Effect Of Three Mutagenesis Methods On Medicago Ruthenica

As a high-quality forage,Medicago ruthenica has low forage and seed yield.In order to improve the production performance of Medicago ruthenica by means of breeding,in the study three mutagenesis methods of Ethylmethylsulfone（EMS）,colchicine,and space loading are used to treat erect Medicago ruthenica（B1）,Mengnong No.2 Medicago ruthenica（B2）,Mengnong No.1 Medicago ruthenica（B3）.The variation of seed germination and seedling growth stage were observed and the photosynthesis efficiency,chlorophyll fluorescence intensity,leaf structure,genetic diversity of mutants and other indicators were analyzed.And the biological effects of Medicago ruthenica under different mutagenesis methods was discussed.The main results are as follows:（1）The semi-lethal dose of 3 Medicago ruthenica materials mutated by 0.9%EMS was 42 h-48 h,and the seed size was significantly positively correlated with relative germination rate,relative germination vigor,and relative seedling emergence;There was no obvious phenotypic variation in M₀ generation.The M₁ generation variation rate was4.78%,and there were 15 phenotypic variation types,which mainly appeared in the cotyledons and the first true leaf;The chlorophyll fluorescence intensity of the mutant plants was significantly different from the control,and the genetic diversity index of the mutant plants was slightly lower than the control.（2）Using 0.1%colchicine to mutate erect Medicago ruthenica for 5 hours,the germination rate was not significantly different from the control,but its emergence rate and seedling rate were lower（3.33%-8.00%）,and the emergence were late for 3-5 days.The induction rate of the tetraploid is 6.52%.The leaf area and internode spacing of the tetraploid Medicago ruthenica increased;The fluorescence intensity of chlorophyll is lower than the control,and the genetic material diversity index is higher than diploid.（3）Using space loading radiation to mutate three Medicago ruthenica materials for 67hours,the relative germination rate of the seeds was B1<B2<B3.there were 7 phenotypic mutations in the three Medicago ruthenicaand the mutation rates were B1:4.26%,B2:3.30%,B3:2.22%;The growth rate of the slender true-leaf mutant plant in the seedling stage was significantly slower than the seedling stage,the growth status of the double-main stem mutant plant were not significantly different from the control,and the leaf area of the dwarf plant was significantly larger than the control;The photosynthetic characteristics of the mutant plants after space radiation were all higher than the control;The fence tissue thickness and cell structure precision of the square true-leaf mutant plants were significantly greater than those of the control;The genetic diversity index was not significantly different from the control.