Abstract. Qur’ani CG, Yoshimura K. 2020. Effect of low light condition on the growth and carbon use of legume seedlings. Asian J For 5: 51-59. Plants exhibit flexible changes of morphological and physiological traits to adapt to low light environments. However, the interaction between growth, functional traits among plant organs, and non-structural carbohydrates (NSCs) concentration to determine the adaptation strategies remain unclear. Three legume- and shade-intolerant species, Robinia pseudoacacia (L.), Falcataria moluccana (Miq.), and Acacia mangium (Willd.) were grown under full light (open) and 15% of light availability (shade). Changes in shoot length, diameter, organ respiration rates, and NSCs concentration were observed throughout 6 months of the growing period. Only R. pseudoacacia developed longer (13.67%) and bigger (26.61%) shoots in open sites than shade sites. Specific Leaf Area (SLA) and Specific Root Area (SRA) were bigger in shade than in open site for all species (SLA=±2 times; SRA=±1-4 times). Dry mass, respiration rates, and NSCs in R. pseudoacacia were allocated more to the roots but were more to the leaves in F. moluccana and A. mangium. Based on the interactions among morphological and physiological parameters, our results show that different legume species develop specific growth, morphological traits and carbon use (NSCs) under shade conditions, which exhibit flexibility changes as part of adaptation strategy to the low-light environment.