During the wheat season from 2016 to 2019, Shimai 15 was taken as the experimental variety and four treatments were set up in Xinji Experimental Station of Hebei Agricultural University, including rotary tillage with two irrigation in spring (RT2), subsoiling tillage with one irrigation in spring (ST1), subsoiling tillage with two irrigation in spring (ST2) and rotary tillage with one irrigation in spring (RT1), to measure the flowering and fruiting characteristics, grain-filling and field input and output of wheat. The results showed that the number of effective panicles was not significantly affected by the times of cultivation and irrigation. The number of sterile spikelets and the ratio of sterile spikelets in the treatment of ST2 and ST1 were 3.2% and 5.7% higher than those in the treatment of RT2 and RT1, respectively. Under the condition of one irrigation, the effective grouting period of subsoiling treatment was significantly longer than that of rotary tillage treatment; under the condition of twice irrigation, the filling rate of subsoiling treatment was higher than that of rotary tillage treatment in 2018 with more precipitation. Under the same irrigation times, the 1000-grain weight of the two subsoiling treatments was significantly higher than that of the rotary tillage treatment, with an average increase of 4.8% in the two growing seasons. The application of subsoil fertilization and rotary tillage could effectively reduce the input of tillage fertilization, and had positive significance to improve the harvest index and the ratio of production to input. ST2 was 4.8% and 28.1% higher than RT2, and ST1 was 11.3% and 46.0% higher than RT1, respectively.

The Yellow River Basin, as a main food and energy base in China, is suffering a potential threat to its sustainable development due to the lack of water resources. To investigate the linkage between water resources and the green development in the study area, in this study, the food water footprint (FWF) and energy water footprint (EWF) from 2011 to 2016 was measured to reveal the effect of virtual water flow on water stress. A green development index was also constructed based on the understanding of " five concepts of development ". In addition, the Tapio decoupling model was conducted to explore the relationship between water resources stress and the sustainable development of the social economy. The results showed that: ①The spatial difference of grain and energy water footprints was large in the Yellow River Basin, and the highest water footprints were found in Shandong and Sichuan. ②The pressure of water shortage exists in most provinces of the Yellow River basin, and Ningxia is extremely short of water. ③The green development index of the whole basin basically showed an increasing trend year by year, and the decoupling state from the water footprint pressure index improved with time. The results of this study have some theoretical significance for ecological protection and high-quality development of the Yellow River Basin.

In order to understand the characteristics of Camellia sap flow, an important physiological index, the sap flow and meteorological factors of Camellia reticulata L had been continuously observed for one year, The correlation analysis method and the dislocation comparison method were used to study the relationship between the stem flow of Camellia reticulata L and meteorological factors, as well as the lag of stem flow to meteorological factors. The results show that: Camellia reticulata L sap flow phenomenon occurs at night, and there is a "noon break" phenomenon during 11∶00-17∶30. Camellia reticulata L sap flow starts at about 6∶15 in summer and reaches the first peak at 8∶00, followed by spring and autumn, and winter at the latest. The stem flux curve of Camellia reticulata L presents a bimodal shape in sunny days, and the sap flow has the best correlation with temperature and relative humidity. The stem flux curve shows a multi-peak shape in rainy days, and the stalk flow has a better correlation with temperature and humidity. There is time lag between stem flow and meteorological factors in sunny and rainy days. The conclusions are as follows: the seasonal difference of sunrise time may lead to the earliest stem flow initiation in summer and the latest one in winter. The sap flow morphology curve of Camellia reticulata L differs between sunny and rainy days. This difference may be caused by the difference in solar radiation, relative humidity and air temperature between sunny and rainy days; Different intensities of solar radiation have different effects on the sap flow of Camellia reticulata L. Air temperature, relative humidity and stem flow show a good correlation between sunny and rainy days. There is an obvious time lag between the sap flow of camellia and solar radiation. Combined with the influence of other meteorological factors on the sap flow, a multiple regression model of the sap flow was established.

In order to study the influence of key parameters of water storage and infiltration irrigation on the distribution of water and nitrogen in red soil area, two factors, irrigation volume and buried depth of irrigator, were set up in the experiment, and each factor was set at 3 levels, a total of 9 treatments. The effects of various factors on soil infiltration rate, moisture content in moist body and distribution of nitrate nitrogen were analyzed.The results showed that the influence of irrigation amount on the infiltration rate was greater than the buried depth of the irrigator before the infiltration reached stability, and the migration distance of the vertical wet front decreased with the increase of the buried depth of the irrigator, but increased with the increase of irrigation amount. And with the increase of the buried depth of the irrigator, the range of the wet body moved to the lower right. Soil moisture content gradually decreased with the increase of soil depth, and the range of soil moisture increased with the increase of irrigation amount. The increase of irrigation amount promoted the infiltration of nitrate nitrogen. The distribution pattern of soil nitrate- nitrogen is low-high-low from the periphery of the emitter to the edge of wetting body. Irrigation amount has greater effect on soil water and nitrogen distribution than the buried depth of irrigation emitter. Increasing the irrigation amount can promote the infiltration of water and nitrogen in the red soil under water storage and infiltration irrigation, while increasing the buried depth of the irrigation emitter makes the soil wetting body move to the lower right of the irrigation device. It is recommended to adopt high irrigation amount and deep depth of irrigation emitter in the irrigation of commercial crops such as navel orange in red soil area.

