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【Background】 Soil microorganisms underpin soil functions, and its community is influenced by a multitude of abiotic and biotic factors. The objective of this paper is to study the combined effect of biochar amendment and subsurface drainage on microbial communities in salinized soil in coastal ecosystems. 【Method】 The experiment was conducted in a field at the Yellow River delta, with the subsurface drains spaced by10 m (S10), 20 m (S20), and 30 m (S30), respectively. For each drain spacing, there was a biochar amendment treatment and non-biochar treatment. During the experiment, we measured the changes in soil physicochemical properties and microbial community structure. And the main driving factors for the changes in microbial community structure under synergistic effect of biochar and subsurface drainage were elucidated. 【Result】 Biochar amendment and subsurface drainage altered soil physicochemical properties. Biochar amendment and drain spacing were interactive having a significant impact on salinity, nitrate nitrogen, organic matter and total phosphorus in the soil. The sequencing of AccuITSTM and Accu16STM showed that drain spacing working separately or in combination with biochar amendment had a significant effect on Agaricomycetes and Acidobacteria_Gp4, albeit the underlying mechanisms are elusive. Redundancy analysis and Pearson correlation analysis showed that the absolute abundance of Agaricomycetes and Mortierellomycetes, beneficial for crop growth, were negatively correlated with soil salinity and sodium ions while positively correlated with organic matter and nitrate nitrogen, both at significant levels. Sodium ion content was the key factor affecting soil bacteria and fungi in all treatments we compared. 【Conclusion】 Amending the salinized soil by biochar coupled with subsurface drainage with the drains spaced 10 m apart worked best for improving soil nutrient and soil microbial community structure. It can be used as an improved technique for soil reclamation and agriculture production in salinized soils in coastal regions.

【Objective】 The purpose of this paper is to give full play to the respective advantages and synergistic effects of straw mulching and suitable irrigation on crop yield and soil carbon sequestration and emission reduction, establish an efficient farmland management mode of emission reduction, increase, and water saving. 【Method】 Taking summer maize in Western Henan as the research object, the mulching method and the lower limit of irrigation water were tested. The mulching method was straw mulching (S) and no mulching (N). The lower limit of irrigation water was set at four levels: 50% (W1), 60% (W2), 70% (W3) and 80% (W4) of field water holding capacity. Soil respiration, crop biomass and grain yield under different treatments were systematically studied. The total amount of soil carbon emission, the amount of soil microbial isooxygen respiration carbon release and the amount of carbon sequestration of farmland net primary productivity were calculated. Farmland net ecosystem productivity (NEP) was calculated as the carbon sequestration of farmland net primary productivity and the carbon release of soil microbial iso-respiration. Carbon emission efficiency (CE) calculated from crop yields and soil carbon emissions reflected the economic and environmental benefits of farmland. NEP and CE were used to objectively evaluate the effects of straw mulching and different irrigation lower limits on crop yield and carbon sequestration. 【Result】 The soil respiration rate of SW4 treatment was the highest and that of NW1 treatment was the lowest. Soil respiration rate of SW4 treatment reached the highest value at anthesis stage 6.08 μmol/(m2·s), and there was no significant difference between SW3 treatment and NW4 treatment. Compared with NW1 treatment, straw mulching and irrigation increased the amount of carbon sequestration in farmland net primary productivity and the amount of soil microbial iso-respiratory carbon release, and that of SW4 treatment was the highest, with no significant difference compared with SW3 treatment and NW4 treatment. SW3 treatment had the highest NEP which was 3.99%-245.74% higher than that of other treatments and the highest CE which were 2.35%-138.80% higher than that of other treatments. Compared with SW4 treatment, NEP of SW3 treatment increased by 2.99% and CE of SW3 treatment increased by 2.35% under the premise of saving irrigation. 【Conclusion】 The lower limit of irrigation water is 70%FC and straw mulching (SW3) treatment, which can effectively coordinate the yield and carbon emission efficiency of summer maize farmland system, promote higher crop yield, achieve higher net ecosystem productivity and carbon emission efficiency, and reduce the carbon emission generated in the production process under the condition of higher irrigation amount. Achieve carbon sequestration and emission reduction and water utilization system promotion. Considering net ecosystem productivity and carbon emission efficiency of farmland, SW3 treatment can be used as a farmland management mode for water saving, emission reduction and yield increase.

【Background and objective】 Soil salinization is a biotic stress facing agriculture production in almost all countries. It not only destroys soil structure but also reduces bioavailable nutrients and the ability of soil to sequester carbon. Amending stalinized soil with biochar is a technology to improve soil quality and productivity, but its efficacy depends on soil texture and the amount of biochar being applied. The objective of this paper is to study the optimal biochar amendment for improving soil quality and fertility for cotton growth. 【Method】 The experiment was conducted in pots with the cultivar Medium S9612 used as the model plant. The soil was amended by biochar at ratios of 0 (CK), 1% (BC1), 1%(BC1), 3% (BC3) and 5% (BC5), respectively. In each treatment, we measured physicochemical properties, enzyme activities of the soil, as well as growth indexes of the cotton at seedling stage. 【Result】 Biochar amendment improved moisture content in the 0~20 cm soil layer, but the increase was negatively correlated with biochar amount; biochar also reduced salt content in the 0~20 cm soil layer. The amendment did not show significant effect on soil pH, total phosphorus, and available phosphorus, but increased soil organic carbon, total nitrogen, total potassium, available potassium, peroxidase (POD), and fibro two glycosidases (FTG), especially BC1 which significantly increased the activity of POD and FTG. In general, biochar reduced soil alkali-hydrolyzable nitrogen and polyphenol oxidase (PPO). BC1 increased stem diameter and above-ground dry matter accumulation of the crop, both significantly, but did not show noticeable impact on plant height. BC3 did not show significant effects on plant height, stem thickness, and above-ground dry matter, while BC5 reduced plant height, stem diameter, and above-ground dry matter. Also, addition of biochar reduced the total nitrogen content in stems and leaves. 【Conclusion】 Biochar can improve soil nutrients and enzyme activities but only when applied at an appropriate ratio. For the saline soil we studied, the optimal biochar amendment was 1%.

