土壤干旱条件下氮素营养对玉米内源激素含量影响

在田间持水量分别保持于35％、55％和75％±5％的土壤水分条件下，利用盆栽实验研究了土壤干旱和氮素营养对玉米内源激素和气孔导度的影响．结果表明，土壤干旱下氮素营养明显降低了玉米根系木质部汁液ABA浓度，而正常供水下施氮处理间则无显著差异(施氮处理仍较低)，同时测定的叶片ABA浓度则呈相反的变化趋势，表现为干旱下施氮处理要高于不施氮处理；施氮处理木质部汁液中ZRs浓度应低于相应的不施氮处理，在调控气孔行为方面并未表现拮抗ABA作用；3种土壤水分条件下，施氮玉米叶片的气孔导度均高于不施氮处理，与木质部汁液ABA浓度呈负相关，说明施氮处理较低的根源ABA浓度是导致其气孔导度较大的主要原因．

Effect of nitrogen nutrition on endogenous hormone content of maize under soil drought conditions

It is realized in recent years that roots play an important role in the control of shoot growth and development, not only because they can continuously provide the shoot with water and nutrients, but also because some chemical messengers are produced in roots to response soil drought stress and transported through transpiration stream to shoot where physiological processes are regulated. Extensive studies showed that the decrease of leaf conductance was closely related to the increase of xylem ABA concentration, suggesting that ABA can act as a water stress signal to regulate the physiological response of shoot. Fertilizer plays an important role in increasing crop yield and water use efficiency (WUE) on dry-land farming. It is not clear, however, whether the application of N fertilizer can affect the root's signal intensity in drought stress and thus regulate its stomatal responses. Experiment with 3 water levels (35%, 55% symbol: see text] 75% +/- 5% of field capacity) and 2 N fertilizer levels (high N and low N) was designed to investigate the effect of soil drought and N nutrition on endogenous hormone concentration (ABA and ZRs) and stomatal conductivity of maize under potted conditions. The results showed that the application of N significantly increased the stomatal conductivity of maize leaf under both drought and watered conditions. Meanwhile, it markedly decreased the ABA concentration in root xylem sap, but increased ABA concentration in leaf of maize under soil drought conditions. The application of N decreased ZRs concentration in root xylem sap as well, which means that ZRs did not play a role in counteractive to ABA under soil drought conditions. The lower ABA concentration in root xylem sap of high N maize rather than the higher ABA concentration in maize leaf accounted for the higher stomatal conductivity of high N maize leaf under soil drought conditions.