Research On Water And Fertilizer Supply Decision System Based On Fruit Diameter And Stem Diameter Of Tomato In Greenhouse

In order to carry out precision irrigation and fertilization on tomato in greenhouse and improve the efficiency of irrigation and fertilization,this paper studies the decision model of water and fertilization supply based on the variation of fruit diameter and stem diameter of tomatoes in greenhouse,and establishes a set of automatic irrigation and fertilization system.The main work of paper is as follows:(1)Establish a prediction model of the fruit diameter variation.According to BP neural network algorithm,a prediction model of the fruit diameter variation was established with effective accumulative temperature,cumulative average radiation and growth days being the input and fruit diameter variation being the output.Through the evaluation and testing of the model,the training results of 12 groups of data models are as follows:the R~2 average value is 0.958,and the RMSE average value is 0.041.Test results of the test set are as follows:the R~2 average value is 0.889,and the RMSE average value is 0.067.Five groups of data were randomly selected from the data of five tomato plants to evaluate the model,and the average value of the evaluation results of the five groups of data was calculated.The evaluation results are as follows:the R~2average value is 0.862,and the RMSE average value is 0.124.(2)A decision model of water and fertilization supply is established based on the variation of fruit diameter and stem diameter of tomatoes in greenhouse.By setting amount gradient of water and fertilization,the variation rule of fruit diameter and stem diameter of tomato is analyzed,and the dynamic adjustment model of water and fertilization is established.Combined with the standard amount of water and fertilization and the difference between the measured and predicted values of fruit diameter and stem diameter,a decision model of water and fertilization supply is established.(3)Establishing automatic irrigation and fertilization control system based on water and fertilization supply decision model.In order to improve the efficiency of irrigation and fertilization for tomatoes and carry out precise irrigation and fertilization,in this paper,the upper computer is developed with C#language,to PLC program is designed with GX Works2 software,and the database is established through the SQL Server data management system.The automatic irrigation and fertilization control system is built,combined with the water and fertilization supply decision model.It can irrigate and fertilize automaticly,through analyzing the growth information data and environmental information data of tomato and combining with the standard amount of water and fertilization.(4)Adjustment test of EC value and p H value of fertilizer solution,water yield uniformity test and verification test of water and fertilization supply decision model.The adjustment experiment of EC value and p H value of fertilizer solution is conducted and the results show that the EC value can be close to the preset value of 1.290m S/cm at 25 S and can be stabilized within 1.290±0.03 m S/cm,the p H value can be close to the preset value of 6.0 and can be stabilized within 6.00±0.07 at 20 S.The uniformity experiment of water yield is conducted at different locations and in different time and the results show that the lowest uniformity coefficient of water yield is 95.4%,the highest is 98.6%,and the error of water yield is 0～8%.The verification experiment of water and fertilization supply decision model is conducted and the results show that,Compared with tomato guided by the standard amount of water and fertilizer,stem diameter and the fruit diameter of tomato guided by water and fertilization supply decision model respectively increase0.0069mm and 0.134mm on average per day,and 920 m L of fertilizer solution could be saved per tomato plant on average.