Comparison of Salt Tolerance of Forage Soybean Varieties（Lines） Hybrided by Cultivated Soybean and Wild Soybean at Germination and Seedling Stages

In order to compare the salt tolerance of different forage soybeans at germination stage and seedling stage, and find higher salt tolerance of forage soybean germplasm, the hybrid offspring of wild soybean and cultivated soybean were used as experimental materials, and the male parent was used as control material to explore the difference of salt tolerance between hybrid offspring and male parent. Hybrids numbered Line 500, 3-2-1 brown-black, 8-4-1 brown, 27-2-1 and 8-3 black-green. The variety material was forage soybean S001（referred to as S001） and the control material was male wild soybean. The effects of different concentrations of NaCl(50,100,150 and 200 mmol·L^-1) on seed germination and seedling growth of seven materials were observed. The results showed that with the increase of NaCl concentration, the germination rate, germination potential, germination index, germination vigor and germination length of seeds of different materials showed a downward trend, and there were differences among materials. With the increase of salt stress intensity, superoxide dismutase（SOD） activity, peroxidase（POD） activity, soluble sugar（SS） and malondialdehyde（MDA） content of feed soybean at seedling stage increased, and the fluctuation ranges of salt resistance physiological indexes of different materials were different. The comprehensive comparison of principal component analysis and membership function of all indexes measured under salt stress at germination stage and seedling stage of all materials showed that the order of salt tolerance of seven materials at germination stage and seedling stage was S001＞wild soybean＞8-3 black green＞8-4-1 brown＞Line 500＞3-2-1 brown black＞27-2-1.Under salt stress, the salt tolerance of S001 was higher than that of its parent wild soybean. S001 can be used for further study on the molecular genetic mechanism of salt tolerance of cultivated soybean improved by wild soybean and used as a excellent soybean germplasm material for breeding new varieties of salt-tolerant cultivated soybean.