Journal of Agronomy and Crop Science最新文献

Climate change presents challenges to agriculture globally, necessitating to develop resilient production systems to safeguard food security, farm incomes and environmental sustainability. This review synthesises current strategies to raise climate resilience, with a focus on climate-smart agricultural practices, the selection and planting of stress-tolerant crop varieties and efficient water management. The review provides a critical analysis of biotechnological tools including gene editing through CRISPR-cas9 and marker-assisted selection that enable rapid development of region-specific crop improvements. The review also examines the under-explored approaches such as the use of beneficial stress-tolerant microbes, diversified cropping systems, and conservation agriculture. By integrating case studies from multiple geographic regions, it presents a comparative synthesis of context-specific successes and challenges. We suggest a framework to align technological innovation with policy support, farmer education and participatory stakeholder engagement. Special attention is given to the needs of smallholder farmers in climate-vulnerable regions. The review concludes by outlining actionable priorities, including the expansion of climate data services and the integration of ecological management practices to balance productivity with ecosystem health.

Low light conditions, caused by prolonged cloudy and rainy weather during the grain-filling stage, lead to significant reductions in rice quality and yield. However, the molecular mechanisms underlying grain filling under low light remain poorly understood. In this study, two Japonica rice varieties, Xinfeng 6 (Xin 6; low light–tolerant) and Nipponbare (NP; low light–sensitive), were employed to investigate these mechanisms. Under low light conditions, Xin 6 exhibited less pronounced changes in 1000-grain weight, chalkiness, starch and storage protein content, and endosperm starch granule structure compared to NP. Transcriptome analyses revealed that the number of genes regulated by low light in NP grains was approximately threefold higher than that in Xin 6 grains. Notably, a significant number of genes associated with sucrose-starch synthesis, glycolysis, and abscisic acid, calcium, and mitogen-activated protein kinase signalling pathways were downregulated in NP but remained unaffected in Xin 6. Gene network analyses suggest that Tre6P signalling integrates respiration, starch synthesis, low-temperature response and trehalose synthesis in grains under low light. These findings provide novel insights into the molecular mechanisms of low light tolerance in rice.

Physiological and photosynthetic nitrogen use efficiency responses to early drought and their contribution to yields in diverse sugarcane genotypes are understudied. This study examines the physiological responses, photosynthetic nitrogen use efficiency (PNUE), and their relationship with yields in various sugarcane genotypes during early drought and recovery periods, providing information relevant to breeding drought-resistant sugarcane. The experiment was arranged in a split-plot in RCBD with three replications. The main plot was two water regimes (i) well-watered (WW) and (ii) early drought stress (DS), whereas the subplot consisted of six sugarcane genotypes in plant cane and ratoon cane. Relative water content (RWC), SPAD chlorophyll matter reading (SCMR), stomatal conductance (gs), photosynthetic rate (Pn), PNUE, and crop growth rate (CGR) were measured during drought and recovery periods. While cane, sugar, and fiber yield were collected at the final harvest. The results indicated that drought stress reduced RWC, SCMR, gs, Pn, PNUE, and CGR. Furthermore, early drought reduced cane, sugar, and fiber yields, as well as CCS levels. After rewatering, RWC, Pn, gs, PNUE, and CGR quickly recovered in only F03-362 genotype. PNUE significantly contributed to CGR under DS conditions and enhanced cane yield during drought. Under DS conditions, F03-362 maintained high PNUE and GCR, while F03-362 and KK09-0358 sustained high PNUE and cane yield. Interestingly, F03-362 as an F1 hybrid showed a good recovery efficiency for Pn, PNUE, and GCR, resulting in a high cane yield. Breeders can use this genotype as a parent in sugarcane breeding for drought resistance, with PNUE and CGR serving as selection criteria. Understanding the water stress-response mechanisms of diverse genotypes is key to successful drought-resistant breeding.

