～(60)Co-γ Irradiation Effect On Three Warm-season Turfgrass Species And Analysis Of Variants Of Cynodon Dactylon L.

Using different dose of ⁶⁰Co-γto irradiate dry seeds of Buchloe dactyloides L., Cynodon dactylon L. and Zoysia japonica Steud., the irradiation effect and the half lethal dose of three Warm-season turfgrass species were surveyed by screening their germination rate, germination rate in field and seedling growth. 11 Variants of Cynodon dactylon L. were selected to compare with 2 commonly used cultivars, The growing and covering ability were characterised, and the ploidy level were measured by using the ploidy analyzer, and difference of peroxidase isozyme and ISSR were also analysed.1 The effect of irradiation on germination rate of the seed in the lab and the field of 3 turfgrassThe results indicated that irradiation of low dose can promote seed germination and increase germination rate, but the germination rate decrease with the increasing of the irradiation dose, the critical dose (dose rate is 1.0Gy/min) of Buchloe dactyloides L., Cynodon dactylon L. and Zoysia japonica Steud. is 300Gy, 400Gy and 450Gy respectively. The critical dose of field germination rate is 250Gy, 350Gy and 250Gy respectively. When the radiation dose below the critical dose was applied, the field germination rate icrease with the increasing of the irradiation dose, and the field germination rate decreased when the dose is over the critical dose.2 The effect of irradiation on seedling grow feature of 3 turfgrassThere are significant difference of taproot and seedling forming of the 3 species of turfgrass when the dry seeds were irradiated by different dose. The length of taproot, heigh and fresh weight of seedling of 3 species are all promoted at first and depressed later. The critical dose for taproot growth of Buchloe dactyloides and Cynodon dactylon is 300Gy, The critical dose for seedling heigh of Buchloe dactyloides and Cynodon dactylon is 250Gy, the critical dose for seedling fresh weigh of Buchloe dactyloides and Cynodon dactylon is 200Gy. The critical dose for taproot growth, seedling heigh and seedling fresh weigh of Zoysia japonica Steud. is 400Gy, 300Gy and 250Gy respectively. The half lethal dose of Buchloe dactyloides,Cynodon dactylon and Zoysia japonica Steud. is 410Gy, 450Gy and 480Gy respectively based on the difmition of the half lethal dose . 3 The analysed on Phenotypic Characters of Variants of Cynodon dactylon11 selected variants were screened in the phenotypic characters togather with the control plant 'Tifway' and 'Tifgreen', The results indicated that the difference of leaf length and internode length and plant height are all significant between variants and the control plant; the difference is significant in internode diameter between variants and the control except for HN003 and HN004; the difference is significant in leaf width between Variants and the control except for HN003 and HN004, HN012,HN015 and HN009. The green-periods range of 18 variants from 242 days to 260 days and the green-periods of HN015 and HN016 are longest and HN010 are shortest.4 The analysed of POD and ISSR of the 18 variantsThe results of POD indicated that the zymogram character is complete identical between HN009 and HN010, HN012 and HN013; The number of bands and locus is identical between HN015 and HN016 except for bands on P8 locus, between HN004 and HN018 except for bands on P5 and P6 locus; The number of bands and locus are obviously difference among the other materials. The difference of zymogram character are obvious between variants and the control plant except for HN010 and HN009.Ten primers were screened from 38 arbitrary primers of ISSR, 18 Genomic DNA of Cynodon dactylon materials were amplified, the results by GS and cluster analysis indicated that GS≥0.8 between HN003 and HN007, HN005 and HN007, HN012 and HN013, HN015 and HN016, and with high Genetic similarity. The Genetic similarity is lowest between HN001 and HN014 because their GS is 0.46. The Genetic Variability between variants and the control plant is significant.