【Objective】 Waterlogging is a common abiotic stress affecting crop growth and soil functions. The purpose of this paper is to experimentally investigate short-term effect of waterlogging on mineral nitrogen and ammonia-oxidizing microorganisms in the rhizosphere and bulk soil of winter wheat. 【Method】 Waterlogging was imposed at the anthesis stage, and lasted 0 days, 3 days and 5 days, respectively. In each treatment, we measured the mineral nitrogen and the copy numbers of ammonia oxidizing microorganisms in the soil at the end of surface waterlogging, the end of subsurface waterlogging, as well as two days after the waterlogging completely eased. 【Result】 Compared with the control (without waterlogging), prolonged surface waterlogging promoted ammonium nitrogen and reduced nitrate nitrogen in both the rhizosphere and the bulk soil (P

【Objective】 Soil problems in southern Xinjiang of China are many and vary, characterized by scarce rainfall, shallow groundwater and high soil salinity. To safeguard crop production, mulched drip irrigation coupled with subsurface drain have been developed as the dominant cultivation in this region. The purpose of this paper is to experimentally study the efficacy of this system in desalinizing cotton fields. 【Method】 A two-year experiment was carried out in a cotton field with shallow groundwater table. Spacing of the subsurface drains varied from 10 m to 30 m, and their buried depth varied from 0.8 m to 1.1 m. Treatment without drains was taken as the control (CK). The field was mulched, and the cottons were drip-irrigated. The effect of the drains on spatiotemporal dynamics of soil salt was measured, and its variation in response to irrigation amounts was analyzed. 【Result】 A lack of drainage system resulted in inter- and intra-annual salt accumulation in the soil surface; installing subsurface drains reduced salt accumulation, with the reduction increasing significantly with the decrease in drain spacing and increase in their burying depth. Irrigation amount did not show a noticeable impact on salt leaching when the drains were absent, while having the drains in place increased the leaching rate by 10%~30%. Significance analysis of the desalination rate of the irrigation showed that salt leaching rate increased significantly with the decrease in drain spacing and the increase in drain depth. Regression analysis found that the desalination rate was impacted by drain spacing more than by the drain depth. The difference in soil salt content before and after the irrigation can be fitted to a leaching curve with R2 > 0.90. Using this curve, we calculated the irrigation amount required to leach salt in the 0~60 cm of soil below a critical value, which can be used to design the subsurface drainage system 【Conclusion】 The optimal design parameters for the areas we studied were: drain spacing 10 m, and drain depth 0.8 m. This can meet the requirement by keeping the salt content in the cotton field below a critical value.

【Background and objective】 Most agriculture-induced eco-environmental problems in north China are due to poor management in irrigation and fertigation of winter wheat, especially the use of nitrogen (N) fertilizer. Uptake of N by the wheat and its associated use efficiency depend on many biotic and abiotic factors, and the aim of this paper is to experimentally investigate how to improve them by optimally combining irrigation and fertigation at the jointing stage. 【Method】 The experiment was carried out in a field. It compared three irrigations: rain-fed (W1), irrigating 60 mm (W2), and 90 mm (W3) of water. For each irrigation treatment, there were three nitrogen top-dressing treatments: 0 kg/hm2 (N1), 75 kg/hm2 (N2) and 150 kg/hm2 (N3). The basal nitrogen application in all treatments was 150 kg/hm2. In each treatment, we measured the physiological traits, yield and N uptake of the crop. 【Result】 The leaf area index (LAI), plant height, aboveground biomass, grain yield and N uptake all increased significantly as the irrigation and nitrogen applications increased. However, when N top-dressing exceeded 75 kg/hm2, a further increase in N application did not have a significant effect on physiological traits of the crop, especially in W3 irrigation treatment. Grain yield was negatively correlated to the 1 000-grain weight at significant level; LAI, plant height, aboveground dry matter, grain numbers per spike, panicle numbers per spike were all positively correlated to the grain yield at significant level. With the increase in irrigation amount at the jointing stage, N production efficiency, grain N absorption and N utilization efficiency all increased, while the WUE decreased. With the increase in N top-dressing amount, N production efficiency, as well as grain N absorption and N utilization efficiency decreased, while the associated WUE increased. W3+N2 significantly increased grain yield and N uptake by 1.33%~65.92% and 4.63%~59.25%, respectively, compared with other treatments. 【Conclusion】 Considering crop growth and yield, as well as N uptake and N utilization efficiency, W3+N2 was the optimal irrigation and fertigation, achieving high yield while in the meantime reducing N application and increasing uptake and utilization efficiency of N by the crop.

【Objective】 Crops often endure various biotic and abiotic stresses during their growth. This paper investigates how thermal and waterlogging stresses occurring at booting stage affect photosynthesis and the ultimate yield of paddy field rice. 【Method】 The experiments were conducted in pots and consisted of four treatments: waterlogging stress by keeping the water on the soil surface 15 cm deep (T1), higher them stress (T2), high thermal stress combined with the waterlogging stress (T3). Conventional irrigation with water on the soil surface kept at 0~5 cm deep was taken as the control (CK). In each treatment, we measured the change in SPAD, photosynthetic traits and yield of the rice. 【Result】 Compared to CK, T2 reduced the photosynthetic rate by 30.77%, while T3 increased SPAD, photosynthetic rate and stomatal conductance of the leaves by up to 51.90%. Compared to CK, the impact of the stresses occurring at booting stage on shoot growth lasted into mature stage. It hence reduced the yield, especially T2 and T3 which reduced the rice yield by 80.09% and 12.33%, and 1 000-grain weight by 16.31% and 11.86% respectively. 【Conclusion】 To alleviate the adverse impact of thermal stress at the booting stage on yield, water in the soil surface should be kept about 15 cm deep to ameliorate the potential thermal damage.

