| In this research, many indices of drought resistance during germination stage and seedling stage were chosed to evaluate comprehensively the drought resistance of 20 Dactylis glomerata L. germplasm from abroad. According to the results, 4 different drought resistance germplasm were selected to study the drought resistance mechanisms. The main results of research are as following:1. The results of germination stage show: the germinating vigor and germinating rate, the growth rate of embryo bud and root were all decreased by PEG water stress. And the drought resistance of all germplasms was evaluated comprehensively by membership function method.Based on the value, the relative drought resistance of 20 Dactylis glomerata L. germplasm was:ZXY04P-201>ZXY04P-136>ZXY03P-122>ZXY04P-57>ZXY03P-227>ZXY04P-4>ZXY04P-155>ZXY04P-75>ZXY04P-101>ZXY04P-207>ZXY03P-173>ZXY03P-191>ZXY04P-226>ZXY04P-22>ZXY04P-89>ZXY03P-22>ZXY03P-69>ZXY04P-189>ZXY04P-239> ZXY04P-148。2. The results of seedling stage show: all the materials showed a decrease to various extent in plant height, shoot and root dry weight, net photosynthetic rate, transpiration rate, stomatal conductance and chlorophyll under drought stress,Whereaseas,they also showed an increase in water saturation deficit, the relative plasmalemma permeability and internal CO2 concentration.The comprehensive evalucation resulted in a strong drought resistance group including ZXY04P-201,ZXY03P-227,ZXY03P-122 and ZX Y04P-136, a weak drought resistance group including ZXY04P-101,ZXY04P-89,ZXY04P-239 and a intermediate group including the others according to the the above indicators.3. The results of study on drought mechanism for 4 Dactylis glomerata L. under continuously water stress and rewatering show: the water saturation deficit of leaves arose hastily, and ZXY04P-239 changed most obviously while ZXY04P-201 changed only slightly under drought stress. ZXY03P-173 and ZXY04P-201 increased in the relative plasmalemma permeability and the soluble sugar content while thant of ZXY04P-75 and ZXY04P-239 showed the trend of initial increasing, reaching the peak at the 8th day, then decreasing under drought stress. With aggravation of drought stress, ZXY04P-75 and ZXY04P-201 increased in proline content while that of ZXY03P-173 and ZXY04P-239 increased initially, reaching the peak at the 8th day, then declined. And the rate of net photosynthetic declined notably with the intensity of drought stress, The minimum of decline rate of net photosynthetic is ZXY04P-201.4. The results of photosynthetic mechanism for 4 Dactylis glomerata L. show: the net photosynthetic rate, transpiration rate,stomatal conductance and chlorophyll decreased dramatically, Compared with weak drought resistance ZXY04P-239,the net photosynthetic rate, transpiration rate, stomatal conductance and chlorophyll in the leaves strong drought-resistance ZXY04P-201 decreased slowly. And meanwhile, the result show that, stomatal restriction was the main factor of the net photosynthetic rate's decrease in the leaves of 4 Dactylis glomerata L. when stress in slight water stress and the non-stomatal restriction was the main factor of the net photosynthetic rate in the leaves of 4 Dactylis glomerata L. when stressed in medium water stress and serious water stress.5. The results of study on endogenesis hormones in Dactylis glomerata L.leaves show: the content of ABA in the leaves of 4 Dactylis glomerata L. increased at different extent and the content of GA3 and ZR were all down under drought stress, while the content of IAA had a different trend according to different material. The general trend of coordination among 4 endogenesis hormones was closeing the stoma and promoting the growth of root,whereas the coordination mechanism of different Dactylis glomerata L. was different.
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