Journal of Agronomy and Crop Science最新文献

Blackgram (Vigna mungo) is an important pulse crop grown mainly under rainfed and partly under irrigated conditions in the North Interior Karnataka region of the Deccan Plateau of India. However, rising temperatures and unpredictable rainfall patterns due to climate change pose a significant threat to its consistent performance and productivity. To assess the effect of projected climates (2021–2040) on blackgram productivity in the region, the DSSAT-CROPGRO model was used, which was calibrated and validated using experimental data recorded at the MULLaRP Scheme, University of Agricultural Sciences, Dharwad, India during the year 2022. The study considered two predominant soil types: black clay and red sandy soils across the study area. Under future climates, blackgram yield in the region is projected to decrease by 19.7% on black clay soils and up to 32.0% on red sandy soils compared to the current climate (2011–2020) period under rainfed situations. Among the 12 districts studied, the highest yield reduction under the projected climate was observed in Gadag (51.5% and 69.2%, respectively, in black clay and red sandy soils), followed by Haveri (43.7% and 56.2%, respectively, in black clay and red sandy soils).

Water stress considerably impairs rice growth and reduces grain yield. Brassinolide (BR) can mitigate the detrimental impacts of various stresses on rice growth. However, the effects of BR on rice root growth under water stress have yet to be studied. This research investigated the impacts of BR application on root morphological and physiological traits, nitrogen accumulation and utilisation, photosynthesis and grain yield in rice subjected to water deficiency. A pool experiment was conducted with two irrigation regimes, namely, continuous watering (W) and water deficit (D) conditions, and four BR concentrations, namely, 0 (B0), 0.1 (B1), 1 (B2) and 5 (B3) μmol L⁻¹, over 2 years. Under the W regime, the application of BR increased the grain yield by 9.6%–54.2% compared with that under WB0. At the same BR level, the grain yield under the D treatment was significantly lower than that under the W treatment. However, compared with DB0, BR application at 0.1 μmol L⁻¹ significantly increased the length, surface area, volume, diameter, activity and total and active absorbing area of the roots; increased the activities of nitrate reductase and glutamine synthetase in the roots; and promoted nitrogen accumulation and utilisation and photosynthesis. Compared with DB0, DB1 resulted in a significantly greater rice yield, with an increase of 67.2%–68.4%. Moreover, the grain yield of DB1 was significantly greater than that of WB0. The grain yield of DB2, which was significantly greater than that of DB0, was similar to that of WB0. DB3 did not result in any yield improvement over DB0. These results suggest that the application of BR at a low concentration promotes the morphological and physiological traits of rice roots under water-deficient conditions, thereby increasing nitrogen uptake, use efficiency and grain yield.

High temperatures during the rice panicle initiation stage can easily lead to yield loss. Although exogenous trehalose has been shown to significantly improve plant tolerance to abiotic stresses, its application in rice remains limited. Therefore, in this study, pot experiments were conducted using two rice varieties with differing heat tolerance to investigate whether exogenous trehalose could alleviate heat stress during the panicle initiation stage and to elucidate the underlying physiological mechanisms. The results demonstrated that exogenous trehalose significantly increased rice yield under high-temperature conditions. In the experiment in 2023, the maximum yield increases for N22 and YR343 were 89.5% and 110.3%, respectively, while in 2024, the increases were 89.2% and 111.6%, respectively. The optimal concentration for exogenous trehalose application was found to be 15 mmol L⁻¹. The yield improvement was primarily attributed to the synergistic effects of exogenous trehalose, which not only enhanced leaf photosynthetic capacity but also improved the activity of key carbohydrate metabolism enzymes, up-regulated the expression of sucrose transporter genes, and enhanced sucrose utilisation in young panicles. Additionally, it elevated endogenous trehalose levels, increased the accumulation of osmoregulatory compounds, and enhanced antioxidant enzyme activity, while reducing membrane lipid peroxidation. Furthermore, the regulation of hormone metabolism contributed to improved high-temperature tolerance in rice. In conclusion, the application of trehalose may provide an effective strategy for mitigating high-temperature damage during the rice panicle initiation stage.

