05) to starter P applied at a rate of 9–31kg per hectare where manure had been applied at rates of circa 120kg N and circa 20kg P per hectare, but less so when the manure was band-injected. This positive response to P was not reflected in the concentration of P in shoots. Positioning of manure via band-injection without extra starter P resulted in silage maize dry matter yields that were similar to yields after even injection combined with a P-starter. Band-injection improved the recovery of the N and P (P <0.05) supplied by the manure and reduced the soil surpluses of N and P. Planting maize close to bands where liquid manure had been injected, thus increased silage yields and contributed to a better balance between the inputs and outputs of plant nutrients.
      Graphical abstract image

      PubDate: 2015-05-26T19:30:09Z
       
  • Does a freely tillering wheat cultivar benefit more from elevated CO2 than
           a restricted tillering cultivar in a water-limited environment?
    • Abstract: Publication date: March 2015
      Source:European Journal of Agronomy, Volume 64
      Author(s): Sabine Tausz-Posch , Raymond W. Dempsey , Saman Seneweera , Robert M. Norton , Glenn Fitzgerald , Michael Tausz
      This study addresses whether a freely tillering wheat cultivar with greater vegetative sink strength (cv. “Silverstar”) can benefit more from increasing atmospheric CO2 concentration [CO2] than a restricted tillering cultivar with greater reproductive sink strength (cv. H45) in a water-limited cropping system. Growth, yield, yield components and nitrogen at three developmental stages (stem elongation, anthesis, maturity) and water soluble carbohydrates (WSC, anthesis) were evaluated at two CO2 concentrations (ambient [CO2], ∼395ppm, elevated e[CO2], ∼550ppm) across six environments using the Australian Grains Free Air CO2 Enrichment (AGFACE) facility. Cv. “Silverstar” had more tillers than cv. “H45” throughout development; whereas, cv. “H45” had greater WSC storage and more and heavier kernels per spike. CO2 enrichment stimulated grain yield in both cultivars similarly, but this stimulation was caused differently: For cv. “Silverstar”, grain yield increase was exclusively linked to an increased number of fertile tillers; whereas, in cv. “H45”, yield stimulation was additionally associated with increased kernel weight and kernel numbers per spike. We conclude that in a Mediterranean-type, water-limited environment high tillering capacity alone does not ensure greater benefits from CO2 fertilization but that both pre and post-anthesis source-sink relationships play a significant role in this environment as well.


      PubDate: 2015-05-26T19:30:09Z
       
  • Quantifying the effects of soil variability on crop growth using apparent
           soil electrical conductivity measurements
    • Abstract: Publication date: March 2015
      Source:European Journal of Agronomy, Volume 64
      Author(s): Anja Stadler , Sebastian Rudolph , Moritz Kupisch , Matthias Langensiepen , Jan van der Kruk , Frank Ewert
      Spatial heterogeneity of crop growth within fields is rarely quantified but essential for estimating yield and optimizing crop management. Relationships in fields between crop growth and soil physical characteristics have been described before but an unrealistically high number of invasive measurements have to be made to obtain spatially continuous soil information. Alternatively, non-invasive methods are available for characterizing soil heterogeneity but relationships to growth characteristics have rarely been investigated. Here, we use an electromagnetic induction (EMI) sensor to measure the apparent electromagnetic conductivity of the soil (ECa), which can be used as a proxy for the relative spatial variability of the prevailing soil properties. We evaluate relationships between ECa and soil and crop characteristics assuming that measured ECa patterns relate to observed growth patterns in the field. The test fields were located in Western Germany where different crops (winter wheat, winter barley, and sugar beet) were grown between 2011 and 2013. Measurements include soil texture, soil moisture and crop growth characteristics taken frequently throughout the vegetation periods for plant height, leaf area index (LAI), dry matter of plants and selected organs (green leaves and storage organs). Spatial variability was observed for soil and crop characteristics that differed among fields, crops and years. Good correlations between ECa and soil texture and soil moisture confirmed that ECa measurements are suitable for characterizing spatial differences in soil properties for our test sites. Averaged over all sampling dates of a vegetation period the differences in the spatial variability of crop characteristics were small between the years and crops considered. However, the within-field crop growth heterogeneity changed throughout the growing period depending on the crop development stage. Correlations were found between ECa and the crop characteristics that varied with time and were most pronounced in the main growth phase when LAI approached its maximum. Crop height correlated better with ECa than yield, LAI, and dry matter but differences were observed between fields, years and crops. Our results suggest that in dry years soil patterns have a stronger influence on the crop growth patterns than in wetter years when water limitation is less severe. We conclude that ECa measurements are suitable for detecting spatial patterns in soil characteristics that influence the spatial crop growth patterns for the region, years and crops considered. However, relationships between patterns in crop growth and soil characteristics within fields are more complex and require further investigation.


      PubDate: 2015-05-26T19:30:09Z
       
  • The use of 13C and 15N based isotopic techniques for assessing soil C and
           N changes under conservation agriculture
    • Abstract: Publication date: March 2015
      Source:European Journal of Agronomy, Volume 64
      Author(s): Kenza Ismaili , Mohammed Ismaili , Jamal Ibijbijen
      A four years experiment was conducted to investigate the effect of tillage and addition of crop residues in wheat–faba bean rotation. The soil was fertilized with a total of 150kgnitrogen (N)ha−1 enriched with 9.96 percent nitrogen-15 (15N) atom excess, in four applications. The first crop was corn, a C4 plant cropped under till (T) and no-till (NT) conditions. Percent N derived from fertilizer (Ndff) by corn was 37.12–48.62. The leaves had the lowest delta carbon-13 (δ 13C) values of −12.7 and the seeds the highest (−11.8). Soil δ 13C was affected by addition of C4 plant residues. Soil under residue and till treatment (RT) had the highest percent 15N values. Residues and no-till (RNT) had the lower percent 15N values. At the end of the corn crop soil percent 15N was 0.211, 0.26, and 0.253 in the three soil depths. Residues and tillage increased significantly the Ndff of wheat: from 6.43 to 6.46kgNha−1 for no residues no-till (NRNT) and no-residues and till (NRT) and from 11.1 to 13kgNha−1 in RNT and RT treatments. In wheat nitrogen derived from residues (Ndfr) was 4.68 and 1.53kgNha−1 in grain and residues, respectively. Residues and tillage affected significantly soil C, N, 15N, and δ 13C from seeding to two months after and have no effect at harvest. The interaction was always significant. After four years the 15N fertilizer contributed only with 1.5–2.85kgNha−1 in NRNT and NRT, respectively, and 3.3–5.63kgNha−1 in RNT and RT, respectively. Cumulated N recovered during the three growing seasons following corn was 8.59–11.07kgNha−1 for NRNT and NRT; 20.24–15.6kgNha−1 for RT and RNT, respectively. Residues increased N mineralization by 50 percent and the quantity of 15N available to plants increased with tillage.


      PubDate: 2015-05-26T19:30:09Z
       
  • Heat stress in cereals: Mechanisms and modelling
    • Abstract: Publication date: March 2015
      Source:European Journal of Agronomy, Volume 64
      Author(s): Ehsan Eyshi Rezaei , Heidi Webber , Thomas Gaiser , Jesse Naab , Frank Ewert
      Increased climate variability and higher mean temperatures are expected across many world regions, both of which will contribute to more frequent extreme high temperatures events. Empirical evidence increasingly shows that short episodes of high temperature experienced around flowering can have large negative impacts on cereal grain yields, a phenomenon increasingly referred to as heat stress. Crop models are currently the best tools available to investigate how crops will grow under future climatic conditions, though the need to include heat stress effects has been recognized only relatively recently. We reviewed literature on both how key crop physiological processes and the observed yields under production conditions are impacted by high temperatures occurring particularly in the flowering and grain filling phases for wheat, maize and rice. This state of the art in crop response to heat stress was then contrasted with generic approaches to simulate the impacts of high temperatures in crop growth models. We found that the observed impacts of heat stress on crop yield are the end result of the integration of many processes, not all of which will be affected by a “high temperature” regime. This complexity confirms an important role for crop models in systematizing the effects of high temperatures on many processes under a range of environments and realizations of crop phenology. Four generic approaches to simulate high temperature impacts on yield were identified: (1) empirical reduction of final yield, (2) empirical reduction in daily increment in harvest index, (3) empirical reduction in grain number, and (4) semi-deterministic models of sink and source limitation. Consideration of canopy temperature is suggested as a promising approach to concurrently account for heat and drought stress, which are likely to occur simultaneously. Improving crop models’ response to high temperature impacts on cereal yields will require experimental data representative of field production and should be designed to connect what is already known about physiological responses and observed yield impacts.


