Impacts of phytohormones on the physiological performance and root profiles of legumes seedlings

It is a great challenge for researchers to enhance physiological performance and root profile of seedlings. This challenge depends on the improvement of germination rate, survival rates of seedlings and seedling establishment. Thus, this experiment was conducted to improve the physiological performances and root profiles of two native legumes, L. leucocephala and P. pterocarpum, from seedling stage using growth regulating hormones. Before sowing, seeds of L. leucocephala and P. pterocarpum were soaked in Gibberellins (GA(3)), Indole-3-Butyric Acid (IBA), GA(3)-FIBA and distilled water for germination. Then, seedlings were grown in soil under greenhouse conditions and their physiological performances and root profiles were investigated. The results showed that GA(3) hormone increased the germination percent of species studied. Additionally, IBA application resulted in higher photosynthetic rates than control. In terms of root profiles, GA(3)-FIBA treated seedlings of both species had the highest root length and root volume. Moreover, GA(3)+IBA treated seedlings had a higher number of fine roots and root tips than control. The photosynthetic rates of the species studied were positively correlated with the stomatal conductance (r=0.82), chlorophyll content (r=0.89) and root length (r=0.75), implying that photosynthetic rate was enhanced by increasing stomatal conductance, chlorophyll content and root length. In conclusion, this study suggested that GA(3)-FIBA hormone is more biologically active than single treatment of IBA and GA(3) and the best choice for seedling establishment as it improved germination percent, physiological performances and root profiles.