Abstract: In order to learn about the effect of salt stress on morphological structure of alfalfa cells for better breeding salt-tolerant varieties, the morphology structure of two kinds of salt-tolerant alfalfa callus induced by Qinglai alalfa was studied. The results showed that callus cell area under salt stress reduced and was only a quarter of the CK. Besides, the radius of CK callus cells was 2.22 times that of the salt-tolerant cells and the vacuole radius of CK callus cells was 2.93 times that of the salt-tolerant cells; Although the influence of salt stress on the size of cell nuclear and chloroplast was insignificant, the callus cells became shorter and was closer to the spherical shape. The cell nucleus was in the center of the cell, and the number of chloroplasts per unit volume was increased, so that the color of the salt-tolerant callus was green-yellow and the cells were uniform, packed tightly and had high hardness.

Key words: salt-tolerant, alfalfa, callus, cell, morphological structure