      PubDate: 2015-05-26T19:30:09Z
       
  • Evaluation of monocropped and intercropped grain legumes for cover
           cropping in no-tillage and reduced tillage organic agriculture
    • Abstract: Publication date: April 2015
      Source:European Journal of Agronomy, Volume 65
      Author(s): Lars Rühlemann , Knut Schmidtke
      Intensive tillage by means of mouldboard ploughing can be highly effective for weed control in organic farming, but it also carries an elevated risk for rapid humus decomposition and soil erosion. To develop organic systems that are less dependent on tillage, a two-year study at Reinhardtsgrimma and Köllitsch, Germany was conducted to determine whether certain legume cover crops could be equally successfully grown in a no-till compared with a reduced tillage system. The summer annual legumes faba bean (Vicia faba L.), normal leafed field pea (Pisum sativum L.), narrow-leafed lupin (Lupinus angustifolius L.), grass pea (Lathyrus sativus L.), and common vetch (Vicia sativa L.) were examined with and without sunflower (Helianthus annuus L.) as a companion crop for biomass and nitrogen accumulation, symbiotic nitrogen fixation (N2 fixation) and weed suppression. Total cover crop biomass, shoot N accumulation and N2 fixation differed with year, location, tillage system and species due to variations in weather, inorganic soil N resources and weed competition. Biomass production reached up to 1.65 and 2.19Mgha−1 (both intercropped field peas), and N2 fixation up to 53.7 and 60.5kgha−1 (both common vetches) in the no-till and reduced tillage system, respectively. In the no-till system consistently low sunflower performance compared with the legumes prevented significant intercropping effects. Under central European conditions no-till cover cropping appears to be practicable if weed density is low at seeding. The interactions between year, location, tillage system and species demonstrate the difficulties in cover crop species selection for organic conservation tillage systems.


      PubDate: 2015-05-26T19:30:09Z
       
  • Impact of data resolution on heat and drought stress simulated for winter
           wheat in Germany
    • Abstract: Publication date: April 2015
      Source:European Journal of Agronomy, Volume 65
      Author(s): E. Eyshi Rezaei , S. Siebert , F. Ewert
      Heat and drought stress can reduce crop yields considerably which is increasingly assessed with crop models for larger areas. Applying these models originally developed for the field scale at large spatial extent typically implies the use of input data with coarse resolution. Little is known about the effect of data resolution on the simulated impact of extreme events like heat and drought on crops. Hence, in this study the effect of input and output data aggregation on simulated heat and drought stress and their impact on yield of winter wheat is systematically analyzed. The crop model SIMPLACE was applied for the period 1980–2011 across Germany at a resolution of 1km×1km. Weather and soil input data and model output data were then aggregated to 10km×10km, 25km×25km, 50km×50km and 100km×100km resolution to analyze the aggregation effect on heat and drought stress and crop yield. We found that aggregation of model input and output data barely influenced the mean and median of heat and drought stress reduction factors and crop yields simulated across Germany. However, data aggregation resulted in less spatial variability of model results and a reduced severity of simulated stress events, particularly for regions with high heterogeneity in weather and soil conditions. Comparisons of simulations at coarse resolution with those at high resolution showed distinct patterns of positive and negative deviations which compensated each other so that aggregation effects for large regions were small for mean or median yields. Therefore, modelling at a resolution of 100km×100km was sufficient to determine mean wheat yield as affected by heat and drought stress for Germany. Further research is required to clarify whether the results can be generalized across crop models differing in structure and detail. Attention should also be given to better understand the effect of data resolution on interactions between heat and drought impacts.


      PubDate: 2015-05-26T19:30:09Z
       
  • Seasonal changes in nutrient content and concentrations in a mature
           deciduous tree species: Studies in almond (Prunus dulcis (Mill.) D. A.
           Webb)
    • Abstract: Publication date: April 2015
      Source:European Journal of Agronomy, Volume 65
      Author(s): Saiful Muhammad , Blake L. Sanden , Bruce D. Lampinen , Sebastian Saa , Muhammad I. Siddiqui , David R. Smart , Andres Olivos , Kenneth A. Shackel , Theodore DeJong , Patrick H. Brown
      Knowledge of the pattern of nutrient uptake and loss and the within-tree allocation of nutrients in trees is critical to the understanding of ecosystem nutrient fluxes and to the management of applied nutrients in agricultural ecosystems. Fluxes of nutrients in whole trees and determination of total annual uptake, nutrient allocation within organs and loss in annual organs were obtained in a mature commercial almond (Prunus dulcis) orchard managed with non-limiting irrigation under varied nitrogen (N) and potassium (K) fertilization regimes from 2008 through 2012. Whole tree nutrient dynamics were derived from multiple in-season measurements of nutrients in leaves and fruits and biomass in all years. Whole tree nutrient budgets in perennial tree parts were derived from whole tree excavations and tree coring in 2011 and 2012 when the orchard had reached >85% full canopy closure. The annual N increment in perennial tree organs was 21kg, 41kg, 44kg and 45kgha−1 for the four N application rates of 140kg, 224kg, 309kg and 392kgha−1 N, respectively. In this orchard maximum agronomic productivity (yield plus increment in tree size) was recorded with an N application rate of 309kgha−1. Under optimal N application the annual increment in P, K, Ca and Mg was 8kg, 38kg, 3.5kg and 2.8kgha−1. Total N in leaves in midsummer in 2012 (a low yield year) was 37kg, 43kg, 54kg and 58kgha−1 for the four N application rates. In contrast, total N in leaves at mid-summer in 2011 (high yield year) was 21kg, 28kg, 35kg and 39kgha−1 for the four N application rates. In years 2009 through 2011 nitrogen in fruit at harvest represented 90% of whole tree N fluxes. In trees provided just adequate N to achieve maximal yield (309kgha−1 in this experiment in years 2009–11), N, P, K, S, Ca and Mg export in fruit was 212kg–366kgha−1, 26kg–45kgha−1, 265kg–389kgha−1, 7.9kg–14.4kgha−1, 24.7kg–29.6kgha−1 and 15.9kg–22.6kgha−1, respectively. The majority of whole tree macro and micronutrient uptake occurred between anthesis and kernel fill with 35–50% of total N uptake occurring before 40 days after full bloom (DAFB) and 80–90% of the total N being accumulated by 112 DAFB coinciding with kernel filling. Over 70% of the total P and 65–80% of the total K was accumulated in fruits by mid-season. Ninety percent of total S, 80–90% of total Ca and 70–85% of total Mg accumulated in fruit by 112 DAFB. The findings from the study can be used for in-season fertilizer management according to plant demand based on expected yield.