Canopy resistance (r_c) is a vital parameter for further estimating crop evapotranspiration (ET_c), and Jarvis model is one of the most widely used models to estimate r_c with parameterizations based on the environmental factors and leaf area index (LAI). However, previous researches on the Jarvis model mainly focused on optimising environmental parameters, which could not explain the great fitting disparity for the r_c estimations of distinct crop species and the uncertain model performances in different growing stages. Therefore, we modified the effective leaf area index (LAI_e) in Jarvis model using a multi-layer method in which we measured stomatal resistance (r_s) and LAI at different layers (0–50, 50–100, 100–150 and 150–200 cm of plant height) of greenhouse cucumber to calculate LAI_e to describe the influences of leaf spatial distribution and photosynthesis efficiency. We compared the performances of the improved and the original Jarvis models on r_c estimation and found the coefficient of determination (R²) and root mean squared error (RMSE) of 0.68 and 163 s m⁻¹, 0.64 and 171 s m⁻¹, respectively, the corresponding errors for hourly ET_c calculation were 0.81 and 0.10 mm h⁻¹, 0.88 and 0.098 mm h⁻¹, respectively. The accuracy of both models gradually raised with the increasing in LAI, and an obvious improvement on ET_c estimation appeared when LAI ≤ 1 m² m⁻² with R² = 0.81 for the improved Jarvis model while R² = 0.77 for the original Jarvis model. Although the accuracy of the improved Jarvis model was not prominently increased for all growing stages, the improved Jarvis model is of great significance in considerations of crop physiological and growth diversity to enhance the model adaptability for distinct crops and reduce the uncertainty of model performance for different growing stages.

Drought resilience strategies are needed to tackle the escalating issue of water scarcity and to sustain crop productivity under water deficit conditions. There is a gap in identifying the most effective consortium of microbial biostimulants and understanding the underlying physiological and antioxidant mechanisms involved in the drought resilience of wheat (Triticum aestivum L.) crop. To address this, three experiments were carried out in laboratory and wire house conditions to identify and optimise the response of drought-tolerant microbial biostimulants for wheat genotypes. Three drought-tolerant microbial biostimulants: Bacillus subtilis, Bacillus megaterium and Trichoderma harzianum were selected from a laboratory study. The two wheat genotypes: Dilkash-2021 and Bakhar Star (drought tolerant and sensitive, respectively) were selected from a wire house experiment. Afterwards, the response of individual and consortium of selected drought-tolerant microbial biostimulants was evaluated in drought-tolerant and sensitive wheat genotypes under well-watered and water deficit regimes. Results indicated that seed inoculation of drought-tolerant genotype with the microbial consortium of Bacillus subtilis, Bacillus megaterium and Trichoderma harzianum significantly increased relative water contents (58%), stomatal conductance (39%), sub-stomatal conductance (70%), water use efficiency (38%) and net leaf photosynthetic rate (34%) as compared with the un-inoculated control under water deficit. Furthermore, a significant reduction in malondialdehyde concentration (36%) and an improvement in proline contents (77%), superoxide dismutase (82%) and peroxidase (51%) were observed with this microbial consortium under water deficit. Therefore, seed inoculation of drought-tolerant wheat genotypes with the microbial consortium might be considered in formulating the best agricultural practices for alleviating the adverse effects of water deficit on the wheat crop.

Cowpea is a valuable legume known for its high-quality protein and multiple uses, but it often suffers from sub-optimal moisture during different growth stages. While the effects of drought at certain stages are studied, comprehensive studies across all growth stages are limited. This study evaluated drought tolerance of two cowpea genotypes by examining morphophysiological, pigments, biomass, yield and quality traits under contrasting soil moisture conditions: control and drought during critical vegetative (V2 and V4) and reproductive (R1 and R4) stages. Gas exchange traits were more affected by drought during the vegetative stages than the reproductive stage, with photosynthesis declining by 86% at the vegetative stage, compared to a 68% reduction at the reproductive stage. The chlorophyll index declined by 54% in the R4 stage, while the V2 stage showed no significant changes under drought. Drought at the R1 stage led to a substantial decrease in seed yield by 46%, followed by 35% in R4, 33% in V2 and 27% in V4. The yield reduction at R1 correlated with an 82%, 68% and 44% drop in stomatal conductance, photosynthesis rate and chlorophyll index, respectively, followed by a 3.4°C increase in leaf temperature. Drought stress during reproductive stages led to an increase in hundred-seed weight and seed protein, while starch content decreased, indicating a shift in resource allocation under stress conditions. Based on seed number and weight, the order of cowpea growth stage resilience to drought stress followed the order of R1 < R4 < V2 < V4. These findings suggest that breeding for a multi-stage drought-resilient genotype is needed to sustain yield under rainfed conditions.