Studies On The Radiation-induced Effects Of Chrysanthemum Under γ-ray

Chrysanthemum is Chinese traditional flower and it's cultivation history has been 1,600 years,with the orchid,plum blossom,bamboo tied together referred to as the"four gentlemen."Colorful chrysanthemums was very popular all the time,and it has extensive use,ground-cover chrysanthemum and rock chrysanthemum can be arranged flower beds,flower and rock garden habitats;Florists Daisy can be medicine or soft drinks.In addition,the chrysanthemum is one of the world's four major cut flowers in recent years,cut chrysanthemum has been the largest sales share in the cut-flower trade, accounting for about 30%of the total.As vegetative propagation of ornamental plants, lots of chrysanthemum varieties have a little or no pollen,and a high degree of genetic heterozygosity and polyploid makes chrysanthemum suite for radiation-induced breeding.In this experiment we researched different doses of ⁶⁰Co_-γ,ray irradiated tissue culture seedlings of cut Chrysanthemum'Jinba'and seeds of Zh99-1,research the biological effects of Chrysanthemum M1 generation with the form of indicators,leaf relative water content,chlorophyll content,seed germination rate and antioxidant enzyme systems.It can provide theoretical support for mutation breeding of chrysanthemum.The main results are listed as follows:1.The semi-lethal dose ofγray irradiation tissue culture seedling of 'Jinba' is about 20Gy.Subculture can increase the survival rate of offspring after radiation,increasing the number of variant groups.Radiation inhibits the majority of traits of M1 generation. Ray radiation have no significant effect on the leaf relative water content of 'Jinba' M1 generation,but after high temperature treatment the relative leaf water content of M1 with radiation was significantly lower than control.The results showed radiation reduced the capacity of leaves water-retention on M1 generation of chrysanthemum. Radiation have no significant effect on chlorophyll content of 'Jinba' M1 generation, high temperature treatment made a significant increase in chlorophyll content on M1 generation.Chrysanthemum seeds were treated by radiation,with the germination potential decreased in radiation dose increased.Low-dose(10 Gy and 20 Gy)on the seed germination rate have no significant impact,high-dose(30 Gy,40 Gy and 50 Gy) significantly inhibited the seed germination rate,the higher the dose the more obvious inhibition.2.The H₂O₂ content of leaves was significantly lower than control after 'Jinba' tissue seedlings of M1 generation were irradiated byγ-ray,the results may be related to the activity of catalase(CAT)and glutathione reductase(GR)significantly increased. The chrysanthemum leaves have not been dealt by radiation with high-temperature treatment also appeared the H₂O₂ content in a significant drop.The results may be related to the activity of CAT and peroxidase(POD) increased significantly.After high temperature treatment of radiation-generation of M1,the H₂O₂ content decreased significantly at the same time along with the GR activity increased significantly. Low-dose(10Gy and 20Gy) radiation made tissue of 'Jinba' M1 generation's superoxide dismutase(SOD) activity was significantly increased;a higher dose(30Gy) had no significant effect.This results show that chrysanthemum by the different stress,play a major role in the antioxidant enzymes may be different.3.The M1 generation plants that irradiated byγray,with the dose increased,the H₂O₂ content first increased and then reduced.10Gy radiations in addition to a significant reduction in GR activity,the activity of other antioxidant enzymes were not significantly affected.From the beginning of irradiation with 20Gy radiation dose increased CAT activity also increased after the first downward trend,while the SOD activity increased with the radiation dose a gradual increase.Dose of 20Gy and above all sharp decline the survival rate of radiation future generations,but there was a dramatic increase in POD activity that can be used as a metabolic marker of radiation future generations'survival rate on ground-cover chrysanthemum.4.γray irradiation treatment on the tissue of 'Jinba' M1 generation have no significant impact to content of malondialdehyde(MDA).High temperature treatment made MDA content of radiation M1 significant higher than the control,radiation may reduce the heat resistance of chrysanthemum's M 1 generation.10Gy radiation treatment on the M 1 by the chrysanthemum seedlings have no significant effect to MDA content, 20Gy radiation treatment significantly increased MDA content and increased with the dose gradually increased MDA content.