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Introduction: Continuous drought stress aggravates agricultural losses and threats food security. However, the responses of crops to continuous drought stress remain uncertain. Methods: To make up the limitations of field experiment and achieve the setting of multiple continuous drought stress scenarios, AquaCrop model is calibrated and validated using field experiment data of summer maize in 2017 and 2018 seasons. Then, the whole growth processes under different continuous drought stress scenarios at two growth stages of maize are simulated. The quantitative responses of transpiration (Tr), biomass accumulation, and yield formation to continuous drought stress are analyzed. Results and discussion: The results show that when the maize encounters serious drought at the seedling stage, the reduction rates of Tr at the jointing stage, the tasseling stage, and the milking stage are 57.45%, 43.61%, and 5.24%, respectively. Drought stress at a growth stage of maize not only have negative impacts on transpiration and biomass accumulation at this stage, but also have after-effects on these elements at the subsequent stages. In addition, continuous serious drought at the seedling and jointing stages reduces yield by 100%, which is higher than the sum of the loss rates at these two stages [>33.30% + 24.16%)], while the loss rate due to continuous light drought is lower than the sum [20.66% < (18.80% + 12.45%)]. The impact of continuous drought stress at two growth stages generally exceeds the sum of the impacts of the two single stages. Nevertheless, drought at the seedling stage promotes the adaptability of maize to drought, alleviating the negative impacts of light drought at the jointing stage, while the adaptability disappears when drought at the jointing stage is serious. Therefore, in the actual production of maize, serious drought at the seedling stage should be avoided to ensure seed survival. Meanwhile, continuous drought at the seedling and jointing stages should be prevented to reduce the severe accumulative effects, which guides drought disaster reduction and sustainable agricultural production. [ABSTRACT FROM AUTHOR]

The present study aims to assess the responses of growth, development, and yield of summer maize to the effects of drought–flood abrupt alternation through comparative tests under single flood, single-drought, and drought–flood abrupt alternation treatments with varying degrees from the elongation to the tasseling stage during the 2021 and 2022 growing seasons. In addition, a water production function model for summer maize was preliminarily established based on the results obtained under the drought–flood abrupt alternation scenarios. The results indicated that drought–flood abrupt alternation with early moderate drought had a certain restricting effect on summer maize, while early moderate drought followed by waterlogging had a compensation effect on the cultivated summer maize. Furthermore, both mild and severe drought followed by waterlogging exert a significant combined constraint on the normal growth and development of summer maize, leading to a sharp decline in maize yield, necessitating a shorter timeframe for mitigating and reducing the effects of waterlogging. Additionally, the water production function model established through a multiple linear regression equation exhibits a high degree of fit and demonstrates a strong linear relationship. This study provides crucial insights for agricultural practices and water resource management strategies, particularly in the evaluation of the integrated impacts of drought and waterlogging on crop yields and the formulation of effective disaster risk reduction and mitigation measures in response to these impacts. [ABSTRACT FROM AUTHOR]

Accurate estimation of soil moisture content (SMC) is vital for effective farmland water management and informed irrigation decision-making. The utilization of unmanned aerial vehicle (UAV)-based remote sensing technology to monitor SMC offers advantages such as mobility, high timeliness, and high spatial resolution, thereby compensating for the limitations of in-situ observations and satellite remote sensing. However, previous research has primarily focused on SMC diagnostics for the entire crop growth period, often neglecting the development of targeted soil moisture modeling paradigms that account for the specific characteristics of the canopy and root zone at different growth stages. Furthermore, the variations in soil moisture status between fields, resulting from the hysteresis of water flow in irrigation channels at different levels, may influence the development of soil moisture modeling schemes, an area that has been seldom explored. In this study, SMC models based on UAV spectral information were constructed using Random Forest (RF) and Particle Swarm Optimization-Support Vector Machine (PSO-SVM) algorithms. The soil moisture modeling paradigms (i.e., input–output mapping) under different growth stages and soil moisture conditions of summer maize were systematically compared and discussed, along with the corresponding physical interpretability. Our results showed that (1) the SMC modeling schemes differ significantly across the various growth stages, with distinct input–output mappings recommended for the early (i.e., jointing, tasselling, and silking stages), middle (i.e., blister and milk stages), and late (i.e., maturing stage) periods. (2) these machine learning-based models performed best at the jointing stage, while subsequently, their accuracy generally exhibited a downward trend as the maize grew. (3) the RF model demonstrates superior robustness in estimating soil moisture status across different fields (moisture conditions), achieving optimal estimation accuracy in fields with overall higher SMC in line with the PSO-SVM model. (4) unlike the RF model's robustness in spatial SMC diagnostics, the PSO-SVM model more reliably captured the temporal dynamics of SMC across different growth stages of summer maize. This study offers technical references for future modelers in UAV-based SMC modeling across various spatial and temporal conditions, addressing both the types of models as well as their input features. [ABSTRACT FROM AUTHOR]

To study the effects of one-off application of slow-release nitrogen (N) fertilizer or controlled release urea on yield, N utilization efficiency and economic benefits of summer maize in Huanghuai regions, field experiments with one-off fertilization of controlled release urea or slow release urea blended with normal urea were conducted at 6 experimental sites in Henan province in 2021. 9 treatments were set under field condition: no nitrogen fertilizer (CK), normal urea alone (U1), farmers' fertilization practices (U2), controlled release urea blended with normal urea (CRU) including 3 ratios of 3:7 (CRU1), 5:5 (CRU2), 7:3 (CRU3), slow release urea blended with normal urea (LCU) including 3 ratios of 3:7 ( LCU1), 5:5 (LCU2) and 7:3 (LCU3) . The effects of controlled release urea or slow release urea blended with normal urea on yield, N utilization and economic efficiency of summer maize were studied. The results showed that N application treatments increased yield by 11.6%~49.1% compared with CK. The average yield of N application treatments was in the order of CRU>LCU>U (U1, U2) . The average yield of CRU and LCU was 23.3% and 9.7% higher than U, respectively, with CRU2 having the highest yield of 9 444.0 kg·hm-2, 8.0%~33.6% higher than other N application treatments, followed by LCU2. Dry matter accumulation, grain number per spike and 1 000-grain weight were significantly higher under CRU and LCU treatments compared with U. The highest N recovery efficiency was 36.9% under CRU2 treatment, followed by LCU2 at 33.2%. Compared with U, CRU and LCU treatments had higher NO-3-N content in 0-40 cm and significantly lower NO-3-N content in deeper soils (40-100 cm), which resulted in an average revenue increase of 2 186 and 995 yuan·hm-2, respectively. The sustainable yield index of summer maize was correlated with high yield and coefficient of variation. CRU2 and LCU2 treatments had more stable yields and better sustainability. Combining yield, N utilization and economic efficiency, the N fertilizer management model of 5:5 combination of controlled release urea and normal urea was recommended for one-off application in summer maize production in Huanghuai regions. Above results could provide a basis for simplified production techniques of summer maize and high yield and efficiency of N fertilizer. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office 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.)

