Study On The Relationship Between Endogenous Hormones And Stay-Green, Drought Resistance In Stay-Green Wheat

This experiment was carried out in pot whithin a rain-proof shelter in Northwest A&F Univesity during 2008 to 2009 using YM66 (stay-green type wheat),WM8 (stay-green type wheat),XY22 (normal type wheat) and WM6 (early-senescence type wheat). There were three water treatments after anthesis, that is control, moderate drought stress, severe drought stress , during grain filling stage. In order to study the relationship between endogenous hormones and stay-green,drought, we research the drought effect of leaf senescence,stomatal conductance,change of endogenous hormones and dry matter production. The results showed:1. During the grain filling stage, the green leaf area,content of chlorophyll and carotenoid of all kinds of wheat reduced gradually. The active of chlorophyllase and proteinase went up.Under different drought conditions, middle stressed wheat showed obvious resistance. Compared with nonstay-green wheat the green leaf area,content of chlorophyll and carotenoid of stay-green wheat are all declined slowly at different levels, which maintained a long leaf functional period and laid the foundation of reserve nutritive material.2. After researching the endogenous hormones content of all the wheat under different water treatment, we found that the content of IAA,ABA and MeJA present a increasing trend, and the content of CTK and GA present a descending trend. Especially, the content of IAA,ABA and MeJA of nonstay-green wheat under severe drought condition increased rapidly. By contrast, the content of IAA,ABA and MeJA of stay-green wheat went up slowly, and the content of CTK and GA went down slowly. After analysis of the correlation between content of endogenous hormones and senescence properties of wheat leaves, we found that the content of CTK and GA has an extremely positive relationship with green leaf area, and the content of IAA and MeJA has a negative relationship with green leaf area, which indicated that at the late stage of grain filling, high content of CTK and GA, low content of IAA and MeJA is the main reason to delay senescence for stay-green wheat.3. During the growth and development period, the stomatal conductance increased from flowering stage and reached their maximal about 10 days after anthesis,and after that,declined gradually. The transpiration rate reached their maximal about 5 days after anthesis, then went down. Under different drought stress, compared with nonstay-green wheat the stomatal conductance and transpiration rate of stay-green wheat are all higher during the grain filling stage. The stomatal conductance and transpiration rate of wheat under severe drought are obvious lower than contral watered wheat.4. Under normal-watered condition, the leaves, stems and shells in different winter wheat present high water content. The leaves , stems and shells of stay-green wheat have a relatively high water content under different drought stress, delay senescence largely, this maybe results of maintaining water ability and high absorption ability of stay-green wheat. The dry matter transloction,dry matter transloction efficiency and the proportion of dry matter transloction in grain of leaves and stems of stay-green wheat are higher than nonstay-green wheat in different winter wheat.5. The ear weight,kernels,grain weight,seed yield,total biomass of different wheat are all descend under severe drought stress, but its not so evident under midding drought stress. The stay-green wheat have larger ear weight,kernels,grain weight,seed yield,total biomass, so it has a better increase production ability.