Abstract: It dealt with dynamics of grassland aboveground biomass and reproductive effects of population of Secale carele L. of the first and the second crop by mowing a time before summer. The results showed that Secale carele L. can be croped two crops in growth date from turngreen to early summer (June 7).The highest total aboveground biomass was 1004.20 g/m². There was an indication that the herb had high efficiency of photosynthesis. Through contrast of productive characteristic of the first and second crop, there were results that the second crop was 57.11% in the highest total aboveground biomass and growth date of the crop was 42.06% in total growth date. To the first crop the ratio of fresh herb and dry herb was relatively high and the ratio of stem to leaf was relatively low. The results showed clearly that the first crop was more suited for fresh fodder or green drink and food, and the second crop was more suited for dry fodder or natural fiber food. Through comparative study of AGR and RGR, it was further testified that later management of the first crop had an important effect on formation of total aboveground biomass. The study provided a scientific basis for applying ecological engineering of efficient agriculture to developing productive characteristic of Secale carele L. to a maximum.

Key words: Mowing, Secale carele L, The first crop, The second crop, Aboveground biomass