The promotion of water-saving irrigation technology is the key to improve agricultural water use efficiency. Taking vegetable farmers in five provinces around the Bohai Sea as the research object, the impact of farmers' psychological expectations on the adoption of water-saving irrigation technology was analyzed from the perspective of network embedding, and the influence path of network embedding on the adoption of technology was grasped. By using the field survey data of 546 farmers in five provinces of Bohai sea in 2019, the farmers expectations are divided into two aspects of expected income and expected cost. Perceived usefulness and perceived ease of use were selected of as the main measure. The technology adoption of surrounding farmers, network centrality and network scale were selected as the measurement indexes of network embedding, probit model was constructed for regression analysis, and stepwise regression method was used to analyze the mediating effect of psychological expectation. The results showed that both network embedding and psychological expectation had significant positive effects on technology adoption behavior, and psychological expectation had partial mediating effects between network embedding and technology adoption. In addition, the number of household labor had a significant negative impact on the technology adoption behavior of the low-income group, and human capital and policy subsidies had a significant impact on the adoption of water-saving irrigation technology in the high-income group. It can be concluded that Network embedment and psychological expectation are important factors that affect farmers' adoption of water-saving technologies. Network embedment has both direct and indirect effects. The implications of the policy are to solve the problem of technology promotion from the perspective of network embedding. To promote water-saving technology, it is necessary to strengthen the selection of demonstration households, encourage farmers to broaden social network, promote information exchange among farmers, and improve farmers' perception of water-saving irrigation technology by strengthening technical training.

Under drip irrigation fertilization, PAM application methods have a great influence on soil water and fertilizer distribution and can directly affect the usage efficiency of soil water and fertilizer. In this study, the effects of control, mixed fertilization and surface application on the migration distance of soil wetting front, the shape and volume of soil wetting body, and the soil moisture and nutrient distribution under drip irrigation fertilization, were studied through an indoor drip irrigation infiltration simulation experiment. The results showed that: ①Comparing with the control and mixed application treatments, surface application treatment could effectively decrease soil surface evaporation and increase soil infiltration capacity in horizontal direction. ②Comparing with the control treatment, mixed application could effectively increase soil water conductivity and water-holding capacity, and reduce deep soil leakage. ③At the end of 120 minutes infiltration process, the shape of wetting body was similar to a flat ellipsoid, and the soil wetting body volume of surface application treatment was the largest and about twice that of control or mixed application treatments, indicating that surface application treatment of PAM can effectively prevent water evaporation and increase the volume of soil wetting body. ④The accumulation of nitrate nitrogen occurred in the middle and upper part of soil wetting body, and the accumulation pattern was in the order of surface application > mixed application > control. The accumulation of available potassium and available phosphorus in the accumulation area was in the order of surface application > mixed application > control, indicating that the accumulation range of available potassium and phosphorus under surface application conditions was larger, which should be more conducive to crop absorption.

In order to reveal the effects of different water and fertilizer treatments of sprinkler irrigation on the photosynthetic characteristics, chlorophyll fluorescence parameters and biomass of alfalfa in low-yield fields, a field experiment with different water and fertilizer treatments of alfalfa was carried out in the experimental extension base of Fengle River Irrigation District. The results showed that irrigation and nitrogen application levels had significant effects on plant photosynthesis. With the decrease of irrigation amount, the factors affecting photosynthetic characteristics of alfalfa gradually changed from stomatal limitation to non-stomatal limitation. The chlorophyll content in medium fertilizer treatment was higher than that in high fertilizer treatment and higher than that in low fertilizer treatment. The alfalfa chlorophyll content in the medium fertilizer treatment 1 was the highest; with the decrease of irrigation amount, Fv/Fm, ETR, Fv, Fm, Fv/Fo, ΦPSⅡ all decreased, and the yield also decreased. Comprehensive analysis shows that medium nitrogen medium water treatment 1 has the best effect. Therefore, it is suggested that alfalfa in this area can refer to the mode of irrigation and fertilization under medium nitrogen medium water treatment 1, with irrigation quota of 416.8 mm and nitrogen application rate of 206.6 kg/hm².

Agricultural water price policy is an important policy tool to encourage farmers to save water. Not only agricultural water price will affect farmers' behavior of irrigation water, but also the incentive structure of agricultural water price may affect farmers' behavior of irrigation water. Based on the survey data of farmers in the Liuxihe River Basin of Guangdong province, the influence of agricultural water price incentive structure on farmers' choice of irrigation water behavior was investigated by using binary Logistic model. The results show that the existing agricultural water price incentive structure has a significant positive impact on farmers' behavior choice of irrigation water. With the increase of water price incentive intensity, large-scale farmers tend to choose water-saving irrigation technology, while small-scale farmers tend to plant cash crops with higher income. The influence direction of agricultural water price incentive structure on small-scale professional growers' irrigation water behavior choice is more to increase operating income by adjusting planting structure to make up for irrigation water expense, but the influence on their water-saving behavior is limited. Therefore, the incentive structure of agricultural water price needs to be further improved and its incentive intensity needs to be improved to encourage more farmers to adopt water-saving irrigation technology to save water.

