| In order to get better understanding the impacts of ? and X-rays radiation on Freesia refracta Klatt M2 generation and Gladiolus gandavensis Vaniot Houtt M3 generation quality and biological characteristics.This experiment planted two varieties of Freesia('F.armstrongii' 'F.corymbosa')M2 generation and Gladiolus('Dowland)',' Berlioz ')M3 generation with five-dose-radiation are potted in the greenhouse.Observed the growth and development of offspring,and measured physiological and biochemical indicators,and then compared the results with the generation M1 or M2 in order to find the optimal radiation dose for radiation mutation breeding.At the same time,the mutant individual plants with ornamental value in the generation M1 were planted separately,and it was observed whether the mutant traits were maintained in the M2 or M3 generation and whether new mutant plants appeared in the contemporary era,eventually selected mutants with stable traits and high ornamental value.In addition,in order to reduce radiation-induced damage and death rates and expanding the mutant population and improve radiation mutagenesis in freesia bulbs after 60Co-? radiation treatments.So in this study,freesia bulbs were treated using 60Co-? radiation at dosages of 55,65,or 75 Gy,then at three different time periods before irradiation,after irradiation,and after germination,use salicylic acid(SA)with a concentration of 150,300,450 mg / L and the concentration of 5,10,15 mg / L Gibberellin(GA)and melatonin(MT)three kinds of protective agents.To study the effects of radiation protectants on the growth and development indexes,malondialdehyde content(MDA)and superoxide dismutase(SOD)of Freesia under various radiation dose groups.Finally,explore and screen the best types,concentrations and times of protective agents for each radiation dose.The results show that:(1)After ? and X-rays irradiation,it has a certain effect on the growth and development of Freesia M2 generation and Gladiolus M3 generation.The germination rate,survival rate,plant height,leaf number,flowering rate,and The M2 generation germination rate,survival rate,plant height,leaf number,flowering rate,and small flower number of two freesia varieties are basically the same as the M1 generation,and each growth index is negatively related to the irradiation dose,indicating that the relative biological effects of the M1 and M2 generations of two freesia species after ? and X-rays irradiation were not significantly different,and the average of the M2 generation at each dose Plant height,leaf number,flowering rate,and small flower number were all slightly higher than those of the M1 generation,indicating that irradiation still had a certain inhibitory effect on the growth and development of the freesia M2 generation,but the inhibitory effect was weakened compared to the M1 generation.Gladiolus has no significant effect on the germination rate and survival rate of M1 generation after ? and X-rays irradiation,but the inhibition degree of germination rate and survival rate is obvious with the increase of dose in M2 generation,and the germination rate and survival rate decrease with the increase of dose in M3 generation.The results showed that the radiation damage effect of ? and X-rays had hysteresis and continuity.At the same time,all the M1-M3 generations exhibited the phenomenon of low promotion and high suppression.When the At a radiation dose was of 25 Gy,the most growth and development indicators were higher than those of the control group,which suggests that 25 Gy radiation be used as an appropriate dose for improving Gladiolus varieties.(2)After two generations of Freesia,the leaf traits of each mutant individual plant are susceptible to change and more instability occurs.In the M2 generation of Freesia(F.armstrongii)mutant single plants,50% of the single plant mutant traits disappeared,and 25% of the single plant mutant traits were partially retained,of which only the XH-X25-1 and XH-X25-2 mutants completely retained the traits of the M1 generation.For Freesia(F.corymbosa),57.14% of the mutant traits completely disappeared,and only 42.86% of the mutants partially retained the previous generation's variant traits,and there were no plants that completely retained the variability.At the same time,no new mutant single plants were found in the M2 generation of the two freesia varieties.In general,after two generations of vegetative propagation of two varieties of Freesia,most of the variation characters of mutant individual plant are difficult to be stable.After 3 generations of vegetative propagation of Gladiolus,the