【Objective】 HYDRUS is a software widely used to simulate soil water movement, but it requires evapotranspiration which is difficult to obtain at large scales. In this paper, we investigated the feasibility of combining it with remote sensing to simulate spatiotemporal soil water dynamics at large scales. 【Method】 The experiment was conducted in a summer maize field in Daxing District, Beijing. The evapotranspiration estimated from the MODIS data and the surface energy balance system (SEBS) model was decoupled into soil-surface evaporation and plant transpiration, which were combined with the HYDRUS-1D to simulate spatiotemporal water dynamics in soil profile. Field-scale soil water dynamics was modelled by embedding the HYDRUS-RS model with the geographic information system (GIS) platform. The models were then applied to simulate spatiotemporal changes in soil water in the summer maize field during its growing season in 2018. 【Result】 The SEBS model was the best in modelling Rn, with the coefficient of determination (R2), bias and root mean square error (RMSE) being 0.81, 11 W/m2, and 54.8 W/m2, respectively. In the experimental area, the estimated daily ET during the growing season of the maize in 2018 varied between 3 and 6 mm/d. This differed slightly from that directly estimated from the soil moistures measured from pre-defined sampling points, but their temporal variation trends were the same. During growing season of the summer maize, soil moisture simulated by the proposed HYDRUS-RS model for the 40-60 cm soil layer was accurate, with the bias, RMSE, and R2 being 0.2%, 2.1% and 0.80, respectively. 【Conclusion】 Combining remote sensing with HYDRUS-1D provides a robust and accurate method for simulating large-scale soil water dynamics in agricultural lands. For the summer maize crop we studied, this integrated approach effectively predicts the changes in soil moisture, particularly in the 40-60 cm root zone.

Based on the stratified survey data of Pleonomus canaliculatus in the soil of winter wheat and summer maize rotation field in North China Plain, the vertical activity of Pleonomus canaliculatus in the soil of winter wheat and summer maize rotation fields, the correlation between meteorological conditions and farmland planting management are observed and analyzed, and effects of Pleonomus canaliculatus damage on the yield of winter wheat are analyzed. By combining the insect population weight index with population density index, characteristics of the harm-dormancy activity of Pleonomus canaliculatus are investigated comprehensively in different soil layers. Results show that in the winter wheat and summer maize rotation growing season, there are 3 harm and 3 dormant periods, 3 harm periods appear in the winter wheat regreening-jointing period, the summer maize seedling period and the autumn seedling period of winter wheat, and 3 dormant periods appear in winter wheat overwintering period, winter wheat ripening-harvesting period and summer maize filling-ripening period. Among 3 harm periods, winter wheat regreening-jointing period is the most serious, which could lead to serious yield reduction of winter wheat. Winter is warmer, and spring temperature is warmer early, so Pleonomus canaliculatus exhibits characteristics of going down late and coming up early, which shortens the dormant period in winter and prolong the harmful activity period. Soil temperature, moisture, and the relationship between food and source affect the damage, dormancy, and feeding activities of Pleonomus canaliculatus. The suitable soil moisture content for it is about 15% to 18%, and the suitable soil temperature is 14 to 18 ℃. In summer, Pleonomus canaliculatus may enter dormancy or reduce activity due to lack of food sources or high temperatures and humidity of soil, Pleonomus canaliculatus can enter the dormancy or reduced activity. The analysis of winter wheat yield reduction caused by Pleonomus canaliculatus damage shows that the yield reduction rate is increased by 5.1% with an increase of 10 m-2 in insect population density or with an increase of 1.0 g·m-2 in insect weight. Results provide reference for agricultural production in North China to address climate change and scientifically manage farm to avoid diseases and pests.

【Background and Objective】 Excessive application of nitrogen and phosphorus fertilizers not only results in environmental pollution but also leads to excessive crop growth, thereby compromising ultimate crop yields. This paper investigates the feasibility of using hyperspectral technology to phenotype crop canopy and crop growth and to improve nitrogen and phosphorus fertilizations. 【Method】 The experiment was conducted from 2022 to 2023 in a maize field. In 2022, nitrogen fertilizations were 0, 120 kg/hm2 and 240 kg/hm2 of nitrogen, and phosphorus fertilization was 0 and 100 kg/hm2 of P2O5. In 2023, the nitrogen applications remained unchanged, but the phosphorus fertilizations changed to 0, 60 kg/hm2 and 120 kg/hm2. All treatments were irrigated by drip irrigation. In the experiment, spectral characteristics of the canopy, dry matter accumulation and grain yield were measured regularly to analyze their response to nitrogen and phosphorus applications. 【Result】 ① The spectral reflectance of the summer maize increased significantly with N and P applications. Compared with the treatments without N and P fertilizations, N fertilization increased the spectral reflectance by 9.61%-18.60% and 3.06%-7.06%, respectively. ② The quality of dry matter and grain yield both increased with the increase in N and P fertilization. The combination of N and P fertilization significantly increased above - ground biomass and grain yield. Compared to control without fertilization, N and P fertilization increased the grain yield by 8.82%-24.27%, while compared to those with only P fertilization, it increased the grain yield by 15.75%-65.79%. N-P coupling had a significant effect on both quality of dry matter quality and grain yield (P

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office 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.)

The low efficiency of light and nitrogen resources, poor yield and profit, and environmental pollution of maize production are main problems in many areas of China. We hypothesized that optimizing nitrogen fertilizer density management strategies could alleviate the above issues. To address this, a 3-year on-site experiment with three planting densities and four nitrogen rates was conducted in the Sichuan Hilly Region. The results indicated that increasing the planting density could increase the extinction coefficient and solar radiation interception of maize populations as well as enhance the utilization efficiency of light and nitrogen resources and yield. For every 100 kg ha−1 increase in nitrogen fertilizer, RUE increased by 0.16%, NUE decreased by 25.0%, and soil apparent nitrogen loss quantity increased by 67.8 kg ha−1. There was a certain interaction between planting density and nitrogen rate. The appropriate planting density and nitrogen rate combination was 67,500 plants ha−1 with 180 kg N ha−1 under the experimental condition. Excessive close planting in weak-light areas and excessive nitrogen reduction after densification are not advisable. This study indicated that nitrogen–density strategies should be matched with the local natural resources such as sunlight. The results provide a theoretical for high-yield and high-quality maize production in these areas. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences 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.)

The Haihe Plain in China is situated in the world's largest groundwater funnel area, with per capita water resources far below the internationally recognized "extremely water-scarce" standard. To address the issue of water shortage in summer maize-planting areas of the Haihe Plain, we conducted research on the variation of summer maize evapotranspiration using a medium-sized lysimeter. This study aims to provide technical support for water-saving irrigation in summer maize fields. Through path analysis, direct and indirect influencing factors affecting the evapotranspiration of summer maize fields were determined. The results showed that the cumulative evapotranspiration of bare ground and farmland during the entire growth period of summer maize was 173.57 mm and 382.97 mm, respectively, with evapotranspiration intensities of 1.52 mm/d and 3.36 mm/d, respectively. Evapotranspiration during the maturity stage of summer maize was the least, accounting for only 1.82% of total evapotranspiration during the entire growth period. The period from the jointing to milk-ripening stage is when evapotranspiration in maize fields is at its highest. During this period, evapotranspiration in maize fields amounted to 265.58 mm, accounting for 69.35% of total evapotranspiration. The evapotranspiration intensity was 3.59 mm/day, which is 1.34 times higher than that of bare soil. The evapotranspiration intensities during each growth stage were ranked as jointing stage > tasseling-silking stage > seedling stage > milk maturity stage > maturity stage. The daily evapotranspiration of summer maize fields showed a "unimodal" curve with low values in the morning and evening, and high values at noon. Path analysis indicated that daily radiation and maximum daily temperature had the greatest impact on the evapotranspiration of maize fields, with the direct effect of maximum daily temperature being restrictive and the indirect effect being promotive, resulting in an overall promotive effect. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office 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.)