As living standards rise, enhancing quality has become a central objective for many researchers. Soilless cultivation, known for its efficient use of resources, is increasingly used in vegetable production. It is critical to develop effective water and fertilizer management strategies to achieve high-quality yields and promote sustainable development in modern agriculture. This study employed an orthogonal experimental design to assess the impact of varying nutrient solution concentrations (50%, 75%, 100%, and 125% of Hoagland's), lower irrigation thresholds (40%, 55%, 70%, and 85% field capacity (FC)), and ozone concentrations (0, 1, 2, and 4 mg·L−1) on lettuce growth, yield, quality, and water–fertilizer use efficiency. The results indicated that fixed nutrient solution concentrations and lower irrigation thresholds enhanced growth metrics for lettuce. Similarly, increasing ozone concentrations initially improved, then reduced growth metrics when the lower irrigation threshold was constant. Furthermore, maintaining stable ozone concentrations while raising the nutrient solution concentration initially boosted, then diminished, growth indicators. Optimal conditions for water and fertilizer management were identified at a nutrient solution concentration of 75% to 100% and an ozone concentration of 0 to 1 mg·L−1. Variance analysis highlighted the significant effects of nutrient solution concentration, lower irrigation thresholds, and ozone concentrations on lettuce yield, quality, and water and fertilizer use efficiency. Range analysis revealed the optimal management combination to be a nutrient solution concentration of 100%, an 85% lower FC irrigation threshold, and an ozone concentration of 1 mg·L−1, yielding 16.82 t·ha−1 of lettuce and a water use efficiency of 40.14 kg·m−3. These findings provide theoretical support for the sustainable advancement of soilless cultivation in contemporary agriculture. [ABSTRACT FROM AUTHOR]

The rice waterlogging stress test was conducted at the experimental base of the College of Agriculture, Yangtze University, using Yangxian You 418 as the test subject, in order to investigate the impact of waterlogging on rice growth during the period from July to August each year. Six waterlogging stress tests with different waterlogging depth (1/4 plant height (1/4PH), 2/4 PH, and 3/4 PH) and duration (5 d and 7 d) were set up at the jointing–booting stage of rice (T1: 1/4 PH, 7 d; T2: 2/4 PH, 7 d; T3: 3/4 PH, 7 d; T4: 1/4 PH, 5 d; T5: 2/4 PH, 5 d; T6: 3/4 PH, 5 d;) with shallow water irrigation (CK) as control. The plant height, population leaf area, above-ground dry matter, and the yield of rice were measured. The correlation between the waterlogging depth and rice yield reduction was analyzed, and the flood disaster threshold index of rice was established. The results showed that at the end of stress, the plant height of all waterlogged treatments exceeded CK, and the plant height of T3 and T6 treatments significantly increased by 31.90% and 15.93%, respectively. The leaf area of rice treated with T1, T3, T4, and T5 was higher than CK (p < 0.05), and the above-ground dry matter of rice treated with T2, T3, T4, T5, and T6 was higher than CK (p < 0.05). When normal irrigation was restored to the maturity stage, the plant height of all rice treated with waterlogging was still higher than CK (p < 0.05). However, as the degree of waterlogging increased, rice yield decreased significantly, with a notable reduction of 31.68% observed in the T3 treatment compared to CK. Assuming a drainage index based on a 20% decrease in rice yield, it is imperative that the ratio of flooded depth to plant height remains below 37% when waterlogging persists for 7 days in rice cultivation. These research findings offer crucial scientific insights for implementing effective drainage management measures during flood disasters in rice paddies. [ABSTRACT FROM AUTHOR]

Winter wheat is an important grain that plays a crucial role in agricultural production and ensuring food security. Its yield directly impacts the stability and security of the global food supply. The accurate monitoring of grain yield is imperative for precise agricultural management. This study aimed to enhance winter wheat yield predictions with UAV remote sensing and investigate its predictive capability across diverse environments. In this study, RGB and multispectral (MS) data were collected on 6 May 2020 and 10 May 2022 during the grain filling stage of winter wheat. Using the Pearson correlation coefficient method, we identified 34 MS features strongly correlated with yield. Additionally, we identified 24 texture features constructed from three bands of RGB images and a plant height feature, making a total of 59 features. We used seven machine learning algorithms (Cubist, Gaussian process (GP), Gradient Boosting Machine (GBM), Generalized Linear Model (GLM), K-Nearest Neighbors algorithm (KNN), Support Vector Machine (SVM), Random Forest (RF)) and applied recursive feature elimination (RFE) to nine feature types. These included single-sensor features, fused sensor features, single-year data, and fused year data. This process yielded diverse feature combinations, leading to the creation of seven distinct yield prediction models. These individual machine learning models were then amalgamated to formulate a Bayesian Model Averaging (BMA) model. The findings revealed that the Cubist model, based on the 2020 and 2022 dataset, achieved the highest R2 at 0.715. Notably, models incorporating both RGB and MS features outperformed those relying solely on either RGB or MS features. The BMA model surpassed individual machine learning models, exhibiting the highest accuracy (R2 = 0.725, RMSE = 0.814 t·ha−1, MSE = 0.663 t·ha−1). Additionally, models were developed using one year's data for training and another year's data for validation. Cubist and GLM stood out among the seven individual models, delivering strong predictive performance. The BMA model, combining these models, achieved the highest R2 of 0.673. This highlights the BMA model's ability to generalize for multi-year data prediction. [ABSTRACT FROM AUTHOR]

