Study On Developmental And Reproductive Characteristics Of Main Rhizomatous Grass In Grassland Vegetation On Mongolia Plateau

At present, clonal plant is one of hotspots in biology and Ecology. Rhizomatous grasses (RG) are typical clonal plant which can reproduce new ramet with rhizome and are important vegetation type of grassland on Mongolia plateau, and have two kind of reproduction, including with clonal reproduction and sex rproduction.It is important meanings in biology and aplling foreground for better using the resources of RG to study its development law. In this paper, RG were studied from the aspect of development and reproduction on Mongolia plateau, which was as a total region, including with the morphological characeristics of ramet with inflorescence, plasticity, development, reproduction characteristics, as well as community characteristics. The results showed that:1 The development time of pogoniasis root in rhizome node were in the period when the rhizome were growing and not after that and the number of pogoniasis root increased with the length of rhizome. The germinating time of rhizome node bud was after that of pogoniasis root. The number of bud in underground were on the rise under cradle.The growth model of internode in all RG had some common law, and may be have some relation with season,and so on .2 Durring overwinter stage, the content of nitrogen in tillering node were higher than other organ in underground. Cutting could increase the content of dissuluble sugar in underorgan, but not in the content of other nitrition. There was obviously difference of ABA yearly dynamics in different RG. The yearly dynamicses of photosynthetic rate (Pn), water utility efficiency (WUE), stomatal conductance (Gs), intercellular carbon dioxide concentration (Ci) were nearly consistent, and they all were single peak curves.3 The elongating growth of rhizome in RG were realized by increasing the number of rhizome node, and rhizome length were more varied with soil type than other morphological index of rhizome.The plasticity of Leymus chinensis in biomass and rhizome morphological characteristics increased with increase of altitude, but the change patterns of the biomass ratio of root to shoot were in a quadratic curve when the altitude increased, which decreased in the former three altitudes, then were on the raise in the following ones, and there wasn't significantly difference in ramet distance. The morphological plasticity of Leymus chinensis ramet were aslo significant, which have a close relation to the ability to surviving in different environments.4 The diffiences between ramet without inflorescence and ramet with inflorescence were mainly in node lengh of shoot, biomass, as well as height, and so on. The factors of soil nitrition, temperature and light had less effect on the percent of ramet with inflorescence. The region, tilization strongth and other environment conditon were no sigificantly effect on the percent of Panicle in L. leymus.5 The percent of Panicle and seed setting were all low in speices of rhizome grasses, but were sinificant in speices and site, and were effected by heredity and environment conditions, and were all higher in artificial grassland than in natural enviroment. The seed of the seven species of RG were all dormant. Their seed germination rates, germination indices, and dormancy were significantly different. The extent of seed dormancy was concerned with rhizomatous types. The longer the rhizomatous were, the more dormancy the seeds were. The more were the percent of rhizome in biomass distribution, the less were that of panicle and pogoniasis root.6 The upper limit of rhizome was very shallow, but the lower limit was deeper and varied in species. The percent of old rhizome in all of species were major in the total rhizome length, varied in 84%-100%, and the new one have less length, under 15.23%. The germination percent of bud in rhizome are very low in all of species, under 25.7%. The bud in rhizome and tillering node have a higher percent of developing ramet, up 80% and a low one to rhizome, under 20%.7 The characteristics of soil in typical steppe on Mongolia were better than one on Inner Mongolia, and the ones in meadow steppe were better than the ones in typical steppe on Inner Mongolia.The corelation analysis of the growth status of RG and the factors of soil were not significant.8 The total coverage of community were usually heigh and the the coverage of rhizomatous grass was not only lower, under 25%, but also vavied with a great scope. There were significantly difference in species saturation in different community of species,and in the hight of RG, and were most in 26-75cm. The importance of RG in community varied with species, community, as well as sites.