In the Hexi Corridor area, water resources are shortage. Unreasonable irrigation caused serious waste of water resources. In addition, mixed wheat varieties and different drought resistance in actual production are not conducive to the maximum effect of farmland irrigation. Therefore, in order to investigate the effects of irrigation on the growth and yield of different wheat varieties, as well as screening of suitable wheat varieties and corresponding irrigation amount in the Hexi Corridor, the irrigation amount for wheat from different varieties was tested in 2018-2019, including three irrigation amount treatments (no irrigation, one times irrigation W1 (joining stage), two times irrigation W2 (joining stage and grouting stage)) and five different varieties (GC24, WC8, LC41, LC33, NC 33) that perform better in the region, in the Huangyang Town Experimental Station of Wuwei City, Gansu Academy of Agricultural Sciences. The flag leaf chlorophyll (SPAD) content, catalase (CAT) activity, malondialdehyde (MDA) content, dry matter accumulation dynamics, yield and yield components were determined. The results showed that irrigation could increase the SPAD value, CAT activity and lower MDA content of wheat flag leaves, regulate dry matter accumulation and distribution. Irrigation could also increase the 1000-seed weight and kernel number per square meter, thereby increase the grain yield and harvest index, but the yield difference between joint irrigation (W1) and joint + grouting (W2) treatments was not significant. Under different irrigation conditions, each index of Longchun 41 (LC41) was significantly higher than other tested varieties. Therefore, it was concluded that the use of LC41 with the irrigation amount of W1 was suitable for the wheat planting mode in this area, and higher yield benefits could be obtained.

Plant has a strong ability to absorb and transform Cd. In order to define the content of heavy metal Cd in soil and fruit and its pollution risk under water storage pit irrigation, field experiments of apple tree water storage pit irrigation were carried out with the test material of 10 years old red Fuji Danxia in 2019. The content of Cd in soil-apple tree system under different irrigation modes were measured using BCR method. Risk assessment of Cd content in soil and individual organs were evaluated by applying the single-factor method. The results showed that the water storage pit irrigation promoted the accumulation of Cd in the surface soil as well as the migration and transformation of Cd into the deep soil. Compared with conventional irrigation, the decrease degree of Cd content in 0~40 cm soil during the whole growth season were lower by 7.59% to 15.72%, while the increase degree of Cd content in 40~160 cm soil during the whole growth season were higher by 0.96% to 20.95%. At the end of growth period, the content of Cd in 20~40 cm depth soil under water storage pit irrigation and 60~160 cm depth soil under conventional irrigation indicated different pollution levels which were still clean. The order of accumulated Cd of individual organs of fruit trees under different irrigation modes from large to small was root, branches, leaves and fruits in turn. The Cd content and enrichment coefficient of each organ under water storage pit irrigation were higher than that under conventional irrigation. However, the Cd content of fruit under different irrigation modes was lower than the Chinese edible safe standard. The research results can enrich the theory of water storage pit irrigation for orchard and provide a scientific basis for restoration of orchard soil environment.

In this study, the variation of appearance quality of rice grain under deficit irrigation was analyzed. The results showed that during the filling period, water deficit would lead to changes in the content of ABA and ACC in rice grains, thus regulating the activity of sucrose-starch metabolizing enzyme. Among them, a certain degree of increased ABA content in rice grains caused by mild water deficit could effectively enhance the activity of sucrose-starch metabolizing enzyme in rice grains, resulting in the increase of filling rate and the decrease of chalkiness in rice grains. With the increase of water deficit, the high level of ABA in rice grains also had adverse effects on grain filling. However, the relationship between rice grain chemical signal ACC and activity of sucrose-starch metabolizing enzyme was relatively complex, which showed that ACC was negatively correlated with ADPG pyrophosphorylase and starch branch enzyme, and positively correlated with starch synthase. This study provided theoretical guidance for optimizing the appearance quality of rice grains by chemical signals.

Because the model parameters of greenhouse drip irrigation system are easily affected by environmental changes, the traditional fuzzy PID control precision is not high. Therefore, this paper proposes a fuzzy PID control method of drip irrigation system with Smith prediction compensation. MATLAB/ Simulink simulation results show that the improved smith prediction compensation fuzzy PID control has better control quality and shorter response time than the traditional fuzzy PID control, and the transition process is shorter, the overshoot is smaller, the stability is higher, the control effect is significantly improved. Meanwhile, the results of greenhouse test show that the maximum overshoot of drip irrigation system is 5.95%, and the soil moisture has remained at 60.22% after the system is stable, which meets the irrigation requirements of greenhouse vegetables. It realizes the precise management and arrangement, and provides a new solution for the development of agricultural irrigation.