Drought stress is one of the key factors restricting crop yield. The beneficial effects of exogenous proline on crop growth under drought stress have been demonstrated in maize, rice, and other crops. However, little is known about its effects on wheat under drought stress. Especially, the water-holding capacity of leaves were overlooked in most studies. Therefore, a barrel experiment was conducted with wheat at two drought levels (severe drought: 45% field capacity, mild drought: 60% field capacity), and three proline-spraying levels (0 mM, 25 mM, and 50 mM). Meanwhile, a control with no stress and no proline application was set. The anatomical features, water-holding capacity, antioxidant capacity, and proline content of flag leaves as well as grain yields were measured. The results showed that drought stress increased the activity of catalase and peroxidase and the content of proline in flag leaves, lessened the content of chlorophyll, deformed leaf veins, and decreased the grain yield. Exogenous proline could regulate the osmotic-regulation substance content, chlorophyll content, antioxidant enzyme activity, water-holding capacity, and tissue structure of wheat flag leaves under drought stress, ultimately alleviating the impact of drought stress on wheat yield. The application of proline (25 mM and 50 mM) increased the yield by 2.88% and 10.81% under mild drought and 33.90% and 52.88% under severe drought compared to wheat without proline spray, respectively. [ABSTRACT FROM AUTHOR]

Applying biochar to saline soil is a novel strategy for improving soil quality. However, how biochar addition amount affects soil nutrients, bacterial communities, and cotton growth at different stages remains unclear. Three biochar treatments, no biochar (BC0), 1% biochar (BC1, w/w), 3% biochar (BC3), and two cotton varieties, salt‐sensitive (SS) and salt‐tolerant (ST), were used in pot experiments, analyzing biochar effects on saline soil nutrients, bacterial communities, and cotton growth. The study found that biochar increased only organic carbon (SOC), total nitrogen (TN), and available potassium (AK) at the seedling stage. However, at the flowering‐boll stage, biochar also increased nitrate (NO3−–N) and available phosphorus (AP) and reduced soil salt content. Biochar did not affect α‐diversity at the seedling stage, but BC3 reduced α‐diversity at the flowering‐boll stage. The principal coordinate analysis revealed changes in the soil bacterial community composition that were closely associated with biochar added. From the redundancy analyses, SOC and AK were the leading environmental factors for soil bacterial community composition changes. SOC, TN, and AK correlated positively with Proteobacteria, which increased their relative abundance through biochar addition and correlated negatively with Bacteroidetes, Chloroflexi, and Acidobacteria, which decreased their relative abundance due to biochar. Furthermore, the random forests analysis showed that SOC, Shannon index, and β‐diversity were significant predictors of cotton biomass. In summary, biochar drives changes in bacterial communities in saline soils by increasing nutrients such as SOC and AK, which affect cotton growth. This study provides data to support the application of biochar on saline soils. [ABSTRACT FROM AUTHOR]

Soil CO2 and CH4 concentrations are crucial determinants of crop physiology and the soil environment. However, the intricate relationships among soil respiration, soil nutrients, enzyme activities, and winter wheat growth in the presence of shallow groundwater remain enigmatic. This study aimed to investigate the dynamics of soil CO2 and CH4 concentrations and their correlations with soil nutrient content, enzymatic activities, and wheat root biomass to better understand the influence of shallow groundwater on soil environmental conditions. Lysimeter experiments were conducted at five groundwater depths (20, 40, 50, 60, and 80 cm) and three fertilizer application rates (low, 75%; normal, 100%; high, 125%). Soil CO2 (soil layer > 10 cm) and CH4 concentrations significantly decreased with increasing groundwater depth. The maximum values of root parameters and shoot biomass were mainly concentrated at 50–60 cm at the high fertilization level (except root length density, which was higher at the normal fertilization level), and were 0.36–77.4% higher than other treatments. Soil CO2 concentration showed positive correlations with organic matter and total N content, enzyme activities, and root biomass. Soil CH4 concentration had significant correlations with soil organic matter, total N, and available K. Compared to the fertilization level, groundwater depth emerged as a crucial factor as it affected soil physicochemical properties, soil enzymatic activities, root respiration, and winter wheat growth in shallow groundwater. [ABSTRACT FROM AUTHOR]

The impacts of rhizosphere microorganisms on the turnover of nutrients are affected by many environmental factors. In this study, rice plants were subjected to deep flooding and heat stress for one week at the jointing stage. Rhizospheric soil was sampled for the analysis of rice rhizosphere bacterial assembly and functional groups responsible for carbon and nitrogen transformation. Compared with the control, both deep flooding and heat stress increased bacterial alpha diversity. Moreover, heat stress and the interactions of heat stress and deep flooding improved the bacterial cooperation. Heat stress reduced the relative abundance of Actinobacteria and Firmicutes, which are responsible for organic carbon decomposition. The relative abundance of the gene encoding lignin-degrading catalases under deep flooding and heat stress treatments reduced by 6% and 8%, respectively. The interaction of heat stress and deep flooding increased the relative abundance of the nifD gene by 5%, may slowed down nitrate reduction to nitrite. Our results highlight the effects of heat and flooding stress on the bacteria-mediated mechanisms responsible for regulating organic carbon sequestration and nitrogen cycling in rhizosphere of paddy fields. [ABSTRACT FROM AUTHOR]

Waterlogging and salinization are considered to be the main threats to agricultural productivity and land resources in coastal areas of China. Thus far, drainage and field soil improvement programs have been ineffective. In this article, we investigated the effect of subsurface drainage combined with biochar (B–S) on soil physicochemical properties and soil bacterial community structure in coastal saline soil. In this study, B–S significantly reduced soil electrical conductivity (EC) and soil water content (W) by 35% and 10.65% compared to no drainage (CK). Compared to CK and drainage alone (S), B–S significantly increased soil total nitrogen (TN) by 24.78% and 39.62%, soil available phosphorus (AP) by 28.29% and 69.82%, soil nitrate (NO3−-N) by 64.65% and 35.45%, and significantly increased soil organic matter (SOM) by 74.69% and 66.10%, respectively. It also significantly increased alkaline phosphatase (ALP) and urease activities. The results of redundancy analysis (RDA) showed that CAT and urease made the greatest response to changes in environmental factors, indicating that CAT is more sensitive to changes in environmental alterations than ALP. AP was the dominant factor in the change in enzyme activity (R2 = 53.0%, p < 0.05), followed by NO3−-N (R2 = 14.8%). SOM was the dominant factor in the variation in microbial abundance content (R2 = 38.5%, p < 0.05), followed by ALP (R2 = 20.0%, p < 0.05). The results of the study can provide guidance for effective land use and sustainable development of agricultural soil ecology in coastal areas. [ABSTRACT FROM AUTHOR]

