Effects of GA₃, ABA and 6-BA on soybean，Glycine max L. Merrill，root growth and development

【Objective】This experiment was conducted to explore effects of different concentrations of GA₃, ABA, and 6-BA on soybean root growth, which could provide a theoretical basis for a further control of soybean root architecture through phytohormone. 【Method】The seedlings of soybean cultivar “HN89” were treated with 0.05, 0.50, 1.00, and 5.00 μmol·L^-1 gibberellin (GA₃), abscisic acid (ABA) and cytokinin (6-BA) respectively for 4 days, then root morphological parameters were quantified and analyzed. 【Result and conclusion】The results showed that 0.05 μmol·L^-1 GA₃ promoted the total root length of soybeans, but increasing GA₃ concentration would constrain primary root and lateral root growth, which decreased the total root length. GA₃ decreased average root diameters, hence resulting in fine roots. 0.05 μmol·L^-1 ABA did not affect the soybean root growth, while increasing ABA concentration higher than 0.5 μmol·L^-1 inhibited primary root and lateral root growth, decreasing the total root length, and slightly increasing average root diameters. 6-BA significantly constrained the soybean root growth and development, for instance, it inhibited primary root elongation, lateral rooting, and the total root length, but it promoted average root diameter, resulting in thick roots. These results indicated that different phytohormones or similar phytohormone with different concentrations can control soybean root architecture by controlling primary roots and lateral roots growth in different ways.