Journal of Agronomy and Crop Science最新文献

Climate change has a detrimental impact on the sustainable development of wheat yield and quality. Delaying sowing dates and adjusting sowing rates represent straightforward and effective strategies for mitigating such effects, albeit with their underlying mechanisms remaining poorly characterised. In this investigation, taking the North China Plain (NCP) as an example, we conducted a meta-analysis of 59 studies and proving experiments at two locations. The results indicated that the wheat yield and ecological conditions had significant correlations, and reasonable late sowing and optimised sowing rates could significantly improve yield. In general, the relevant analysis showed that there was a positive correlation of 0.488 between soil organic matter and yield, and the negative correlations of yield on temperature and precipitation were 0.245 and 0.466, respectively. Furthermore, late sowing ≤ 10 days could increase yield by 3.05%–11.80% and the yield raised 1.31%–13.16% at a sowing rate of 201–300 kg/hm² under the precipitation > 600 mm, temperature ≥ 12°C and > 15 g/kg soil organic matter in the study. Late sowing and increasing sowing rates had a negative impact on wheat quality, which requires other management measures to be taken to balance production. In conclusion, our study elucidates the influence of late sowing and sowing rates on wheat yield and quality, providing a theoretical basis for subsequent research on the relationship between climate factors and crop yields–quality trade-offs.

The scarcity of good-quality irrigation water has driven farmers to use saline water for crop production, which can adversely affect soil fertility and plant growth. Therefore, a long-term (2006–2025) field experiment was conducted to investigate the effects of saline water application by different irrigation methods on cotton seedling emergence and growth, and to promote safe saline water use. The field experiment employed two irrigation methods, namely border irrigation (B) and furrow irrigation with channels (F), with each irrigation method paired with six salt concentration levels (1.3, 3.4, 7.1, 10.6, 14.1, 17.7 dS·m⁻¹; 1.3 dS·m⁻¹ was the freshwater control). Observations showed that compared with furrow irrigation, the soil moisture contents and salinity levels under border irrigation increased by 0.9%–4.1% and 0.1%–27.7%, respectively. Additionally, soil moisture content and salinity rose as irrigation water salinity increased in both irrigation methods. Topsoil (0–20 cm) moisture content and salinity exhibited significant interannual fluctuations, with no steady salinity accumulation due to precipitation and associated climatic conditions. The seedling establishment rate declined with increasing water salinity under both methods; border irrigation was superior at water salinity ≤ 8.3 dS·m⁻¹, while furrow irrigation performed better above this threshold. Stability and sustainability of the establishment rate decreased markedly at water salinity ≥ 10.6 dS·m⁻¹. The relative establishment rate over the years (referenced to the freshwater treatments with an electrical conductivity of 1.3 dS·m⁻¹) exhibited a significant quadratic relationship with irrigation water salinity. When the seedling establishment rate began to decline and reached a 10% reduction, the corresponding irrigation water salinity thresholds for border irrigation were 2.2 dS·m⁻¹ and 10.0 dS·m⁻¹, and for furrow irrigation were 1.9 dS·m⁻¹ and 10.4 dS·m⁻¹, respectively. High salinity significantly delayed cotton emergence and reduced seedling growth parameters (plant height, leaf area, and dry matter weight). Seedling growth was better under border irrigation than under furrow irrigation at irrigation water salinity ≤ 10.6 dS·m⁻¹. This study provides a scientific basis and practical reference for cotton cultivation using local saline water resources.

The impact of climate change, as evidenced by increasingly higher temperatures and decreasing precipitation, presents a substantial threat to wheat crops globally. In the Indo-Gangetic Plains (IGP), which is the breadbasket of India, it is evolving as the biggest threat to food security and livelihoods for the farming fraternity. A 3-year field study evaluated the effects of drought and heat stress on wheat yield and how these effects interact with morphophysiological traits. This study deployed staggered sowing and controlled irrigation to simulate droughts synchronising with vegetative and reproductive stages of the crop across 13 wheat cultivars selected based on their prevalence among farmers. Principal component analysis (PCA) and Pearson's correlation matrices were used to reduce data dimensionality for shortlisting independent morphophysiological variables before measuring average treatment effects. Findings highlighted a decline in levels of relative water content (RWC), chlorophyll and carotenoid under stress treatments. A sharp reduction of almost 50% in grain yield was observed when the crop encountered drought and heat stress simultaneously. Another finding revealed that RWC, chlorophyll content and proline accumulation were strongly associated with resilience to these stresses. The study identified two wheat cultivars (HD 2967 and HI 1531) that demonstrated superiority in coping with stress conditions consistently under both timely and late sowing conditions. These findings are insightful for wheat breeders, highlighting potential plant traits for climate-resilient breeding programmes. The study also generated important evidence that can potentially inform policy makers around sowing time, irrigation scheduling and seed systems of wheat in eastern India and similar agroecological regions.

