Study On The System Of In Vitro Regeneration For Southern Type Of Medicago Sativa L.

Alfalfa (Medicago sativa L.) is a kind of important forage legume with high quality, and its protein content is very high. Along with the increasing of planting area in the south of China, the aluminum in acid soil, the wet and torrid climate, the grievous weed harm, and the plant diseases and insect pests became important limiting factors. To solve these problems radically, we must take the breeding technique into account. The traditional breeding technique needed too long time, and had no efficiency, so it was necessary to use biologic technology to accelerate the breeding process, improve the alfalfa characters, and make it adapt to the environment of south China. The biologic technique studying needs an efficient tissue culture system, but this system of southern type of alfalfa tissue culture has not been build, which limited the using and application of biologic technology. In order to select alfalfa genotypes with high somatic embryogenesis ability, build tissue culture system suiting to them and provide the base of biologic technology studying for southern type of alfalfa, we carried out this study. The results of this study are below:On improved SH medium, improved MS medium, B5 medium and SM medium, leaves of 19 varieties used for this experiment were induced to form callus efficaciously, the induction rate on the SH medium was most high and the average rate reached 96.4%. However, the inductivity on Blayde's medium was lower and callus was not formed in some genotypes. The difference among callus inductivity of different varieties was significant, and the average inductivity of "L1", "Moapa69", "Okca", "L2" and "Cuf101" all exceeded 90%. But only for a few varieties the callus differentiated and formed somatic embryos. The callus differentiation rates of "L1" and "L2" were higher, and the average of each was 42.2% and 38.6%, respectively. By further experiment, only "L2" was found to have good repeatability. So, later experiments were carried out with "L2" as explants source and the improved SH as basic induction medium. There was no significant difference of the callus inductivity among different genotypes in intra-variety.There was no "L2" callus forming on improved SH medium when 2,4-D was not existed; when the concentration of 2,4-D was between 2~10mg/L, the deference among rates of callus induction were not significant, but the deference among rates of callus differentiation on MSO medium were significant, when the concentration of 2,4-D was 5mg/L, the rate of callus differentiation was higher significantly than the others. KT had no significant effect on rate of callus induction, but it had significant effect on the quality of callus. When the KT was not existed, the rate of differentiation was very low and even no callus differentiated was found. When added 2,4-D5mg/L+KT1mg/L in...