The Studies On Irradiation Effects Of ⁶⁰Co-γ Ray On Sophora Viciifolia

In order to speed up the use of the elite germplasm, creating excellent mutation and cultivate Sophora viciif olia varieties, this experiment used wild Sophora viciif olia seeds collected from Guizhou were radiated by ⁶⁰Co-γ ray, determined the suitable irradiation dose. The irradiation effects on the growth characteristics, photosynthetic characteristics, physiology and biochemistry and molecular markers of Sophora viciifolia were analyzed. The main research results are as followed:（1） ⁶⁰Co-γ ray had a stimulating effect on the growth of seedling, seedling maintaining high survival rate, with the condition of low dose radiation（20 80 KR）. The damage of seedling exposed to high dose radiation was bigger, and the plant emergence rate, surviving rate and shoot height showed the inhibition effect.（2） Taking the radiation dose, which the relative emergence rate was 60⁷5% as the most appropriate dose of Sophora viciifolia. The theory value of appropriate dose（LD60） was 120.42 KR,（LD75） was 74.97 KR, combined with actual emergence rate and synthetical effects of the radiation, the most appropriate dose of Sophora viciifolia was 80¹20 KR.（3） Under different radiation dose, agronomic traits performance of Sophora viciifolia of seedling stage, growing period and maturation stage were different, the performance of seedling stage was relatively consistent. 80 KR was beneficial to the growth of branch length, stem diameter and branch number per plant in seedling stage. Compared to other doses, the normal growth of plant was inhibited stronger under 120 KR.（4） The content of Chl a, Chl b and Chl a+b were obvious promoted by100¹20 KR radiation. The effect of radiation on carotenoid content is not obvious.（5） The MDA of Sophora viciifolia content was higher in each period under radiation of 60 KR and 80 KR. The POD activity was in each period minimum in the control, which was higher under the 80¹20 KR. The SOD activity in each period have different performance, which was strongly influenced by radiation in the seedling stage, increasing gradually with rising dose, and reached the peak at 120 KR. The SOD activity in growing period and maturation stage were less affected by radiation. In seedling stage and growing period, the contents of soluble protein and soluble sugar reached maximum value at 100 KR. Soluble protein contents in maturation stage at 60 KR reached maximum value. Soluble sugar contents in maturation stage at 40 KR reached maximum value, and all the values were significantly higher than the control. The proline contents in seedling stage at 120 KR reached maximum value, in growing period at 20¹00 KR reached maximum value, and in maturation stage at 140 KR reached maximum value, which were signif icantly high er than the control. The Lower radiation dose improved the plant enzyme activity and had a promoting effect of osmotic regulation substances. The higher radiation dose showed inhibitory effect on osmotic regulation substances. This phenomenon is more obvious in the seedling stage.（6） This paper transformed 14 comprehensive index of agronomic traits, photosynthetic characteristics and physiology and biochemistry into 14 principal component. The cumulative contribution rate of first 4 principal components of seedling stage, growing period and maturation stage reached 97.426%, 92.917%, 93.302% respectively. Combined with the comprehensive evaluation of subordinate function, the radiation dose of seedling stage comprehensive ranking might be more consistent with the fact. At 80 KR、100 KR、120 KR radiation dose the plant had better comprehensive performance.（7） Screened out 20 ISSR primers and six RAPD primers, which were clearer, good stability and abundant polymorphism. 183 bands were amplified out with ISSR markers totally, the polymorphism rate was 51.37%. A total of 37 bands were amplif ied out with RAPD markers, the polymorphism rate was 27.03%. The number of alleles, effective number of alleles, Nei’s gene diversity and average Shannon’s Information index of ISSR markers were more than RAPD markers. MI value of ISSR markers（1.28） was 6.4 times of RAPD markers（0.20）. ISSR markers clustering analysis showed the genetic similarity coefficient among eight treatments was 0.6885⁰.8579. RAPD markers clustering analysis showed the genetic similar ity coefficient among eight treatments was 0.8108⁰.9730. The results of integrated ISSR and RAPD markers were similar, which was closer to the ISSR clustering results.