Heat stress severely impairs wheat yields and poses significant challenges to food security. In the present investigation, 72 diverse bread wheat genotypes were evaluated in the completely randomised block design with two replicates at four locations under normal and heat stress conditions during Rabi, 2022–23. The mean maximum temperature was above congenial (> 25°C) at 27.9°C, 28.8°C, 33.4°C and 33.3°C at Karnal, Hisar, Niphad and Pune locations, which imposed adverse effects at the heading and grain filling stages. Under heat stress, the pooled mean grain yield varied from 294.8 g (DHTW60) to 660.2 g/plot (RWP2017-21). The genotype DBW173 showed an 8.07% yield reduction under heat stress, followed by DBW187 (9.51%), PBW826 (10.25%), 29^th SAWYT-303 (10.36%), Raj3765 (11.41%), and RWP2017-21 (11.54%). The 1000 grain weight (TKW) reduction was also low for these genotypes, except for 29^th SAWYT-303 (19.80%). Here, the yield stability index (YSI) and heat susceptibility index (HSI) ranged from 0.56 to 1.02 and −0.09 to 1.95, respectively. In contrast, the relative heat index (RHI) and percent yield reduction (PYR) varied from 0.73 to 1.31 and −1.99 to 43.63, respectively. The low HSI values (< 0.60) were recorded for NIAW1342, HI1605, DBW173, DBW187, PBW826, 29^th SAWYT-303, 20^th HTWYT-2, Raj3765, RWP2017-21, K7903 and K9465. PCA clustered 13 heat stress indices into three clusters, where TOL, HSPI, HSI and PYR were grouped into a single segment. The genotypes DBW173, DBW187, HI1531, HI1605, NIAW1342, PBW826, Raj3765, RWP2017-21, 20^th HTWYT-2, 20^th HTWYT-13, 20^th HTWYT-41, 29^th SAWYT-303 and WAP96 appeared as heat tolerant. The higher TKW, grains/spike, coupled with higher NDVI values, can be used as selection criteria under heat stress breeding. The indices HSI, PYR, HRI, YI and YSI can be employed effectively in future studies.

Global seasonal heat and drought have become the main limiting factors affecting maize growth and grain yield. Huanong138 (HN138) and Zhengdan958 (ZD958) were used as the experimental material. The greenhouse experiment was conducted to uncover tassels and ear morphological development and grain fertility rate of maize under three stressors (heat (H), drought (D), and heat + drought (H + D)) at tasselling for 14 days. On average of the two hybrids, grain yield decreased by 17.3%, 31.2% and 45.4% in H, D and H + D, respectively, compared with CK. The grain fertility rate of stress treatments significantly reduced by 11.6%–28.7% under natural pollination (H♀ × H♂, D♀ × D♂), and reduced by 6.7%–24.7% under the condition of positive pollination (CK♂ × H or/and D♀), while reduced by 24.2%–48.9% under the condition of reverse pollination (CK♀ × H or/and D♂) than control, respectively. Moreover, pollen quantity, total spikelet number and density of tassels, silk viability significantly decreased, while anthesis silking interval was prolonged by 0.5–3.4 days in two genotypes under individual and combined stress than control. Individual and combined stress treatments suppressed grain sucrose metabolism via coordinated downregulation of sucrose synthase (SS) by 16.1%–59.2% and sucrose-phosphate synthase (SPS) activities by 2.6%–44.9% in developing grains, concomitantly triggering sucrose translocation to leaves and stalk, suggesting source-sink redistribution under stress constraints. Notably, the reduction of grain yield mainly resulted from stunted pollen development and limited sugar transport. These provided a strategy for future selected hybrids with the shorter ASI, higher pollen viability and quantity adapting well to climate change.

The cultivation strategy of ‘postponed nitrogen with increased panicle fertilization (PNIPF)’ boosts rice yield but the balance between lodging remains unclear. We evaluated three panicle nitrogen ratios (0%, 20% and 40% of total 165 kg N ha⁻¹) in two late indica rice varieties (Meixiangzhan 2 and Taiyou 871) to assess this trade-off. Results demonstrated that: (1) Compared to R₀, PNIPF to 20% showed no difference on yield, while R₄ raised grain yield by 4.84% and 8.69% but increased lodging index by 30.5% and 35.8% in TY871 and MXZ2. (2) Relative to R₀, R₄ induced taller plants with elevated center of gravity, reduced culm diameter, diminished culm mechanical strength, and decreased structural carbohydrate content (cellulose −29.2%, lignin −23.8%). The effect of R₂ is weaker than R₄ on plant morphology. (3) Compared to R₀, R₄ manifested more profound anatomical deterioration than R₂. (4) Significant variety differences existed; PNIPF exhibited a more profound impact on MXZ2 than TY871 by inferior morphological, physiological and anatomical traits. We recommend limiting panicle nitrogen to below 20% to achieve synergistic improvement of yield and lodging resistance in high-quality late indica rice production.

High temperatures impact sweet maize production; however, their specific effects on grain yield and kernel quality across different growing seasons remain unquantified. This study investigated high-temperature season effects, evaluated the yield and kernel quality responses in two sweet maize hybrids with different heat tolerance, and analysed the response mechanisms of dry matter accumulation (DMC), flowering, and grain filling in South China. Two contrasting sweet maize hybrids were planted annually in spring, summer, and autumn over a 2-year field experiment in Guangdong, South China. An evaluation of extreme degree days at different growth stages revealed that the sweet maize crops experienced high-temperature stress during their reproductive stages in the spring and summer growing seasons. In the high-temperature season, ‘HMT8’ showed heat sensitivity, with the grain yield significantly decreasing because of the lower kernel weight. The reduced grain-filling rates, especially in the early stages, contributed to lower kernel weight, which may be related to the decreased leaf area index (LAI) and post-anthesis DMC. Comparatively, ‘GLT27’ was heat-tolerant, with the grain yield slightly increasing because of the increased kernel number. However, it appeared cold-sensitive during the grain-filling stages in autumn. ‘GLT27’ exhibited stable or slightly increased pollen viability, LAI, post-anthesis DMC, and grain-filling rates. Furthermore, both hybrids showed reduced sucrose and elevated free amino acid content in the high-temperature seasons. Early grain-filling and post-anthesis DMC rather than reproductive organ viability may limit sweet maize during high-temperature seasons. Managing crops by selecting varieties and cultivation practices for different annual growing seasons is crucial.

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.