60Co-γ辐射对兜兰组培苗的诱变效应

为了选育兜兰新品种,明确⁶⁰Co-γ对兜兰不同发育时期的诱变效应,筛选适宜辐射剂量。以种子、瓶苗（不定芽增殖、不定根分化阶段）及小苗为材料,采用0、5、10、20、30、40 Gy的⁶⁰Co-γ进行辐射,观测生长发育和变异情况,测定生理生化指标。结果表明,种子萌发阶段和不定根分化阶段为5 Gy,不定芽增殖阶段和小苗阶段为20 Gy。6.92 Gy是兜兰种子的半致死剂量。随着辐射剂量增大,种子的发芽率、不定芽殖增率、不定根分化率、小苗生长势下降,变异增多。同时,电导率、丙二醛含量、可溶性糖含量、可溶性蛋白含量、脯氨酸含量以及过氧化物酶、超氧化物歧化酶活性呈现先升高后降低的趋势。兜兰种子在萌发阶段和不定根分化阶段需要适宜的低辐射剂量,不定芽增殖阶段和小苗阶段较高。在合适的辐射剂量下,诱导的变异性状明显,效果稳定。

Mutagenic Effect of 60Co-γ on Tissue Culture Seedlings of Paphiopedilum

The aims are to breed new varieties of Paphiopedilum, clarify the mutagenic effect of 60Co-γ on different developmental stages of Paphiopedilum and select appropriate radiation dose. Seeds, bottle seedlings (adventitious bud proliferation and adventitious root differentiation stage) and seedlings were used as materials which were treated under the radiation dose of 0 Gy, 5 Gy, 10 Gy, 20 Gy, 30 Gy and 40 Gy of ⁶⁰Co-γ. The growth and variation were observed and the physiological and biochemical indexes were measured. The results showed that the appropriate radiation dose for seed germination and adventitious root differentiation stage was 5 Gy, while the optimal radiation dose was 20 Gy for adventitious bud proliferation and seedling stage. 6.92 Gy was the semi-lethal dose for Paphiopedilum seeds. With the increase of radiation dose, the seed germination rate, adventitious bud growth rate, adventitious root differentiation rate, and seedling growth potential decreased and the variation increased. Simultaneously, the electrical conductivity, malondialdehyde content, soluble sugar content, soluble protein content, proline content and the activities of peroxidase and superoxide dismutase increased first and then decreased. The ideal radiation dose for Paphiopedilum was low at seed germination and adventitious root differentiation stage, and was relatively high at adventitious bud proliferation and seedling stage. The induced variation was obvious and the effect was stable with the appropriate radiation dose.