外源蔗糖对NO3- 胁迫下叶用莴苣生长及品质的影响

采用水培方法，以常规营养液（7.5 mmol·L^-1 NO₃^-）、叶面喷施清水作为对照， 在75 mmol·L^-1 NO₃^-胁迫下，通过叶面喷施0 mmol·L^-1（T1）、1 mmol·L^-1（T2）、5 mmol·L^-1（T3）的蔗糖，研究外源蔗糖对NO₃^-胁迫下叶用莴苣生长及品质的影响。结果表明：T1 处理叶用莴苣的生长受到显著抑制，同时显著降低了VC 含量。外源蔗糖处理可以缓解NO3- 胁迫对叶用莴苣生长的抑制作用，提高VC 含量，同时可略降低硝酸盐含量，其中T2 处理效果较好。与对照相比，T2 处理和T3 处理均可降低叶用莴苣可溶性蛋白含量，T3 处理可提高可溶性糖含量，但差异均不显著。

Effects of Exogenous Sucrose on Growth and Quality of Lettuce under NO3- Stress

Taking conventional nutrient solution（7.5 mmol·L^-1 NO₃^-）and foliar spraying water as CK，the influence of exogenous sucrose on the growth and quality of lettuce cultivated in nutrient solution under 75 mmol·L^-1 NO₃^- stress was investigated by spraying sucrose of 0 mmol·L^-1（T1），1 mmol·L^-1（T2），5 mmol·L^-1（T3）at the leaf surfaces．The results showed that the growth of lettuce（Lactuca sativa L.）was significantly restrained by T1 treatment and the VC content was significantly reduced．Exogenous sucrose treatment could alleviate the suppression of NO3- stress to the growth of lettuce and increase its VC content，and at the same time slightly reduce the nitrate content．Of all the 3 treatments，T2 had better result．Compared with the CK，T2 and T3 all could reduce the soluble protein contents in lettuce leaf，and T3 could increase the soluble suger content，but the difference was not significant．