施氮水平和间断施氮对生菜生长和品质的影响

Effects of Nitrogen Application Level and Intermittent Nitrogen Application on Growth and Quality of Lettuce

以“意大利全年耐抽薹(208)”生菜为试材,采用水培法,设置3个施氮水平N4(4 mmol·L^(-1))、N8(8 mmol·L^(-1))、N12(12 mmol·L^(-1))和4个间断施氮频率F0(0 d)、F3(3 d)、F6(6 d),F9(9 d),研究不同施氮水平和间断施氮频率对生菜采收期生长状况、类黄酮、总酚、花青素和抗坏血酸含量以及对硝酸盐、亚硝酸盐含量的影响,以期为生菜水培栽培时营养品质提升提供参考依据。结果表明:持续性施氮(F0)能够提高生菜的株高和地上部鲜质量,N8水平下,随着施氮间断频率的增加,生菜地上部的鲜质量越来越低;在施氮水平为8 mmol·L^(-1),间断施氮频率6 d时,抗坏血酸含量和亚硝酸还原酶含量最高,比最低的N12F9高83.68%,亚硝酸还原酶含量比最低的N12F3高60.79%,硝酸盐含量则是最低。因此,施氮水平为8 mmol·L^(-1),间断施氮频率6 d能保证植株生长的同时提高抗坏血酸含量,并且降低硝酸盐的积累。

Taking‘Italian Resistant-bolting tolerance(208)(Lactuca sativa L.)’lettuce as test material,hydroponics was used as treatment,three nitrogen application levels N4(4 mmol·L^(-1)),N8(8 mmol·L^(-1)),N12(12 mmol·L^(-1))and four intermittent nitrogen application frequencies F0(0 day),F3(3 days),F6(6 days),F9(9 days)were set,the effect of different nitrogen application levels and intermittent nitrogen application frequency on the growth status,flavonoids,total phenols,anthocyanins and ascorbic acid contents,nitrate and nitrite contents of lettuce during harvesting period were studied,in order to provide reference for improving the nutritional quality of lettuce in hydroponics.The results showed that continuous nitrogen application(F0)could improve the plant height and aboveground fresh weight of lettuce.Under the N8 level,aboveground fresh weight of lettuce became lower and lower with the increase of nitrogen application interruption frequency.8 mmol·L^(-1),when the frequency of intermittent nitrogen application was 6 days,the content of ascorbic acid and nitrite reductase was the highest,which was 83.68%higher than that of the lowest N12 F9,and the content of nitrite reductase was 60.79%higher than that of the lowest N12 F3.Nitrate content was the lowest.Therefore,the nitrogen application level of 8 mmol·L^(-1)and the intermittent nitrogen application frequency of 6 days could ensure the growth of plants,increase the content of ascorbic acid,and reduce the accumulation of nitrate at the same time.