Copyright of Irrigation & Drainage is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Exploring the impact of subsurface drainage on microbial community structures in saline-alkali soils is of great significance for maintaining the sustainability of saline-alkali fields. In this study, seven field treatments were designed in cotton fields: two drain depth (0.8 and 1.1 m) and three drain spacing (10, 20, and 30 m) treatments, as well as no drainage (control). Soil samples were obtained in the seedling and flowering and boll-setting (FBS) stages, and the soil properties and microbial communities (bacteria and fungi) were analyzed. The results displayed that compared with the control group, soil salt was significantly decreased in all subsurface drainage treatments. Subsurface drainage treatments have no effect on microbial richness and diversity. Both drain depth and spacing had significant effects on bacterial and fungal composition structures in the seedling stage, but only drain depth significantly altered soil microbial composition structures in the FBS stage. Based on the null model, the assembly of soil microbial communities was mainly driven by stochastic processes. The contributions of the deterministic process for soil bacterial community assembly at the seedling stage and FBS stage were 18.1% and 22.1%, respectively. In contrast, soil fungal community assembly was mainly determined by dispersal limitation and drift. [ABSTRACT FROM AUTHOR]

Timely and accurate monitoring of the nitrogen levels in winter wheat can reveal its nutritional status and facilitate informed field management decisions. Machine learning methods can improve total nitrogen content (TNC) prediction accuracy by fusing spectral and texture features from UAV-based image data. This study used four machine learning models, namely Gaussian Process Regression (GPR), Random Forest Regression (RFR), Ridge Regression (RR), and Elastic Network Regression (ENR), to fuse data and the stacking ensemble learning method to predict TNC during the winter wheat heading period. Thirty wheat varieties were grown under three nitrogen treatments to evaluate the predictive ability of multi-sensor (RGB and multispectral) spectral and texture features. Results showed that adding texture features improved the accuracy of TNC prediction models constructed based on spectral features, with higher accuracy observed with more features input into the model. The GPR, RFR, RR, and ENR models yielded coefficient of determination (R2) values ranging from 0.382 to 0.697 for TNC prediction accuracy. Among these models, the ensemble learning approach produced the best TNC prediction performance (R2 = 0.726, RMSE = 3.203 mg·g−1, MSE = 10.259 mg·g−1, RPD = 1.867, RPIQ = 2.827). Our findings suggest that accurate TNC prediction based on UAV multi-sensor spectral and texture features can be achieved through data fusion and ensemble learning, offering a high-throughput phenotyping approach valuable for future precision agriculture research. [ABSTRACT FROM AUTHOR]

As one global issue, soil salinization has caused soil degradation, thus affecting the sustainable development of irrigated agriculture. A two-year study was conducted in 2018 and 2019 to identify the effects of subsurface drainage spacing on soil salinity and groundwater level, the latter of which is in a high-water table in drip irrigation cotton fields in the Tarim Basin oasis in southern Xinjiang, China. Three subsurface drainage treatments, with a drain spacing of 10 m (W10), 20 m (W20), and 30 m (W30), respectively, and a drainage-absent treatment (CK), are tested. With CK, soil salinity in the 0–60 cm layer was accumulated within a year. In contrast, the subsurface drainage reduced the soil salinity at a leaching rate of 10–25%. When decreasing the drain spacing, it was found that the soil desalination rate increased significantly (p < 0.05) with good repeatability. Experimental results showed that the fitting equation of the soil salinity leaching curve could accurately describe the soil salinity leaching pattern of drip irrigation, and thus could be further used to inversely determine the theoretical drip irrigation leaching quota for those soils with different salinity degrees. As such, subsurface drainage could effectively control the groundwater table. Compared with CK, subsurface drainage deepened the groundwater table and mitigated the fluctuation of the groundwater level. These effects were strengthened by reducing the drain spacing. Correspondingly, the influence of the fluctuation of the groundwater table was reduced. [ABSTRACT FROM AUTHOR]

Copyright of Irrigation & Drainage is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Stomatal regulation plays a pivotal role in the adaption of plants to different water conditions. In order to understand characteristics of stomatal resistance of crops with different irrigation methods, differences in leaf stomatal resistance and contribution of stomatal aperture to water vapor transfer were investigated with a field experiment conducted under alternative deficit water supply and under conventional furrow irrigation. Results indicated that for individual maize leaf, regardless of irrigation methods, the stomatal resistance decreased gradually from the base to the tip of the maize leaf. At the population level, the stomatal resistance of maize leaf increased gradually from canopy top to bottom. For the change of the leaf stomatal resistance in time, diurnal variation of leaf stomatal resistance was in a W shape. Diurnal and daily changes in the leaf stomatal resistance in the upper canopy were relatively small. The upper surface of maize leaf contributed more to CO2 and water vapor transfer than the ones underside. Except at the seedling stage, the leaves in the upper and middle part of maize canopy contributed more than 80% of the total CO2 and water vapor. Stomatal resistances of maize leaves decreased with the increase in leaf age during the vegetative growth stage. Differences in stomatal resistance among maize leaves of different ages were increased by the alternative deficit water supply. During the reproductive growth phase, leaf age had no significant influence on the stomatal resistance in matured leaves. Compared with the conventional furrow irrigation with sufficient water supply, the alternative deficit water supply increased the ratio of the stomatal resistances between the upper side and underside of maize leaves. The vertical gradient of stomatal resistance from canopy top to bottom increased significantly (P<0.05), decreasing leaf stomatal conductivity rapidly, and improving the contribution of the stomatal aperture in the upper canopy to water vapor transfer. Therefore, the leaf stomatal resistance of maize was regulated by furrow irrigation methods and soil water condition, and it was affected by the leaf age, leaf area index and natural feature of stomatal aperture. The study is useful for controllable irrigation technology and water vapor cycle in soil plant atmosphere continuum (SPAC). [ABSTRACT FROM AUTHOR]

