| Melastoma affine Linn., as a member from Melastoma genus (Melastomataceae), whose wild resource is widely distributed, has a high medicinal value, and is also a wild plant with great developing prospect. Until now, most of the research focused on its medical compositons and efficacy, while the study on ornamental value was not commom, and mainly used traditional breeding methods. Therefore, screening and cultivating mutants with landscaping ornamental value by using different breeding technique would become the most important thing in garden breeding.In this research, the seeds of M affine were radiated with 60Co-y, with the intention of producing mutants, so that ideal new cultivated varieties which could be used in landscaping could be screened. Seed germination, principles of morphology and physiology were used to study the effects after radiated by 60Co-y on morphology (plant height, stem diameter, intermodal length, number of leaves per plant, length of leaves per plant, width of leaves per plant, sprout number per plant, length of roots per plant), physiology (dry and fresh weight, chlorophyll, soluble protein, soluble sugar, sucrose, starch, flavone), Stomata of leaves and epidermal hair, and analysed its reaction to radiation of 60Co-y. By measuring photosynthetic rate of seedlings, chlorophyll fluorescence, the differences of 60Co-γ on growth condition and growth potential were further analyzed. Results showed that:(1)After radiation treatment, germination rate, vigor, germination index of the seeds increased firstly and then decreased with the rise of dose of radiation, and reached peak in 175 Gy.(2)Semi-lethal dose of seeding of Melastoma affine was 196 Gy. Morality of seeding was positively correlated with the radiation dose. Survival ratio was 0 when the dose was above 355 Gy.(3)Morphological differences of Melastoma affine after radiation increased with the rise of dose under 205 Gy, and decreased after the dose. Amplification of the characters were different in different monthes. The amplification was larger from october,2014 to december,2014 than from december,2014 to february,2015, and the amplification of each characters was larger in 145 Gy,175 Gy and 205 Gy. The changes in lobate and color were the leaves became darker and asymmetry, leave base became swelled.(4)Stomatal frequency and upper epidermal hair of leaves increased and then decreased with the dose of radiation, while the lower epidermal hair of the leaves decreased and then increased.(5) Physiological index of Melastoma affine seedlings(including dry and fresh weight, chlorophyll, soluble protein, soluble sugar, sucrose, starch, flavone) increased and decreased with the rise of dose, the suitable radiatioin dose of Melastoma affine is between 145Gy and 235Gy.(6)The difference on photosynthetic rate of seedlings of Melastoma affine were mainly that:net photosynthetic rate, transpiration rate, stomatal conductance, Intercellular CO2 concentration increased and then decreased with the rise of the dose, and was higher on 145 Gy,175 Gy and 205 Gy, and reached its peak on 175 Gy.(7)There were differences in chlorophyll fluorescence in seedlings of Melastoma affine. Photochemical quenching coefficient (qP), non photochemical quenching coefficient (qN), NPQ value of Non photochemical quenching coefficient, value of ETR, value of Fv/Fm, value of Fv/Fo increased and decreased with the dose, and was higher on 145 Gy,175 Gy and 205 Gy, and reached its peak on 175Gy.The seeds of M. affine were radiated with 60Co-y, the results showed that:seed germination percentage, indexes of morphological characteristics and physiology showed an increase followed by a decrease with the rise of the dose, by using seed germination experiment, observation of morphology, and mensuration of physiology. |
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