Xiaoman Qiang

Regulated deficit irrigation is a vital method for developing water-saving agriculture. The degree of and the period of water deficit are two key factors determining the effectiveness of regulated deficit irrigation. In this study, winter wheat was used as the experimental material, and water deficit was imposed by reducing the irrigation lower limit. Three water deficit treatments were established, with irrigation lower limits set at 65%, 55%, and 45% of field capacity, respectively. There were three stages of water deficit: the jointing stage, the heading-anthesis stage, and the ripening stage; full irrigation (with a minimum irrigation level of 75% field capacity) served as the control. The physiological and growth indicators were measured, including plant water status, osmotic regulation, antioxidant activity, leaf gas exchange and yield. The variation patterns of physiological indicators during the irrigation cycle under reduced irrigation lower limits at different growth stages were explored. The synergistic response relationships among physiological indicators were analyzed; the physiological mechanism by which the degree and stage of water deficit jointly influence winter wheat yield was elucidated. The results indicate that lowering the lower limit of irrigation reduces net photosynthesis prior to irrigation. When the lower irrigation threshold exceeds 55%, chlorophyll content remains largely unaffected. However, increased stomatal conductance following irrigation results in higher net photosynthesis under the low irrigation threshold treatment compared to the control. When the irrigation lower limit is below 55%, chlorophyll content decreases significantly, resulting in net photosynthesis remaining markedly lower than the control even after irrigation. During the jointing stage and heading-anthesis stage, plants exhibit weaker osmotic regulation and antioxidant capacity, and the chlorophyll content is greatly affected by water deficit, resulting in reduced net photosynthesis before and after irrigation, leading to a greater decrease in winter wheat yield. The results on the physiological and biochemical characters (excluding gas exchange parameters) are limited to one year. The research findings provide the theoretical reference for regulated deficit irrigation of winter wheat.

Drought stress induced by climate change is a major limiting factor for crop growth. Selenium (Se) is recognized as an important exogenous regulator that can mitigate drought and other abiotic stresses, but the effects of Se application at different growth stages remain unclear. In this study, greenhouse-grown tomato plants were subjected to four Se treatments (T1: control; T2: Se at seedling stage; T3: Se at flowering stage; T4: Se at both stages) combined with three irrigation regimes (W1: 50–55%, W2: 65–70%, W3: 80–85% of field capacity). The impacts of Se timing on antioxidant enzymes, osmotic regulators, and growth parameters were evaluated. Drought stress induced oxidative damage, reduced photosynthesis, and inhibited biomass accumulation, while proline content increased with drought severity. Se application showed clear growth-stage specificity: under mild stress, Se at the flowering stage most effectively enhanced antioxidant activity, regulated proline metabolism, improved photosynthetic performance, and promoted growth. Dual-stage application did not provide additional benefits. These findings indicate that applying Se during the flowering and fruiting stage is optimal for alleviating drought-induced growth inhibition in tomato. The results contribute to understanding Se-mediated drought tolerance and may support the development of stage-specific Se fertilizer management strategies.

Soil salinity and water deficit are important challenges for sustainable agricultural development in arid and semi-arid regions. While soil salinity and water deficits may result in lower crop yields, they may improve crop quality. The quantitative relationship between water–salt stress, crop yield, and quality is key to achieving stable yield and enhanced quality through the coordinated regulation of soil water and salt. The interaction between soil salinity and deficit irrigation on tomato quality needs to be further understood, and the model simulating the response of tomato quality to deficit irrigation under simulated soil salinity needs to be further optimized. In this study, a two-year experiment was conducted in northwest China consisting of combinations of three soil salinity levels (0 g, 3 g, and 5 g mixed salt added to 1000 g air-dried soil, respectively) and four water regimes relative to the field capacity (θ_f) (W0, W1, W2, and W3 refer to 95% θ_f, 80% θ_f, 70% θ_f, and 60% θ_f as the upper limit of soil water content, respectively). The responses of plant stem water potential (φ), fruit osmotic potential (φ_π), fruit Na⁺ content, fruit fresh weight, fruit water content, total soluble solids (TSS), lycopene (Ly), soluble sugars content (SSC), and color index (CI) to the degree of water deficit and the stage of water deficit were analyzed under soil salinity. The results show that both soil salinity and water deficit significantly reduced φ, but there is no significant interaction. TSS, SSC, and CI are all significantly affected by soil salinity, degree of water deficit, and stage of water deficit, and there is a significant interaction between the degree of water deficit and soil salinity. Fruit fresh weight, TSS, Ly, SSC, and CI are all strongly correlated with φ, and the straight lines of regression of each index with φ are significantly affected by soil salinity content. Soil salinity significantly increased the Na⁺ content in the fruit, and water deficit significantly enhanced the effect of soil salinity on the Na⁺ content of tomato fruit. A functional model to simulate fruit quality was developed based on the response of fruit quality parameters to φ and the effect of fruit Na⁺ accumulation under the compound effect of soil salinity and water deficit. The validation results of the model show that this function model effectively simulates tomato fruit quality under the combined effects of soil salinity and water deficit, providing a theoretical basis for soil water–salt management in arid and semi-arid regions.