      PubDate: 2015-05-26T19:30:09Z
       
  • Evaluating coffee yield gaps and important biotic, abiotic, and management
           factors limiting coffee production in Uganda
    • Abstract: Publication date: February 2015
      Source:European Journal of Agronomy, Volume 63
      Author(s): N. Wang , L. Jassogne , P.J.A. van Asten , D. Mukasa , I. Wanyama , G. Kagezi , K.E. Giller
      Coffee is Uganda’s biggest export commodity, produced mainly by an estimated one million smallholder farmers (<2.5ha). Arabica (Coffea arabica L.) and Robusta (Coffea canephora Pierre ex Froehn.) are the two coffee species grown. Robusta is dominantly cultivated at lower elevations (<1400m) such as in Central and Northern Uganda and Arabica is dominant at higher elevations (>1400m) such as Eastern, Southwest, and Northwest Uganda. Actual yields are far below (<30%) potential due to various biotic, abiotic, and management constraints, yet there is no quantitative information on site-specific production constraints and the yield gaps attributed to those constraints. In this study, yields and diverse production factors were monitored in 254 plots of five major coffee growing regions (i.e., Central, North, East, Southwest, and Northwest). Boundary line analysis was applied to evaluate the relative importance of the individual production factors in limiting coffee production and to quantify the associated yield gaps at regional level. The impacts of rainfall variation on coffee yield were evaluated separately by regression analysis. The results of boundary line analysis indicated that biotic constraints (coffee twig borer) and poor management practices (unproductive coffee trees and low coffee plant density) restricted Robusta production in the Central region; poor soil nutrient status (especially potassium) and lack of mulching were the causes of yield loss of Robusta grown in the Northern region. For Arabica, unfavorable soil properties (high soil pH and phosphorus concentration) and excessive number of shade trees were the most important constraints in the East; high soil magnesium concentration and poor mulching limited coffee yield in the Southwest; poor soil nutrient status (especially phosphorus and potassium) and low coffee plant density were the important yield limitations in the Northwest. Average explained yield gaps of individual coffee plot due to the most important production constraints were 45%, 52%, 57%, 49%, and 50% of attainable yield, respectively, in the Central, Northern, Eastern, Southwest, and Northwest regions. Considerably less annual precipitation was received in 2009/2010 coffee growing season compared with that in the previous three years (2006–2008). Seasonal rainfall shortage occurred in the Southwest was a significant limitation to Arabica production, while excessive rainfall across the whole growing season was associated with yield reduction in the Eastern and Northwest regions. We conclude that there was a large yield gap for both Robusta and Arabica coffee grown in Uganda. Boundary line analysis allows the evaluation of relative importance of individual production constraint directly in the plot. The important production constraints varied strongly depending on the regions, which calls for site-specific management implementations. Soil fertility can be improved by implementing integrated soil fertility management (ISFM) that makes use of nutrients from the soil, recycled crop residues, mulch and chemical fertilizers. Attentions should also be given to other management practices such as coffee plant density, unproductive coffee trees and shade trees etc.


      PubDate: 2015-05-26T19:30:09Z
       
  • Designing eco-efficient crop rotations using life cycle assessment of crop
           combinations
    • Abstract: Publication date: April 2015
      Source:European Journal of Agronomy, Volume 65
      Author(s): Thomas Nemecek , Frank Hayer , Emmanuel Bonnin , Benoît Carrouée , Anne Schneider , Christophe Vivier
      Intensive arable crop production has major impacts on the environment and solutions for their reduction are needed. Diversification of crop rotations together with improved nitrogen management is an option for more eco-efficient cropping systems. The potentials for reducing the environmental impacts cropping systems were investigated by means of life cycle assessment (LCA) in three regions in France (Beauce, Burgundy and Moselle). The crop management data were compiled by the Chambers of Agriculture in the three regions based on field survey data (2002–2009 in Burgundy and Moselle and 2004–2008 in Beauce) and completed by experts. The LCA calculations were carried out by the SALCA-crop tool, using the ecoinvent and SALCA inventory databases and SALCA emission models. The LCAs were calculated for crop combinations, which were an efficient way to analyse a large number of crop rotations. A crop combination is defined as the inventory of a given crop, with a defined preceding crop and eventually including a catch crop. Nitrogen management revealed to be a key driver for the environmental impacts. It dominated the non-renewable energy demand, the global warming potential, the ozone formation potential, the acidification potential, and the eutrophication potential. Strong correlations between N fertilisation and these environmental impacts were found. The introduction of pea allowed to reduce the total eutrophication over the whole crop rotation. The mitigation of environmental impacts was not only possible per hectare, but also per € gross margin II. The eco-efficiency can thus be improved by reducing the level of N fertilisation. A reduction of N fertilisation could be achieved also by a reduction of the fertiliser doses to the non-legume crops, in addition to the introduction of legumes. Both ways proved to be effective and the combination of both was the most promising. However, trade-off between environmental and economic goals was identified. Diversification of cereal intensive crop rotations proved to be generally favourable from an environmental point of view. Catch crops had favourable effects on nutrient leaching a slightly favourable effects on biodiversity and soil quality. The ecotoxicity potentials were dominated by a few active ingredients only; the diversification did not lead to generally reduced ecotoxicity potentials. Diverse crop rotations with reduced N input are a promising way to reduce the environmental impacts of intensive arable crop rotations.


      PubDate: 2015-05-26T19:30:09Z
       
  • Meta-modelling of the impacts of regional cropping system scenarios for
           phoma stem canker control
    • Abstract: Publication date: August 2015
      Source:European Journal of Agronomy, Volume 68
      Author(s): L. Hossard , V. Souchere , E. Pelzer , X. Pinochet , M.H. Jeuffroy
      In agricultural landscapes, pest and disease control mainly rely on cropping system characteristics and location. We have combined a participatory approach and a spatially-explicit model, to design and assess cropping system scenarios for future contextual changes in the small region of Picardie, France. Phoma stem canker of winter oilseed rape (WOSR), a widespread disease responsible for major economic losses, was used as a case study to investigate the effects of modifying cropping systems, at a regional scale, on disease controlling and on the sustainability of a newly introduced specific resistance gene (RlmX). Meta-models were fitted to assess the effects of cropping practices and weather conditions included in scenarios on three complementary model outputs: size of the pathogen population, yield loss, and fraction of the virulent population on RlmX-cultivars. We ran three replicates of each cropping practice scenario, varying the location of WOSR and associated cropping characteristics within the region. Outputs differed slightly between replicates, but there were no significant differences between replicates (alpha=0.001) for each output. The size of the pathogen population was well explained by winter oilseed rape acreages, cultivar landscape composition and tillage, and the yield loss was explained by weather conditions and cultivars. The fraction of the virulent population on RlmX-cultivars was explained primarily by cultivar landscape composition. These differences in explanatory variables for the different outputs highlighted their complementarity. Cropping practices and weather impacts on the three variables remained consistent among the explored possible future contexts. Highlighting the most efficient cropping practices to be applied in the event of different future changes could help local decision-makers to design cropping practices in the face of contextual change.


      PubDate: 2015-05-26T19:30:09Z
       
  • “Productivity, quality and sustainability of winter wheat under
           long-term conventional and organic management in Switzerland”
    • Abstract: Publication date: April 2015
      Source:European Journal of Agronomy, Volume 65
      Author(s): Jochen Mayer , Lucie Gunst , Paul Mäder , Marie-Françoise Samson , Marina Carcea , Valentina Narducci , Ingrid K. Thomsen , David Dubois
      Long-term sustainability and high resource use efficiency are major goals for high quality baking wheat production throughout the world. Present strategies are low input systems such as organic agriculture or improved conventional systems (integrated). The fertilisation level and strategy, crop protection as well as preceding crop effects may modulate system performance with respect to wheat grain yield, quality and environmental performance of the systems. Our aim was to evaluate data of winter wheat (Triticum aestivum L.) performance from the DOK long-term systems experiment in Switzerland comparing two mixed organic (biodynamic and bioorganic: BIODYN and BIOORG) and a mixed conventional cropping system (CONFYM) using mineral fertilisers and farmyard manure at two fertilisation intensities (level 1: 50% of standard fertilisation, level 2: standard fertilisation) since 1978. A conventional system was fertilised exclusively minerally at level 2 (CONMIN) and a control remained unfertilised (NOFERT). We compared crop yields, baking quality parameters, the nitrogen use efficiency and the effect of maize and potatoes as preceding crops obtained between 2003 and 2010 along with long-term soil sustainability parameters. The mean grain yields across both fertiliser levels of the organic cropping systems (BIODYN and BIOORG) were 64% of CONFYM, whereas crude protein contents were 79% of CONFYM at fertilisation level 2 and achieved 90% at level 1. The main driving factor of lower yields was a reduction of the numbers of ears per m2 and the thousand kernel weight. The apparent nitrogen use efficiency decreased with increasing N fertilisation. Doubling the organic fertilisation in the organic systems only slightly improved wheat grain yields but was not able to improve grain baking quality, due to low mineral N additions via slurry and farmyard manure. In contrast the effects of the preceding crop potatoes in comparison with preceding silage maize outperformed the organic fertilisation effects, resulting in 33% higher yields and 11% higher crude protein contents. The yield components recorded in the case of preceding potatoes demonstrated a more synchronised nutrient supply throughout the wheat development. Over all low input systems and both fertilisation levels in the conventional mixed farm system at half standard fertilisation (level 1) performed best with distinctly higher grain yields and crude protein contents than in the organic systems with standard fertilisation. However, all systems, organic and conventional, with the low or zero organic fertiliser inputs performed poorly considering the long-term soil quality parameters, indicating a degradation of soil quality. The DOK long-term experiment allows an integrated view on the performance of baking wheat production and long-term sustainability. The results emphasise the importance of a sufficient supply of soils with organic fertilisers as well as the need to improve the availability of organic nitrogen and synchrony between nutrient supply and demand in organic baking wheat production, beside the selection of a suitable preceding crop.


