60Co-γ辐射对杂交兰诱变效应的研究OA

To clarify the mutagenic effect of 60Co-γ radiation on hybrid Cymbidium Cv.GZ3-7 and determine the optimal radiation dose,this study used protocorms of GZ3-7 as materials and set six radiation doses(0 Gy as control,5,10,20,30,and 40 Gy).By measuring the lethality,adventitious bud differentiation rate,half-lethal dose(LD50),and half-differentiation dose(DD50)of protocorms,combined with phenotypic analysis of 1-year-old and 3-year-old irradiated seedlings(including plant height,number of leaves,leaf length,leaf width,leaf thickness,cross-sectional area of pseudobulbs,total number of seedlings,and number of new buds),the correlation patterns between radiation dose,phenotypic variation of hybrid Cymbidium,and mutant induction were systematically explored.The results showed that the LD50 and DD50 of protocorms were 25 and 15 Gy,respectively,which jointly defined the suitable radiation dose range as 15 to 25 Gy.Medium-low doses(5 to 10 Gy)improved the growth uniformity of seedlings,while medium doses(10 to 30 Gy)exerted a significant dwarfing effect on plants.Through screening,one stably heritable variegated mutant(treated with 10 Gy)and six dwarf mutants(treated with 10 to 30 Gy)were obtained.Notably,the 20 Gy treatment yielded a higher utation rate(dwarf mutants:3/20 plants,accounting for 15％).The variegated leaf mutant exhibited a stable"green-yellow"striped phenotype for 3 consecutive years,with prominent ornamental value.High doses(＞30 Gy)resulted in a low survival rate of 3-year-old seedlings,with only 11 seedlings survived under the 40 Gy treatment.Based on comprehensive observation and analysis of multi-year growth indicators of protocorms and seedlings,the optimal radiation dose for protocorms of hybrid Cymbidium CV.GZ3-7 was finally determined to be 20 Gy.This study provides data support for radiation dose selection in hybrid Cymbidium mutagenesis breeding,enriches the research foundation of protocorm-based irradiation mutagenesis in hybrid Cymbidium,screens high-quality mutants,and lays a foundation for subsequent improvement of orchid breeding efficiency and industrialized.