Journal of Agronomy and Crop Science最新文献

Drought is a significant meteorological disaster that affects winter wheat production in the arid region of northwest China. In order to understand the mechanisms and factors associated with rain-fed winter wheat drought in the arid region of northwest China, the monthly meteorological data from 1987 to 2016 was employed to analyse the characteristics of both meteorological drought and the Standardised Precipitation Evapotranspiration Index (SPEI_w) incorporating crop coefficients, respectively. In addition, we calculated the propagation time and probability of winter wheat drought caused by meteorological drought in different growth stages. The main factors that influenced different types of winter wheat drought were also clarified. The main results were as follows: The frequency, duration, severity and areas affected were greater for rain-fed winter wheat drought than meteorological drought in each growing stage. The propagation time from meteorological drought to rain-fed winter wheat drought was 1 month in the initial, developmental and late stages, and 2 months in the middle stage. The probability of propagating from meteorological drought to rain-fed winter wheat drought was higher when the degree of meteorological drought was higher, and winter wheat drought was more likely to be severe. When the degree of drought was greater in rain-fed winter wheat during different growing stages, a smaller SPI threshold was required to trigger it. Rain-fed winter wheat drought induced by non-meteorological drought was influenced mainly by the relative humidity, net surface radiation and sunshine hours on a short time scale (1 month), whereas winter wheat drought induced by meteorological drought was mainly affected by various meteorological factors over a longer time scale.

In the context of water scarcity, enhancing water use efficiency (WUE) of winter wheat has become a crucial objective in the advancement of water-saving agriculture. This study aimed at comparing the changes in WUE in winter wheat of different spike types, and to elucidate the factors influencing intrinsic water use efficiency (WUEi) of leaf characteristics and photosynthetic traits. Field experiments involved two winter wheat spike types: large-spike (SN30, TN18) and multi-spike (JM22, QH001). We assessed genotypic variations in photosynthetic parameters, WUEi, instantaneous water use efficiency (WUEn), and leaf stable carbon isotope discrimination (Δ¹³C) across major growth stages. The results demonstrate that the average yield of the large-spike (10.81 × 10³ kg ha⁻¹) was 18.04% higher than that of the multi-spike. The photosynthetic rate of winter wheat was highest at anthesis stage (between 16.68 and 24.88 μmol m⁻² s⁻¹ depending on genotypes); the Δ¹³C values exhibited a range of 20.59‰–21.68‰ in the large-spike. Significant inter-annual differences emerged in transpiration rates (Tr), WUEi, and WUEn. Overall, large-spike wheat demonstrated superior photosynthetic capacity and water use efficiency. The results indicated a negative correlation between WUEi and Δ¹³C and stomatal conductance (Gs), which suggests that the decline in WUEi is primarily limited by stomatal conductance. These findings emphasise the interaction between leaf photosynthetic characteristics and WUEi acclimation strategies.

The superior productivity under drought conditions in New Rice for Africa (NERICA) upland rice is expected to overcome low yields in sub-Saharan rainfed regions of Africa. However, the core processes and contributing functions of the productivity of this rice under drought are not fully understood. Biomass production (BP) is one component of grain production (GP) (GP = BP × HI, where HI is harvest index) and BP is indicated by the water use efficiency coefficient (k) × transpiration per vapour water deficit of air (T/VWD). Our objective was to determine which of k, T/VWD, and HI strongly contributed to the maintenance of GP during drought conditions in the reproductive stages, thereby identifying a key function in the water use process that maintains GP in NERICA upland rice under drought conditions. First, the k and T/VWD values in four NERICA upland cultivars and three Oryza sativa cultivars with contrasting traits for drought resistance were compared in a 4 L pot held under three different field capacities for 14 days. k was approximately constant under different soil moisture contents and mainly T/VWD changed BP. Second, the responses of T/VWD to soil drying in these seven cultivars were compared in 15 L pots for 10 days. The ratios of T/VWD in desiccated soil to watered control plants (T/T₀) in all cultivars similarly decreased with a decrease in the fraction of transpirable soil water (FTSW). Third, the FTSW values were compared for two NERICA upland cultivars and one drought sensitive O. sativa cultivar selected from these seven cultivars in 31 L pots with depths of 1 m irrigated at four different soil depths. The FTSW values weighed by root distribution in NERICA upland cultivars watered deep in their soils were higher than those in the O. sativa cultivars, resulting in higher BP, GP, and HI values. These results indicate that the process by which drought reduced grain production in NERICA upland rice was as follows: the decreased FSW caused by reductions in water supply suppressed biomass production by reducing the transpiration level and moreover, the reduced harvest index due to sterility. Reductions of biomass production and harvest index decreased grain production. Hence, greater FTSW due to more developed roots could be a key elemental function for maintaining rice productivity due to keeping transpiration and harvest index.

