Journal of Agronomy and Crop Science最新文献

Rapeseed is an essential source of edible oil, primarily cultivated in temperate regions worldwide. This crop exhibits a marked sensitivity to elevated temperatures, particularly during the stages preceding and following flowering. The ongoing challenges posed by global climate change and increasing temperatures significantly threaten its yield. It is essential to elucidate the dynamics of rapeseed's response to sustained heat stress (HS), especially during the flowering phase, to advance research on enhancing its heat tolerance. In the present study, we analysed transcriptomic modifications in rapeseed plants subjected to HS at 33°C, spanning from the pre-flowering stage to the commencement of blooming. Our findings revealed that rapeseed produced diminutive flowers with nonviable pollen and exhibited a decline in pistil receptivity. Transcriptome analysis revealed that 5588 and 5994 genes were upregulated and downregulated, respectively. KEGG enrichment analysis demonstrated that these DEGs were linked to hormone signal transduction pathways, energy metabolism (including starch and sucrose metabolism and glutathione metabolism), and plant-specific MAPK signalling pathways. Furthermore, genes encoding reactive oxygen species (ROS) scavenging enzymes and heat shock transcription factors were prominently expressed under HS conditions. This study provides foundational insights into the mechanisms underlying heat tolerance in rapeseed and holds significant implications for the genetic enhancement of heat-tolerant rapeseed varieties.

Increasing waterlogging events due to intense rainfall pose a significant threat to global food security, risking the production of the third most important staple crop, maize by 25%–34%. Therefore, futuristic studies focusing on understanding the stage-wise response of maize to varying intensities of waterlogging, along with effective mitigation strategies, are essential. In this context, studies were conducted over 2 years (2022–23 and 2023–24), involving three factors: crop growth stages, different waterlogging durations, and mitigation strategies. Among the growth stages, waterlogging at 15 days after emergence (DAE) was found to be the most sensitive, resulting in poor root morphological features, impaired physiological activities, and the highest grain yield reduction (46.01%). In contrast, maize plants exhibited higher tolerance to waterlogging at 25 DAE. Similarly, increasing waterlogging duration from 3 to 15 days consistently reduced maize growth and grain yield. Regarding mitigation strategies, foliar application of urea (2%) improved stomatal conductance by 41.32%, net photosynthetic rate by 36.03%, and dry matter accumulation compared to water-sprayed plants. Consequently, it increased grain yield by 17.37%, enhancing stress tolerance and yield stability. Notably, urea spray (2%) on plants subjected to 3–5 days of waterlogging at 25 DAE effectively prevented the negative impacts of waterlogging on grain yield by promoting superior growth and yield-determining traits. Thus, this study demonstrates that foliar application of 2% urea is an effective and practical strategy to minimise waterlogging-induced yield losses by enhancing stress recovery and tolerance in maize.

Drought stress prior to anthesis slows down maize silk extension and thus causes the greater anthesis and silking interval, resulting in a significant reduction in grain set. This study aims to characterise the transcriptional and physiological responses of silk elongation to moderate drought stress. A trial of two hybrids with contrasting drought tolerance, AN591 and ZD909, under well-watered (WW) and moderate flowering drought stress (FDS) conditions was performed. Compared to the WW group, the silking under FDS was delayed by 1 day in AN591 and by 3.3 days in ZD909, suggesting that AN591 exhibits greater resilience to FDS than ZD909. The comparative transcriptomic profiling between FDS and WW for both hybrids highlighted the significance of sugar metabolism in promoting silk elongation, while also identifying phenylalanine metabolism and phytohormone signalling as inhibitory factors. Pathways exclusive to AN591 were largely linked to carbon and energy metabolism, while those in ZD909 were primarily associated with stress defence, suggesting AN591 was better adapted to FDS. Physiological assays confirmed that stronger sucrose decomposition in AN591, regulated by cell wall invertase, alleviated FDS-induced suppression on silk elongation. This may also explain its reduced lignin synthesis and other defence responses. Conversely, the unique phytohormone signalling in ZD909, characterised by negative auxin response and positive abscisic acid response, may further exacerbate the inhibitory effect on silk elongation by driving more sugar consumption. Together, combined transcriptomic and physiological analyses revealed that the trade-off between growth and defence was mediated through adjustments in sucrose metabolism, phytohormone signalling and secondary metabolic pathways.

Climate-induced increases in temperature and water scarcity threaten global soybean production. While the individual effects of drought or heat stress on yield are well documented, their combined impact on specific yield components remains poorly defined. To address this gap, we conducted a two-year study in Japan using a temperature gradient chamber and a single soybean cultivar. The study applied four temperature gradients under well-watered and drought stress conditions to examine seed yield and its components. Combined drought and heat stress reduced total yield more than either stress alone. In 2024, average yield under combined stress declined by 19.4% compared to 2023, coinciding with an increase of 1.5 kPa in maximum vapour pressure deficit and 2.5°C in maximum temperature. This yield reduction was primarily attributed to lower seed weight on branches rather than on the main stem. Pearson correlation and multiple regression analyses identified the number of nodes per branch as the key yield determinant under stress conditions. We further found that the transition from vegetative growth to beginning bloom was the most stress-sensitive stage. During this period, maximum temperature and vapour pressure deficit reached 53.3°C and 10.7 kPa, significantly inhibiting node formation on branches and limiting subsequent pod and seed set. These findings advance understanding of how concurrent drought and heat stress constrain soybean yield through specific developmental pathways, and underscore the need to incorporate branch-level traits into stress-resilient breeding strategies.

