The coupling of photosynthesis and transpiration in plant leaves forms the basis of carbon–water coupling in terrestrial ecosystems. Previous studies have attributed the coupling of leaf photosynthesis and transpiration to joint stomata control, but they lack analyses of the coupling mechanism. In this study, winter wheat (Triticum aestivum L.) was selected as a plant material on the North China Plain. Under the conditions of warming and drought stress, the photosynthetic rate (An), transpiration rate (Tr), water pressure saturation (VPD), and leaf temperature (T1) of wheat were recorded on clear days at the jointing, flowering, and grain-filling stages from 9:00 to 12:00 a.m. Then, the measured values were fitted to the simulated values obtained using the Ball–Berry and Penman–Monteith models. The results showed that the stomatal size, stomatal conductance, An, and Tr of winter wheat leaves were decreased by warming, drought stress, and their synergistic effects. Based on the Ball–Berry model, different fitting effects were observed in the treatments of adequate water supply with warming (R-g), water deficit with warming (R-d), adequate water supply without warming (N-g), and water deficit without warming (N-d). The R² values of the R-g, R-d, N-g, and N-d treatments were 0.962, 0.958, 0.964, and 0.943, respectively. The Tr values were fitted based on the Penman–Monteith model. In the R-g, R-d, N-g, and N-d treatments, the R2 values of the R-g, R-d, N-g, and N-d treatments were 0.923, 0.849, 0.934, and 0.919, respectively. In conclusion, both warming and water deficit reduce stomatal conductance, An, Tr, and the coupling effect of photosynthesis and transpiration.

To develop optimal management strategies for water and nitrogen fertilizer application in winter wheat cultivation, we conducted a potted experiment to investigate the effects of different irrigation levels and nitrogen fertilizer treatments on the activity of starch synthesis-related enzymes and the grain quality of winter wheat. The potted experiment consisted of three irrigation levels, with the lower limits set at 50–55% (I₀), 60–65% (I₁), and 70–75% (I₂) of the field capacity. In addition, four levels of nitrogen fertilizer were applied, denoted as N₀ (0 kg N hm⁻²), N₁ (120 kg N hm⁻²), N₂ (240 kg N hm⁻²), and N₃ (300 kg N hm⁻²), respectively. The results revealed the significant impacts of irrigation and nitrogen treatments on the activities of key starch-related enzymes, including adenosine diphosphoglucose pyrophosphrylase (ADPG-PPase), soluble starch synthase (SSS), granule-bound starch synthase (GBSS), and starch branching enzymes (SBE) in wheat grains. These treatments also influenced the starch content, amylopectin content, and, ultimately, wheat yield. In summary, our findings suggest that maintaining irrigation at a lower limit of 60% to 65% of the field capacity and applying nitrogen fertilizer at a rate of 240 kg hm⁻² is beneficial for achieving both high yield and high quality in winter wheat cultivation.

Objective: This study aims to elucidate the mechanisms by which rhamnolipid-modified biochar enhances saline soil quality and increases peanut yield, while preliminarily exploring its potential ecological risks. The findings are expected to provide theoretical and technical support for the sustainable improvement of saline soils in arid regions and for the green production of peanuts. Methods: A field experiment was conducted with three treatments: a control (CK, no biochar application), biochar (BC, application of cotton stalk biochar), and modified biochar (RBC, application of rhamnolipid-modified biochar). The amelioration effects and driving mechanisms of modified biochar on saline soil were investigated by analyzing soil physicochemical properties, microbial community structure, enzyme activities, and peanut yield under different treatments. Results and discussion: The results showed that, compared with the control, the application of rhamnolipid-modified biochar significantly increased total carbon (by 30.33%-45.20%), total nitrogen (by 28.66%-55.76%), organic carbon (by 244.07%-370.10%), and moisture content (by 25.61%-42.42%) in the 0-20 cm soil layer, while significantly decreasing the total salt content (by 39.40%-56.78%). Furthermore, the RBC treatment activated the activities of soil urease, sucrase, and cellulase. Regarding the microbial community, modified biochar mitigated the inhibitory effect of unmodified biochar on bacterial diversity. It enriched nutrient-rich microbial groups such as Proteobacteria, Acidobacteria, and Firmicutes, as well as salt-tolerant functional bacteria like Neobacillus and Luteitalea, and the fungal phylum Ascomycota. Concurrently, it suppressed the abundance of pathogenic fungi such as Basidiomycota and Colletotrichum, thereby reducing the risk of soil-borne diseases. Random forest analysis identified total carbon, total organic carbon, and soil carbon loading as key environmental factors driving changes in the soil microbial community. Partial least squares path modeling further confirmed that modified biochar improved soil physicochemical properties, activated enzyme activities, subsequently regulated the fungal community, alleviated the suppression of the bacterial community, and fostered the formation of a synergistic microbial network structure. These combined effects ultimately enhanced soil quality and led to a significant 27.57% increase in peanut yield.

