| In this study, Hefeng 50 and Longken 310 were selected as test varieties. After soaking the seeds with GABA at different concentrations (5, 10, 25, 50, 100 mmol·L-1) for 8 hours, the seeds were placed in a 9 cm petri dish and then incubated at 25℃. Seeds soaked in distilled water were used as the control. The effects of different concentrations of GABA on soybean seed germination, root morphology, antioxidant system, endogenous GABA and metabolites were compared to clarify the regulatory effects of GABA on soybean seed germination and root morphogenesis. The study can provide theoretical basis and guidance for cultivating strong seedlings and improving soybean yield by applying exogenous GABA in agricultural production. The results showed that with the increase of GABA concentration, the germination, root morphology and related physiological indexes of Hefeng 50 and Longken 310 were firstly increased and then decreased. Among them, 10 mmol·L-1GABA had the most significant promoting effect on Hefeng 50 and Longken 310. Compared with the control, germination index and vitality index increased by 12.2% and 14.7%, 98.9% and 77.9%, respectively. Root length, lateral root number and fresh root weight increased by 27.3% and 27.1%, 93.4% and 90.5%, 28.5% and 77.2%, respectively. SOD, POD, CAT and APX activities in roots increased by 91.3% and 88.3%, 38.5% and 33.3%, 48.7% and 35.8%, 64.3% and 46.2%, respectively. In addition, the root diameter increased gradually with the increase of GABA concentration, and the maximum increase was 37.9% and 27.6% under 100 mmol·L-1 treatment, respectively. Comprehensive analysis shows that GABA immersion at the appropriate concentration can significantly improve the germination potential of soybean seeds, promote root morphogenesis, and facilitate seedling strengthening. |