Microplastic (MP) pollution in agriculture is garnering growing concern due to its potential detrimental impact on soil properties and crop growth, particularly affecting staple food crops such as rice. Irrigation plays a crucial role in the migration of MPs. However, limited research has focused on how different irrigation modes affect the migration of MPs in paddy fields. To simulate real-world conditions, in this experiment, two different irrigation modes were set: shallow–frequent irrigation (FWI, I₀) and controlled irrigation (CI, I₁). The experiment also included treatments with and without duckweed (D₀ and D₁, respectively), as well as treatments with and without MPs (M₀ and M₁). This resulted in a total of eight treatments: I₀M₀D₀, I₀M₀D₁, I₁M₀D₀, I₁M₀D₁, I₀M₁D₀, I₀M₁D₁, I₁M₁D₀, and I₁M₁D₁. Our findings indicated that compared to CI, FWI significantly increased the MP concentration in the leakage but reduced the numbers of MPs in the first soil layer and adhered by duckweed. Notably, dry–wet cycles under CI induced soil cracking, and the MP concentrations in cracked areas were significantly higher than those of crack-free soil. Moreover, compared with the MP-free treatment, MP treatments significantly influenced rice root growth, such as enhancing the average root diameter by 13.44%, root volume by 46.87%, root surface area by 30.81%, and biomass aboveground by 26.13%, respectively. The abundance of some microorganisms was also significantly influenced by the relative mobility (R_M) of MPs. Furthermore, the root length was positively correlated with Planctomycetota. Meanwhile, Actinobacteriota was negatively correlated with the root surface area, root volume, and branch number, and Bacteroidota was negatively correlated with the number of root tips. However, further research is needed to elucidate how MPs influence microorganisms and, in turn, affect rice root growth.

Straw strip burial in saline soil is an effective method for tideland reclamation in China, but optimal forms of straw strips for regulating soil water and salinity remain unclear. An indoor soil column test investigated the water and salt distribution in soil treated with four different straw forms under freshwater irrigation. The treatments included no straw layer (CK), straw stalks arranged longitudinally (T₅), horizontally (T₂₅), longitudinally combined horizontally in layers (T_25+2.5), and randomly (T_2.5). The results showed that compared to CK, T₂₅, T₅, and T_25+2.5 significantly reduced the infiltration rate of irrigation water, leading to prolonged infiltration times. Wetting front curves under T₅, T_25+2.5, and T₂₅ exhibited similar inverted “V” shapes, while CK and T_2.5 showed fluctuating parallel lines. Water retention in the soil was higher under straw strip treatments (T₅, T₂₅, T_25+2.5) and straw layer treatment (T_2.5) compared to CK after 24 h of the first irrigation. T₅ demonstrated the most effective salt removal, surpassing other treatments, with a desalination rate of 97.71%. Additionally, T₅ had the highest salt leaching efficiency (SLE) in the 0–20 cm soil layer, recommending it as the optimal form for managing saline soils in crop production due to its simplicity and higher SLE. We found that buried straw strips reduced soil water infiltration rate and wetting front propulsion speed, increased soil water content and enhanced salt leaching efficiency in the saline soil. Our findings provide a basis for developing strategies that improve soil quality and irrigation efficiency, mitigate the effects of salinity on crop production, and ensure food security for a rapidly growing global population.

Drought stress can impact the physiological and biochemical properties of crops. However, selenium (Se) can effectively alleviate the abiotic stress experienced by plants. This study aims to investigate how applying selenium to tomato leaves affects their antioxidant system and photosynthetic traits when subjected to drought conditions. The experiment used four different foliar selenium concentrations and three different irrigation levels. The investigation scrutinized the effects of foliar spraying employing different selenium concentrations on the antioxidant system, osmotic adjustment substances, photosynthetic performance, and growth indices of tomatoes under drought stress. The findings indicated that drought stress led to cellular oxidative damage, significantly elevating peroxide, MDA, proline, and soluble sugar content (p < 0.001). Under severe drought stress, malondialdehyde (MDA) and proline levels increased by 21.2% and 110.0% respectively, compared to well-watered conditions. Concurrently, the net photosynthetic rate exhibited a reduction of 26.0% and dry matter accumulation decreased by 35.5%. However, after spraying with a low concentration of selenium, selenium reduced oxidative damage and malondialdehyde content by reducing the content of peroxide in leaves, restoring photosynthesis, and promoting the normal growth of tomato. Compared to the control group, spraying with 2.5 mg·L⁻¹ selenium resulted in a 21.5% reduction in MDA content, a 111.8% increase in net photosynthetic rate, and a 29.0% increase in dry matter accumulation. When subjected to drought stress conditions, foliar spraying of low concentrations of selenium (2.5 mg·L⁻¹) can effectively reduce oxidative damage caused by drought stress and alleviate growth constraints in tomatoes. In addition, treatments with high selenium concentrations exhibited specific toxic effects. These findings offer valuable insights into the mechanisms governing selenium-induced drought tolerance in tomatoes, thus advancing our comprehension of standard tomato production practices.

