Age structure features of cloning population hibernation of Poa pratensis var.anceps cv.Qinghai

Characteristics of age structures of one to sixyear pasture of Poa pratensis var.anceps cv. Qinghai was studied in the experiment. The results indicated that age structures of hibernated buds were from 0 to 4 years old with 5 classes, while hibernated seedlings and parent strains had 4 classes from 1 to 4 years old. For the hibernated buds, the 0 years old number was the highest, but for the seedlings and parent strains the 1 years old number was the best. However, all of them were decreased when ages increased. The fouryear number of hibernation components of parent strain was the highest, for 672.337.74; while the oneyear numbers of hibernated seedlings and buds were the highest, 191.825.34 and 137.6728.97 respectively.Hibernated seedling age structure was fitted with a linear model, which was S=-35.96 t+221.3, while the hibernated bud was fitted with a growth curve, S=e5.472-0.374 t, and parent strain was followed a quadratic curve, S=-86.417 t2+547.455 t-279.752. When the each of age class number curve of hibernate seedlings and buds was fitted with a power curve, the higher the F value, the more likely growthtype age class structure. In conclusion, 1 and 2year pasture were growth age structure; 3 and 4year were stable age structure; and 5 and 6year were recession age structure.