The Study On Optimal Water-nitrogen Coupling Model Of Greenhouse Tomato Under Separate Furrow Irrigation

Improving quality has become a concept of vegetable industry development in ourcountry under the premise of guarantee the production. But extensive production has lead towasting a lot of water and fertilizer, nitrificating soil and decling quality.Therefore, in orderto search for optimial water-nitrogen coupling model with the goal of yield, quality and wateruse efficiency, a research on water and nitrogen transport, tomato growth, yield, quality wasdone by an experiment with8treatments that was designed by two factors and every factorincluding two levels of water and nitrogen, each combination of water and nitrogen includingtwo types of irrigations that were alternate furrow irrigation and fixed furrow irrigation,which according to the research results at home and abroad and combineing with localproduction experiences, the experimrnt material was tomato. Some following main resultswere obtained.（1） The amount of irrigation water and N applied, wate-nitrogen coupling effect andirrigation methods were all the important factors that affected the distribution of soil moisturecontent and soil NO₃^--N content.At the same water level, increasing the amount of nitrogenappropriately was beneficial to maintain soil moisture. At the same nitrogen level, increasingthe amount of irrigation water appropriately could improve the soil moisture content. T4withlow water and low nitrogen was the most detrimental treatment to maintain soil moisture. Theinfluencing factors of residual soil NO₃^--N content were N applied was more than irrigationwater under fixed furrow irrigation, but, it was opposed in alternate furrow irrigation. T4andT7had least residual soil NO₃^--N content.（2） It was beneficial to promote the vegetative growth of tomato in alternate furrowirrigation than fixed furrow irrigation. Stem diameter and leaf area index of tomato were twoimportant indicators predicting and evaluating tomato yield. Befor the fertilizer applied,increasing the amount of irrigation water was conducive to increase the surface area of root,average root diameter and root volume, but reduced the root length. After the fertilizer applied,reducing the amount of N applied could improve the tomato root length, surface area of root,average root diameter, but decrease the root volume under fixed furrow irrigation; and it couldimprove average root diameter, but decrease surface area of root and the root volume under alternate furrow irrigation.（3） The influencing factors of tomato leaf chlorophyll content were: irrigation water> Napplied; the treatments with low water all could improve chlorophyll content of tomato;nitrogen effect on chlorophyll content was relatively complex under the treatment with highwater; low nitrogen with low water and fixed furrow irrigation were all beneficial to improvetomato leaf chlorophyll content.Befor the fertilizer applied: the average photosynthetic rate,average transpiration rate, average stomatal conductance were significantly positivecorrelation, and that were bigger in alternate furrow irrigation than fixed furrow irrigation, butthe average intercellular CO₂concentration has no significant difference. After the fertilizerapplied, the treatment with alternate furrow irrigation and high nitrogen could improve theaverage photosynthetic rate of tomato significantly; alternate furrow irrigation could improvethe tomato average transpiration rate obviously. Water, fertilizer, irrigation methods had smallinfullenence on average stomatal conductance and intercellular CO₂concentration.（4） Water, nitrogen, water-nitrogen coupling effect and irrigation methods all had asignificant impact on tomato yield, average fruit weight and water use efficiency, thesensitivity to water was greater than the sensitivity to nitrogen on yield and the averageweight, but it was opposited on water use efficiency. It was conducive to improve tomatoyield, average fruit weight and water use efficiency in alternate furrow irrigation than fixedfurrow irrigation.（5） Water, nitrogen, water-nitrogen coupling effect and irrigation methods were all theimportant factors that affected the quality of tomato. Among them, water had an obviouseffect on organic acid, V_C, soluble sugar and nitrate content; nitrogen had an more obviouseffect on soluble solids, organic acid, soluble sugar, nitrate content and lycopene content;water-nitrogen coupling effect had an obvious effect on soluble solids, V_C, nitrate content andlycopene content.（6） T8（AFI） was the optimal water-nitrogen coupling model with best yield and wateruse efficiency （recommended irrigation water was1100m³/hm², N applied was150m³/hm²）;T6（AFI） was the optimal water-nitrogen coupling model with best quality （recommendedirrigation water was1300m³/hm², N applied was150m³/hm²）; and T6（AFI） was thecomprehensive optimal of water-nitrogen coupling model with recommended irrigation waterwas1300m³/hm²and N applied was150m³/hm².