查看更多>>摘要：? 2022Appropriate use of cover crops and crop rotation in agriculture can contribute to food security and sustainable production. However, the impacts of Orychophragmus violaceus (O. violaceus) as rotation cover crop in maize on soil physicochemical properties and crop nutrient uptake have rarely been verified and quantified via field studies. With a conventional wheat (Triticum aestivum L.)-maize (Zea mays L.) rotation used as a control, a field experiment was conducted on the North China Plain in 2017–2018 and 2018–2019 to evaluate the dynamic variations in soil chemical properties and maize agronomic indexes and the impacts on maize nutrient uptake and yield under continuous maize and O. violaceus-maize rotation. We observed that rotation of O. violaceus with maize positively impacts soil chemical properties and subsequent maize productivity. Compared to those in the wheat-maize rotation, the mean contents of soil organic matter (SOM), soil alkali–hydrolyzable nitrogen (SAN), soil available phosphorus (SAP), and soil available potassium (SAK) in the O. violaceus-maize rotation increased by 8%, 11%, 13% and 18%, respectively, within the 0–60 cm soil layer, thereby increasing the maize N and P uptake and yield at maturity. According to correlation analysis and path model results, the most powerful direct factor affecting the maize yield was plant nutrient uptake rather than biomass accumulation. The O. violaceus-maize rotation was superior to the wheat-maize rotation and continuous maize in term of SOM, SAN, plant agronomic indexes, and maize nutrient uptake and yield. Overall, O. violaceus-maize is a reasonable rotation system for use on the North China Plain and provides new insight into the mechanisms and processes underlying crop yield and nutrient uptake.
查看更多>>摘要：? 2022 Elsevier B.V.In Mediterranean type environments large variability in grain plumpness, defined as the proportion of grains retained over a 2.5 mm sieve, is a critical source of uncertainty for brewers and farmers. Understanding the mechanisms that regulate grain size under stressful environments will assist breeders to promote stability and improve grain size. Using an unbiased data set (n = 171) derived from 21 different environments (Years x Locations) and 29 European malt barley varieties, we aimed to (i) analyze the effect of genotype × environment interaction on plump grains and yield components variation from the viewpoint of phenotypic plasticity and (ii) explore the extent to which grain size associates with grain yield (GY) potential, grain number and grain protein content (GPC). Plump grains (% grains>2.5 mm), was the trait with the highest plasticity in two-rowed barley. A thorough assessment of the relationship between Thousand Kernel Weight (TKW) and the different grain size classes (i.e. > 2.8 mm; 2.5–2.8 mm; > 2.5 mm; 2.2–2.5 mm; < 2.2 mm) revealed that the stability of TKW was preserved by adjusting not only the number of seeds set, but also proportions among the different grain size classes. Our data supported the following hierarchy of plasticities: plump grains > grains/m2 > GY > spikes/m2 > TKW > Harvest Index > grains/spike. With decreasing GY there was also an apparent decrease in plump grains production. The number of grains/m2 had a markedly larger negative effect on plump grains under low-yielding conditions compared to medium and high-yielding conditions. In addition, a high inherent number of grains/spike (> 26) not only had a negative effect on GY, but also undermined grain plumpness. Under the tested G × E interaction, both grain yield and plump grains were positively affected when grain yield formation was mainly based on a greater number of spikes/m2 with fewer and heavier (≈larger) grains/spike. GPC had a relatively strong negative association with plump grains. However, when the conditions favoured plump grains formation, the risk of recording low GPC was increased. This revealed that under Mediterranean conditions the challenge is not only the high values of GPC, but the low ones as well.
