Abstract: Taking Calystegia hederacea as material, the seedlings were grown under overground competition （with overground competition and without overground competition） and under light conditions （strong light and weak light）, and the changes of overground stem length and average stem node length with plant growth were monitored. Biomass of each part and number of branches were measured at harvest. The results showed that compared with no above-ground competition, the relative growth rate of above-ground stems was faster, and the biomass distribution of stems and leaves was increased, while that of roots was decreased. The weak light treatment compared with the strong light treatment, the growth rate of the stems was faster, the number of branches was less, the biomass distribution of the stems and leaves was higher, and the biomass distribution of the roots was lower. The competition intensity was calculated by using the length of the overground stem as the reference index. In terms of biomass allocation, ANOVA analysis showed that there was no significant interaction between light condition and competitive effect. In addition, while the stem length increased with time, the average stem node length decreased slightly with time.

Key words: above-ground competition, light availability, limiting resource, stem length, biomass allocation, Calystegia hederacea