Study on salt tolerance of Elymus dahuricus, Hordeum brevisubulatum and their new hybrid lines at seedling stage

In order to evaluate the salt tolerance of grass seedlings between new lines forage P₁₃（Elymus dahuricus×Hordeum brevisubulat-um ×Hordeum brevisubulatum）,Y₃₃（Hordeum brevisubulatum×Elymus dahuricus ×Hordeum brevisubulatum） and its parents（Hordeum brevisubulatum, Elymus dahuricus）, the above four forage varieties were used as materials and four salt concentration gradients of 0（CK）, 1%, 2% and 3% were set up in the experiment, every 2 d replaced a concentration.The malondialdehyde content, relative water content, relative permeability of cell membrane, free proline content and chlorophyll content of four materials(Hordeum brevisubulatum, Elymus dahuricus, P₁₃, Y₃₃) were measured before treatment and on the 3 rd, 6 th and 9 th day after treatment. The salt tolerance of the four forage varieties was comprehensively evaluated by scoring method and fuzzy membership function method. The grey correlation analysis method was used to analyze the correlation between the indexes and salt tolerance of four forage varieties. The results showed that with the increase of salt stress intensity, MDA content, relative permeability of cell membrane, and free proline content of Elymus dahuricus, Hordeum brevisubulatum and their new hybrid lines increased, while relative water content and chlorophyll content decreased.The order of salt tolerance of each material by scoring method was as follows: Hordeum brevisubulatum＞ Y₃₃＞ P₁₃＞Elymus dahuricus. The order of salt tolerance of the materials evaluated by fuzzy membership function method was: Hordeum brevisubulatum = Y₃₃＞ P₁₃＞Elymus dahuricus. According to the grey correlation analysis, the correlation degree values of the five physiological indexes were all high, which could be used as the identification indexes of Hordeum brevisubulatum, Elymusdahuricus and their new hybrid lines under salt stress. The results indicated that salt tolerance of Y₃₃ and P₁₃ was stronger than that of Elymus dahuricus.