No-tillage of summer maize after the harvest of winter wheat is the primary agricultural practice on the North China Plain. However, prolonged no-tillage without deep tillage practices negatively impacts soil properties, which is detrimental to the growth and yield of summer maize. In this study, Xianyu 688 and Jifeng 2 were used as test maize materials, no-tillage and surface fertilizing with normal nitrogen (N) (BC240), no-tillage and surface fertilizing with N reduction (BC180), subsoiling layered fertilization with normal N (FC240) and subsoiling layered fertilization with N reduction (FC180)were designed, in order to assess root distribution, N utilization and grain yield of summer maize. In the two maize cultivars, the FC240 and FC180 treatments significantly reduced soil bulk density in the 10–50 cm depth soil layer compared to the other two treatments, and also increased total N content in the 20–50 cm depth soil layer. Compare BC 240 treatment, the FC240 treatment significantly increased root length in the 20–40 cm soil layer and root rap bleeding. Additionally, the FC240 and FC180 treatments enhanced dry matter and N accumulation, grain yield, N uptake efficiency and N fertilizer partial factor productivity. In various treatment, Xianyu 688 exhibited increased grain yield, N uptake efficiency and N fertilizer partial factor productivity compare with Jifeng 2. When employing a total N application level of 180–240 kg N/hm2, the synergistic improvement of summer maize grain yield and N efficiency can be achieved by incorporating subsoiling combined with layered nitrogen application. [ABSTRACT FROM AUTHOR]

In recent years, the frequency and intensity of exposure to heat stress have increased gradually, seriously hampering the production of maize. This paper presents a study designed to analyze how the development, physiology and dispersal of pollen from the heat‐resistant maize variety Zhengdan958 and the heat‐sensitive maize variety Xianyu335 are affected by exposure to heat stress during the tasselling stage. Our results showed That exposure to heat stress significantly increased the antioxidant enzyme activity in pollen. Upon visual inspection of the pollen, we found that the lower water content had given rise to wrinkles in the pollen surface, sunken germination pores, and morphological deformations. In addition, the anther dehiscence process was hindered, resulting in a reduced amount of pollen being dispersed. We also found elevated levels of abscisic acid (ABA), jasmonic acid (JA) and its derivatives, indole acetic acid (IAA) and gibberellin‐3 (GA3) in heat‐pollens, as well as elevated ratios of IAA to ABA and ABA to GA3. Ultimately impaired pollen fertility. Summarizing, our experiment revealed that reduced pollen quantity and quality are significant contributors to fertility losses in summer maize exposed to heat stress at anthesis, and we hope that our analysis of the physiological mechanisms involved can contribute to the development of crop management measures aimed at countering the increasingly detrimental effects of heat stress on the production of summer maize. [ABSTRACT FROM AUTHOR]

【Objective】 Root acquisitions of water and nutrients and their subsequent translocation and consequences for crop growth are complex processes interactively influenced by a myriad of biotic and abiotic processes. This paper aims to experimentally find the optimal irrigation and nitrogen fertilization for rotated winter wheat and summer maize under subsurface drip irrigation. 【Method】 The experiment was conducted in a wheat-maize rotation field. The irrigation treatments for the winter wheat were 2 580 m3/hm2 (W1), 2 240 m3/hm2 (W2), 2 020 m3/hm2 (W3), 1 560 m3/hm2 (W4). For the summer maize, the irrigation treatments were 1 306 m3/hm2 (W1), 1 088 m3/hm2 (W2), 814 m3/hm2 (W3), 650 m3/hm2 (W4). For each irrigation treatment, there were two nitrogen fertilizations for the two corps: 180 kg/hm2 (F1) and 100 kg/hm2 (F2). During the experiment, we measured soil moisture, nitrogen content, dry mass of the shoots and grain yield of the two crops at different growth stages. We also calculated water consumption, water use efficiency, partial nitrogen fertilizer productivity of the two crops to assess the impact of water-nitrogen coupling on these traits. 【Result】 For winter wheat, the W2F1 was the optimal water-nitrogen coupling which gave the highest grain yield. For summer maize, its grain yield increased with irrigation amount for both fertilization treatment. Soil nitrogen residual content was higher in F1 than in F2. With the increase in irrigation amount in the winter wheat field, residual nitrogen content decreased first followed by an increase. In contrast, residual nitrogen content in the maize field peaked in W1 treatment. The partial productivity of nitrogen fertilizer mirrored the yield of both crops. Water consumption of both crops increased with irrigation amount, yet their water use efficiency increased with irrigation amount initially and then declined when irrigation amount exceeded a threshold value. 【Conclusion】 Analysis of irrigation amount, yield and water use efficiency of the two crops indicates that the optimal irrigation amount and nitrogen fertilization for winter wheat and summer maize were 214 mm and 100 kg/hm2, and 103 mm and 100 kg/hm2 respectively. They can be used as an improved irrigation and fertilization for maize production in the studied region.

Abstract Global climate change, with warming as its main feature, has altered the spatial-temporal evolution of factors such as precipitation and temperature that can cause meteorological disasters. The complex and changeable climate has led to frequent natural disasters, while the frequency and intensity of extreme climate events have also significantly increased, posing an enormous threat to societal production and human life. As the most important geoecological transitional zone of mainland China, the stability of agricultural production in China’s north–south transitional zone is crucial for ensuring food security under climate change. With the use of daily precipitation and potential evapotranspiration data from 1961 to 2018, this study focused on analysing disturbances such as extreme precipitation and drought disasters at different time scales during the winter wheat and summer maize growing seasons in the north–south transitional zone of China from an agricultural production perspective and attempted to answer the following questions: first, from an agricultural production perspective, what are the temporal and spatial distribution patterns of extreme precipitation and arid climate events in the north–south transitional zone? Second, which areas are at high risk of being disturbed by different types of meteorological disasters and require increased attention? The results indicated that (1) in terms of the overall temporal variation, the degree of extreme precipitation and drought stress faced by agricultural production in the region is decreasing. However, the temporal variation at each station in the north–south transitional zone was not completely consistent with the overall trend, and both increasing and decreasing trends were observed. The sites exhibiting an increase overlapped with typical regions of the north–south transitional zone to varying degrees, indicating that the typical regions represented not only theoretical potential risk areas under climate change but also suffered from meteorological disaster disturbances. (2) The precipitation distribution during the winter wheat growth period in the south–north transitional zone was uneven and varied significantly. High values of extreme precipitation indices during the winter wheat growth period were mainly concentrated in the southern part of the eastern section of the north‒south transitional zone. The precipitation distribution during the summer maize growth period significantly differed, with the highest amount of heavy rain and largest number of rainstorm days concentrated in the southeastern part of the north‒south transitional zone. The spatial distribution of the drought frequency in the north–south transitional zone, as indicated by the monthly standardized precipitation evapotranspiration index (SPEI1), showed that the areas with high total drought frequencies were mainly concentrated in northeast Jiangsu, southeast Henan, and north Anhui, which primarily experienced light drought. The central part of Jiangsu Province exhibited a high frequency of moderate drought, while southern Jiangsu Province and southwestern Shaanxi Province were prone to severe drought. Additionally, southeastern Hebei and eastern Henan were identified as areas with a high frequency of extreme drought. Finally, the central region of Sichuan Province was characterized by both severe and extreme drought conditions. Based on the SPEI12-derived spatial distribution of the drought frequency in the north–south transitional zone, the areas with a high total drought frequency were mainly concentrated in central and eastern Henan, southeast Shaanxi, southeast Shandong, and central Sichuan, which primarily experienced light to moderate drought. The northwestern part of Jiangsu, the southern part of Hebei, and the western part of Shandong are regions with a high frequency of severe drought, while the eastern part of Henan is an area with high frequencies of both severe and extreme drought. (3) High-value areas of extreme precipitation and drought disturbance in the north–south transitional zone overlapped with the edge of the transitional zone to varying degrees. Approximately 63.58% of the north‒south transitional zone of China was characterized by moderate or high stress levels, primarily concentrated along the southern boundary and central core area, and nearly 39.5% of all counties experienced two or more types of disaster stresses.

