Reproductive allocation and reproductive yield of Vicia unijuga at Gannan Tibetan region

Biomass allocation of Vicia unijuga at Gannan Tibetan region was studied by the method of Standing Reproductive Allocation. The results showed that vegetative biomass proportion gradually decreased and reproductive biomass gradually increased throughout the growing season although vegetative biomass always had an absolute advantage with less than 10% of reproductive biomass. The reproductive biomass allocation increased with increasing of reproductive age for the young plants of perennial V.unijuga. The reproductive biomass of two-year-age plants was higher. Reproductive conversion ratio from flower buds to flowers and from flowers to pods for two-year-age plants was 1∶1.17 and 1∶1.36, respectively, while that of five-year-age plants was 1∶0.94 and 1∶1.31, respectively. These results indicated that the loss of flowers and pods was obvious for five-year-age plants and reproductive modules utilization was higher for two-year-age plants. The lower seed production of V.unijuga in this area may be resulted from low reproductive investment proportion and the loss in the process of reproductive conversion, which may be influenced by some factors, such as environmental disturbance and nutrient competition.