Study On Growth Character And Biomass Composition Of Poa Pratensis Var. Anceps Gaud Cv. Qinghai In Alpine Region

The botany characteristics, tiller and characteristics change of seeds of the second year Poa pratensis var. anceps Gaud cv. Qinghai growing in Alpine Region, Qinghai province were quantitatively detected to disclose the regulation of biomass accumulation, to find out the key time of biomass accumulation and tiller and to decide the optimum period for seeds harvest. The main results are as follows:The biomass of stems and leaves and the total above ground biomass showed"S"curves along with the growing of Poa pratensis var. anceps, while the ear biomass was increased at beginning and then decreased. The biomass accumulations of all parts during the growth of Poa pratensis var. anceps may be presented by y=a+bx+cx~2+dx~3. The crucial period for leaf biomass accumulation is in the first month after the grass recovered from winter, while that for stem and ear is in mid May and mid June respectively. The above ground biomass accumulation is mainly affected by plant height.The total under ground biomass and the biomasses of main root, rhizome and capillary root showed"U"model presented by y=a+bx+cx~2+dx~3 along with the growth of Poa pratensis var. anceps. The crucial period for main root biomass and rhizome increase is in a month and a half after grass maturity, in a month and a half before the plant withers respectively, while capillary root in its biomass accumulation is smooth during the whole growing period. Leaf area is the key deciding under ground biomass accumulation. The root of Poa pratensis var. anceps mainly is distributed in the soil layer of 0-5 cm. Rhizome, capillary root and the total under ground biomass displayed a"â–½"type distribution presented by exponent function in vertical in all growing period, except capillary root showed">"type distribution in the period of recovering from winter.The change regulation of rhizome length of Poa pratensis var. anceps is more complicated showed with a unitary quintic equation while tiller number of rhizome showed with y=a+bx+cx~2. The crucial period for both of tiller number and length of rhizome is in maturity to withered period. Both of tiller number and length vertical distribution of rhizome showed"â–½"type distribution, which can be presented by exponent function. The scalar relationship between the above ground biomass, the ground biomass and tiller number can be indicated by y=a+bx+cx~2+dx~3, y=a+bx+cx~2 respectively.The seed falling rate of Poa pratensis var. anceps reaches to 42.3% while be harvested. The seed of Poa pratensis matured physiologically with water content of 35% and seed falling rate of 15.89% after 28d blooming, and this is the optimum time for seed harvest.