Given the present situation of high nitrogen fertilizer application, low utilization rate, and increasing environmental problems on maize, active alginic acid was selected as a synergist to modify and enhance urea and carried out the regulation of alginate acid-enhanced urea on yield formation, nitrogen absorption, utilization and loss of summer maize, in order to provide a theoretical basis for realizing nitrogen fertilizer reduction, improving nitrogen use efficiency and reducing environmental load. Summer maize was used as the test crop, and 15N isotope tracing technology was combined with field trials in this experiment. Seven treatments were set up：no urea application (CK), urea(U), 0.5% alginic acid-enhanced urea(AU1), 2.5% alginic acid-enhanced urea(AU2), 5.0% alginic acid-enhanced urea (AU3), 20% reduction of standard urea(U-N), 2.5% alginic acid-enhanced urea reduction 20%(AU2-N). One-time fertilization was adopted, and ammonia volatilization and nitrous oxide emissions were measured after fertilization. The results show that the carbohydrate C-OH stretching vibration of alginic acid-enhanced urea was observed at about 1 038 cm-1, and the intensity of NH2 vibration peak increased in 3 426-3 325 cm-1 range and at 1 584 cm-1, and C-N vibration peak at 1 450 cm-1 and 1 143 cm-1 . In constant treatment, applying alginic acid-enhanced urea could increase maize yield by an average of 5.04%, nitrogen accumulation increased by an average of 13.55 kg·hm-2, and nitrogen use efficiency increased by an average of 4.63 percentage points. In reduction treatments, the yield of the U-N treatment was not significantly reduced, but the yield of the AU2-N treatment was 2.30% higher than that of the AU2 treatment, and the nitrogen use efficiency increased by 7.16 percentage points. Nitrogen residues in 0-60 cm soil increased by 2.94 and 8.21 kg·hm-2 in AU1 and AU2 treatments, respectively, compared with the U treatment. Alginic acid-enhanced urea could reduce the loss of nitrous oxide emission and leaching, and an average of 6.16 percentage points reduction rate of nitrogen fertilizer loss from constant alginic acidenhanced urea compared with U treatment and 9.95 percentage points for the AU2-N treatment compared with the U-N treatment. Under the experimental conditions, considering maize yield, nitrogen absorption and utilization, residue, and loss, 2.5% alginic acid-enhanced urea application with 20% reduction can achieve better results. [ABSTRACT FROM AUTHOR]

Water shortages and population surges pose notable challenges to food security. North China is an important grain base of the country, with limited available water resources. Therefore, it is necessary to research the patterns of photosynthate accumulation, distribution, and transfer in summer maize under water stress. On the basis of existing methods, in this study, we considered the impact of water stress with two methods, namely the distribution coefficient method and the distribution index method. The results showed that the water correction coefficient indices of the stem–leaf ratio spike–stem ratio, and root–shoot ratio were 0.2705, 0.3530, and −0.2097, respectively, which revealed that water stress caused a decrease in the stem–leaf ratio and spike–stem ratio and an increase in the root–shoot ratio. Water stress caused a reduction in the stem distribution index and leaf distribution index and a slight increase in the spike distribution index. The filling stage was the critical period for water stress to affect the distribution coefficient of each organ, while the jointing stage was the critical period for water stress to affect the leaf distribution index. During the middle growth period, water stress exerted the greatest impact on the distribution parameters. Water stress imposed a greater influence on the distribution coefficient than on the distribution index. The two methods effectively simulated the accumulation and distribution process of photosynthates under water stress conditions, and the R2, average absolute percentage and root mean square error values were 0.9358–0.9997, 4.15–22.71%, and 2.6–24.37%, respectively. The change trend of the photosynthate transfer rate calculated by the distribution coefficient method under water stress conditions was more consistent with that of the actual values. The distribution coefficient method generally performed better than the distribution index method. This study avoids the problem of solely relying on experimental data to determine crop growth dynamics and provides a way to describe crop photosynthate accumulation continuously and quantitatively. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences 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.)

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board 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.)

Global climate change, with warming as its main feature, has altered the spatial-temporal evolution of factors such as precipitation and temperature that can cause meteorological disasters. The complex and changeable climate has led to frequent natural disasters, while the frequency and intensity of extreme climate events have also significantly increased, posing an enormous threat to societal production and human life. As the most important geoecological transitional zone of mainland China, the stability of agricultural production in China's north–south transitional zone is crucial for ensuring food security under climate change. With the use of daily precipitation and potential evapotranspiration data from 1961 to 2018, this study focused on analysing disturbances such as extreme precipitation and drought disasters at different time scales during the winter wheat and summer maize growing seasons in the north–south transitional zone of China from an agricultural production perspective and attempted to answer the following questions: first, from an agricultural production perspective, what are the temporal and spatial distribution patterns of extreme precipitation and arid climate events in the north–south transitional zone? Second, which areas are at high risk of being disturbed by different types of meteorological disasters and require increased attention? The results indicated that (1) in terms of the overall temporal variation, the degree of extreme precipitation and drought stress faced by agricultural production in the region is decreasing. However, the temporal variation at each station in the north–south transitional zone was not completely consistent with the overall trend, and both increasing and decreasing trends were observed. The sites exhibiting an increase overlapped with typical regions of the north–south transitional zone to varying degrees, indicating that the typical regions represented not only theoretical potential risk areas under climate change but also suffered from meteorological disaster disturbances. (2) The precipitation distribution during the winter wheat growth period in the south–north transitional zone was uneven and varied significantly. High values of extreme precipitation indices during the winter wheat growth period were mainly concentrated in the southern part of the eastern section of the north‒south transitional zone. The precipitation distribution during the summer maize growth period significantly differed, with the highest amount of heavy rain and largest number of rainstorm days concentrated in the southeastern part of the north‒south transitional zone. The spatial distribution of the drought frequency in the north–south transitional zone, as indicated by the monthly standardized precipitation evapotranspiration index (SPEI1), showed that the areas with high total drought frequencies were mainly concentrated in northeast Jiangsu, southeast Henan, and north Anhui, which primarily experienced light drought. The central part of Jiangsu Province exhibited a high frequency of moderate drought, while southern Jiangsu Province and southwestern Shaanxi Province were prone to severe drought. Additionally, southeastern Hebei and eastern Henan were identified as areas with a high frequency of extreme drought. Finally, the central region of Sichuan Province was characterized by both severe and extreme drought conditions. Based on the SPEI12-derived spatial distribution of the drought frequency in the north–south transitional zone, the areas with a high total drought frequency were mainly concentrated in central and eastern Henan, southeast Shaanxi, southeast Shandong, and central Sichuan, which primarily experienced light to moderate drought. The northwestern part of Jiangsu, the southern part of Hebei, and the western part of Shandong are regions with a high frequency of severe drought, while the eastern part of Henan is an area with high frequencies of both severe and extreme drought. (3) High-value areas of extreme precipitation and drought disturbance in the north–south transitional zone overlapped with the edge of the transitional zone to varying degrees. Approximately 63.58% of the north‒south transitional zone of China was characterized by moderate or high stress levels, primarily concentrated along the southern boundary and central core area, and nearly 39.5% of all counties experienced two or more types of disaster stresses. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office 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.)