      PubDate: 2015-05-26T19:30:09Z
       
  • Cotton yield and fiber quality affected by row spacing and shading at
           different growth stages
    • Abstract: Publication date: April 2015
      Source:European Journal of Agronomy, Volume 65
      Author(s): Fábio R. Echer , Ciro A. Rosolem
      Carbohydrate production and reproductive structure development in cotton (Gossypium hirsutum) depends on light availability, a determinant of cotton yield. Light availability is decreased by cloud cover or self-shading when cotton plants are grown in dense populations. The objective of this study was to evaluate the effects of shading during cotton growth and its interactions with plant row spacings on yield and fiber quality. Three independent experiments were conducted as follows: in Paranapanema (23°39′S; 48°58′W), cotton was planted in November in row spacings of 0.45, 0.75 and 0.96m; in Primavera do Leste (15°33′S; 54°11′W), planting was in January with at row spacings of 0.45 and 0.76m; and in Chapadão do Céu (18°38′S; 52°40′W), cotton was planted in February in rows spaced at 0.45 and 0.90 m. Plants were exposed to shading during the phenological stages B1 (floral bud), F1 (early flowering), PF (peak flowering) and 3OB (fruit maturity). In addition, there was one treatment without shade. There were no interactions of crop spacing with shading. Increasing plant population and shading both decreased net photosynthetic rate. The number of bolls m−2 increased with higher plant populations only when planting was delayed, and were not affected by shading. When cotton was planted in November and January, higher yields were obtained at 0.75/0.76m, but when planting was delayed to February, 0.45m resulted in higher yields with no effect on fiber quality. Shading for eight or ten days decreases boll weight and yields, but do not affect fiber quality. Cotton yield is the most decreased when shading occurs during flowering. These results may be used to build management strategies to minimize shading effects by adjusting cotton sowing time and plant density, by selecting cultivars with increased shade tolerance and by choosing an adequate irrigation period to improve yield.


      PubDate: 2015-05-26T19:30:09Z
       
  • Climatic risk assessment to improve nitrogen fertilisation
           recommendations: A strategic crop model-based approach
    • Abstract: Publication date: April 2015
      Source:European Journal of Agronomy, Volume 65
      Author(s): B. Dumont , B. Basso , B. Bodson , J.-P. Destain , M.-F. Destain
      Within the context of nitrogen (N) management, since 1950, with the rapid intensification of agriculture, farmers have often applied much larger fertiliser quantities than what was required to reach the yield potential. However, to prevent pollution of surface and groundwater induced by nitrates, The European Community launched The European Nitrates Directive 91/6/76/EEC. In 2002, in Wallonia (Belgium), the Nitrates Directive has been transposed under the Sustainable Nitrogen Management in Agriculture Program (PGDA), with the aim of maintaining productivity and revenue for the country’s farmers, while reducing the environmental impact of excessive N application. A feasible approach for addressing climatic uncertainty lies in the use of crop models such as the one commonly known as STICS (simulateur multidisciplinaire pour les cultures standard). These models allow the impact on crops of the interaction between cropping systems and climatic records to be assessed. Comprehensive historical climatic records are rare, however, and therefore the yield distribution values obtained using such an approach can be discontinuous. In order to obtain better and more detailed yield distribution information, the use of a high number of stochastically generated climate time series was proposed, relying on the LARS-Weather Generator. The study focused on the interactions between varying N practices and climatic conditions. Historically and currently, Belgian farmers apply 180kgNha−1, split into three equal fractions applied at the tillering, stem elongation and flag-leaf stages. This study analysed the effectiveness of this treatment in detail, comparing it to similar practices where only the N rates applied at the flag-leaf stage were modified. Three types of farmer decision-making were analysed. The first related to the choice of N strategy for maximising yield, the second to obtaining the highest net revenue, and the third to reduce the environmental impact of potential N leaching, which carries the likelihood of taxation if inappropriate N rates are applied. The results showed reduced discontinuity in the yield distribution values thus obtained. In general, the modulation of N levels to accord with current farmer practices showed considerable asymmetry. In other words, these practices maximised the probability of achieving yields that were at least superior to the mean of the distribution values, thus reducing risk for the farmers. The practice based on applying the highest amounts (60–60–100kgNha−1) produced the best yield distribution results. When simple economical criteria were computed, the 60–60–80kgNha−1 protocol was found to be optimal for 80–90% of the time. There were no statistical differences, however, between this practice and Belgian farmers’ current practice. When the taxation linked to a high level of potentially leachable N remaining in the soil after harvest was considered, this methodology clearly showed that, in 3 years out of 4, 30kgNha−1 could systematically be saved in comparison with the usual practice.


      PubDate: 2015-05-26T19:30:09Z
       
  • Associations between drought resistance, regrowth and quality in a
           perennial C4 grass
    • Abstract: Publication date: April 2015
      Source:European Journal of Agronomy, Volume 65
      Author(s): Yi Zhou , Christopher J Lambrides , Shu Fukai
      Climate change has brought a sharp and renewed focus on plant breeding programs to develop cultivars with improved performance in dry environments. The pleiotropic effects of selection for drought resistance are not well understood in perennial C4 grasses. The objective of this study was to determine the commercial production characteristics including sod strength and post-harvest regrowth of bermudagrass ecotypes selected for drought resistance. These attributes were studied in a set of bermudagrasses (Cynodon dactylon), a species used extensively around the world for forage and turfgrass. Three field experiments using 12 genotypes contrasting for drought resistance were evaluated, on bermudagrass turf production facilities, for quality and regrowth after the canopy (sod) was mechanically removed. Among the genotypes tested, there was large genotypic variation for rhizome dry matter (RhDM) (0.01–0.81kgm−2), aboveground dry matter (ADM) (0.59–0.17kgm−2) and root dry matter (RDM) (0.04–0.12kgm−2). Regrowth of the canopy was positively correlated to RhDM (r=0.79∼0.80) and negatively correlated to ADM (r=−0.69∼−0.74) but there was no association with RDM. Biomass partitioning determined at the time of the second harvest revealed that genotypes with more rapid regrowth had larger proportional DM distributed to rhizome (63.5% vs 7.1%) than to aboveground (27.2% vs 86.5%) and root (8.5% vs 8.1%). Our previous research with these genotypes showed a strong correlation between drought resistance and RhDM prior to the drought period. Consequently, an analysis of the relationship between drought resistance measured previously and post-harvest regrowth in the experiments described here revealed a strong positive correlation (r>0.64). Genotypic variation for sod strength, an important turf quality attribute, was large ranging from 1281kgm−2 to 5671kgm−2. However, sod strength was neither correlated to drought resistance, nor the traits measured from harvested sod such as stolon diameter, internode length, number of branches and single stolon strength, nor to dry matter distribution. These results may reflect the existence of a range of different mechanisms for sod strength present in the material tested. Nevertheless, there were genotypes e.g., MED1 that combined the favorable traits of drought resistance, faster regrowth rate and higher sod strength and could be used as an important genetic resource for future breeding. MED1 was one of several highly rhizomatous genotypes in the study that originated from the Mediterranean climatic zone of Australia.