查看更多>>摘要：? 2022 Elsevier B.V.Straw return into agricultural soil is one of the most important management practices in China. However, the direction and magnitude of crop yield to straw return are inconsistent from individual studies in wheat-maize cropping systems of Chinese upland soils. Hence, we conducted a meta-analysis of 1071 comparisons from 177 peer-reviewed publications to evaluate the effect of straw return on the yield in the wheat-maize cropping system varied with climate conditions, management practices, and soil properties. Overall, crop yield response to straw return in the mono-cropping system (11.8%) is significantly greater than that in the double-cropping system (5.5%). The positive effect is obvious in regions with subtropical climates (> 15 °C annual temperature and > 800 mm annual precipitation). Without fertilizer application, straw return has no improvement on crop yield in the mono-cropping system, or even decreases crop yield by 2.42% in the double-cropping system, while it will yield more under N fertilizer application of 150–200 kg ha?1 yr?1 for mono (16.4%) and > 300 kg ha?1 yr?1 for double (6.99%) cropping system. For both cropping systems, yield increase peaked at around 10–15 years. The positive effect of straw return on crop yield is more obvious under the conditions with irrigation, and deep tillage. For straw return method, straw incorporation presents a greater effect than straw mulching does. The increase in crop yield after straw return is closely related to the improvement of soil organic carbon, soil structure and nutrients. Therefore, our results indicate that straw incorporation under the conditions with deep tillage, irrigation and fertilization, has great potential to increase crop yield in the wheat-maize cropping system.
查看更多>>摘要：? 2022Producing more food with less input is imperative in feeding the increasing world population. Here, for the first time we characterize the multipartite responses of maize to nutrient-rich patches and demonstrate significant synergistic effects between root morphological and physiological responses on improving nutrient-use efficiency and yield. Our results showed that maize root length, lateral root formation, acid phosphatase (APase) secretion, and expression of ammonium transporter genes increased in the ammonium-containing patches; moreover, ammonium-induced rhizosphere acidification enhanced activity of APase. These root responses were associated with improved maize nutrition and growth even with reduced fertilizer input, suggesting an adaptive benefit of synergistic root foraging strategies. These new findings improve our understanding of root-foraging responses to nutrient-specific cues and are crucial for engineering root and rhizosphere properties to improve nutrient-use efficiency for sustainable crop production.
查看更多>>摘要：? 2022 Elsevier B.V.Spring sweet corn as a short duration cash crop is gaining popularity in northern India owing to increasing demand in urban and peri-urban regions. Under hot dry climate and minimal rainfall, irrigation is the major yield contributing factor for attaining superior quality cobs and higher economic returns. The study aimed at examining the effect of irrigation scheduling (I) (IW/CPE 1.0, 1.2, 1.4), sowing methods (S) (flat and furrow) and moisture conservation practices (M) (no-residue, rice straw mulch 6.0 t ha?1 and rice straw biochar 3.0 t ha?1) on spring sown sweet corn yield, quality, profitability and water use efficiency in the Tarai region (sandy loam soil texture) of Uttarakhand, India. The experiment was conducted in split factorial design (Main I x S, Sub M) with 18 treatment combinations and three replications. Results indicated that the combination IW/CPE 1.4 +furrow+mulch being at par with IW/CPE 1.4 +furrow+biochar were superior in terms of dehusked cob yield which was ~42% higher over IW/CPE 1.0 +flat+control. Application of biochar 6 t ha?1 and straw mulch 3 t ha?1 increased dehusked cob yield of sweet corn by ~6–9% over control (no-residue) during both years. Among irrigation schedules, IW/CPE 1.0 obtained highest irrigation water use efficiency (IWUE) followed by IW/CPE 1.2. Mulch and biochar being on par recorded 7–10% higher IWUE over no-residue control. Likewise, furrow sowing increased IWUE by 39–44% over flat method with ~25% higher water savings. Average soil moisture content under mulch and biochar was 25% and 12% higher respectively over no-residue. Maximum net returns was obtained under the combination IW/CPE 1.4 +furrow+mulch (1672 USD ha?1) which was 69% higher over IW/CPE 1.0 +flat+no-residue. Sweet corn quality parameters viz., total soluble solids and non-reducing sugar was significantly higher under IW/CPE 1.0 and 1.2 in comparison to 1.4, as well as under furrow sowing over flat sowing. Therefore, although maximum yield and profitability of sweet corn was obtained under irrigation schedule IW/CPE 1.4, the treatment combination of IW/CPE 1.2 with furrow sowing and mulch/biochar application may be adopted for attaining superior quality parameters and improved water use efficiency of sweet corn.