In order to provide a theoretical basis for reducing the biological activity of heavy metals in paddy soil by water regulation, in this paper, the influence of water content on the form of polluted heavy metal Cr in paddy soil was studied through indoor cultivation experiments. The BCR sequential extraction method proposed by the European Community Reference Division was used to determine the content of Cr in paddy soil under different water management conditions. The results showed that the content of exchangeable Cr decreased with the increase of incubation time, increased rapidly in the first 30 days, and then tended to balance. The content of reducible Cr showed an upward trend with the increase of incubation time, and increased significantly within 30 days before culture, and then tended to balance. The content of oxidizable Cr increased first and then decreased slowly with the increase of time. There was no significant difference in the content of residual heavy metal Cr in the short-term culture. After 30 days of soil culture, the content of residual heavy metal increased with the increase of culture time. When the exogenous heavy metal Cr entered the soil, the exchangeable Cr content decreased faster under the condition of 60% field capacity than under other water conditions, and the exchangeable Cr content was relatively small, which reduced its bioavailability. Increasing soil field water holding capacity in agricultural irrigation can effectively promote the conversion of exchangeable heavy metal Cr into reducible and oxidizable state, significantly reduce the biological activity of heavy metals, and reduce the toxic effects of heavy metals in soil.

In order to determine the optimal amount of water fertilizer needed for maize growth under straw returning in Huang-Huai-Hai Plain, the effects of irrigation amount and fertilizer amount on stomatal morphology and spatial distribution pattern of maize in different growth stages were investigated through field water and fertilizer experiments under straw returning. The results showed that: ①The stomatal density on the abaxial surface was significantly higher than that on the adaxial surface in both the jointing and filling stages, indicating that the responses of irrigation amount and fertilizer application amount were not consistent between the adaxial surface and the abaxial surface of maize leaves. ②Stomatal pore area and stomatal shape index at the jointing stage were higher than those at the filling stage, indicating that the response of morphological traits of individual stoma to the irrigation and fertilization treatments was different between the jointing and filling stages, and stomatal morphology was more sensitive to water and fertilizer at jointing stage than at filling stage. ③At jointing stage, the stomatal distribution of maize leaves was the most regular under 750 m³/hm² irrigation and 750 kg/hm² fertilizer (W₇₅₀F₇₅₀). While at the grain-filling stage, The stomatal distribution pattern was the most regular with the irrigation amount of 750 m³/hm² and the fertilizer amount of 600 kg/hm² (W₇₅₀F₆₀₀). The results indicated that the stomatal morphology and spatial distribution pattern of maize were most conducive to improving the gas exchange efficiency under the optimal irrigation amount (750 m³/hm²) and fertilizer amount (600 kg/hm²), thus increasing the net photosynthetic rate of maize leaves and grain yield in the Huang-Huai-Hai Plain.

In order to reveal the difference and key influencing factors of water use efficiency of different returning farmland to forest vegetation, in this study, the forests of Armeniaca sibiricat, Hippophae rhamnoides, Pinus tabulaeformis, Populus simonii, Robinia pseudoacacia and Robinia pseudoacacia Amygdalus davidianamixed forest that had been restored for 20 years in loess hilly region were taken as research objects, the gas exchange method was used to determine the instantaneous water use efficiency of different forest vegetation, and the related influencing factors were measured. The results showed that there were extremely significant differences in water use efficiency between different forest tree species. The highest was Pinus tabulaeformis (6.39 μmolCO₂/mmolH₂O), followed by Robinia pseudoacacia mixed forest (5.89 μmolCO₂/mmolH₂O), and the lowest was Armeniaca sibiricat. The first two were 1.83 and 1.61 times higher than the Armeniaca sibiricat respectively. Compared with the Robinia pseudoacacia forest, the water use efficiency of Robinia pseudoacacia mixed forest was increased by 38.0%. Correlation analysis showed that WUE had a significant negative correlation with Gs, Tr, Ci, RWC values of vegetation factors. It had a very significant positive correlation with soil factors SOC, TN, DOC, Ks, and had a significant positive correlation with pH. Stepwise regression analysis showed that plant factors had a stronger influence on WUE than soil factors, among which stomatal conductance, chlorophyll SPAD value, total nitrogen content and saturated water conductance of plant and soil had stronger influence on WUE. In summary, the water use efficiency of Pinus tabulaeformis forest land was the highest, while that of Prunus arundinacea was the weakest. Stomatal conductance, chlorophyll content, total soil nitrogen content and saturated hydraulic conductivity were the main factors affecting water use efficiency in this study. This study provided a scientific basis for the cognition of water resources utilization capacity and its influencing mechanism of the forest vegetation.