Maize jointing stage is an important period for reproductive growth and vegetative growth and also in this stage, corn is sensitive to waterlog. In the study area in the jointing stage of corn, frequent waterlog in field often occur causing damage of corn yield. Therefore finding out the upper threshold for number of days that corn can endure waterlog, and understand the corn physiological reaction after flooding can help to develop management tools to improve corn production. The bottomless pit measurement was set at different waterlogging days (1, 2, 3, 5, and 7 d) to determine the corn response to waterlogging duration and the effect of waterlogging duration on corn growth, grain fill, dry mater distribution and yield characteristics. At the vegetative growth stage, the results showed that the average plant height of corn with 1, 2, 3, 5, and 7 days of waterlog was reduced by 2.26%, 2.26%, 2.45%, 11.36% and 10.17%, respectively, and the LAI (leaf area index) was decreased respectively by 23.79%, 18.93%, 13.04%, 32.74% and 34.27% as compared with the CK (control treatment). With the waterlogging duration more than 5 days at the jointing stage, the plants became dwarf and the leaves turned yellow. For plant physiological response, three days after each flooding duration test showed that chlorophyll content of leaves with the flooding duration of 1, 2, and 3 days was higher (p<0.05) than CK, and root activity increased. But the chlorophyll content of leaves and root activities of flooding duration of five and seven days decreased as compared to the CK. The result also showed that with the flooding duration more than 5 days, chlorophyll content of leaves from corn filling stage to milk-ripe stage was 10.87% lower (p<0.05) than that of the CK. Therefore once the waterlogging duration was more than five days at the jointing stage, chlorophyll content of leaves would stay lower and not be recovered. For the reproductive growth stage, flooding duration at the corn jointing stage affected the grain quality of post filling. The result indicated that compared with the CK, the grain yield of waterlogging duration with 1, 2, and 3 days was rather similar, but with 5 days, it was lower (p <0.05) and it was the lowest with flood duration of 7 days. The ear rows and ear width of corn decreased with the increase of the number of days of flooding, but it was not significantly different as compared to the CK. The corn ear tip-barren had significant difference (p<0.05) than the CK. The corn ear tip-barren from waterlogging duration of 1, 2, 3, and 5 days was about two times higher than the CK, the flooding duration of the 7 days was five times higher than the CK. The ear length, ear weight, ear grain weight and hundred-grain weight of corn decreased as the waterlogging day increased. The yield of corn with 1, 2, 3, 5, and 7 waterlogging days were reduced by 16.58%?16.65%?26.11%?34.32% and 39.01%, respectively. Therefore waterlogging duration over 5 days not only affected the normal growth of corn, but also reduced the yield significantly. The research provided information for waterlogging monitoring, fast evaluation of damage and waterlogged field drainage standard determination. [ABSTRACT FROM AUTHOR]

The global demand for cotton makes sustainable cotton production an important issue that can be improved by a better understanding of the influence of soil microbes on cotton growth. We collected cotton field soils at the seedling and flowering/boll-setting (FBS) stages in order to obtain soil properties and cotton growth indices. Bacterial and fungal community compositions were assessed by high-throughput sequencing of 16S rRNA and internal transcribed spacer genes, respectively, after which the differences in microbial functions and their influencing factors at different growth stages were analyzed. Both the diversity and composition of soil bacterial and fungal communities were found to be significantly different between the seedling and FBS stages. Microbes in the seedling stage had significantly higher richness and biomass than those in the FBS stage. Compared with the seedling stage, the stability of the soil bacterial communities was decreased. The cotton growth indices at both the seedling and FBS stages were associated with compositional shifts in the bacterial community and but not the fungal community. The abundance of specific soil microbial taxa (e.g., Pseudarthrobacter, Thiobacillus, Cephalotrichum, Chaetomium, and Fusarium) were correlated with cotton growth indices at the seedling stage, being mainly regulated by soil salinity and nitrate content. Our results highlight the importance of soil microbial communities in mediating cotton growth and will be useful in providing better strategies for the improvement of cotton agriculture. [ABSTRACT FROM AUTHOR]

In recent years, the alternating occurrence of high temperature and waterlogging disasters in South China has seriously reduced the yield of single cropping rice. Studying the changes in anatomical structure of the rice root system could provide theoretical basis for understanding the mechanisms of high temperature and waterlogging stress. To examine interactions between temperature and waterlogging stress, an experiment was set up in a growth chamber consisting of two temperatures (moderate, 30–34 °C and high, 35–38 °C) with three depths of flooding (0–5, 10 and 15 cm). Treatments commenced at the booting stage and lasted five days, after which all treatments were returned to a 0–5 cm flooding depth and the same temperature regime. Observations were made immediately after cessation of treatments, then after 5, 10 and 20 d to test the effect of treatments on subsequent root anatomical development. The low-stress control (0–5 cm, medium temperature) showed no change with time in aerenchyma area, thickness of the outer root, stele diameter, and the number nor diameter of xylem vessels. Root diameter and stele diameter under the high-stress control (0–5 cm, high temperature) were decreased by 29.09% and 15.28%, respectively, at the booting stage, whereas the high stress control (15 cm, high temperature) affected only the vessel diameter, reducing it by 14.11% compared with that in the low-stress control (0–5 cm, medium temperature). Compared to the high-stress control (0–5 cm, high temperature), the interaction of high temperature and waterlogging stress alleviated the inhibiting effect of the changes in the root system, especially after the end of the stress. We thought that waterlogging could reduce the damage of high temperature on rice root growth. Low water depth waterlogging has little effect on rice root system and aerenchyma area root diameter at 0, 5, 10 and 20 d after the stress ended, and the thickness of the outer root, stele diameter and the number and diameter of vessels at 0 d under M15 (15 cm, medium temperature) had no significant difference compared with M5 (0–5 cm, medium temperature). However, the increase in rice root diameter, stele diameter, thickness of the outer root cortex depth and vessel diameter were inhibited under high temperature stress at the booting stage. Root diameter and stele diameter under H5 (0–5 cm, high temperature) were decreased by 29.09% and 15.28%, respectively, at the booting stage, whereas H15 (15 cm, high temperature) affected only the vessel diameter, reducing it by 14.11% compared with that in the M5. Compared to H5, the interaction of high temperature and waterlogging stress alleviated the inhibiting effect of the changes in the root system, especially after the end of the stress. We thought that waterlogging could lighten the damage of high temperature on rice root growth. [ABSTRACT FROM AUTHOR]