The yield, quality, and water–fertilizer use efficiency of crops are important parameters for assessing rational water and fertilizer management. For an optimal water and fertilizer system with respect to the nutrient solution irrigation of greenhouse tomatoes using cultivation substrates, a two-year greenhouse cultivation experiment was conducted from 2022 to 2023. Three drip fertigation treatments (T1, T2, and T3) were implemented in the experiment, where nutrient solutions were supplied when the substrate’s water content reached 60%, 70%, and 80%. The frequency of nutrient solution applications is based on weighing coconut coir strips in the morning and evening at 7:00 to determine the daily water consumption of plants. Nutrient solutions were supplied when the substrate’s water content reached the lower limit, and the upper limit for nutrient supply was set at 100% of the substrate water content. The nutrient solution application was carried out multiple times throughout the day, avoiding the midday heat. The nutrient solution formula used was the soilless tomato cultivation formula from South China Agricultural University. The results show that plant height and the leaf area index rapidly increased in the early and middle stages, and later growth tended to stabilize; the daily transpiration of tomatoes increased with an increase in nutrient solution supply, and it was the greatest in the T3 treatment. Between the amount of nutrient solution application and the number of years, the yield increased with the increase of the amount of nutrient solution, showing T3 > T2 > T1. Although the average yield of the T2 treatment was slightly lower than that of the T3 treatment by 3.65%, the average irrigation water use efficiency, water use efficiency, and partial fertilizer productivity of the T2 treatment were significantly higher than those of the T3 treatment by 29.10%, 19.99%, and 28.89%, respectively (p < 0.05). Additionally, soluble solid, vitamin C, and soluble sugar contents and the sugar–acid ratio of tomatoes in the T2 treatment were greater than those in the other two treatments (p < 0.05). Using the TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) method, it was concluded that the nutrient solution application rate of 70% can significantly increase water and fertilizer use efficiency and markedly improve the nutritional and flavor quality of the fruit without a significant reduction in yield. This finding provides significant guidance for the high-yield, high-quality, and efficient production of coconut coir-based cultivated tomatoes in greenhouses.

An appropriate water supply strategy is imperative for obtaining tomatoes of a high yield and quality; the lack of one has caused resource wastage and quality deterioration. To determine the suitable irrigation amount and simulate daily transpiration under these optimal irrigation conditions, a two-year greenhouse cultivation experiment was conducted over 2022–2023. Commencing at anthesis, three distinct irrigation gradients were triggered and designated as irrigation controls with the lower limits set at 80% (T1), 70% (T2), and 60% (T3) of the substrate water-holding capacity. We determined the optimal irrigation amount by ranking the treatments using the TOPSIS method, balancing the tomato yield and quality. A segmented daily transpiration model under optimal irrigation conditions driven by crop and environmental factors was established using the Marquardt method and data from 2022, and the model was validated using data from 2023. The results indicated that T2 was the optimal irrigation amount, with the water use efficiency increased by 18.0%, but with a 10.9% decrease in yield, while the quality indices improved significantly. The R² values of the segmented model in the flowering and fruit-setting stage and the picking stage were 0.92 and 0.86, respectively, which could provide support for optimized water management for tomato planting in greenhouse substrate cultivation.

In order to explore the effects of subsoiling tillage measures on the construction of soil cultivated horizon and the yield and water use efficiency of winter wheat in the North China Plain, three tillage methods, including no tillage (PZ), rotary tillage (PR), and subsoiling (PS), combined with straw returning measures were implemented in the winter wheat season in Xinxiang, Henan Province from 2016 to 2018. The effects of tillage measures on the improvement of cultivated land quality and the water saving and yield increase of winter wheat were investigated. The results showed that compared with no-tillage treatment, subsoiling significantly reduced soil bulk density by 8.88% and increased soil porosity by 13.04% in 20–40 cm soil layer; significantly reduced soil compaction by 56.96% in 0–40 cm soil layer; subsoiling combined with straw returning significantly increased soil organic carbon content in plough layer of winter wheat, whereas rotary tillage decreased soil organic carbon content. Subsoiling is more conducive to soil moisture movement to the deep layer after irrigation or rainfall, and the water consumption of subsoiling is the largest in the whole growth period of winter wheat. Subsoiling could better coordinate the relationship between water consumption and yield, which increased yield by 34.48–38.10% and water use efficiency by 19.57–21.96% compared with no-tillage treatment, respectively. Therefore, subsoiling before sowing combined with straw returning was beneficial to the reasonable construction of soil cultivated horizon, and significantly improved the yield and water use efficiency of winter wheat under the climatic conditions in the North China Plain.