Abstract: The reproductive tillers of Elymus excelsus population in Songnen Plain were randomly marked with labels every other four days (five times in total) at early earring stage, and the marked tillers were harvested at dough stage, with the differences of their quantitative characteristics as well as the relationships between the quantitative characteristics and the shortened time of reproductive growth were analyzed. With the shortened time of reproductive growth, the quantitative characteristics of the reproductive tillers decreased gradually, which was not beneficial to the reproductive growth, reproductive allocation, and fruiting of reproductive tillers. The later the earring time, the larger the impact on fruiting and reproductive allocation was. When the reproductive growth time was shortened by 16 days, the grain biomass, setting penentage,  reproductive allocationⅠ, and reproductive allocation Ⅱ decreased by 99.4%, 98.8%, 54.3%, and 99.2%, respectively. With the shortened time of reproductive growth, the tiller height decreased linearly, spike biomass, reproductive allocationⅠ, and setting penentage decreased exponentially, tiller biomass, spike length, and floret number decreased powerly, and grain biomass, grain number, and reproductive allocationⅡ decreased logarithmically.

Key words: Elymus excelsus, reproductive growth, reproductive allocation, quantitative characteristics, earring stage