Abstract: Studies on the reproductive characters of Leymus chinensis population in two plots showed that the density of L.chinensis population declined significantly in plowing plot,while the density of reproductive tillers varied insignificantly.The reproductive tiller had longer ear,longer inter-node,higher ratio of reproductive growth,higher seeding percentage,more ear-nodes,more spikelets,more florets and grains in plowing plot than in enclosing plot.The grain yield,net weight of grain,and the weight of 1000 grains was 2.68 times,3.49 times and 1.3 times higher in plowing plot than in enclosing plot,respectively.The reproductive tillers with double-spikelet were 16% more in plowing plot than in enclosing plot,and they developed more double-spikelets.Relatively,the reproductive tiller in plowing plot developed few double-spikelets,more florets and more grains,so that,the grain yield of the population was enhanced largely.The reproductive allocations of L.chinensis didn't response differently to both plowing and enclosing at three module levels,including population to reproductive tiller,reproductive tiller to ear,and ear to grain,but the allocation of population to ear and to grain,and the allocation of reproductive tiller to grain were significantly higher in plowing plot than in enclosing plot.

Key words: Songnen plains, Degenerated grassland, Leymus chinensis population, Reproductive module, Reproductive allocation