Effects Of Water And Nitrogen Control On Growth And Quality Of Tomato Under Alternate Partial Root-zone Irrigation

The production method of much more water and fertilizer in vegetable cultivation not only affect the yield and quality of vegetables, but also damage soil ecological environment and human health seriously. Therefore, according to the law of water and fertilizer requirement of vegetables, regulating and controlling moisture reasonably, optimizing water and fertilizer management, achieve the best fertilizer model, which is a key to realize the high quality and stable yield of vegetables.By using crop genetic, characteristics of ecological and physiological, and response mechanism of drought stress signal ABA to achieve the goal under alternate partial root-zone irrigation (APRI), which is high efficient water-saving and good quality and high yield, and turn to water saving and optimal yield irrigation from traditional type of high water and yield. There is few report about water utilization mechanism and the optimal water supply model under APRI.This study took tomato as an example, adopted potted plant water control, contrast to conventional irrigation(CI, water control range((70%-85%)θf), set up two period of water control by the method of alternate partial root-zone irrigation: Vegetative stage (early) and reproductive stage (late); two water levels:high water(WH,80%of the irrigation quota of CI); low water(WL,60%of the irrigation quota of CI); three nitrogen levels:high nitrogen (NH)0.45g/kg of dry soil, nitrogen (NM)0.30g/kg of dry soil, low nitrogen (NL)0.15g/kg of dry soil.The experiment conducted in the greenhouse in key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas of Ministry of Education, Northwest Agricultural and Forestry University from July to December,2012. The primary research of this paper concentrates mainly on the effect on tomato growth characteristics, physiological property, water and nitrogen utilization and quality, under APRI irrigation method, irrigation rate and nitrogen rate. The main results of this study as follows:(1) Under APRI, water consumption of medium nitrogen was the highest, the plant height of medium nitrogen was higher, root length and root volume of medium nitrogen was the highest, dry mass accumulation of middle nitrogen was higher; the mean water use efficiency of continuous high water treatment was1.05and1.12times that of continuous low water treatment and high water treatment with conventional irrigation respectively. Tomato dry mass accumulation and water use efficiency of high water and middle nitrogen treatment with alternate partial root-zone irrigation was higher. (2) There was a positive correlation between chlorophyll and nitrogen content under APRI. In the same level of irrigation, the root activity of middle nitrogen was the highest; In the same level of nitrogen fertilizer, the root activity of early low water and late high water treatment was the highest.(3) Soil NO3-N content was positively correlation with the nitrogen and negatively correlation with the moisture content in the soil. Compared to conventional irrigation, APRI inhibited nitrogen accumulation of tomato. Under APRI, the amount of nitrogen accumulation of middle nitrogen treatment was increased by11.72%and10.98%that of high nitrogen treatment and low nitrogen treatment respectively.(4) Under APRI, Lycopene, vitamin C and soluble sugar content of tomato was higher, and the content of machine acid keep low level. There was a positive correlation between nitrate and nitrogen content. Tomato vitamin C content of low water in earlier stage and high water in late stage was the largest, the lycopene content of high water in earlier stage and low water in late stage was the largest.Considering factors of dry matter accumulation, water and nitrogen use and quality, the optimal model of water and nitrogen supply is low water treatment in vegetative growth phase (WL,60%of the irrigation quota of CI), high water treatment in reproductive growth phase (WH,80%of the irrigation quota of CI) and middle nitrogen treatment (NM,0.30g/kg of dry soil).This experiment results could provide practice reference for water and nitrogen use efficiency of vegetables, which have certain theoretical and practical significance. Due to the study was conducted under the condition of potted simulation, the result still need field experimental verification.