      PubDate: 2015-05-26T19:30:09Z
       
  • Nitrogen management is the key for low-emission wheat production in
           Australia: A life cycle perspective
    • Abstract: Publication date: May 2015
      Source:European Journal of Agronomy, Volume 66
      Author(s): Weijin Wang , Ram C. Dalal
      Farm management affects the global greenhouse gas (GHG) budget by changing not only soil organic carbon (SOC) stocks and nitrous oxide (N2O) emissions but also other pre-farm, on-farm and off-site emissions. The life cycle assessment (LCA) approach has been widely adopted to assess the “carbon footprint” of agricultural products, but rarely used as a tool to identify effective mitigation strategies. In this study, the global warming impacts of no-till (NT) vs. conventional till (CT), stubble retention (SR) vs. stubble burning (SB), and N fertilization (NF) vs. no N fertilization (N0) in an Australian wheat cropping system were assessed using in situ measurements of N2O fluxes over three years, SOC changes over forty years and including other supply chain GHG sources and sinks. The results demonstrated the importance of full GHG accounting compared to considering SOC changes or N2O emissions alone for assessing the global warming impacts of different management practices, and highlighted the significance of accurately accounting for SOC changes and N2O emissions in LCAs. The GHG footprints of wheat production were on averaged 475kg carbon dioxide equivalent (CO2-e) ha−1 (or 186kg CO2-e t−1 grain) higher under NF than N0. Where fertilizer N was applied (70kgNha−1), the life cycle emissions were 200kg CO2-e ha−1 (or 87t−1 grain) lower under NT than CT and 364kg CO2-e ha−1 (or 155t−1 grain) lower under SR than SB. Classification of the emission sources/sinks and re-calculation of published data indicated that under the common practices of SR combined with NT, N-related GHG emissions contributed 60–95% of the life cycle emissions in the predominantly rain-fed wheat production systems in Australia. Therefore, future mitigation efforts should aim to improve N use efficiency, explore non-synthetic N sources, and most importantly avoid excessive N fertilizer use whilst practising NT and SR.


      PubDate: 2015-05-26T19:30:09Z
       
  • Do soil organic carbon levels affect potential yields and nitrogen use
           efficiency? An analysis of winter wheat and spring barley field trials
           
    • Abstract: Publication date: May 2015
      Source:European Journal of Agronomy, Volume 66
      Author(s): Myles Oelofse , Bo Markussen , Leif Knudsen , Kirsten Schelde , Jørgen E. Olesen , Lars Stoumann Jensen , Sander Bruun
      Soil organic carbon (SOC) is broadly recognised as an important parameter affecting soil quality, and can therefore contribute to improving a number of soil properties that influence crop yield. Previous research generally indicates that soil organic carbon has positive effects on crop yields, but in many studies it is difficult to separate the effect of nutrients from the effect of SOC in itself. The aim of this study was to analyze whether the SOC content, in itself, has a significant effect on potential yields of commonly grown cereals across a wider range of soil types in Denmark. The study draws on historical data sets from the Danish national field trials consisting of 560 winter wheat (Triticum aestivum L.) trials and 309 spring barley (Hordeum vulgare L.) trials conducted over the past 20 and 17 years, respectively. We hypothesised that for these two crops, the potential grain yield, the yield with no fertiliser N application and the N use efficiency would be positively affected by SOC level. A statistical model was developed to explore relationships between SOC and potential yield, yields at zero N application and N use efficiency (NUE). The model included a variety of variables and aimed to elucidate the sole effect of SOC by controlling for potential confounding variables. No significant effect of SOC on potential winter wheat was found, whilst for spring barley, only for the course sandy loam soil type was a borderline significantly positive effect of SOC on potential yields found. The relationship between unfertilized plot yields and SOC was positive for winter wheat, although not significant, whilst for spring barley a significant positive effect of SOC was found only for the coarse sandy soil type, and a borderline significant positive effect of SOC was found for the coarse sandy loam soil type. A significant negative relationship was found between SOC and NUE for both winter wheat and spring barley. Based on the large dataset analyzed, we cautiously challenge the importance of SOC in contributing to crop productivity in contexts with similar soils and climate, and we speculate that in situations where nutrient limitation does not occur, SOC levels above 1% may be sufficient to sustain yields. In light of the findings presented in this study, further work should be conducted which can further elucidate the effect of SOC on yields.


      PubDate: 2015-05-26T19:30:09Z
       
  • Analyzing inter-factor substitution and technical progress in the Chinese
           agricultural sector
    • Abstract: Publication date: May 2015
      Source:European Journal of Agronomy, Volume 66
      Author(s): Boqiang Lin , Rilong Fei
      In this paper, we employ a trans-log production function model for China’s agricultural sector, with capital, labor and energy as input factors. The output elasticity, substitution elasticity and relative difference in technical progress among the factors are analyzed. The results show that during the period 1980–2012 the growth of the agricultural economy in China benefited from the combined effects of factors accumulation and technical progress. Among the factors, the output elasticity of labor is the largest, followed by capital and energy. Capital, labor and energy are substitutes for one another, but the elasticity of substitution between capital and energy is the highest, with a value of 1.1. In the meantime, the relative difference in technical progress among these factors is insignificant and there is a convergence trend over time. We suggest increasing technological innovation in order to improve the contribution of technology progress as well as allocating more capital into the agricultural sector in order to alleviate the shortage of energy supply and the current problem of “hollow” in the rural labor force. This is of great significance to reducing energy consumption and improving the total factor productivity in the China’s agricultural sector.


      PubDate: 2015-05-26T19:30:09Z
       
  • Surface liming and nitrogen fertilization for crop grain production under
           no-till management in Brazil
    • Abstract: Publication date: May 2015
      Source:European Journal of Agronomy, Volume 66
      Author(s): E.F. Caires , A. Haliski , A.R. Bini , D.A. Scharr
      Supplying a large amount of NO3 − in the subsurface can be a strategy to combat subsoil acidity under no-till systems. However, soil acidification caused by ammoniacal fertilizers can increase both aluminum toxicity and lime requirement. A field experiment was performed in the period from 2004 to 2012 in Parana State, Brazil, on a loamy, kaolinitic, thermic Typic Hapludox to evaluate the effects of surface liming and ammoniacal fertilization on soil chemical attributes and yields of crops in rotation under continuous no-till. The region has a mesothermal, humid subtropical climate, with mild summer, frequent frosts during the winter, and no defined dry season. The average altitude is 970m and the annual precipitation is about 1550mm. The treatments consisted of annual applications of NH4NO3 at 0, 60, 120, and 180kgNha−1 to subplots within plots with surface-applied lime previously at 0, 4, 8, and 12Mgha−1, calculated to raise the base saturation in the topsoil (0–20cm) to 40, 65, and 90%. Lime was broadcast on the soil surface in May 2004. The nitrogen rates were applied during the period from 2004 to 2011 in top dressing at tillering of winter crops [black oat (Avena strigosa Schreb.) or wheat (Triticum aestivum L.)], before growing corn (Zea mays L.), soybean (Glycine max L. Merr.) or bean (Phaseolus vulgaris L.) during the summer (2004–2012). Surface-applied lime under no-till was effective in alleviating soil acidity from the soil surface to a 20cm depth. The soil pH increased in the layers below the soil surface to 20cm depth during a 6 years period following surface lime application. Ammoniacal fertilization had an acidifying effect and did not change the effectiveness of surface applied lime to alleviate subsoil acidity. Soil organic matter content was higher in the upper few centimeters under no-till and remained unchanged over time after surface liming and ammoniacal fertilization. Increasing the rate and frequency of ammoniacal fertilizer application increased crop response to surface liming, but did not change the lime requirement to achieve higher crop grain yields. The lime rate estimated by the soil base saturation method at 70% in the 0–20cm depth was appropriate for surface liming recommendation, even when substantial amounts of ammoniacal fertilizer were applied in a no-till system. The results suggest that nitrogen fertilizer use for winter crops could be dramatically reduced in areas under a continuous no-till system, particularly where lime has been applied.


