Study Of The Nitrogen Fertilization On The Nitrate Accumulation And Mechanism Of The Greenery Vegetables

In order to provide certain technical measurement for actual production in cultivating low nitrate content vegetables ,we studied the influence on the growth of Chinese cabbage,spinach,lettuce, three kinds of higher nitrate accumulation green vegetables, nitrate accumulation and quality when fertilizing different nitrogen, and established reasonable nitrogen fertilization application level, the experiments were cultured in soilless and open field under different nitrogen fertilizer level, the results are follows:1 The nitrate contents of the Chinese cabbage,spinach,lettuce were increased greatly with higher nitrogen fertilizer level, but nitrite content descended.There was positive correlation between nitrate content and nitrogen fertilization application level, in the field culture relative coefficients are follows: Chinese cabbage r=0.9629**, spinach r=0.9538*,lettuce r=0.9551*;in the soilless culture Chinese cabbage r=0.9770**, spinach r=0.9401*, lettuce r=0.9928**。2 The nitrate and nitrite contents of the Chinese cabbage,spinach,lettuce were in different growing periods。The nitrate content was relatively higher while the nitrite content was lowest at maturity。3 Nitrate reductase activities of Chinese cabbage,spinach,lettuce were greatly affected by nitrogen fertilizer applied level,while there was curvilinear correlation between the nitrate reductase activity and nitrite content。4 Under two kinds of cultivation models,the vitamin C content in three kinds of green vegetables have prominent correlation with different nitrogen application level。5 The vegetables yield increased as reasonable amount of applied nitrogen fertilizer increased。Taking the good vegetable nutritious quality and relatively high economic yields into consideration,the most suitable nitrogen fertilizer amount was N10(0150㎏/hm2) in the soilless and open field culture。...