In order to explore the distribution of water and nutrients in aeolian sandy soil and make rational use of aeolian sandy soil resources, the field experiment was carried out with different irrigation water amount as the experimental factor. The irrigation water amount was set at five levels of 0.4 (IR1), 0.6 (IR2), 0.8 (IR3), 1.0 (IR4) and 1.2 (IR5). The recommended fertilization amount (pure nitrogen) was 225 kg/hm2.The effects of different irrigation conditions on soil water and nutrient distribution were studied by measuring soil water and nitrate nitrogen content under different irrigation conditions. The results showed that increasing irrigation on Aeolian sand soil could not increase the water storage of soil, but may increase the uneven distribution of soil water. In the horizontal direction, the larger the amount of irrigation to the 0~20 cm range, the farther the water movement distance; in the vertical direction, the 0~30 cm soil layer was the main distribution layer of soil water. The content of nitrate nitrogen in aeolian sand soil was distributed unevenly with obvious concentration. In the horizontal direction, the larger the amount of irrigation, the farther the peak value of nitrate nitrogen content from the emitter; in the vertical direction, there was obvious surface accumulation of nitrate nitrogen, and the increase of irrigation was conducive to the increase of nitrate nitrogen content in each layer. In addition to the positive correlation between soil water content and soil nitrate nitrogen, the vertical distribution had a high correlation, while the spatial distribution had little correlation. It can be concluded that in order to better control soil water and nutrients within the root distribution layer, 0.8 was recommended as the water requirement coefficient in the irrigation system calculation formula when using drip irrigation to irrigate maize in sandstorm soil areas.

Actual evapotranspiration (ET) is an important process for water exchange and is critical to understanding surface water balance. Based on the flux and meteorological data of Shouxian National Observatory of Anhui Province for many years, this paper analyzed the characteristics of ET changes in rice-wheat rotation crops in the Jianghuai River Basin, and identified the ET influencing factors of winter wheat and rice by using path analysis methods. The results showed that: ① the annual average total ET of rice-wheat rotation fields in the Jianghuai River Basin was 740.3 mm, in which winter wheat, rice, and bare land accounted for 40.7%, 52.3%, and 7.0%, respectively. The daily average ET of winter wheat was 1.40 mm/d. During the growing season, the change of ET showed a weak “double-peak type” characteristic. The two peaks were at the emergence-three-leaf and flowering stages. The daily average ET of rice was 3.23 mm/d, and the change of ET during the growing season was a “single peak type”, and the peak value was at the jointing stage. ② ET of winter wheat was mainly controlled by net radiation (Rn) and leaf area index (LAI). The direct effect of Rn was the most obvious, while LAI had an indirect effect on ET mainly through the Rn path. ET of rice was mainly controlled by Rn and 20 cm soil volumetric water content (VSWC20), and the direct effect of Rn was more obvious. Comparing the two crops, Rn had a decisive effect on ET, LAI had a significantly higher effect on ET in winter wheat than rice. VSWC20 had a significant promotion effect on ET in rice, but it could be ignored in promoting ET change in winter wheat.

Potential evapotranspiration (ET0) is the basis for estimating crop water requirements. Based on the data of daily meteorological elements such as temperature, wind speed, and relative humidity at 5 meteorological stations in Shiyang River Basin for five years, the Penman-Monteith formula is used to calculate ET0 in Shiyang River Basin. Six-factor, four-factor, and three-factor support vector machine model (SVM) and artificial neural network model (ANN) are established to simulate the daily ET0, and then the simulated values are compared with the calculated values. Root mean square error (RMSE), mean absolute error (MAE), deterministic coefficient (DC), and Pearson correlation coefficient (R) are used as the performance evaluation index of the models, and the models are tested to obtain models with higher simulation accuracy. The results show that under the same factor input, the ANN model has higher simulation accuracy than the SVM model in Shiyang River Basin to simulate daily ET0. The study can provide a feasible method for simulating daily ET0 for sites with incomplete meteorological data.