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences 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.)

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences 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.)

【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.

The experiment used the main summer maize variety Denghai 605 as the test object, in order to explore the effect of different fertilization treatments on soil physicochemical properties, nitrogen, phosphorus and potassium contents in straw and grains, corn yield and economic coefficient, and calculated the utilization rates of nitrogen, phosphorus and potassium fertilizers for summer maize. The results showed that different fertilization treatments reduced soil pH and organic matter, alkalihydrolyzed nitrogen, and available phosphorus; total nitrogen, phosphorus, and potassium increased the yield of summer maize grains and straw, as well as the nutrient absorption of grains and straw. In this experiment, the utilization rate of nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer were 32.96%, 14.25% and 41.67%, respectively, and the utilization rates of comprehensive fertilizer was 40.34%. Economic coefficient of maize was 0.47-0.51. [ABSTRACT FROM AUTHOR]

The present study aims to assess the responses of growth, development, and yield of summer maize to the effects of drought–flood abrupt alternation through comparative tests under single flood, single-drought, and drought–flood abrupt alternation treatments with varying degrees from the elongation to the tasseling stage during the 2021 and 2022 growing seasons. In addition, a water production function model for summer maize was preliminarily established based on the results obtained under the drought–flood abrupt alternation scenarios. The results indicated that drought–flood abrupt alternation with early moderate drought had a certain restricting effect on summer maize, while early moderate drought followed by waterlogging had a compensation effect on the cultivated summer maize. Furthermore, both mild and severe drought followed by waterlogging exert a significant combined constraint on the normal growth and development of summer maize, leading to a sharp decline in maize yield, necessitating a shorter timeframe for mitigating and reducing the effects of waterlogging. Additionally, the water production function model established through a multiple linear regression equation exhibits a high degree of fit and demonstrates a strong linear relationship. This study provides crucial insights for agricultural practices and water resource management strategies, particularly in the evaluation of the integrated impacts of drought and waterlogging on crop yields and the formulation of effective disaster risk reduction and mitigation measures in response to these impacts.

Accurate estimation of soil moisture content (SMC) is vital for effective farmland water management and informed irrigation decision-making. The utilization of unmanned aerial vehicle (UAV)-based remote sensing technology to monitor SMC offers advantages such as mobility, high timeliness, and high spatial resolution, thereby compensating for the limitations of in-situ observations and satellite remote sensing. However, previous research has primarily focused on SMC diagnostics for the entire crop growth period, often neglecting the development of targeted soil moisture modeling paradigms that account for the specific characteristics of the canopy and root zone at different growth stages. Furthermore, the variations in soil moisture status between fields, resulting from the hysteresis of water flow in irrigation channels at different levels, may influence the development of soil moisture modeling schemes, an area that has been seldom explored. In this study, SMC models based on UAV spectral information were constructed using Random Forest (RF) and Particle Swarm Optimization-Support Vector Machine (PSO-SVM) algorithms. The soil moisture modeling paradigms (i.e., input–output mapping) under different growth stages and soil moisture conditions of summer maize were systematically compared and discussed, along with the corresponding physical interpretability. Our results showed that (1) the SMC modeling schemes differ significantly across the various growth stages, with distinct input–output mappings recommended for the early (i.e., jointing, tasselling, and silking stages), middle (i.e., blister and milk stages), and late (i.e., maturing stage) periods. (2) these machine learning-based models performed best at the jointing stage, while subsequently, their accuracy generally exhibited a downward trend as the maize grew. (3) the RF model demonstrates superior robustness in estimating soil moisture status across different fields (moisture conditions), achieving optimal estimation accuracy in fields with overall higher SMC in line with the PSO-SVM model. (4) unlike the RF model’s robustness in spatial SMC diagnostics, the PSO-SVM model more reliably captured the temporal dynamics of SMC across different growth stages of summer maize. This study offers technical references for future modelers in UAV-based SMC modeling across various spatial and temporal conditions, addressing both the types of models as well as their input features.

In order to study nitrogen utilization efficiency of summer maize in wheat-maize crop rotation area affected by flood in 2022, a plot experiment was designed to study the effects of different nitrogen rates on the yield, agronomic traits, economic benefit of maize. Conventional P and K fertilizer (T1 ), cconventional fertilization reduces N application by 15% (T2 ), conventional fertilization reduces N application by 5% (T3 ), conventional fertilization (T4 ), conventional fertilization increases N application by 5% (T5 ) and conventional fertilization increases N application by 15% (T6 ) treatments were set. The results showed that under the experiment conditions, ear length, ear diameter and plant height of maize gradually increased with the increase of nitrogen rates, however, the length of bare tip tends to decrease. T5 performed best. And the yields showed a trend of first increasing and then decreasing with the increase of nitrogen rates. And the yields of T5 and T6 treatments were 9 201. 0 and 9 166. 5 kg / hm 2, respectively, which were significantly higher than that of the corresponding nutrient deficiency fertilizer treatments T1, T2 and T3 . Compared with T1 , the economic benefit of different nitrogen application rates increased in different degrees, and T5 reached the highest at 23 922. 6 yuan / hm 2 . Comprehensive consideration of yield and economic benefit, T5 was the optimal combination. [ABSTRACT FROM AUTHOR]

