Effects Of Irrigation And Nitrogen Supply On Tomato Yield, Quality, Water And Nitrogen Use Eiffciency In Solar-Greenhouse

The objective of this study is to research the optimal water-and-fertilization patternwhich is water-and-fertilization saving, steady yield and good quality for tomato ingreenhouse. The experiment was conducted in the town of Qingyuan in Wuwei in the Gansuprovince Basin Agricultural Demonstration Area for Sand Industry from December2010toJuly2011. The growing index, water consumption, yield and quality of the greenhouse tomatoand the absorption of NO₃-N in soil, were monitored and analyzed.The main results are:(1) The total yield and the First-Fruit yield of the greenhouse tomato increased underwater deficit, though it also increased the Discarding-Fruit yield, it does not matter. Increasingnitrogen increased the proportion of the Discarding-Fruit yield among the total yield of thegreenhouse tomato on the same amount of irrigation, and it decreased the proportion of theFirst-Fruit yield among the total yield. Increasing nitrogen could promote tomato mature,which increased the proportion of the earlier period yield among the total yield. As the marketprice higher in the earlier period, economic benefits of the greenhouse tomato increased. Theplant height and stem diameter of the greenhouse tomato were not affected obviously underdifferent water and nitrogen levels.(2)Within the quality of commodity index of the greenhouse tomato, all of the indexwere not affected obviously under different water and nitrogen levels unless the index of fruitweight. Increasing nitrogen increased fruit weight of the greenhouse tomato which woulddecreased when water deficit, especially in fruiting stage. Within the quality of internal indexof the greenhouse tomato, Increasing nitrogen increased total soluble solid content on fullirrigation, while increasing nitrogen decreased total soluble solid content on water deficit.Vitamin C content improved to water deficit in fruiting stage. Increasing nitrogen properlycould decreased Nitrate content on the same amount of irrigation, but increasing nitrogenwould increased Nitrate content to water deficit.(3) The soil moisture along soil profile was more sensitive to water deficit than nitrogen,and it was more sensitive to water deficit in fruiting stage than in flower appearing stage. Theaverage absorption of NO₃-N in the depth of0～100cm soil were not affected obviouslyunder different water and nitrogen levels in the whole growing stage of the greenhouse tomato.The absorption of NO₃-N in the depth of surface0～10cm and80～100cm soil were higher, while the absorption of NO₃-N was lower in the depth of40～60cm soil. With the nitrogenincreased, the absorption of NO₃-N was increased with the depth of soil. The absorption ofsoil water NO₃-N to water deficit were significantly lower than to full irrigation on the sameamount of nitrogen.(4) Under the test conditions, the water consumption characteristic was: fruit maturationstage> fruiting stage> flower appearing stage. The water use efficiency was improved towater deficit especially in fruiting stage than in flower appearing stage. The water-fertilizationuse efficiency was improved to water deficit especially in flower appearing stage than infruiting stage. Increasing nitrogen increased yield of the greenhouse tomato while decreasedwater-fertilization use efficiency to water deficit in fruiting stage.(5)Water production function of greenhouse tomato was calculated by three waterproduction function model with wide range of applications, and the sequence of sensitivityindexes to water deficit of greenhouse tomato in different stages was: fruit maturation stage>fruiting stage> flower appearing stage. According to the sequence, Blank model was the bestwater production function of greenhouse tomato under the test conditions.