Salt and alkaline stress negatively affect the growth, physiology and yield of crops in saline-alkali soil. To date, more studies have focused on crop response to salt stress, but fewer studies have concentrated on the alkali stress on crop production, so that the physiological mechanisms of plants' response to alkali stress are still unclear. In this study, 15 oat varieties were tested for alkali tolerance under four Na₂CO₃ treatment levels (0, 10, 20 and 40 mM Na₂CO₃ solution). The growth characteristics and physiological mechanisms of oat seedlings under alkali stress were investigated, and their alkali tolerance was comprehensively evaluated using methods such as principal component analysis. The results showed that Na₂CO₃ stress significantly inhibited the plant height, root length, stem diameter, total root volume and total root surface area of oat seedlings, with the degree of inhibition increasing with higher alkali stress concentrations (p < 0.05). The activities of peroxidase (POD), superoxide dismutase (SOD), catalase (CAT) and the malondialdehyde (MDA) content in oat seedling leaves generally increased with increasing alkali concentrations. On the basis of growth and physiological characteristics, the alkali tolerance threshold for oats was identified as 10 mM Na₂CO₃. Moreover, principal component analysis and membership function methods were used to comprehensively evaluate alkali tolerance across indicators, identifying strongly tolerant varieties such as Hammer (V1), Monica (V4) and Tyke (V6) and weakly tolerant varieties such as Baiyan 2 (V5) and Apollo (V12). The present investigation comprehensively evaluated the alkaline tolerance of different oat varieties by integrating above-ground phenotypic and below-ground root morphological indicators, providing technical support for the breeding of alkali-tolerant forage crops.

Climate-driven heat stress increasingly threatens waxy maize production, particularly during the jointing stage. Although exogenous salicylic acid (SA) and nitric oxide (NO) are known to improve heat tolerance in plants, their combined (SA-NO) mechanisms in waxy maize remain unclear. This study investigated the effects of exogenous SA, NO and SA-NO co-application on alleviating heat stress in waxy maize during the jointing stage. Results revealed that high temperature (HT) severely impaired plant growth, elevating leaf oxidative damage, disrupting photosynthetic systems and reducing shoot dry weight by 42.7%, compared with the control. Exogenous application of SA, NO and SA-NO mitigated these adverse effects, with the SA-NO combination being most effective. Compared with HT, the SA-NO reduced malondialdehyde and reactive oxygen species levels and increased shoot dry weight by 33.3%. Transcriptomic analysis revealed that SA-NO upregulated photosynthesis-related genes, stabilised starch and sucrose metabolism and glycolysis/gluconeogenesis pathways and enhanced activities of antioxidant enzymes. These changes helped reverse the HT-induced declines in photosynthetic parameters. Additionally, SA-NO restored hormonal balance by modulating ABA, IAA and CTK pathways, upregulating PYR/PYL and CRE1 while downregulating PP2C and SnRK2. These results demonstrate that SA-NO synergistically improves thermotolerance through enhanced antioxidant capacity, restored photosynthetic and hormonal regulation. This strategy offers a promising approach to protect heat-stressed crops in a climate of change.

In areas with freshwater resource shortages, although saline water irrigation can alleviate agricultural water-use pressure, long-term application may lead to soil salinisation and ecological function degradation, thereby affecting greenhouse gas emissions. To clarify its influence on the soil carbon cycle and greenhouse gas emissions, this study collected farmland soil subjected to long-term saline water irrigation (S1: 1 g/L, S2: 4 g/L, and S3: 8 g/L) and analysed the dynamic changes in CO₂ emissions and carbon and nitrogen components through controlled indoor experiments. The soil moisture gradient was defined as follows: W1, W2, and W3 correspond to 45%, 60%, and 75% of the field water-holding capacity, respectively. The results indicated that soil total carbon and total nitrogen decreased over time and were more strongly affected by salinity than by moisture, with both parameters peaking at a salinity level of S2. Both dissolved organic carbon and microbial biomass (microbial biomass carbon, microbial biomass nitrogen) responded distinctly to moisture and salinity: dissolved organic carbon decreased initially and then increased as the salinity increased (S3 > S1 > S2), but it consistently decreased with increasing soil moisture (W1 > W2 > W3), while microbial biomass carbon and microbial biomass nitrogen rose as the soil moisture increased (W3 > W2 > W1). Microbial biomass nitrogen demonstrated higher salt tolerance than carbon biomass, peaking at S2, whereas microbial biomass carbon declined with rising salinity (S1 > S2 > S3). Soil moisture and salinity significantly influenced CO₂ emissions. CO₂ levels increased with rising soil moisture (W3 > W2 > W1). Moderate salinity promoted CO₂ emissions, whereas high salinity suppressed them (S2 > S1 > S3). Compared to the W3S2 treatment, which showed the maximum value (p < 0.05), CO₂ emissions were reduced by 13.84% in W3S1, 24.85% in W3S3, 33.63% in W1S2, and 20.54% in W2S2. These results recommend controlling irrigation salinity at ≤ 4 g/L and maintaining water content at 60%–75% of the water holding capacity to synergistically sustain soil health and emission reduction benefits.

