硝酸态氮及亚硝酸态氮在不同pH条件下对蔬菜生长的影响

以番茄、黄瓜、甘蓝和小白菜为材料,用营养液栽培法研究了不同硝酸态氮(NO_3-N)与亚硝酸态氮(NO_2-N)配比(NO_3-N:NO_2-N分别为12:0,8:4,4:8,0:12mM),不同pH值(pH7、6、5三组),对蔬菜生长和NO_3-N,NO_2-N、游离氨基酸累积的影响。结果表明,这四种蔬菜明显地分为两类:番茄、小白菜易感受NO_2-N的危害,并且有随溶液中pH值的下降而受害加剧的趋势;而黄瓜和甘蓝则对NO_2-N具有较强的耐受性。供试植株内NO_3-N与NO_2-N的累积量,随营养液中硝酸盐及亚硝酸盐的浓度增大而增加。叶莱较果菜易于累积NO_3-N与NO_2-N。大量施用亚硝酸态氮肥,会导致蔬菜内个别氨基酸的异常积累,引起氮素代谢的紊乱。番茄积累最多的是苏氨酸,小白菜为天门冬氨酸。

EFFECTS OF NITRATE AND NITRITE ON VEGETABLE GROWTH IN DIFFERENT pH

Effects of nitrate and nitrite on vegetable growth were investigated by solution culture in different proportions of NO_3-N and NO_2-N (12:0, 8:4, 4:8, 0:12mM)and different pH value (7, 6, 5).Tomato, euettmber, cabbage and pak choi were used as material. Results indicated that these vegetables can obviously divide into two types: 1. tomato and pak choi were sensitive to nitrite toxicity and lower the pH value the more serious of the toxic effect is. 2. cucumber and cabbage were not very sensitive to the nitrite toxicity. Accumulation of nitrate and nitrite in plants would be increased when concentration of nitrate and nitrite in solution were increased. Leaf vegetables accumulated more nitrate and nitrite then fruit vegetables. If a large amount of NO_2-N was applied, unnormal accumulation of individual amino acid would be resulted in causing the metabolic disturbance of nitrogen in the vegetables. The most accumulation of amino acids was THR in tomato and ASP in pak choi.