Impacts Of Water Stress On The Propagulum Germination、Seedng Growth And Distribution Of Cynodon Dactylon

Cynodon dactylon is paid more and more attention beeause of its uniquemorphology、reproduction mode and broad distribution.The application of it hasbroadened in the gardening and ecological protection; Seeds of Cynodon dactylonwere treated by Simulation of soil water potential gradient (-0.2~-1.0MPa) of thedifferent concentrations of hypertonic solution polyethylene glycol(PEG-6000), toinvestigate effects of water stress on its germination. The germination time,germination rate, relative germination rate, germination potentiality, germinationindex in different kinds of water stress were recorded and analyzed. Cynodon dactylonStolons was influenced by Soil water content on germination and Seedling growth inthe process of biological and ecological indexes by pot culture experiment, Six soilSamples with water content of C0(5%), C1(10%), C2(20%), C3(25%), C4(30%)and C5(35%)，in order to predict the germination and seedling of optimum soilmoisture ecological amplitude value and limit ecological amplitude value. Accordingto the vegetation of Baishazhou Poyang Lake,Combining the data,which came fromthe results of investigation, with the purpose of analysising the influence of moistureon distribution and growth status of Cynodon dactylon.The purpose of the thesis is to study water stress mechanisms of physiologicaladaptation of Cynodon dactylon.The study can provide guidance to water-droughtresistance and cultivation application for the growth of Cynodon dactylon seedlingswith Praetieal signifieanee. The main results showed that;(1)As water stress aggravated, seed germination and seedling growth wereinhibited more, the germination percentage,germination potentiality, the shoot androot’s length and the number of leaves and roots were decreased, while the relativegermination rate was increased at first but then decreased. Germination of the C.dactylon Seeds has certain resistance in water stress environment and affected by theearly, delayed its germination time ranging from1~7d. By established linearregression equation（y=72.621x2+151.58x+83.05）of seed germination under waterstress, predict the drought tolerance critical value is-0.25Mpa.(2)With soil moisture content increased, the germination rate, seedling height,leaf number, leaf length, leaf chlorophyll and biomass per plant of Cynodon dactylonStolons were increased firstly and then decreased; With soil moisture content changed,its biological and ecological characteristics (seedling height, leaf number, leaf length, biomass per plant) value in the presence of significant or extremely significant strongcorrelation; Analysis the response of Cynodon dactylon stolons on different soilmoisture by Gauss model. we could predict the germination and seedling of optimumsoil moisture ecological amplitude value and limit ecological amplitude valuewas[14.78%,30.15%] and [5.65%,38.26%]. Germination seedling biomass andaverage length of blade of Cynodon dactylon stolons on soil moisture content were themost sensitive factors.(3)The research of investigation in Poyang Lake and the experimental results areconsistent, the growth state of Cynodon dactylon in mild water stress environmentwas better than that in the environment of extreme drought; at the same time thatCynodon dactylon is widely distributed in the eastern part of Poyang Lake, and haslaw of zonal distribution in the near shore area, showed Cynodon dactylon has certainresistance to drought.