| In this paper,water dynamic simulation,crop growth simulation,and moisture prediction are carried out on greenhouse cucumbers and eggplants.The economic irrigation system is used to obtain the economic irrigation water limit.The effect of increasing the production and income of cucumbers and eggplants is carried out through the combination of moisture prediction and economic irrigation water limit.The comparison provides a basis for economic irrigation of the greenhouse group.In this study,the parameters were calibrated using the greenhouse data of the Shanxi Central Irrigation Experimental Station,and the greenhouse data of Wuqing District,Tianjin City were used for inspection and verification.The experiment site is located in the greenhouse of Shanxi Central Irrigation Experimental Station,Liuhulan Town,Wenshui County,Lvliang City,Shanxi Province(112°12 ’E,37°17 ’N,altitude 749.5 m).It has a temperate continental climate,with an average rainfall of 457 mm.The types of vegetables planted in this experiment are cucumbers and eggplants,which will be tested in 2018,2019,and 2020.The cucumber varieties tested in the central station are"Chunxiaqiushuang" and "Jinchun 4",and the varieties of eggplant are " "Hanfeng Black Crown" and "Black Marshal".The experiment mainly set up two irrigation treatments,100%and 50% irrigation treatments for each crop,and the irrigation method is drip irrigation under the film.Lay a drip irrigation belt under the mulch,and differentiate between 100% and 50%irrigation by adjusting the number of irrigation times,respectively,T1 and T2(T1 is an irrigation design based on local experience,called 100% irrigation,and T2 is a 50% reduction compared to T1.Irrigation).In this study,the experimental data of greenhouse crops(cucumber and eggplant)in 2018,2019 and 2020 in Shanxi Central Experimental Station were analyzed.The environmental factors inside and outside the greenhouse were compared and correlated.The soil moisture content was simulated and forecasted using the principle of water balance,the crop coefficient parameters were obtained by the programming solution,the crop growth simulation was performed,and the temperature stress index was obtained by the programming solution.Transformation factor and water stress index;determine the economic irrigation water limit,using a combination of water demand,crop growth model,irrigation schedule,and soil moisture prediction.The results are as follows:(1)Through research,it is found that the correlation between the active accumulated temperature in the greenhouse and the outdoor accumulated effective radiation is: the central station can reach more than 0.98,and the northern spring can reach more than 0.99.The solar radiation in the two greenhouses is related to the net solar radiation outside the greenhouse.Very good linear relationship,can reach more than 0.92.Controlling ventilation and heat preservation at the same time is an important step in regulating the air temperature and humidity in the greenhouse.(2)Through comparison,it is found that different irrigation treatments have a greater impact on the dry matter of the fruit.The dry matter weight of the fruit under 100% irrigation is higher than the dry matter weight of the fruit under 50% irrigation.That is,the more irrigation,the higher the yield.high.(3)Using the 2020 data of the central station,the research on crop water demand,and the crop growth model carried out simulate dry matter accumulation,and the values of various parameters were determined and tested and verified.Through comparison,it was found that the dry matter simulation effects of the central station and Wuqing District were equal better.(4)Based on the soil moisture content data of cucumber in 2018 and eggplant in 2019 in greenhouse,the dynamic prediction model of soil moisture content was established,and the fitting results of model parameters,fitting accuracy,prediction accuracy and qualified rate were analyzed respectively.The following conclusions were drawn: 1.The parameters of the realtime moisture prediction model changed with time,and the variation range decrease with the increase of the modeling series length;2.The real-time moisture prediction model has good adaptability to different crops and different degrees of drought;3.The relative error of prediction decreases with the increase of modeling series,and the relative error of prediction value of 15-day modeling series is the smallest.(5)The economic irrigation lower limit values of cucumber and eggplant are obtained in shanxi central experimental station and Tianjin Bei Guo Zhi Chun area,which can achieve the goal of guiding irrigation.(6)The combination of moisture forecast and crop economic irrigation has a significant effect of saving water,increasing production and increasing income.Compared with empirical irrigation,the cucumber production in the central station increase by 11.13%,the benefit increased by 9.28%,the eggplant output increased by 5.89%,and the benefit increased by5.98%.Similarly,comparing the yield and benefits under the greenhouse economic irrigation indicators in Bei Guo Zhi Chun,it can be seen that the yield of cucumber increased by 21.02%and the benefit increased by 21.95%.The increase in eggplant production and income is not obvious,but it can save water by 14.3%... |
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