      PubDate: 2015-05-26T19:30:09Z
       
  • Sowing date affected shoot and root biomass accumulation of lucerne during
           establishment and subsequent regrowth season
    • Abstract: Publication date: August 2015
      Source:European Journal of Agronomy, Volume 68
      Author(s): Richard E. Sim , Derrick J. Moot , Hamish E. Brown , Edmar I. Teixeira
      The pattern of perennial dry matter (DM) was manipulated over two seasons to determine if the establishment of lucerne (Medicago sativa L.) is regulated by the demand for assimilate by perennial organs, (taproot plus crown) or crop ontogeny. Crops of ‘Stamina 5’ lucerne were established from spring to late summer at two sites which differed by 230mm to 2.3m soil depth in plant available water content (PAWC) at Lincoln University, New Zealand. The establishment phase was characterised from sowing until crops reached a maximum accumulation of perennial biomass of ∼5tDMha−1. Demand for biomass offered insight into the variability in fractional partitioning of DM to the perennial organs (P root) during establishment. This showed that P root was 0.48 until a perennial biomass of 2.9±0.28tDMha−1. Lucerne continued to partition DM to the perennial organs until a maximum biomass of ∼5tDMha−1, but at a decreasing rate shown by a linear decline in P root in response to increasing perennial biomass. This meant P root was independent of crop ontogeny, but most likely still under the control of environmental influences, and the establishment phase extended into the second season for crops which had not attained a perennial biomass >3tDMha−1. These crops continued to prioritise the allocation of DM to the perennial organs which explained the 20–25% decrease in shoot yield in the second season when sowing was delayed. This study quantified the establishment phase of lucerne to perennial biomass demand as independent of crop ontogeny. It showed establishment was regulated by biomass demand of these perennial organs. The spring sown crops on the High PAWC soils completed this phase at the earliest in 4 months. In contrast, autumn sown crops on the Low PAWC soils took nearly 9 months to complete this phase. These results indicate different management strategies may be required to establish lucerne rather than solely using first flowering as a sign that the establishment phase is complete. Results can be incorporated into the current partitioning framework to improve the simulation modelling of lucerne.


      PubDate: 2015-05-26T19:30:09Z
       
  • A simple approach to predict growth stages in winter wheat (Triticum
           aestivum L.) combining prediction of a crop model and marker based
           prediction of the deviation to a reference cultivar: A case study in
           France
    • Abstract: Publication date: August 2015
      Source:European Journal of Agronomy, Volume 68
      Author(s): Matthieu Bogard , Jean-Baptiste Pierre , Bertrand Huguenin-Bizot , Delphine Hourcade , Etienne Paux , Xavier Le Bris , David Gouache
      Predicting wheat growth stages using ecophysiological models is of particular interest as it allows anticipating important agricultural managements. Numerous ecophysiological models exist but they need cultivar-specific parameterization, which is often costly and time consuming. The work presented here proposes a simple approach to predict wheat growth stages using the allelic composition of wheat cultivars. It relies on using the prediction of a modified version of the ARCWHEAT model for a well parameterized reference cultivar (Soissons) and the marker-based predicted deviation in days to the reference cultivar. First, the deviations to the reference cultivar Soissons for the beginning of stem elongation (δZ30) and heading date (δZ55) were calculated for a large panel of cultivars. Analysis of variance showed prominent genetic effects for δZ30 and δZ55 and possible genotype×environment interactions (G × E) for δZ30. Genotypic means δZ30 and δZ55 were used in association genetics revealing 90 and 83 genetic markers associated to these traits, respectively. Multiple linear regression models predicting δZ30 using 11 genetic markers (R 2 =76%) or δZ55 using 17 markers (R 2 =85%) were obtained by a stepwise procedure. Marker PPD-D1 had the largest impact in both models. Finally, marker-based deviations added to the prediction for the reference cultivar Soissons allowed predicting Z30 or Z55 for a large independent validation dataset. The root mean square error of prediction for Z30 and Z55 using the approach proposed in this paper (6.8 and 4.7 days, respectively) was comparable to the one obtained using the conventional approach with cultivar-specific parameters values (6.5 and 4.1, respectively). The models proposed in this paper appeared sufficient in order to predict growth stages of cultivars which cannot be parameterized such as new cultivars coming out on the market. Moreover, genetic markers involved in the multiple linear regression models predicting δZ30 and δZ55 may provide interesting candidates to unravel new genes determining earliness in winter wheat.


      PubDate: 2015-05-26T19:30:09Z
       
  • Winter wheat cultivars and nitrogen (N) fertilization—Effects on
           root growth, N uptake efficiency and N use efficiency
    • Abstract: Publication date: August 2015
      Source:European Journal of Agronomy, Volume 68
      Author(s): Irene Skovby Rasmussen , Dorte Bodin Dresbøll , Kristian Thorup-Kristensen
      One way to reduce nitrate leaching losses from agricultural land is to increase crop nitrogen uptake efficiency (NUpE). In this aspect, root growth is an essential parameter, as more and deeper roots may improve the uptake from deeper soil layers and reduce nitrate leaching. This study examined the root growth, soil N depletion and yields of modern, commercial winter wheat (Triticum aestivum L.) cultivars in a two-year field experiment conducted on sandy loam soils. The effects of N fertilization on root growth and inorganic soil N utilization were quantified. In order to obtain data from the entire winter wheat rooting zone, the measurements were conducted to 2.3m soil depth. Root growth was studied by means of minirhizotrons. Parallel to the belowground measurements, the effects on aboveground biomass and N uptake were measured. In the two experimental years the average maximum root depths were 1.1 and 1.5m, respectively, and the average root depth penetration rates were 0.7 and 1.0mm°C day−1, respectively. N fertilization affected root density, which increased at least up to an application of 150kg N ha−1. The effect on root density was mostly seen in soil layers below 0.5m. N fertilization did not appear to affect root depth. There were root growth differences among the cultivars, though not strongly pronounced. The cultivar Hereford showed tendencies to higher root densities and deeper root growth, and this trend was correlated with a tendency to increased subsoil N depletion. Also, Hereford showed higher N use efficiency (NUE) compared to the other cultivars, as it produced more grain per N supply. Under the existing experimental conditions, a spring application up to 150kg N ha−1 did not increase the amount of nitrate left in the soil at harvest. In contrast, by an increase of N fertilization from 150 to 250kg N ha−1, on average 36 % of the extra 100kg N ha−1 was left in the soil. With a further increase from 250 to 350kg N ha−1, up to 90% of the extra N was left in the soil. The soil N increase at high N fertilization was most profound in the upper soil layer but also significant in the subsoil.


      PubDate: 2015-05-26T19:30:09Z
       
  • Leaf gas exchange and radiation use efficiency of sunflower (Helianthus
           annuus L.) in response to different deficit irrigation strategies: From
           solar radiation to plant growth analysis
    • Abstract: Publication date: March 2015
      Source:European Journal of Agronomy, Volume 64
      Author(s): Pasquale Garofalo , Michele Rinaldi
      Most studies on radiation use efficiency (RUE) have focussed only on the relationship between intercepted solar radiation and biomass accumulation, without considering the intermediate steps that underlie the development of the crop. The present study aims to estimate the RUE of sunflower (Helianthus annuus L.) under different deficit irrigation schemes, with the introduction of an intermediate step at the leaf scale, the net photosynthesis rate (PN), and the exploration of the relationship between RUE and PN. The linear relationship between intercepted photosynthetically active radiation (iPAR) and total plant dry matter was defined during the vegetative phase, and a single value of RUE (2.08gMJ−1) was predictive of biomass accumulation; the curvilinear response of RUE with respect to PN explained one of the hierarchical processes that governs the smooth and stable conversion efficiency of iPAR to biomass. However, different RUE values should be used to estimate seed yield when irrigation is suspended at the heading (RUE, 0.29gMJ−1), flowering (RUE, 0.35gMJ−1) or milking (RUE, 0.44gMJ−1) stages, because after the vegetative stage, synchronization of the processes underlying the late growth – grain filling phases was lost. Despite this, even if the yield performance followed the water treatment (2.69, 3.61 and 4.36tha−1 for increasing water supply), the productivity of sunflower with small (150mm) or moderate (270mm) amounts of water ensured satisfactory seed production and water saving (74% and 53% reduction, compared to well-watered treatment) in water-limited environments.