Purpose: Cover cropping during the summer fallow is a feasible practice for soil residual nitrogen (N) absorption and subsequent N supply in greenhouse vegetables. However, the change in these effects with a progression in the cultivation years of greenhouse vegetables remains unknown. This study aimed to evaluate the effects of different cover crops on the uptake of residual N in soil and N mineralization as affected by the planting years of greenhouse vegetables. Methods: Five soil samples were collected from fields that had been cultivated with greenhouse vegetables for different number of years (0, 5, 10, 15, and 20 years); upper layers (0–30 cm) of the soil were sampled from a major vegetable production area in Xinxiang City, Henan Province, China. Three cover crop treatments were included for each soil sample: no cover crop planted during summer fallow with no straw return (CK), summer maize (Zea mays L.) planted and straw return (SM), and alfalfa (Medicago sativa L.) planted and straw return (A). Pot and incubation experiments were conducted to determine the amounts of N absorbed by cover crops during the fallow and soil N mineralization after cover crop straw return. Results: The effects of cover crops on soil residual N absorption and subsequent N mineralization changed with cover crop types and greenhouse vegetable planting years. SM performed better as a cover crop than A in crop biomass development (on average 6.67 times larger), soil residual N absorption (4.46 times larger), and loss (3.61 times smaller) control, regardless of the greenhouse vegetable planting years. In terms of soil net N mineralization and straw-induced N mineralization, SM was inferior to A (1.15 and 2.12 times smaller). With the increase of planting years, total biomass yield and N uptake by the SM increased, whereas these parameters decreased for treatment A due to the plants' different tolerance to soil available N and pH (pondus hydrogenii). For all cover crop treatments, with the increase of greenhouse vegetable planting years, net N mineralization of the soil increased due to the positive contribution of soil organic matter, whereas straw-induced N mineralization decreased due to the negative regulation of accumulated soil nitrate nitrogen. Conclusions: Non-legumes, as represented by SM, were a good choice for cover cropping regardless of the greenhouse vegetable cultivation years. However, attention should be paid to N supplementation at an early stage of subsequent crop cultivation, especially in newly built greenhouse vegetables. [ABSTRACT FROM AUTHOR]

The North China plain (NCP) is an important production base for winter wheat and summer maize in China. Severe droughts seriously restrict agricultural production in this region, threatening food security. Based on the standardized precipitation evapotranspiration index (SPEI), this study explored the spatial and temporal drought characteristics during the winter wheat and summer maize growing seasons in the region. The study found that: 1) From 1980 to 2013, the drought trend of the winter wheat growing season in the NCP has intensified, with Huang-Huai Plain agricultural area (HH_P) showing the most significant drought trend. However, the summer maize growing season has become wetter, with the Shandong hilly agricultural and forestry area (SD_Q) showing the most significant wetting trend. 2) After the year 2003, the results from Mann-Kendall trend analysis revealed that the drought trend of HH_P during the winter wheat growing season became particularly pronounced, but the wetting trend of SD_Q and HH_P during the summer maize growing season became more evident. 3) The dominant spatial patterns observed in the NCP during the growing seasons of winter wheat and summer maize were marked by a consistent distribution of drought and wetness conditions. For winter wheat, the southern regions of the foothill plain area of Yanshan and Taihang Mountains (YT_ P) and the low-lying plain area of Hebei, Shandong, and Henan (JLY_P) were more sensitive to the changes of drought and wet conditions. For summer maize, SD_Q was more sensitive to the changes of the drought and wet conditions. The results of this study could provide references for the formulation of drought relief strategies of winter wheat and summer maize in the NCP. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences 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.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office 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.)

Summer maize was used as the research object, firstly, ground hyperspectral data were obtained for four key fertility stages（pulling stage, trumpeting stage, tasseling stage, filling stage）, and the above-ground biomass（AGB） of each fertility stage was measured empirically. Secondly, waveband optimization algorithms based on arbitrary waveband combinations were constructed for six different waveband combination forms of two-band and three-band spectral indices, respectively. Then, the 12 constructed spectral indices were correlated with the ground-truthed AGB, from which the best correlated spectral index was selected as the optimal spectral index to construct the AGB estimation model for summer maize at full fertility. Finally, the performance of the optimal spectral index for estimating AGB at each critical fertility stage of summer maize was systematically evaluated. The results showed that the optimal three-band spectral index TBI6（760,925,895） screened based on the band optimization algorithm had good correlation with the AGB of summer maize at all fertility stages and the whole fertility period, and the AGB estimation model constructed by it had high accuracy, which could provide a reference for the rapid and nondestructive estimation of AGB of summer maize at the whole fertility period and the integration and development of AGB monitoring devices. [ABSTRACT FROM AUTHOR]

Summer maize constitutes a major food crop in the Yellow River Basin. Optimizing nitrogen (N) application management for this crop not only elevates its yield but also reduces N leaching, thereby ensuring food security and lessening agricultural surface pollution. Utilizing two years of summer maize field experiments, the soil water heat carbon and N simulator (WHCNS) was calibrated and validated against empirical measurements. Subsequent analyses employed the calibrated WHCNS to analyze 56 different N management scenarios. These scenarios varied in terms of N application levels, basal N to topdress application ratios, and chase ratios. The entropy-weighted TOPSIS method was utilized for the optimization, considering agronomic, environmental, and economic aspects. The model's calibration accuracy was validated by root mean square errors, relative root mean square errors, and mean errors for soil volumetric water content and soil nitrate N content. The calibration results demonstrated that the new model was capable of simulating the soil hydraulic characteristics, N cycling, and the growth and development of summer maize during the reproductive phase in the Yellow River Basin. Scenario analyses revealed that increasing the N application initially elevated, then stabilized, summer maize yields, whereas the N agronomic efficiency first increased and then decreased. Moreover, reducing the basal N to topdress application ratios and increasing the chase ratios during the tasseling and flowering stages could minimize the nitrate N leaching and optimize both the yield and N fertilizer agronomic utilization. Specifically, the optimal N management for the current year involved applying 170 kg·ha−1 of N with a basal N to the topdress N application ratio of 1:5 and a chase ratio of 1:1 during the tasseling and flowering stages. This study lays the foundation for developing N fertilizer management strategies for summer maize cultivation in the Yellow River Basin. Furthermore, the methodology established here can be adapted for optimizing the management of diverse crops in different geographical regions. [ABSTRACT FROM AUTHOR]

Maize is one of the important grain crops grown globally, and growth will directly affect its yield and quality, so it is important to monitor maize growth efficiently and non-destructively. To facilitate the use of unmanned aerial vehicles (UAVs) for maize growth monitoring, comprehensive growth indicators for maize monitoring based on multispectral remote sensing imagery were established. First of all, multispectral image data of summer maize canopy were collected at the jointing stage, and meanwhile, leaf area index (LAI), relative chlorophyll content (SPAD), and plant height (VH) were measured. Then, the comprehensive growth monitoring indicators CGMICV and CGMICR for summer maize were constructed by the coefficient of variation method and the CRITIC weighting method. After that, the CGMICV and CGMICR prediction models were established by the partial least-squares (PLSR) and sparrow search optimization kernel extremum learning machine (SSA-KELM) using eight typical vegetation indices selected. Finally, a comparative analysis was performed using ground-truthing data, and the results show: (1) For CGMICV, the R2 and RMSE of the model built by SSA-KELM are 0.865 and 0.040, respectively. Compared to the model built by PLSR, R2 increased by 4.5%, while RMSE decreased by 0.3%. For CGMICR, the R2 and RMSE of the model built by SSA-KELM are 0.885 and 0.056, respectively. Compared to the other model, R2 increased by 4.6%, and RMSE decreased by 2.8%. (2) Compared to the models by single indicator, among the models constructed based on PLSR, the CGMICR model had the highest R2. In the models constructed based on SSA-KELM, the R2 of models by the CGMICR and CGMICV were larger than that of the models by SPAD (R2 = 0.837), while smaller than that of the models by LAI (R2 = 0.906) and models by VH (R2 = 0.902). In summary, the comprehensive growth monitoring indicators prediction model established in this paper is effective and can provide technical support for maize growth monitoring. [ABSTRACT FROM AUTHOR]