Waterlogging adversely affects winter wheat ( Triticum aestivum L.) growth by deteriorating soil environmental factors. The objective of this study is to test the effects of groundwater depth and fertilization level on soil properties, enzyme activities, and wheat yield. Experiments were carried out in micro-lysimeters at the groundwater depths of 0.2, 0.4, 0.5, 0.6, and 0.8 m under low, normal, and high fertilization levels in the winter wheat growth season from Oct. 2015 to May 2016. Soil water content, pH, organic matter content, total N, available P, available K as well as sucrase, urease, and phosphatase activities were measured in various growth stages of winter wheat, and yield component and grain yield were also measured after its harvest. Results indicated that soil water content and pH decreased with the increased groundwater depth. The lower contents of soil organic matter and nutrients appeared when groundwater depth was 0.5–0.6 m. Sucrase in the heading stage, urease in the jointing stage, and phosphatase activities increased significantly with the increased groundwater depth. Grain yield increased with groundwater depth to its maximum or approximate steady value. Total N and available P contents and urease activity appeared to increase with fertilizer application rate but available K content showed a contrary tendency. Grain yield increased with fertilizer application rate, but the effect of fertilization level on grain yield was lower than that of groundwater depth. A significant interaction between groundwater depth and fertilization level on grain yield existed. Soil enzyme activities were significantly correlated with available P content, and phosphatase activity was correlated with soil water, pH, organic matter, total N, and available K contents. It can be concluded that controlling groundwater depth and appropriate fertilizer application level can improve crop growth environment and promote winter wheat growth and its grain yield. [ABSTRACT FROM AUTHOR]

The contradiction between land improvement in saline-alkali areas and water-saving irrigation in the arid regions is becoming increasingly prominent, affecting the movement of soil water and salt as well as cotton growth. To effectively improve soil quality and alleviate soil salinization issues under the premise of water conservation to increase cotton yields, a method involves conducting brackish water leaching during the non-growing season and utilizing freshwater drip irrigation during the growing season for cotton under subsurface drainage. A 2-year field experiment using six subsurface drainage systems at different depths of 0.8 and 1.1 m and different spacings of 10, 20, and 30 m respectively, alongside a non-drainage treatment as control (CK) was conducted in Aral, Xinjiang, China. Furthermore, efficient simulations of soil water and salt dynamics as well as cotton growth in arid regions under subsurface drainage conditions could be achieved using AquaCrop and DRAINMOD-S models. The results showed that soil salinity leaching could be achieved effectively with the use of appropriate brackish water and subsurface drainage pipes with the proper technical parameters during the non-growing season. Compared with the non-drainage treatment, the subsurface drainage and drip irrigation with freshwater reduced soil salinity effectively and improved growth indices and cotton yield considerably during the growing season. The rate of soil desalination exhibited an upward trend as the distance of subsurface pipes decreased, and the growth indices of cotton increased with the decrease in distance and depth of t subsurface pipes. This study concluded that using brackish water in the non-growing season, appropriate selection of irrigation water volume, spacing, and depth of subsurface pipes can simultaneously improve soil salinity drainage and cotton yield. This research suggests new irrigation and management recommendations for agricultural production and achieves more efficient water use and crop cultivation under arid conditions, providing a new insight into the efficient use of saline soil resources in the arid regions in Xinjiang. • Leaching with brackish water and drip irrigation with freshwater reduced salinity. • Subsurface drainage is beneficial to soil salt leaching and cotton growth. • Drainmod-S and AquaCrop models can simulate soil salt transport and cotton growth. [ABSTRACT FROM AUTHOR]

Abstract: After measuring root morphological indices, such as the length, diameter, volume density, surface area and tip number of both living and dead roots on the ridge and slope under alternate furrow irrigation (AFI) and conventional furrow irrigation (CFI, control treatment) using Minirhizotrons, the responses of root morphology and distribution in maize to AFI were analyzed. Results show that root morphological indices of living or dead roots were lower on the ridge than on the slope under AFI, whereas root morphological indices of living or dead roots were higher on the ridge than on the slope under CFI. Compared to CFI, AFI significantly increased root tip number and surface area of fine roots (with the diameter of ≤2.5×10−1 mm) and promoted roots to deeper soil on the slope, and then simulated root water uptake. AFI only decreased the grain yield by 0.9%, but increased water use efficiency on seed yield by 8.3%. Thus AFI promoted root growth and metabolism on the slope, increased the effective absorption area of root system and improved water use efficiency without significant reduction of grain yield. [Copyright &y& Elsevier]