The water consumption of greenhouse crops is closely related to the change of plant stem flow. So understanding the change of stem flow of greenhouse crops can improve the rationality of irrigation system. In this study, the greenhouse drip irrigation tomato was taken as the research object, based on the comprehensive consideration of the influence of meteorological factors and crop growth condition on tomato stem flow (Tf) variation, the feasibility of stem flowmeter method to monitor the water demand of tomato in greenhouse was explored, the variation rule and influencing factors of tomato Tf under different typical weather conditions were analyzed, the relationship between LAI and Tf was considered, and the method was compared with the weighing method. Finally, the regression equation of weather factor and Tf was established by path analysis. The results indicated that the Tf of tomato was different at different weather conditions, showing sunny> cloudy > rainy days. The Tf of tomato was closely related to LAI, with a correlation coefficient of 0.77, reaching a significant level (P<0.01). In addition, the differences of Tf at different plants could be reduced by using LAI to normalize Tf. Path analysis results showed that the relationship between meteorological factors and Tf could be expressed as Tf=0.213 Rs +1.536 VPD-0.305, the influence of air temperature (Ta) and wind speed (u2) on Tf was mainly achieved through solar radiation (Rs) and water vapor pressure difference (VPD). The impact of Rs on Tf was larger than that of VPD. This study provides a theoretical basis for determining the water requirement of drip irrigation tomatoes in a greenhouse based on a stem flow meter method.

Water shortage is a limiting factor for sustainable vegetable production in Beijing suburbs. In order to explore the regulation potential of exogenous spray of drought-tolerant substances and reduced irrigation measure, a field experiment was designed to investigate the effects of spraying fulvic acid (FA) and betaine (GB) as well as reducing drip irrigation volume from DI1 to DI2 on yield, water use ability, quality and planting benefit of lettuce. The results showed that, spraying FA and GB at DI1 level increased the yield of lettuce by 6 735 and 9 736 kg/hm2, respectively; increased the irrigation water use efficiency by 8.4 and 12.2 kg/m3 respectively; and increased planting benefit by 18 558, 26 425 yuan/hm2, respectively. The soluble sugar content and leaf CAT enzyme activity was observed increased in FA and GB treated plants. Spraying GB at DI1 level showed an additional effect of increasing VC content. Spraying FA and GB at DI2 level also played a role in increasing the yield, water use efficiency and planting benefit of lettuce, however, their effect at DI2 level was far less than that at DI1 level, which might be ascribed to low irrigation input set by DI2. When the irrigation level was reduced from DI1 to DI2, sharply decrease of yield and responsive increase of leaf antioxidant enzyme activity were detected. Although the water use efficiency of lettuce was increased by reduced irrigation measure, the simultaneous decrease of yield and planting income made this measure unrealistic to apply. Comprehensively thinking, DI1+GB and DI1+FA are the recommended “yield-increasing and water-saving” measure for lettuce production.

In order to study the effect of different application methods on soil moisture and potato growth in sloped farmland under the combined application of PAM and SAP, field experiments were carried out in Zhuozi County, Inner Mongolia. With no application treatment as the control, 3 groups of experimental treatments were set. The results showed that the combined application of PAM and SAP could increase the moisture content of 0~40 cm soil layer, and the moisture content increased with the increase of application amount. Compared with P3 and control treatment, the maximum increase of H3 was 26.97% and 21.04%.The application of PAM and SAP could increase the soil water storage of 0~80 cm in the sloping farmland at the seedling stage, and the soil water storage was positively correlated with the application amount. However, the soil water storage after treatment was lower than that of the control group during other growth periods of potato. From sowing to harvest, potato biomass of P2 reached the maximum, and its water use efficiency increased by 29.54% compared with control. Therefore, proper application of PAM and SAP can improve soil moisture environment and increase potato yield.

As a simple fertilization injector relying on the vacuum effect at centrifugal pump inlet, pump suction fertilization system has been widely applied in small -scale micro jet field fertilization. Because the whole process of fertilizer absorption and its influencing factors have not been studied, the scientific application of pump fertilization system is limited. In this paper, a mathematical model for pipes of pump suction fertilization system was set up, and three types of fertilization pipes and well water pipes varying in diameter were selected separately. A variety of combinations were set to simulate the effects of liquid level, pipe diameter and dynamic head of water pump on hydraulic performance of fertilization system. The results showed that: the flow rate of fertilization pipe was greatly influenced by liquid level, followed by that of well water pipe, and the flow rate of main pipe was basically kept constant; the larger the difference between the diameter of fertilization pipe and that of well water pipe, the stronger the anti-interference ability of the system; the hydraulic characteristic curve of centrifugal pump must be considered in the hydraulic calculation of pump suction fertilization pipeline; the change of diameter of fertilization pipe would lead to the great change of its flow rate.