To improve the yield and water-nitrogen (N) use efficiency of summer maize, a two-year field experiment with four irrigation soil layers (0–10, 0–20, 0–30, and 0–40 cm, denoted as W10, W20, W30, and W40, respectively) and three N applications (180, 240, and 300 kg ha–1, denoted as N180, N240, and N300, respectively) was performed using micro-sprinkling irrigation system in 2018 and 2019. The interaction between water and N application significantly affects dry matter accumulation (DM). Under the same N application, the grain yield of W10 was significantly lower than that of W40. The irrigation amount and evapotranspiration for W20N180 and W20N240 significantly decreased by 47.18%–52.31% and 12.32%–12.68%, respectively, over that of W40N300, and water-use-efficiency (WUE) significantly increased by 7.75%–12.47%. Compared with N180, the N partial factor productivity of N240 and N300 decreased by 21.02%~22.04% and 37.12%~38.24%, respectively; with no significant difference in yield. Grain yield was significantly positively correlated with leaf area index at tasseling, grains per ear, DM at maturity, and evapotranspiration. Overall, suitable irrigation (W20) and N application (180–240 kg ha–1) can achieve higher grain yield and WUE for summer maize in the Huang-Huai-Hai Plain of China. [ABSTRACT FROM AUTHOR]

The experiments were carried out on the long-term positioning experiment platform of Dongping Agricultural Research Institute since 2010. The split-plot experimental design was used with different P2O5 input in the main plots and different K2O input in the sub-plot and different N input in the sub-sub plots. The P2O5 values were 0, 90, 120, and 150 kg hm-2, which were represented as P0, P1, P2, and P3, respectively. The K2O was 0, 180, 240, and 300 kg hm-2, expressed in terms of K0, K1, K2, and K3, respectively. The N was 0, 180, 240, and 300 kg hm-2, denoted as N0, N1, N2, and N3, respectively. From 2020 to 2021, Denghai 605 was used as the experimental material to deeply analyze the effect of nutrient application rate on dry matter and nitrogen concentration of summer maize leaves, aimed to build a critical nitrogen dilution curve for the nutrient growth stage of summer maize leaves, and explore the feasibility of diagnosing and evaluating nitrogen nutrition status of summer maize with nitrogen nutrition index model under different fertilizer application rates. The results showed that the dry matter and nitrogen concentration of summer maize leaves prior anthesis increased with the increment of nitrogen, phosphorus, and potassium fertilizer application. The nitrogen concentration in leaves decreased with the growth process and the accumulation of leaves dry matter, showing a dilution phenomenon. The variations of leaves dry matter and nitrogen concentration could be divided into two groups: nitrogen limitation and non-nitrogen limitation. Further, the curve model of critical nitrogen concentration at the vegetative growth stage of summer maize leaves under different phosphorus and potassium levels was constructed: NLC0 = 2.745 LDM-0 529, NLC1 = 3.245 LDM-0 334, NLC2 = 3.557 LDM-0 290, NLC3 = 3.639 LDM-0286. Nitrogen nutrition index was calculated based on the critical nitrogen concentration dilution curve, which was highly significantly related to the relative leaves dry matter and the relative grain yield. Combining the linear plus platform relationship between nitrogen nutrition index and the relative leaves dry and the relative grain yield, the crop nitrogen status could be well evaluated under the conditions of nitrogen limitation and non-nitrogen limitation. Therefore, the critical nitrogen concentration and nitrogen index at vegetative growth stage of summer maize can effectively predict the critical nitrogen concentration and characterize the nitrogen nutrient status of summer maize. [ABSTRACT FROM AUTHOR]

Post-silking heat stress is one of the main stresses affecting grain filling and yield formation of summer maize in the Huang-Huai-Hai plains. At present, it has been confirmed that increasing nitrogen application can alleviate the inhibition of post-silking heat stress on the yield formation of wheat, maize, and rice, but the regulatory pathways and physiological mechanisms remain unclear. In this study, two maize varieties Zhengdan 958 (ZD958) and Xianyu 335 (XY335) were selected in pot experiment. To study the effects of increased nitrogen application on carbon and nitrogen metabolism of maize under heat stress during post-silking stage, two temperature treatments [ambient temperature (CK) and heat stress (HS)], three nitrogen application levels [low nitrogen application rate (LN): 120 kg hm-2, middle nitrogen application rate (MN): 240 kg hm-2, and high nitrogen application rate (HN): 360 kg hm-2] were set. The results showed that the dry weight of ZD958 and XY335 cultivars at maturity stage decreased by 10.6%-19.3% after 20 days of post-silking heat stress (35°C) compared with the ambient temperature. However, the decrease of kernel dry weight under heat stress was gradually decreased with the increase of nitrogen application rate, and the decrease rate (10.6%-11.2%) of kernel dry weight under medium nitrogen application rate (MN) and high nitrogen application rate (HN) was lower than that (16.2%-19.3%) under low nitrogen application rate (LN), which indicating that increased nitrogen application could significantly increase maize kernel dry weight under post-silking heat stress. This was mainly due to the increasing application of nitrogen effectively alleviated the inhibitory effect of early post-silking heat stress on maize grain nitrogen metabolism, and significantly increased the activities of key enzymes of nitrogen metabolism such as glutamine synthetase (GS) and glutamate synthetase (GOGAT). At the same time, the activities of sucrose phosphate synthetase (SPS) and sucrose synthetase (SS), which were key enzymes of carbon metabolism, were maintained, and the synthesis of soluble sugar in grains was increased, thus ensuring a larger amount of material for grain filling. In conclusion, increasing nitrogen application can alleviate the inhibition of post-silking heat stress on grain carbon and nitrogen metabolism and promote the accumulation of assimilates in grain and increase the kernel weight and yield, which provides a way for the resistant cultivation of summer maize in the Huang-Huai-Hai plains. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology 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.)

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering 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.)

To investigate the dynamic changes in dry matter accumulation in maize after anthesis, we established a logistic model to describe grain filling characteristics (GFC), and analyzed differences between spring and summer maize, and the influence of meteorological factors. The results showed that the logistic model accurately simulated the dynamic changes in grain growth. For spring maize, the fitted hundred-grain weight at maturity was closely related to the average grain filling rate until maturity, days of the active grain filling period, time of the maximum grain filling rate, and duration of the rapid increase in grain weight. For summer maize, it was closely related to the time of the maximum grain filling rate, days of active grain filling period, duration of gradual grain weight, and the rapidly increasing period. The filling characteristics of spring and summer maize differed because of the different meteorological conditions and biological characteristics. The grain filling duration of spring maize was longer than that of summer maize. The maximum grain filling rate of spring maize occurred later than that of summer maize. Temperature and precipitation were the main meteorological factors affecting the hundred-grain weight of spring maize, whereas temperature was the main factor affecting summer maize. The response of spring maize GFC to meteorological factors was more complex than that of summer maize. These results are important for the development of appropriate strategies for improving maize productivity in China.