Lodging is one of the main limiting factors threatening crop yields. Although the technology to modify plant morphology and improve lodging resistance using plant growth regulators (PGRs) is well developed, the understanding of the effects and underlying mechanisms of PGRs in regulating stem traits at different growth stages of wheat remains limited. In this study, two cultivars, Shidong 0358 (SD0358, a lodging resistant cultivar) and Xindong 18 (XD18, a lodging-sensitive cultivar), were used to investigate the effects of chlorocholine chloride (CCC) and gibberellin (GA₃) treatment on wheat stem characteristics, lodging resistance, lignin and cellulose biosynthesis processes and yield during the jointing and booting stages. The results showed that in the lodging-sensitive cultivar (XD18), exogenous CCC treatment (CC) at the jointing and booting stages shortened the second basal internode during the flowering and filling stages, while increasing lignin and hemicellulose content, stem breakage strength and stem lodging resistance index, resulting in a decrease in wheat lodging rate and an increase in total yield, compared with CK. However, exogenous CCC and GA₃ (CG) treatments during the jointing and booting stages increased the height of the gravity centre of wheat, reduced the activity of 4-Coumaroyl-CoA and Cinnamyl Alcohol Dehydrogenase, resulting in a decrease in cellulose and hemicellulose content, thereby increasing lodging rate. Meanwhile, under CC treatment, the lodging-resistant cultivar (SD0358) showed enhanced stem breakage strength and enhanced yield with advantageous lignin biosynthesis ability. Interestingly, compared to CC, CG treatment showed an increase in cellulose and hemicellulose content in the stem of SD0358 and a further increase in final yield. Overall, the application of CCC during the jointing and booting stages improved stem morphology and quality, thereby enhancing lodging resistance and final grain yield, especially in lodging-sensitive cultivars. The combined strategy of applying CCC during the jointing stage and GA₃ during the booting stage is an effective chemical regulation method to balance lodging resistance and yield potential in lodging-resistant cultivars.

Seedling-water can effectively ensure the survival of sweet potato seedlings after transplanting. However, improper irrigation of acclimation water can lead to an uncoordinated rhizosphere environment, negatively affecting the formation of storage roots. We conducted field experiments to assess the effects of three seedling-water irrigation treatments on sweet potato root differentiation, monitoring soil water content (SWC), O₂ and CO₂ concentrations, and temperature at 0–30 cm depths, while measuring the expression of genes related to sweet potato root differentiation, shoot biomass, the number of storage roots per plant (NSRPP), and yield. The results indicated that the moderate irrigation treatment (W2) significantly increased NSRPP and yield compared to the insufficient irrigation treatment (W1) and excessive irrigation (W3). Specifically, NSRPP for W2 increased by 48.9% (2022) and 73.2% (2023) relative to W1, and by 12.7% (2022) and 14.1% (2023) compared to W3. Similarly, yield improved by 43.1% (2022) and 32.3% (2023) compared to W1, and by 11.0% (2022) and 23.8% (2023) compared to W3. Correlation analysis revealed that NSRPP is positively correlated with the expression levels of cambium-related genes (IbSRD1 and IbNAC083), while it is negatively correlated with the expression levels of xylem-related genes (IbCAD1, IbEXP1 and IbPAL1). PLS-SEM analysis indicated that soil SWC and soil CO₂ concentrations significantly influenced NSRPP, whereas temperature and soil O₂ concentrations had no significant effect. Multivariate analyses of SWC, soil CO₂ concentrations, and NSRPP revealed that the optimal amount of irrigation ranges from 112.2 to 209.5 m³ hm⁻². These conditions ensured that water, gas, and heat conditions in the rhizosphere are maintained within a range conducive to root differentiation, ensuring that a greater proportion of root differentiation events develop into storage roots. The findings of this study will provide practical guidance for water management during the rooting and branching periods of sweet potatoes.