In view of the influence of the difference of vegetation cover on the accuracy of remote sensing monitoring regional drought, the precipitation, latent heat flux and sensible heat flux data of 44 districts and counties in Jilin Province from 1978 to 2017 were obtained by GLDAS, so as to construct the standardized Bowen ratio index (SBI), on this basis, the standardized precipitation index (SPI) was combined, and the comprehensive dryness reflecting soil moisture and precipitation was constructed by copula function. The drought index (MSBP) was used to analyze the spatial and temporal characteristics of drought in Jilin Province. By comparing the performance of SBI, SPI and MSBP in historical drought years, and analyzing the correlation between the three indexes and grain yield, the application effect of different drought monitoring indexes could be evaluated. The results showed that: ① MSBP was more comprehensive and accurate in describing the characteristics of drought and the impact of drought on grain yield. ② MSBP could accurately describe the duration of drought process and the intensity of drought in different time. ③ In the years with serious drought, the drought characteristics described by MSBP were consistent with the actual drought process. ④ MSBP could well reflect the fluctuation of grain yield caused by drought. The above results provide a reference for regional drought monitoring.

Based on the long series hydrological data of Binggou Hydrological Station and Yuanyangchi Reservoir Station, through the comparative analysis of Tennant method, median improvement method and mode improvement method, the ecological flow of the Taolai River in the general water use period and peak water use period is finally determined, and the ecological discharge flow in the current level year is compared and evaluated. The results show that: ① The peak ecological flow of Binggou Hydrological Station is 2.332 m3/s, and the general water use period is 1.258 m3/s; while the peak ecological flow of Yuanyangchi Reservoir Station is 0.989 m3/s, and the general water use period is 0.778 m3/s; ② In the current level year (2016), the average monthly flow of Binggou Hydrology Station and Yuanyuangchi Reservoir Station can reach the optimal range of corresponding ecological flow in the peak period of water use and the general water use period. ③ In 2016, the number of days when the ecological flow of Binggou Hydrology Station reached the optimal ecological flow in the general water use period was 181 days, the number of days when the ecological flow of Yuanyangchi Reservoir Station reached the optimal ecological flow in the general water use period was 137 days, the number of days when the ecological flow reached the excellent ecological flow was 19 days, and the number of days when the ecological flow reached the good ecological flow was 22 days. Therefore, Binggou Hydrology Station and Yuanyangchi Reservoir Station can basically meet the ecological flow during the general water use period of the river.

Soil moisture content is one of the important parameters affecting crop growth. In order to improve the accuracy of soil moisture inversion under crop cover condition, in this paper, based on sentinel-1 radar data and Landsat8 optical data, an improved water cloud model was used to obtain the backscattering coefficient of the surface soil under the corn cover at the pulling stage. Moreover, the implicit mapping between remote sensing image and soil moisture was established by SAE deep learning method to invert soil moisture under maize cover. The results showed that the inversion accuracy of the modified water-cloud model was improved after removing the influence of vegetation, with R2 up to 0.657 7, which was 0.150 6 higher than the traditional water-cloud model. RMSE was 0.038 7cm3/cm3, and the error was reduced by 0.002 5 cm3/cm3, providing a reference for using multi-source remote sensing data to retrieve farmland surface soil moisture.

Mesh filter is one of the filter devices widely used in the micro-irrigation system. In order to achieve better filtering effect, filters with different filtering precision are often combined in the micro-irrigation system. However, it also leads to problems such as large space occupied by the filter group, many connecting parts and inconvenient cleaning. In response to these issues, based on the analysis of the filter mechanism of the mesh filter, a micro-irrigation multi-stage composite mesh filter was designed to effectively concentrate the screens with different filtration precision in a same casing, and a brush body for cleaning the multi-stage filter was designed and a control device was also designed. On the basis of the design, the prototype was produced and the hydraulic performance test was carried out. The results showed that the clean pressure drop curve of the self-developed composite mesh filter still conformed to the mesh filter, which could be expressed by a power function. The head loss was only 1.5 m in the case of over flow 30 m3/h, which proved the rationality of its structure.