查看更多>>摘要：? 2022Summer peanut – winter wheat is considered a feasible alternative to the traditional summer maize – winter wheat on the North China Plain, and it has great potential to maintain crop yield and reduce environmental costs. However, the yield, water consumption, and nitrogen utilization of subsequent wheat responses to peanut residue incorporation are not well-documented. Thus, a two-year field experiment with peanut root, shoot, and total residue incorporations, as well as a control with no residue, was established for the summer peanut – winter wheat cropping system. Peanut residue incorporation had no significant yield benefits for subsequent wheat and subsequent peanut, compared with no peanut residue input. The wheat yield was positively correlated with previous peanut yield, due to complementary utilization of residual nitrogen and water resources. Therefore, residue incorporation increased the annual yield of the summer peanut – winter wheat system by 5–13%, decreased the annual evapotranspiration by 3–12%, and boosted annual water use efficiency by 8–26%. Yield increases caused by peanut residue incorporation were detected only from the perspective of multiple cropping systems rather than single crop seasons. This indicated that at least two crop seasons were needed to verify the effects of residue incorporation on the North China Plain. Remarkably, no significant differences in yield, nitrogen yield, or wheat equivalent yield were detected between root and total residue incorporations. This clearly indicates that shoot removal has a negligible effect on the annual crop yield and performance of the summer peanut – winter wheat system. In conclusion, the yield benefits of legume residue incorporation are mainly attributed to the belowground residue, and the benefits may be underestimated when only one crop season after residue retention was investigated.
查看更多>>摘要：? 2022 Elsevier B.V.Owing to the high contents of oil and protein, soybean [Glycine max L. (Merr.)] seeds are energy-rich. Genetic improvement of soybean yield is linked to the dilution in seed protein; changes in low-energy compounds such as carbohydrates have received less attention. We tested the hypothesis that selection for yield in soybean has shifted seed composition in favor of low-energy compounds. We characterized the dynamics of three seed fractions (protein, oil, and residual) during seed filling in seven commercial soybean varieties released between 1980 and 2013 in a two-year field experiment. Genetic gain in yield was linked with reduced seed energy cost: seed protein concentration decreased by 0.06% yr?1, oil remained stable, and the residual fraction increased by 0.09% yr?1. Seed accumulation of the residual fraction revealed a shorter lag phase and a longer effective filling period for the modern relative to the older soybean varieties. Seed energetic requirement significantly decreased ? 0.06% yr?1. Resource availability per seed during the seed-filling period was not limiting across all tested varieties. Further research is warranted on the biochemical nature of the residual fraction, and on the implications of seed composition for future breeding, soybean meal and end uses.
查看更多>>摘要：? 2022 Elsevier B.V.Crop models are essential tools for analysing the effects of climate variability, change on crop growth and development and the potential impact of adaptation strategies. Despite their increasing usage, crop model estimations have implicit uncertainties which are difficult to classify and quantify. Failure to address these uncertainties may result in poor advice to policymakers and stakeholders for the development of adaptation strategies. Since the 1990s, the number of crop model uncertainty assessments that consider different sources of model uncertainty (model structure, model parameters and model inputs such as climate, soil, and crop management practices) has increased significantly. We present the outcomes of a systematic review focused on uncertainty assessments of crop model outputs (mainly grain yield) and crop model uncertainty decomposition. We reviewed 277 articles from 1991 to 2019 which included studies conducted in 82 countries (460 locations) across all continents. 57% of the articles have been published between 2015 and 2019. 52% of the studies focus on input uncertainty assessments with climate change projections as the most frequently considered source of input uncertainty. Only 28% and 20% of the studies, respectively, dealt with uncertainties related to model parameters and model structure. The latter was mainly quantified using multi-model ensembles. Over half the studies were carried out in European and Asian countries, 34% and 23%, respectively. Most articles estimated model uncertainty focusing on the grain yield of major cereal crops (wheat > maize > rice) using the Decision Support System for Agrotechnology Transfer (DSSAT) model. Sensitivity analysis was the most used technique to quantify the contribution of different sources of uncertainty although the range of approaches for uncertainty quantification was wide. There is a need for standard procedures to estimate crop model uncertainty and evaluate estimates. We discuss the challenges of quantifying the components of uncertainty within crop models and identify research needs to better understand sources of uncertainty and thus improve the accuracy of crop models.
