不同施氮量对蕹菜品质及氮肥利用率的影响

为探明蕹菜高产、优质的合理氮肥施用量，采用盆栽试验与^15N标记示踪技术，分析了氮肥施用量与蕹菜产量、品质及氮肥利用率的关系．结果表明，将每1kg的氮肥施用量x（g）与每盆的产量y（g）拟合成回归方程为y=14．81＋1208．60x-2959．52x^2（F=46．85），表明产量随氮肥施用量的增加呈先增加后下降的变化趋势；每1kg土的合理氮肥施用量为0．140-0．170g；氮肥利用率y（％）和每1k土氮肥用量x（g）之间的一元一次方程为：y=48．93x＋45．88（r=0．984）．适宜的氮肥用量能提高可食部分维生素C，可溶性糖和蛋白质含量，降低蕹菜可食部分硝酸盐含量．

Effects of N Applying Rates on Yield,Quality of Water Spinach and the N Use Efficiency

Current global nitrogen fertilizer use has reached approximately one hundred billion kg per annum.In many agricultural systems,a very substantial portion of applied nitrogen fertilizer is lost from soil to groundwater,rivers and oceans.In vegetable cultivation,especially under facility cultivation conditions,more nitrogen fertilizer was applied than in crop cultivation to achieve high yield.To rationalize nitrogen application rate on yield,quality of water spinach,environment pollution and nitrogen use efficiency,pot experiments were carried using 15N trace technique.The results showed that the correlation between nitrogen rates and yield(fresh weight) of water spinach followed the regression equation ? =14.81 1 208.60x-2 959.52x2(F=46.85*),which indicating water spinach increased its yield with the reasonable N fertilizer increasing,but more unreasonable nitrogen fertilizer applying would have a negative effect on the water spinach yield.The correlation between nitrogen use efficiency and nitrogen rates followed the regression equation ? =-48.93x 45.88(r = 0.984**),which indicating nitrogen use efficiency decreased with the increasing of nitrogen application.The result also showed reasonable nitrogen rates,which ranged from 0.140 to 0.170 g/kg soil,would improve the content of soluble sugar,vitamin C and protein and decrease the nitrate content of esculent part of water spinach.