分别以纯水和自来水为生长介质对莴笋和菠菜进行水培试验，以揭示不同氮素形态及配比对蔬菜生长和品质的影响。结果表明，以纯水为水培水源，ＮＯ－３－Ｎ∶ＮＨ＋４－Ｎ为１∶１或单独供应ＮＨ＋４－Ｎ，对作物生长均有一定程度的抑制作用，而以后者的生长量最低。以自来水作水培介质时，以ＮＯ－３－Ｎ为唯一氮源预培养一段时间后，再提高营养液中ＮＨ＋４－Ｎ比例，有利于蔬菜的生长发育及硝酸盐含量的降低，使莴笋维生素Ｃ含量也有所降低，菠菜则无明显变化。当植物生长量较大时，尿素作水培氮源不能满足作物对氮素的需求 The water culture experiments of lettuce and spinach with pure water and tap water as growth medium were carried out to reveal the effects of different nitrogen forms and proportions on the growth and quality of vegetables. The results showed that with pure water as the water culture source, NO-3-N: NH + 4-N was 1: 1 or NH + 4-N was supplied separately, which inhibited the growth of crops to a certain extent, while the latter had the lowest growth. When tap water is used as a medium for hydroponics, the proportion of NH + 4-N in the nutrient solution after pre-culturing with NO-3-N as the only nitrogen source for a period of time is beneficial to the growth and development of vegetables and the reduction of nitrate content, so that the lettuce vitamin C content also decreased, spinach no significant change. When plant growth is large, urea as a source of hydroponics can not meet the crop’s demand for nitrogen