Soil properties and microbial diversity are markedly enhanced by the long-term effects of organic fertilizers. However, the short-term impacts of inorganic and organic fertilizers vary in different agroecosystems, especially when combined with different irrigation conditions. Here, we examined the influence of different fertilizer types (NPK: mineral fertilizer, NPKM: mineral fertilizer plus organic fertilizer, NPKWS: mineral fertilizer plus straw) combined with different irrigation regimes (AWMID: shallow water layer, AWMOD: alternate wetting and moderate drying, AWSD: alternate wetting and severe drying) on the soil properties and bacterial communities at the wheat harvest stage of a one-year rice-wheat rotation system (RWRS), in the rice zone along the Yellow River of China. Our results revealed that the irrigation mode had a stronger impact on the soil properties, and bacterial community than the fertilizer regime, although most indicators did not differ significantly, probably owing to the short duration of the trial. Several low-abundance bacteria were recognized to be strongly (P < 0.05) influenced by different irrigation and fertilizer regimes in the RWRS using LEfSe analysis, but no definite trends were observed among the treatments. A co-occurrence network uncovered the modular clustering patterns of bacteria, which were significantly correlated with the available phosphorus content and some soil enzyme activities. Moreover, the denitrification, nitrite respiration, and sulfur respiration capacities of soil microbes were significantly improved in the mineral fertilizer combined with the alternate wetting and moderate drying treatment. In addition, the wheat yield did not significantly (P < 0.05) decrease after water-saving irrigation regime during the previous rice season. Further research is warranted to elucidate the long-term effects of partial substitution of chemical nitrogen with organic nitrogen and water-saving irrigation regimes on an RWRS. • Irrigation impacts the soil properties and bacterial community stronger than fertilization. • AWD can save irrigation water without reducing crops yield in RWRS for short-term. • Irrigation and fertilization regimes in RWRS strongly influenced several low-abundance bacteria. [ABSTRACT FROM AUTHOR]

The timely and precise prediction of winter wheat yield plays a critical role in understanding food supply dynamics and ensuring global food security. In recent years, the application of unmanned aerial remote sensing has significantly advanced agricultural yield prediction research. This has led to the emergence of numerous vegetation indices that are sensitive to yield variations. However, not all of these vegetation indices are universally suitable for predicting yields across different environments and crop types. Consequently, the process of feature selection for vegetation index sets becomes essential to enhance the performance of yield prediction models. This study aims to develop an integrated feature selection method known as PCRF-RFE, with a focus on vegetation index feature selection. Initially, building upon prior research, we acquired multispectral images during the flowering and grain filling stages and identified 35 yield-sensitive multispectral indices. We then applied the Pearson correlation coefficient (PC) and random forest importance (RF) methods to select relevant features for the vegetation index set. Feature filtering thresholds were set at 0.53 and 1.9 for the respective methods. The union set of features selected by both methods was used for recursive feature elimination (RFE), ultimately yielding the optimal subset of features for constructing Cubist and Recurrent Neural Network (RNN) yield prediction models. The results of this study demonstrate that the Cubist model, constructed using the optimal subset of features obtained through the integrated feature selection method (PCRF-RFE), consistently outperformed the RNN model. It exhibited the highest accuracy during both the flowering and grain filling stages, surpassing models constructed using all features or subsets derived from a single feature selection method. This confirms the efficacy of the PCRF-RFE method and offers valuable insights and references for future research in the realms of feature selection and yield prediction studies., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Li, Zhou, Cheng, Zhai, Mao, Li and Chen.)

Identifying the potential factors associated with the impact of long-term drip irrigation (DI) on soil ecosystems is essential for responding to the environmental changes induced by extensive application of DI technology in arid regions. Herein, we examined the effects of the length of time that DI lasts in years (N DI ) on soil bacterial diversity as well as the soil bacterial community assembly process and the factors influencing it. The results showed that long-term DI substantially reduced soil salinity and increased soil bacterial diversity while affecting the soil bacterial community structure distinctly. Null model results showed that the soil bacterial community assembly transitioned from stochastic processes to deterministic processes, as N DI increased. Homogeneous selection, a deterministic process, emerged as the dominant process when N DI exceeded 15 years. Both random forest and structural equation models showed that soil salinity was the primary factor affecting the bacterial community assembly process. In summary, this study suggested that soil bacteria respond differently to long-term DI and depends on the N DI , influencing the soil bacterial community assembly process under long-term DI., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Li, Qiu, Tian, Zhao, Zhou and He.)

Objective: To verify the clinical efficacy on postmenopausal osteoporosis treated with acupoint injection of salmon calcitonin., Methods: Ninety patients of postmenopausal osteoporosis were randomized into three groups, 30 cases in each one. In the acupoint injection group, Shenshu (BL 23) and Zusanli (ST 36) were selected bilaterally. The injection 4 mL was prepared with salmon calcitonin 100 U (1 mL) and 0.9% sodium chloride injection. Each acupoint was stimulated with the injection, 1 mL. In the blank group, 0.9% sodium chloride injection was applied to bilateral Shenshu (BL 23) and Zusanli (ST 36), 1 mL at each acupoint. In the intramuscular injection group, salmon calcitonin 100 U was injected at gluteus maximus. The treatment was given once every two days in the patients of the three groups and lasted for 2 months. The levels of bone mineral density (BMD), bone alkaline phosphatase (NBAP), C-terminal telopeptides of typeⅠcollagen (CTX), urine calcium/creatinine (Ca/Cr) and the symptom score of osteoporosis were detected in the patients of the three groups before and after treatment., Results: In the patients of the three groups, NBAP and BMD in lumbar vertebra after treatment were higher than those before treatment (all P <0.05); CTX, Ca/Cr and symptom score were lower than those before treatment (all P <0.05). After treatment, NBAP was (32.7±2.5) μg/L in the acupoint injection group, higher than those in the blank group and the intramuscular injection group (both P <0.05). In the acupoint injection group, CTX was reduced to (239.7±63.6) μmmol/L and Ca/Cr was reduced to 0.525±0.274, apparently lower than those in the blank group and intramuscular injection group (both P <0.05). After treatment, in the acupoint injection group, BMD of lumbar vertebra was (0.731±0.062) g/m 2 , higher than the level of the rest two groups (both P <0.05). After treatment, the symptom score was 5.2±0.6 in the acupoint injection group, lower than those in the blank group and intramuscular injection group (both P <0.05)., Conclusions: Salmon calcitonin injec-tion at Zusanli (ST 36) and Shenshu (BL 23) achieves significant efficacy on postmenopausal osteoporosis, stimulating osteoblast activity and inhibiting bone absorption of osteoclast.