      PubDate: 2015-05-26T19:30:09Z
       
  • Assessment of plant nitrogen status using chlorophyll fluorescence
           parameters of the upper leaves in winter wheat
    • Abstract: Publication date: March 2015
      Source:European Journal of Agronomy, Volume 64
      Author(s): Wei Feng , Li He , Hai-Yan Zhang , Bin-Bin Guo , Yun-Ji Zhu , Chen-Yang Wang , Tian-Cai Guo
      Non-destructive, rapid diagnosis of plant nitrogen status is important for the evaluation of wheat growth and the dynamic management of nitrogen nutrition. Two wheat cultivars, Zhengmai 366 (high protein content) and Aikang 58 (medium protein content) were grown in field trials at five different nitrogen levels (0, 90, 180, 270 and 360kgha−1) in two consecutive growing seasons at Zhengzhou, China. Leaf chlorophyll fluorescence (ChlF) parameters, leaf and stem biomass, and nitrogen content were measured simultaneously at different growth stages, establishing an evaluation model of plant nitrogen nutrition in wheat using ChlF parameters. The results showed that the differences in ChlF parameters between the three top leaves (1–3LFT) was small from the reviving to the flowering stages. With increasing nitrogen levels, the difference in ChlF parameters between the fourth leaf (4LFT) and the first three leaves (1–3LFT) decreased gradually, indicating that 4LFT is sensitive to N fertilizer application and has a disadvantage in competition for redistributed N. The correlation coefficients between ChlF parameters for the upper, fully expanded leaves and N concentration of the corresponding leaves were 0.628 for F v, 0.607 for F m, 0.579 for F v/F o, and 0.600 for F v/F m at P <0.01, but only 0.248 for F o at P <0.05. At the reviving and jointing stages, the relationships between the normalized differences between 1–2LFT and 4LFT (NDF12/4) for F v/F o and F v/F m to plant nitrogen concentration (PNC) were the most significant (r <−0.79, P <0.001), the determination coefficient (R 2) for F v/F m was much higher than for F v/F o, and the two regression equations were grouped at reviving and jointing with similar R 2 values between the stages. At booting and flowering, the normalized differences between 1–2LFT and 4LFT for F o, F m, and F v better reflected the changes in PNC; the R 2 values were 0.654–0.797 (P <0.001) at booting and 0.515–0.584 (P <0.001) at anthesis, and the two regression equations were grouped at booting and anthesis with greater differences in R 2 between the stages. The unified regression equation could be used to express the relationship between plant nitrogen sufficiency index (NSI) and ChlF parameters with R 2 values of 0.623 (P <0.001) for NDF12/4 for F v/F m, and 0.567 (P <0.001) for NDF12/4 for F v/F o during the reviving and jointing stages, while R 2 =0.666 (P <0.001) for NDF12/4 for F m and 0.615 (P <0.001) for NDF12/4 for F v during booting and anthesis. These results show that the relationship between NDF and NSI was stable and reliable over the different years, varieties, and N supply levels. We conclude that the spatial differences in ChlF parameters between 1–2LFT and 4LFT should be ideal indicators of plant nitrogen status in wheat, and will provide a decision-making method for N diagnosis and regulation in field production.


      PubDate: 2015-05-26T19:30:09Z
       
  • Which cropping systems to reconcile weed-related biodiversity and crop
           production in arable crops? An approach with simulation-based
           indicators
    • Abstract: Publication date: August 2015
      Source:European Journal of Agronomy, Volume 68
      Author(s): Delphine Mézière , Nathalie Colbach , Fabrice Dessaint , Sylvie Granger
      Weed management must both control weed harmfulness for crop production and promote weed contribution to biodiversity as an essential component of biodiversity in agricultural landscapes. The objective of the present paper was to evaluate a large range of existing cropping systems to determine management rules for reconciling weed-related biodiversity and weed harmfulness, comparing 26 contrasting cropping systems identified via farm surveys in two contrasting French regions, Burgundy and Poitou-Charentes. These systems were simulated, using the weed dynamics model FlorSys which predicts weed flora dynamics over the years, depending on cropping system and pedoclimate. The simulated flora was translated into five weed harmfulness indicators (crop yield loss, harvest contamination, harvesting difficulty, field infestation, additional crop disease due to weeds) and five weed-related biodiversity indicators (weed species richness and equitability, weed-based trophic offer for birds, insects and pollinators). Cropping system performance was assessed with a Principal Component Analysis (PCA) on the 10 weed-impact indicators, followed by a hierarchical clustering analysis. Five contrasting profiles in terms of weed harmfulness and contribution to biodiversity were identified, combining different levels of weed harmfulness and biodiversity. To identify management strategies (i.e., combinations of cultural practices) for reaching these different performance profiles, tree-based regression and classification models (CART) were constructed to explain performance profiles as a function of cropping system descriptors and pedoclimatic variables. Ten management strategies were identified for reaching the five performance profiles. The most interesting performance profile, which minimized all harmfulness indicators (except harvest contamination and harvesting difficulty) and maximized all biodiversity indicators (except species richness), was reached by a single strategy type, consisting of low or no-till systems. Systems with cover crops and little or no mechanical weeding also reconciled most production and biodiversity goals. Multiple management pathways for reaching a given goal present the advantage of letting farmers choose the strategy most compatible with the objectives and constraints of their farm. The present results were obtained with annual weed species only, and taking into account the management of perennial weeds will probably modify the strategies. The same method was also applied to identify strategies for reconciling crop production, biodiversity and reduced herbicide use, though none of the investigated cropping systems was able to reconcile all three objectives, indicating that novel cropping systems must be designed specifically for this objective.


      PubDate: 2015-05-26T19:30:09Z
       
  • More rice with less water – evaluation of yield and resource use
           efficiency in ground cover rice production system with transplanting
    • Abstract: Publication date: August 2015
      Source:European Journal of Agronomy, Volume 68
      Author(s): Yueyue Tao , Yanan Zhang , Xinxin Jin , Gustavo Saiz , Ruying Jing , Lin Guo , Meiju Liu , Jianchu Shi , Qiang Zuo , Hongbin Tao , Klaus Butterbach-Bahl , Klaus Dittert , Shan Lin
      Adoption of the innovative water-saving ground cover rice production system (GCRPS) based on transplanting of rice seedlings under high soil moisture conditions, resulted in an overall increase in grain yield compared to previous reports on GCRPS employing direct seeding. However, there is a lack of quantitative information on water and nitrogen use efficiency as affected by water and nitrogen management in GCRPS-transplanting. To close this knowledge gap, we conducted a two-year field experiment with traditional paddy rice (Paddy) and GCRPS-transplanting under two soil moisture conditions (GCRPSsat and GCRPS80%), combined with 3 nitrogen fertilizer management regimes (0, 150kg urea-N/ha as basal fertilizer for Paddy and GCRPS, 150kg urea-N/ha in 3 splits for Paddy or 75kg urea-N/ha plus 75kg N/ha as chicken manure for GCRPS). Grain yield, water and nitrogen use efficiency, stable isotope 13C of plant shoots and yield components were evaluated. The study showed: (1) compared to Paddy, both GCRPSsat and GCRPS80% produced significantly more grain yield, while no significant difference in grain yield was found between both GCRPS treatments. (2) Irrigation water use efficiency was increased by 140% in GCRPSsat and >500% in GCRPS80%, while total water use efficiency was improved by 52–96% as compared to Paddy. (3) δ 13C of plant shoots was significantly higher in GCRPS than in Paddy, and showed significant positive correlations with total and irrigation water use efficiencies. (4) Compared to Paddy, agronomic N use efficiency was significantly higher in both forms of GCRPS. However, N recovery rates were only significantly higher in GCRPS than in Paddy when all urea nitrogen was applied as basal fertilizer before transplanting. With improved fertilizer N management, i.e., split N application in Paddy or combined application of urea and chicken manure in GCRPS, there were no significant differences. Overall, this quantitative evaluation of water use efficiency highlights that the use of GCRPS involving transplanting of seedlings has a great potential to reduce irrigation water input, increase grain yield and resource use efficiency.
      Graphical abstract image

      PubDate: 2015-05-26T19:30:09Z
       
  • Response of primary production and biomass allocation to nitrogen and
           water supplementation along a grazing intensity gradient in semiarid
           grassland
    • Abstract: Publication date: February 2015
      Source:European Journal of Agronomy, Volume 63
      Author(s): Xiao Ying Gong , Nicole Fanselow , Klaus Dittert , Friedhelm Taube , Shan Lin
      Herbivory and resource availability interactively regulate plant growth, biomass allocation, and production. However, the compensatory growth of plants under grazing intensities and manipulated environmental conditions is not well understood. A 2-year experiment with water (unirrigated and irrigated) and nitrogen fertilizer (0 and 75kgNha−1 year−1) addition was conducted at sites with 4 grazing intensities (0–7 sheepha−1) in an annually rotational grazing system in Inner Mongolia. In this study, grazing had no significant effect on aboveground net primary production (ANPP) and net primary production (NPP). However, high grazing intensity strongly reduced the fraction of belowground net primary production to NPP. Water and nitrogen additions significantly increased ANPP by 39% and by 23%, respectively, but had no effect on belowground net primary production. ANPP showed lower response to nitrogen addition at high grazing intensity sites than at low grazing intensity sites. We found no evidence for grazing optimization on primary production of semiarid steppe, regardless of resource supplementations. Grazed plants minimized the reduction of ANPP by altering allocation priority and morphological traits. Our study highlights the “whole-plant” perspective when studying plant–herbivore interactions.