Coincidence of heat with reproductive stages of wheat deteriorates baking attributes and decreases crop yield. The current study focuses on (i) the evaluation of relative heat sensitivity of terminal stages of wheat (ii) investigating heat-triggered deteriorations in grain yield and wheat-based industrial traits (iii) quantifying an optimised dose of selenium as a potent heat alleviator (iv) exploring the strength and nature of correlations of baking traits with grain yield. The experiment was repeated over a two-year period under a randomised complete block design having a split treatment structure. Treatments comprised heat stress in the main plot viz. control; heat from spike to grain filling and heat from flowering to grain filling. Foliar selenium (Se) viz. 0, 25, 50, 75 and 100 mg Se L⁻¹ were maintained in sub plots. ‘Heat from spike to grain filling’ proved more damaging for grain yield, starch, gluten and viscoelastic attributes compared to ‘heat from flowering to grain filling’. More pronounced improvements in these traits were quantified with the 100 mg L⁻¹ foliar selenium. Although the application of 75 mg L⁻¹ Se and 100 mg L⁻¹ Se proved equally effective for gluten, peak viscosity, trough viscosity, setback viscosity and final viscosity. ‘Heat from spike to grain filling’ proved more heat susceptible compared ‘heat from flowering to grain filling’ stage. Selenium at 100 mg L⁻¹ produced more remarkable improvements in recorded traits across three heat-imposed environments. All recorded parameters, except damaged starch content, had strong positive correlations with each other.

Maize is a staple crop worldwide due to its extensive food, feed and industrial applications. With climate change, heat waves are becoming more frequent and intense, leading to a significant decrease in maize production. To meet the growing demand for maize products, it is critical to understand the mechanisms by which maize crops respond to heat stress. During anthesis, maize is particularly sensitive to heat, especially in the development of kernels, where kernel number is a major yield component. This sensitivity can vary considerably among different cultivars. However, studies on this topic have been infrequently reported thus far. We comprehensively reviewed controlled experiments from 13 independent, observation-based publications and summarised the negative impacts of heat stress on maize yield and yield components. Our findings indicate that maize is more sensitive to heat stress after silking, particularly during the first 4 days following silking, compared to the period before silking. Moreover, maize yield is further reduced by increased maximum air temperature (T_max) and accumulated heat degree days (HDD) for T_max values exceeding 30°C. Among all the studied maize cultivars, the heating degree days threshold for mild heat stress ranged from 35°C·day in the heat-sensitive cultivar to 59°C·day in the heat-tolerant cultivar. Failing to select the appropriate heat-tolerant cultivars for planting may lead to a significant reduction in maize production. Therefore, we strongly recommend that maize growers select heat-tolerant cultivars or other varieties from the same series before planting to effectively combat climate change.

Salt stress is a major factor limiting the growth, development, and yield of soybeans (Glycine max (Linn.) Merr), yet the regulatory networks underlying soybean resistance to salt stress remain largely unresolved. This study aimed to elucidate the mechanisms of soybean resistance to salt stress by integrating phenotypic, physiological, transcriptomic, and metabolomic analyses of the salt-tolerant soybean cultivar HD6 and the salt-sensitive cultivar ZH929. We found that HD6 exhibited significantly stronger osmotic regulation capacity, enhanced antioxidant capacity, and greater photosynthetic efficiency compared with ZH929. Transcriptomic analysis revealed that differentially expressed genes under salt stress were primarily enriched in pathways related to arginine biosynthesis and isoflavone biosynthesis. Consistently HD6 accumulated higher levels of amino acids and flavonoids. Integrated analysis of transcriptomic and metabolomic data further underscored the critical roles of amino acid and flavonoid biosynthesis regulatory networks in conferring salt resistance. Notably, genes LOC547724 (glutamate decarboxylase, GAD), LOC102661752 (succinate dehydrogenase [ubiquinone] iron–sulfur subunit 2, SDH2), and CHS10 (chalcone synthase 10, CHS), along with metabolites including L-glutamine and rutin, were identified as central components of these networks. Additionally, weighted gene co-expression network analysis highlighted the importance of hub genes such as LOC100820620 (peroxidase) in the salt stress response. Collectively, these findings demonstrate that amino acids and flavonoids are crucial for soybean resistance to salt stress.

Chickpea cultivation during the summer season in the semi-arid tropics offers a potential strategy to enhance cropping intensity, but high temperatures and moisture stress remain major constraints to productivity. A three-year field study was undertaken to assess phenological responses, reproductive efficiency, yield performance and yield stability of nine chickpea genotypes under summer conditions. The short-duration crop recorded substantially reduced grain yield, though with wide genotypic variation ranging from 77 – 651 kg ha⁻¹. Genotypes JG-14 and IPC 06–11 consistently achieved the highest yields (> 540 kg ha⁻¹), primarily due to a higher number of seeds per plant. Reproductive efficiency of the summer crop was impaired, with a mean pollen viability of 63% and pollen germination of 31%. However, JG-14, IPC 06–11 and ICE-15654-A maintained > 70% pollen viability and > 40% pollen germination, coupled with cooler canopy temperatures and relative water content exceeding 60%, indicating superior physiological resilience. Correlation analysis revealed strong negative associations between phenological traits (days to flowering, maturity and reproductive duration) and grain yield, while elevated temperatures during both vegetative and reproductive phases further suppressed productivity. Stability analyses identified JG-14 as the most stable and high-yielding genotype across environments, whereas IPC 06–11 and ICE-15654-A performed comparatively better under relatively cooler and more humid spring conditions. Overall, the study highlights considerable genotypic variability, with JG-14, IPC 06–11 and ICE-15654-A emerging as promising candidates for summer chickpea cultivation in the semi-arid tropics. Further evaluation of a broader germplasm base is warranted to identify lines with stable yield performance under resource-limited summer environments.