Abstract: The study shows that the allocation rate of the biomass in Leymus chinensis for its rhizome and vegetative growth was much higher, and that for sexual growth was less than 10%. The ratio of the biomass of rhizome and vegetative shoot was as much as 20～40% of the total, while that of seed was less that 1.5%. The low investment in sexual reproduction of L.chinensis was the main reason for its low seed production.

Key words: Biomass reproductive allocation, Leymus chinensis population, Reproduction, seedling, natural regeneration, water use efficiency, chlorophyll content, photosynthetic characteristics