查看更多>>摘要：? 2022 Elsevier B.V.Rainfed crops rely on two sources of water: stored soil water at sowing and seasonal rain. In strongly seasonal winter-rainfall environments, stored soil water at sowing is minor, and uncertain seasonal rainfall is a source of risk. In south-eastern Australia, under-fertilisation is a common outcome of nitrogen risk management with implications for wheat yield and mining of soil organic matter. Here we explore the use of carbon isotope composition (δ 13C) to capture the effects of crop water status on grain yield in a context of nitrogen top dressing. In the sampled environments, crops receive at least 50% of seasonal rainfall by stem elongation, and at least 70% of seasonal rainfall by flowering. In a sample of 1518 plots, yield varied from 0.07 to 9.96 t ha-1 and correlated with δ 13C measured with isotope ratio mass spectrometer (IRMS) at flowering (r = ?0.76, p < 0.0001); this is consistent with the rainfall pattern and the physiology of the crop featuring a critical period for yield from 300 °Cd before to 100 °Cd after anthesis. In a sample of 135 plots, yield varied from 1.2 to 8.4 t ha-1 and correlated with δ 13C measured with IRMS at stem elongation (r = ?0.56, p < 0.0001). Yield response to nitrogen, defined as the difference between yield in fertilised crops (50–200 kg N ha-1) and unfertilised controls, correlated with δ 13C measured with IRMS at stem elongation, except for late-sown crops. Mid-infrared spectroscopy (MIR) returned estimates of δ 13C that agreed with δ 13C measured with IRMS (calibration: R2 = 0.82, RMSE = 0.53‰, n = 833; validation: R2 = 0.70, RMSE = 0.75‰, n = 364). We conclude that a MIR based, high-throughput, affordable measurement of δ 13C could be scaled to guide nitrogen management of wheat in winter-rainfall environments.
查看更多>>摘要：? 2022 Elsevier B.V.The consequent and accurate monitoring of the seasonal dynamics of crop leaf area index (LAI) is critical to yield estimation and agriculture policy development. It is difficult for a single sensor to balance spatial and temporal resolution. Spatiotemporal fusion is an effective way to meet the need for high spatial and temporal applications. Among the fusion methods, regression model Fitting, spatial Filtering and residual Compensation (Fit-FC) may be recommended for vegetation dynamic monitoring because of its outperformance for the cases with considerable phenological changes. However, it is not good at capturing image structure and textures. To overcome the limitations, an enhanced version of Fit-FC, referred as Enhanced-Fit-FC (EFF), was developed. The EFF method can be applied with one (unidirectional prediction, Uni-EFF) or two (bidirectional prediction, Bi-EFF) coarse-fine image pairs as input for near real-time or post-growth applications. The visual and quantitative assessments indicated that EFF mitigated the blurring effect of Fit-FC and generated accurate reflectance, especially Bi-EFF contributed to capturing land cover changes. Compared with Fit-FC, the correlation coefficient (CC) and quality index (QI) of EFF increased by more than 0.12, and the root mean square error (RMSE) decreased by 0.16 at the maximum. Further, we identified the robustness and adaptability of deep neural network (DNN) model for time-series LAI estimation. The results substantiated the effectiveness of DNN in dealing with nonlinear problems and alleviating spectral saturation with higher CC and lower RMSE and relative RMSE (rRMSE) at whole growth-stages (CC= 0.91, RMSE= 0.28, and rRMSE= 7.18%) and vegetative stage (CC=0.94, RMSE=0.24, and rRMSE= 5.81%). In conclusion, the EFF method proposed in this study is competent in constructing time-series synthetic images for near real-time or post-growth applications. Moreover, the DNN model shows the potential for LAI estimation at whole growth-stages. This research not only contributes to dense time-series remote sensing-based applications (e.g., land cover change monitoring, yield forecast), but also is valuable for high-spatial-precision farmland management.
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