Effect Of Stress On Substances Related With Resistance Of The Three Typical Adaptable Cultivating Grassese In The Fountain Head Region Of The Yangtze, Yellow And Meikong River.

Poa pratensis l.cv QingHai ,Kengyilia thoroldiana,Elymus nutans are typical adaptable cultivating grass in the fountain head region of the Yangtze,Yellow and Meikong river. Based on these three kinds of grasses, the physiological-biological indexes were discussed comprensive under low temperature stress and drought stress in leaves ; effect of polyethylene glycol (PEG) on seed germination was studied; a few substance related with resistance were determined in leaves . By dicussing superoxide dismutase(SOD),membrane permeability,soluble protein,soluble sugar , chlorophyll,malondialdehyde(MDA) and proline, studing the physiological -biological index change orderliness under low temperature stress and drought stress; knowing the characteristic of germination in different PEG concentration;ascertaining the seasonal Dynamic change of substance related with resistance . The main conclusions can be drawn as follows:1. Poa pratensis l.cv QingHai ,Kengyilia thoroldiana,Elymus nutans were treated with 0℃low temperature stress .The characteristic on three kinds of herbage grasses were ascertained by measuring physiological-biological indexes about superoxidedismutase(SOD),malondialdehyde(MDA),membrane,solubleprotein,solube sugar ,chlorophyll. The result showed that with low temperature treat, content of MDA , soluble sugar and membrane were increased ;the activity of SOD and content of soluble protein are increase in the 2th day ,then decrease in the 4th day ;the content of chlorophyll was decrease . 2. Under low temperature strees,based the chang of SOD activity ,the order of chilling resistance for those kinds grasses: Poa pratensis l.cv QingHai>Kengyilia throldiana Elymus nutans. Based the chang of soluble protein ,membrane , chlorophyll and MDA , the order of chilling resistance for those kinds grasses: Poa pratensis l.cv QingHai= Kengyilia throldiana>Elymus nutans; Based the chang of soluble sugar, the order of chilling resistance for those kinds grasses: Kengyilia throldiana>Poa pratensis l.cv QingHai. >Elymus nutans3. Treated with distilled water and PEG solution with different concentration of 5%, 10%, 15%,20%,25%,studied the effect of PEG on seed germination of Poa pratensis l.cv QingHai, Kengyilia throldiana and Elymus nutans. Carried out to determine the seed germination rate and the ratio of embryonic root ,embryonic dud and seeding length .The result indicated In 5%,relatively germination of Poa pratensis l.cv QingHai were increased ,of Elymus nutans and Kengyilia throldiana were declined. Different treat have influence for the seed germination rate and the ratio of embryonic root ,embryonic dud and seeding length of this kinds grass, declining of Kengyilia throldiana is least.so the rank of drought resistance in seed germinating stage for this kinds grass: Kengyilia throldiana>Poa pratensis l.cv QingHai > Elymus nutans.4. Treated the seedling of Poa pratensis l.cv QingHai, Kengyilia throldiana and Elymus nutans with continuous drought stress methonds. The result showed that membrane, proline, soluble sugar and MDA were increases.Relative water content in leaves were decreased.5. In seedling stage, based the chang of relative water content,the sequence of drought resistance ability of those kinds grasse: Kengyilia throldiana>Poa pratensis l.cv QingHai >Elymus nutans. based the chang of membrane and soluble sugar, the sequence of drought resistance ability of those kinds grasse: Kengyilia throldiana>Poa pratensis l.cv QingHai=Elymus nutans . based the chang of content of proline and MDA, the sequence of drought resistance ability of those kinds grasse: Kengyilia throldiana>Elymus nutans> Poa pratensis l.cv QingHai .6. A few substance related with resistance were determined seasonally in the leaves of Poa pratensis l.cv QingHai, Kengyilia throldiana and Elymus nutan.The results show that content of soluble sugar was increase seasonally,while content of chlorophyll, MDA, soluble protein , and SOD activity rose at first,then fallen down. The variations were associated with special alpine climate and important physiological responses to ecological environment.7. Based on the above analyses, Kengyilia throldiana has better the ability of tolerance to drought and chilling,it exist adaptable in alpine plain ; Poa pratensis l.cv QingHai has high ability of toleranc to chilling, it exist adaptable in alpine meadow . Elymus nutan exist adaptable in alpine plain and in alpine meadow. This result was consistented with field investigation.