In order to explore the hydraulic characteristics of dual-medium and single-medium filter under muddy water condition, laboratory physical model tests were carried out on three different medium, namely stone-plastic mixture, quartz sand and PVC plastic. The results show that quartz sand medium has the worst hydraulic performance, fast clogging and large head loss, but the best sand removal rate and serious surface blockage; The PVC plastic medium has the best hydraulic performance, but the filtering effect is poor, and the clogging is very slow, resulting in a low sand removal rate and instability, and there is basically surface filtration; The hydraulic performance of the stone-plastic mixed medium is between the quartz sand and the PVC plastic medium. The change trend is roughly the same as that of the PVC plastic medium and is very close. The sand removal rate is relatively good. The filter layer intercepts the sediment as a whole. There is no large area of surface filtration. The stone and plastic mixed medium gives full play to their respective advantages, the hydraulic performance is close to PVC plastic media, achieves energy saving and consumption reduction, overcomes the shortcomings of the use of a single medium, optimizes the filter structure of the filter layer, avoids the surface filtration of the filter layer, and stratifies to trap sediment. This experiment provides technical support for exploring more multilayer composite media filters.

In this paper, crop water requirement, crop water surplus deficit index(CWSDI), drought classification and irrigation schedule of different hydrological years of maize in the central region of Heilongjiang Province were studied. Maize water requirement, effective precipitation and irrigation water requirement were calculated by CROPWAT model based on the meteorological data from 1955 to 2014, soil data and maize crop parameters in Harbin. CWSDI was calculated to classify the drought level. Changing trend of above factors was analyzed by Mann-Kendall trend test. Irrigation schedule of different hydrological years were also established. The results showed that: the water requirement of maize decreased at the rate of 9.41 mm/10 a from 1955 to 2014; the maize water requirement in wet year, normal year, dry year and extremely dry year was 407.80, 423.80, 452.00, 485.60 mm, respectively; annual average CWSDI didn’t change significantly, however, monthly CWSDI changed significantly. The drought analysis showed that the maize was suffering more seriously drought in the early and late stage of the growth period. Drought conditions varied in different hydrological years, the effective precipitation was difficult to meet the demand of maize water requirement except for the wet year, and therefore, irrigation schedule of different hydrological years should be established. The net irrigation amount of extremely dry year, dry year and normal year was 151.30, 117.10, 39.70 mm, respectively.

In view of the current deficiencies in the optimization of water-saving irrigation management mode, the attribute weight optimization algorithm model was established based on G1 method and improved entropy weight method to calculate the index weight. The TOPSIS method was improved, and the optimization model of water-saving irrigation management mode based on the TOPSIS method was established. Based on the model, an empirical study is carried out to verify the feasibility and effectiveness of the model method.

Ecological irrigation district is an inevitable choice of the development of existing irrigation districts and also a main battlefield to achieve thriving business, pleasant ecological environment and efficient utilization of resources. In the new era, the construction of ecological irrigation districts will effectively boost the implementation of rural revitalization strategy. “Red Line” is an obligatory target with legal effect, and the effective connection between the development of ecological irrigation district and “Red Line” will lay a solid and sustainable foundation for the environmental development of irrigation districts. In this paper, under the guidance of rural revitalization strategy, it is proposed that the major contradiction in irrigation districts in the new era is the contradiction between low industrial quality, great pressure on the green environment, low efficiency of resource utilization and the demands for sustainable and green development with high yield and high quality agricultural products, beautiful environment and livable ecology of people living in irrigation districts. Then through literature analysis and interpretation of policies and documents, the “three red lines”, namely, the bottom line of agricultural quality and yield, the bottom line of ecology and environment and the construction and management of upper limit ecological irrigation district for resource development and utilization are analyzed. Then from the perspective of “three properties and four aspects”, the connection and difference between the “three red lines” and ecological red lines are explained. The proposal of the “three red lines” is a higher-level requirement for the construction and management of ecological irrigation districts in the context of rural revitalization strategy, which is an effective way to solve the main contra diction in irrigation districts in the new era and an important measure to promote the sustainable and green development of ecological irrigation districts. Hence, the “three red lines” are of guiding significance to the construction and management of ecological irrigation districts.