蔬菜硝酸盐含量与硝酸还原酶活性的研究

对镇江地区9种主要蔬菜70个样品的硝酸盐含晕测定结果表明，该地区根、苹、叶类蔬菜硝酸盐污染较严重，其中以小青菜、茼蒿、芹菜、萝卜、蕹菜和苋菜最为突出，莴苣其次，生菜和土豆较轻。50mmol/L硝酸钾诱导下，各种蔬菜幼苗组织的硝酸还原酶活性(NRA)增加，但变化规律不同。不同浓度的硝酸钾诱导2h，蔬菜叶片中NRA也增加，但峰值浓度不同。NRA高的蔬菜对硝酸盐的耐受性好，诱导后高活性作用时间长。

Nitrate Content in Vegetables and Influence of Nitrate on Nitrate Reductase Activity

The nitrate content of 70 samples of 9 main vegetables varieties in Zhenjiang was investigated separately. The resultsshowed that the nitrate content of root, shoot and leaf vegetables was seriously higher than the standard level, such as Chinesecabbage, crowndaisy chrysanthemum, celery, radish, water spinach and three-colored amaranth. Lettuces were pollutedintermediately, while romaine lettuces and potatoes less. Nitrate reductase activity (NRA) in different tissues of differentvegetables increased with the inducement of 50mmol/L KNO3 solution, but the rule of variation was dissimilar. NRA in differentvegetable leaves was also enhanced after seedlings were dipped in various concentration of KNO3 solution for 2h, but the peakvalue's concentration of KNO3 solution was different. The vegetable with higher NRA had better nitrate resistance, and the activitytime of high NRA was longer after being induced by nitrate.