Recent studies have explored the use of exogenous bio-stimulants to enhance crop growth and stress tolerance, with most focusing on growth rather than yield. This meta-analysis seeks to answer whether exogenous bio-stimulants, particularly salicylic acid (SA), can improve the yield of wheat under salinity conditions and assess its economic feasibility in wheat production. A systematic search strategy was followed by using databases such as Google Scholar and Web of Science without any restrictions on language or time to identify articles published by June 2023 (updated in April 2025). The meta-analysis found that the total yield of wheat production under stress is reduced significantly compared to the control condition, and the pooled variance is 0.67 with 95% CI (confidence interval) 0.59 to 0.76. It was also found that wheat yield improved significantly under both non-saline and saline conditions by applying exogenous SA, with the pooled estimates of 1.14 with 95% CI 1.09 to 1.19 and 1.26 with 95% CI 1.18 to 1.33, respectively. The economic analysis demonstrates that SA application is a profitable intervention for wheat cultivation in salinity-affected areas, showing an overall benefit–cost ratio of 1.295. Based on these findings and the established yield benefits, we recommend farmers apply SA at concentrations of 0.5–1 mM through foliar spraying for optimal wheat yield.

Frost resistance is a crucial trait in wheat breeding, and accurately assessing the phenotype of frost damage is vital for the genetic improvement of wheat resistance to frost damage. However, the unpredictability of cold wave events and regional variations in frost damage levels complicate the precise evaluation of frost damage. Survival rate and frost damage grade (on a scale of 1 to 5) are commonly used indicators for evaluating frost damage. However, these methods are mainly effective in extreme low-temperature conditions that cause significant wheat mortality or result in severe frost damage ratings above 3. They are not well-suited for the more subtle phenotypic variations associated with common low temperatures, such as those ranging from −10°C to −5°C. In this study, we employed four different phenotyping methods to evaluate the severity of frost damage in a panel of 50 wheat recombinant inbred lines in two distinct environments, and proposed a novel approach to quantify frost damage based on the proportion of frost-damaged leaves (PFD), which proves to be simple and robust for assessing the severity of frost damage in wheat across multiple biological replicates and a spectrum of environmental conditions.

Heat stress is one of the most detrimental abiotic stresses, causes significant reduction in plant growth and yield in tropical and sub-tropical regions. Mitigating the adverse effects is crucial for sustainable crop production and global food security. The use of bacterial consortia represents a promising and eco-friendly approach to enhance heat tolerance in plants, offering a biological strategy to improve resilience under climate-induced stress conditions. In this study, three heat-tolerant Bacillus species (Bacillus velezensis, Bacillus altitudinis and Bacillus cereus) and two maize hybrids DK-6103 (heat tolerant) and SW-1080 (heat sensitive) were selected from laboratory and glasshouse experiments. The bacterial strains were screened in laboratory at various heat stress levels (30°C, 40°C and 50°C for 96 h), while maize hybrids were evaluated in glasshouse conditions [30°C ± 3 (control) and 45°C ± 3 (heat stress) for 6 h per day over a period of 8 consecutive days]. Subsequently, the response of best performing heat-tolerant Bacillus spp. as individual and consortium was explored in selected maize hybrids under heat stress [45°C ± 3; 6 h/day over a period of 8 consecutive days] based on morpho-physiological and antioxidant activity. The results revealed that seed inoculation with a bacterial consortium of B. velezensis, B. altitudinis and B. cereus resulted significant improvements in plant growth, morpho-physiological traits and antioxidant mechanisms. Inoculation treatment demonstrated a rise in shoot and root length (39% and 30%) attributed to enhancements in net leaf photosynthetic rate (25%), soluble protein content (46%), superoxide dismutase (73%), catalase (94%) and proline content (151%) compared to the control. Additionally, seed inoculation also led to a reduction in leaf transpiration rate and malondialdehyde contents indicating a stress response in plants. Consortium-inoculated seedlings exhibited the highest increases in net leaf photosynthetic rate, soluble protein content, superoxide dismutase, catalase and proline under heat stress. It highlights the effectiveness of bacterial inoculation in enhancing thermotolerance in maize hybrids. In conclusion, seed inoculation with a bacterial consortium effectively enhances seedling growth, physiological traits, antioxidant activities and osmolytes production under heat stress.