In order to ensure national grain and oil security, it is imperative to expand the soybean planting area in the Xinjiang region. However, the scarcity of water resources in southern Xinjiang, the relatively backward soybean planting technology, and the lack of a supporting irrigation system have negatively impacted soybean planting and yield. In 2022 and 2023, we conducted an experiment which included three irrigation amounts of 27 mm, 36 mm, and 45 mm and analyzed the changes in dry mass and yield. Additionally, we simulated the potential yield using the corrected DSSAT-CROPGRO-Soybean model and biomass based on the meteorological data from 1994 to 2023. The results demonstrated that the model was capable of accurately predicting soybean emergence (the relative root mean square error (nRMSE) = 0, the absolute relative error (ARE) = 0), flowering (nRMSE = 0, ARE = 2.78%), maturity (nRMSE = 0, ARE = 3.21%). The model demonstrated high levels of accuracy in predicting soybean biomass (R² = 0.98, nRMSE = 20.50%, ARE = 20.63%), 0–80 cm soil water storage (R² = 0.64, nRMSE = 7.78%, ARE = 3.24%), and yield (R² = 0.81, nRMSE = 10.83%, ARE = 8.79%). The biomass of soybean plants increases with the increase in irrigation amount. The highest biomass of 63 mm is 9379.19 kg·hm⁻². When the irrigation yield is 36–45 mm (p < 0.05), the maximum yield can reach 4984.73 kg·hm⁻²; the maximum efficiency of soybean irrigation water was 33–36 mm. In light of the impact of soybean yield and irrigation water use efficiency, the optimal irrigation amount for soybean cultivation in southern Xinjiang is estimated to be between 36 and 42 mm. The simulation results provide a theoretical foundation for soybean cultivation in southern Xinjiang.

Optimizing water and nitrogen management is an effective measure to reduce nitrogen fertilizer loss and environmental pollution risks. This study aims to quantify the impacts of different water and nitrogen management strategies on the soil microenvironment and yield of spring soybeans in southern Xinjiang. In this study, two irrigation quotas were established: W1—36 mm (low water) and W2—45 mm (high water). Three nitrogen application gradients were established: low nitrogen (150 kg·hm⁻², N1), medium nitrogen (225 kg·hm⁻², N2), and high nitrogen (300 k kg·hm⁻², N3). The analysis focused on soil physicochemical properties, enzyme activities, microbial community diversity, soybean yield, and soybean quality changes. The results indicate that the activities of nitrate reductase and urease, as well as total nitrogen content, increased with higher irrigation and nitrogen application rates. The W2N3 treatment significantly increased 0.15 to 4.39, 0.18 to 1.04, and 0.31 to 1.73 times. (p < 0.05). Alkaline protease and sucrase activities increased with higher irrigation amounts, while their response to nitrogen application exhibited an initial increase followed by a decrease. The W2N2 treatment significantly increased by 0.10 to 0.34 and 0.07 to 1.46 times (p < 0.05). Irrigation significantly affected the soil bacterial community structure, while the coupling effects of water and nitrogen notably influenced soil bacterial abundance (p < 0.05). Increases in irrigation and nitrogen application enhanced bacterial diversity and species abundance. Partial least squares path analysis indicated that water–nitrogen coupling directly influenced the soil microenvironment and indirectly produced positive effects on soybean yield and quality. An irrigation quota of 4500 m³ hm⁻² and a nitrogen application rate of 300 kg·hm⁻² can ensure soybean yield while enhancing soil microbial abundance. The findings provide insights into the response mechanisms of soil microbial communities in spring soybeans to water–nitrogen management, clarify the relationship between soil microenvironments and the yield and quality of spring soybeans, and identify optimal irrigation and fertilization strategies for high quality and yield. This research offers a theoretical basis and technical support for soybean cultivation in southern Xinjiang.