Generating spatial distribution maps of canopy temperature (Tc) is the basis for the dynamic management of a variable rate irrigation (VRI) system based on infrared thermometers (IRTs). To improve the accuracy of management zone delineation based on Tc maps for summer maize and winter wheat with IRTs mounted on a moving sprinkler irrigation system, the influence of sampling time interval of Tc was studied and the VRI prescription maps were compared with those obtained from unmanned aerial vehicle (UAV) thermal imaging on the same day. The experimental sites were located in Shunyi, Beijing, for summer maize and in Dacaozhuang, Hebei Province, for winter wheat. The sampling time intervals were selected as 0.5–26 min. The results demonstrated that the nRMSE of the predicted and measured values for Tc increased and that their correlation coefficient decreased with the extension of the sampling time interval. When the sampling time interval ranged from 0.5 to 5 min, the correlation coefficient and nRMSE between the predicted and measured values for Tc changed little, and the overlap percentage of the same management zones delineated with NRCT between 5 min and the minimum sampling time interval (0.5 or 1 min) was greater than 79%. For any two measuring dates of Tc, their overlap percentage changed greatly, with a maximum value of 67% for NRCT. The average irrigation amount based on the prescription maps of the IRTs system and UAV thermal imaging system on the three observation days was equal. Our results demonstrated techniques to collect IRTs data and to generate VRI prescription map based on this data, and a sampling time interval of no more than 5 minutes was recommended for Tc.

Objectives] This study was conducted to verify the field application effect of slow-release nitrogen fertilizer on summer maize in Shajiang black soil area by simultaneous sowing and fertilization, and explore the application scope and nitrogen metabolism mechanism, so as to lay a foundation for fertilizer reduction and efficiency improvement. [Methods] With maize variety Beiqing 340 and sulfur-coated urea as experimental materials, five nitrogen application levels were set, namely, control (CO), slow-release nitrogen 70 kg/hm² (C70), slow-release nitrogen 140 kg/hm² (C140), slow-release nitrogen 210 kg/hm² (C210) and slow-release nitrogen 280 kg/hmc (C280). The phosphorus and potassium fertilizers were all in accordance with the unified standard. [Results] With the application rate of slow-release nitrogen increasing, the nitrogen accumulation in organs increased first and then decreased after tasseling stage of maize. In order to reduce the fertilizing amount and increase efficiency, 210 kg/hm² of slow-release nitrogen fertilizer was the best fertilizing amount for summer maize in Shajiang black soil area. [Conclusions] This study provides reference for fertilizer reduction, efficiency improvement and sustainable development of summer maize in Shajiang black soil area. [ABSTRACT FROM AUTHOR]

The low efficiency of light and nitrogen resources, poor yield and profit, and environmental pollution of maize production are main problems in many areas of China. We hypothesized that optimizing nitrogen fertilizer density management strategies could alleviate the above issues. To address this, a 3-year on-site experiment with three planting densities and four nitrogen rates was conducted in the Sichuan Hilly Region. The results indicated that increasing the planting density could increase the extinction coefficient and solar radiation interception of maize populations as well as enhance the utilization efficiency of light and nitrogen resources and yield. For every 100 kg ha−1 increase in nitrogen fertilizer, RUE increased by 0.16%, NUE decreased by 25.0%, and soil apparent nitrogen loss quantity increased by 67.8 kg ha−1. There was a certain interaction between planting density and nitrogen rate. The appropriate planting density and nitrogen rate combination was 67,500 plants ha−1 with 180 kg N ha−1 under the experimental condition. Excessive close planting in weak-light areas and excessive nitrogen reduction after densification are not advisable. This study indicated that nitrogen–density strategies should be matched with the local natural resources such as sunlight. The results provide a theoretical for high-yield and high-quality maize production in these areas.

The Haihe Plain in China is situated in the world’s largest groundwater funnel area, with per capita water resources far below the internationally recognized “extremely water-scarce” standard. To address the issue of water shortage in summer maize-planting areas of the Haihe Plain, we conducted research on the variation of summer maize evapotranspiration using a medium-sized lysimeter. This study aims to provide technical support for water-saving irrigation in summer maize fields. Through path analysis, direct and indirect influencing factors affecting the evapotranspiration of summer maize fields were determined. The results showed that the cumulative evapotranspiration of bare ground and farmland during the entire growth period of summer maize was 173.57 mm and 382.97 mm, respectively, with evapotranspiration intensities of 1.52 mm/d and 3.36 mm/d, respectively. Evapotranspiration during the maturity stage of summer maize was the least, accounting for only 1.82% of total evapotranspiration during the entire growth period. The period from the jointing to milk-ripening stage is when evapotranspiration in maize fields is at its highest. During this period, evapotranspiration in maize fields amounted to 265.58 mm, accounting for 69.35% of total evapotranspiration. The evapotranspiration intensity was 3.59 mm/day, which is 1.34 times higher than that of bare soil. The evapotranspiration intensities during each growth stage were ranked as jointing stage > tasseling-silking stage > seedling stage > milk maturity stage > maturity stage. The daily evapotranspiration of summer maize fields showed a “unimodal” curve with low values in the morning and evening, and high values at noon. Path analysis indicated that daily radiation and maximum daily temperature had the greatest impact on the evapotranspiration of maize fields, with the direct effect of maximum daily temperature being restrictive and the indirect effect being promotive, resulting in an overall promotive effect.

No-tillage of summer maize after the harvest of winter wheat is the primary agricultural practice on the North China Plain. However, prolonged no-tillage without deep tillage practices negatively impacts soil properties, which is detrimental to the growth and yield of summer maize. In this study, Xianyu 688 and Jifeng 2 were used as test maize materials, no-tillage and surface fertilizing with normal nitrogen (N) (BC240), no-tillage and surface fertilizing with N reduction (BC180), subsoiling layered fertilization with normal N (FC240) and subsoiling layered fertilization with N reduction (FC180)were designed, in order to assess root distribution, N utilization and grain yield of summer maize. In the two maize cultivars, the FC240 and FC180 treatments significantly reduced soil bulk density in the 10–50 cm depth soil layer compared to the other two treatments, and also increased total N content in the 20–50 cm depth soil layer. Compare BC 240 treatment, the FC240 treatment significantly increased root length in the 20–40 cm soil layer and root rap bleeding. Additionally, the FC240 and FC180 treatments enhanced dry matter and N accumulation, grain yield, N uptake efficiency and N fertilizer partial factor productivity. In various treatment, Xianyu 688 exhibited increased grain yield, N uptake efficiency and N fertilizer partial factor productivity compare with Jifeng 2. When employing a total N application level of 180–240 kg N/hm2, the synergistic improvement of summer maize grain yield and N efficiency can be achieved by incorporating subsoiling combined with layered nitrogen application.