      PubDate: 2015-05-26T19:30:09Z
       
  • Effects of free air CO2 enrichment on root growth of barley, sugar beet
           and wheat grown in a rotation under different nitrogen supply
    • Abstract: Publication date: February 2015
      Source:European Journal of Agronomy, Volume 63
      Author(s): Andreas Pacholski , Remigius Manderscheid , Hans-Joachim Weigel
      Elevated atmospheric CO2 concentrations [CO2] are known to change plant growth by stimulation of C3 photosynthesis and by reduction of transpiration of both C3 and C4 crops. In comparison to the information on above ground plant responses only limited knowledge exists on the response of root growth of arable crops to elevated [CO2] which is particularly true for temperate crop species under real field conditions. A free air CO2 enrichment (FACE) study (550ppm at daylight hours) was carried out in a crop rotation of winter barley, sugar beet and winter wheat repeated twice in the course of six years on a sandy loam soil at Braunschweig, Northern Germany. Winter barley and sugar beet were included for the first time in a FACE study. A possible interaction with restricted nitrogen (N) supply was studied by fertilizing the CO2 treatment plots with adequate and 50% of adequate N supply. Fine root samples were taken in the plough layer and below at 3–4 sampling dates during the vegetation period and root dry matter (excluding sugar beet storage root), shoot root ratio, root length density, specific root length and root tissue composition (CN ratio) were determined. Main effects of elevated [CO2] on the investigated variables were slightly significant. Significant CO2 effects were observed in interaction with the sampling date. In most cases elevated [CO2] increased root dry matter early in the vegetation period with a maximum growth stimulation of up to 54% as compared to ambient [CO2]. Concomitantly, root length densities were increased in both winter wheat and sugar beet. For winter barley also a significant decrease in root dry weight and significant increase of shoot root ratio was detected at final harvest while such an effect was not significant for sugar beet. Specific root length as an indicator of root morphology was mainly influenced by crop species. As a result, there was no consistent overall effect of elevated [CO2] on biomass partitioning in this study as changes in shoot root ratio only occurred at specific sampling dates indicating a similar stimulation of roots and above-ground biomass due to elevated [CO2]. Nitrogen supply did not alter the effect of elevated [CO2] on any of the root variables apart from CN ratios. A significant increase of root CN ratios in wheat and sugar beet was observed under elevated [CO2], but this effect was much smaller than the effect of N supply.


      PubDate: 2015-05-26T19:30:09Z
       
  • Integrative effects of soil tillage and straw management on crop yields
           and greenhouse gas emissions in a rice–wheat cropping system
    • Abstract: Publication date: February 2015
      Source:European Journal of Agronomy, Volume 63
      Author(s): Li Zhang , Jianchu Zheng , Liugen Chen , Mingxing Shen , Xin Zhang , Mingqian Zhang , Xinmin Bian , Jun Zhang , Weijian Zhang
      Significant efforts have been made to assess the impact of tillage regimes on crop yields and/or greenhouse gas (GHG) emissions across single crop growing season. However, few studies have quantified the impact across a whole rotation cycle in multiple cropping systems. Utilizing on a long-term tillage experiment with the rice–wheat rotation system in East China, we examined the GHG emissions under different tillage practices with or without crop straw incorporation. Results showed that compared to the no-straw control, straw incorporation increased wheat yield by 28.3% (P <0.05), irrespective of tillage practices, but had no significant effect on rice yield. Although straw incorporation did not significantly affect CH4 emissions during the wheat season and N2O emissions during the whole rice–wheat cycle, it significantly stimulated CH4 emissions by 98.8% (P <0.01) during the rice season. Also, there were no significant differences in CH4 and N2O emissions between tillage practices during the wheat season. Compared to plowing, rotary tillage increased CH4 emissions significantly by an average of 38.8% (P <0.01) but had no significant impacts on N2O emissions during the rice season. Across the rotation cycle, annual yield-scaled global warming potential of CH4 and N2O emissions under no-tillage plus rotary tillage was 26.8% (P <0.01) greater than that of rotary tillage plus plowing with or without straw incorporation. Significant interactions between soil tillage and straw management practices were found on annual GHG emissions, but not on crop yields. Together, these results indicate that plowing in the rice season plus rotary tillage in the wheat season may reduce GHG emissions while increasing crop yield in rice–wheat cropping areas.


      PubDate: 2015-05-26T19:30:09Z
       
  • Genetic improvement of root growth increases maize yield via enhanced
           post-silking nitrogen uptake
    • Abstract: Publication date: February 2015
      Source:European Journal of Agronomy, Volume 63
      Author(s): Xiaohuan Mu , Fanjun Chen , Qiuping Wu , Qinwu Chen , Jingfeng Wang , Lixing Yuan , Guohua Mi
      Root breeding has been proposed as a key factor in the “second green revolution” for increasing crop yield and the efficient use of nutrient and water resources. However, few studies have demonstrated that the genetic improvement of root characteristics directly contributes to enhancing nutrient-use-efficiency in crops. In this study, we evaluated the contribution of root growth improvement to efficient nitrogen (N) acquisition and grain yield under two different N-levels in a 3-year field experiment. We used two near-isogenic maize testcrosses, T-213 (large-root) and T-Wu312 (small-root), derived from a backcross of a BC4F3 population from two parents (Ye478 and Wu312) with contrasting root size. We found that the root length density, root surface area, and dry weight at the silking stage were 9.6–19.5% higher in T-213 compared with the control T-Wu312. The root distribution pattern in the soil profile showed no significant differences between the two genotypes. The overall increase in root growth in T-213 enhanced post-silking N uptake, which increased grain yield by 17.3%. Correspondingly, soil nitrate concentrations in the >30cm soil layer were reduced in T-213 under the high N treatment. These positive effects occurred under both adequate and inadequate N-supply and different weather conditions. Our study provides a successful case that increasing root size via genetic manipulation contributes directly to efficient N-uptake and higher yield.


      PubDate: 2015-05-26T19:30:09Z
       
  • Breeding effects on the cultivar×environment interaction of durum
           wheat yield
    • Abstract: Publication date: August 2015
      Source:European Journal of Agronomy, Volume 68
      Author(s): Joan Subira , Fanny Álvaro , Luis F. García del Moral , Conxita Royo
      Understanding the effect of past durum wheat breeding activities on the cultivar×environment (C×E) interaction of yield and yield components may guide future breeding strategies. A historical series of 24 cultivars released in Italy and Spain during the 20th century was grown in 13 environments with average yields ranging between 1425 and 6670kgha−1. The most important environmental factors affecting the C×E interaction for yield were reference evapotranspiration before anthesis and water input during grain filling. The response of cultivars to environmental variables in terms of yield and yield components was associated to the allelic composition for the Rht-B1 locus. Improved semi-dwarf cultivars (carrying the Rht-B1b allele) had the best yield performance in environments with high water input after anthesis, while tall cultivars (carrying allele Rht-B1a) were better adapted to environments with high evapotranspirative demand before anthesis and low water input after it. The introduction of the Rht-B1b allele improved the capacity of the crop to respond to water availability during grain filling by increasing the number of grains spike−1 and grain weight. Yield increases due to breeding caused a loss of stability from the static viewpoint, but not from a dynamic approach based on the superiority measure (Pi ). Some semi-dwarf cultivars maintained the levels of yield stability characteristic of the old tall ones. Our results suggest that durum breeding in the 20th century enhanced the response of the crop to environmental improvements.


      PubDate: 2015-05-18T11:02:54Z
       
 
 
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