Research on tomato water requirement with drip irrigation under plastic mulch in greenhouse

According to the test data of environmental factors in greenhouse during tomato growth period, the change of soil moisture was simulated by the method of the water balance equations. The objective function is the total of the difference between simulated soil moisture and measured soil moisture for using to calculate the crop coefficients and the water requirement with drip irrigation under plastic mulch in greenhouse. The results showed that the simulated data of soil moisture during tomato growth period is consistent with the measured data. The relative error of the simulated data and measured data is within 10%. Crop coefficient in the early stage of the growth has gradually increased. Crop coefficient in the growth period reaches the maximum of 1.075, and then decreased gradually. The changing of crop coefficient is consistent with the leaf area index. The water requirement pattern from 0.2-5.9mm/d of tomato in greenhouse in the early growth period is greater. The water requirement pattern from 0.3-3.3mm/d of tomato in the late growth period is small.