stability of leaf morphology and plant height of the mutant individual plants were poor,and the radiation effect lasted for a long time.From M1-M3,there were only four mutants individual plant relatively stable.The mutation numbers GR-D-4-8 and GR-B-3-9 showed whitening at the base of the leaf and the number GX-B-3-4 leaf color is yellow-green,and the number GR-B-3-1 leaf is yellowish.And in the M3 generation,there were four mutant singles that did not appear in the previous two generations,the mutant singles with the mutation numbers GX-B-2-4 and GX-B-3-5 showed whitening at the base of the leaf and accompanied by rose red,the mutation numbers GX-D-3-3,GX-D-3-9 showed wave-shaped leaves,indicating that the genetic variation of leaf color traits was stable.(3)After two kinds of radiation treatment,the physiological characteristics of Freesia M2 generation and Gladiolus M3 generation changed to some extent.The total chlorophyll content of the M2 generation of two freesia varieties reached a maximum at 25 Gy.When the radiation dose was more than 25 Gy,the total content of chlorophyll a,chlorophyll b and chlorophyll all decreased slightly.The content of MDA in the leaves of M1 and M2 generation of two varieties of freesia was shown as follows: with the increase of radiation dose,the content of MDA in the leaves gradually increased.The SOD activity in the leaves increased first and then decreased with the increase of radiation dose,but most of the irradiation treatment group was higher than the control group.The total chlorophyll content of the two gladiolus varieties in the M3 generation showed a gradual decrease with the increase of radiation dose.After ?-ray irradiation,the MDA content in the leaves of Dolan leaves did not change much,and Berlioz was greatly affected by ?-rays in the M3 generation,and the MDA content gradually increased with the increase of radiation dose.25 Gy irradiation can increase SOD activity in M3 generations of two gladiolus varieties,which are 42.22% and 26.49% more than those in the radiation control group,respectively.(4)Treatment of Freesia M1 seed ball with ?-ray radiation and salicylic acid,melatonin,gibberellin three protective agents.The experimental results show that the protective agent has a better protective effect on the growth and development of Freesia.From the overall growth trend of radiated Freesia,the protective effects of three protective agents soaked after irradiation> spraying after germination> soaking before irradiation.When the At a radiation dose of 55 Gy,150mg / LSA were better protected after irradiation,germination rate and flowering rates in bulbs were 90% and 33.33%,respectively.At a radiation dose of 65 Gy and 75 Gy,450mg / L SA,15 mg / L MT,and 15 mg / L GA were better protected after irradiation,and the effect was obvious Improve Freesia germination rate,survival rate,leaf area,flowering plant rate and number of small flowers,especially under high dose(75Gy)irradiation,the survival rate in bulbs treated with 450 mg / L SA were 66.67%,which was 36.67 percentage points higher than that of in the radiation control group,the flowering plant rate was 500.6% higher than that in the radiation control.It shows that the protective agent with low concentrations is selected under low dose radiation,and the protective effect with high concentrations of protective agent under high dose radiation is better.After analyzing the coefficients of variation of each growth index of Freesia M1,it was found that under different irradiation doses,the coefficients of variation of each growth index of Freesia were greater than those of the non-irradiated group,and the coefficient of variation of each growth index increased with dose Large and gradually increasing trend.The degree of variation is leaf number> plant height> flowering number> leaf length> leaf width.at a high dose(75Gy)irradiation,the mutation rate reached 24.44%,which was slightly lower than 55 Gy.Among them,the number of single mutants under SA treatment was the largest.(5)After treatment with different concentrations of SA,MT,and GA,most treatment groups can significantly reduce the MDA content in Freesia M1 leaves.Three kinds of protective agents were used after irradiation,the SOD activity of most radiation protection agent treatment groups did not increase,but was lower than that of the radiation control group at each dose.This may be because the three protective agents SA,MT,and GA can directly scavenge oxygen free radicals,thereby delaying the enzyme activity of the antioxidant enzyme system in plants.Overall,Freesia was soaked with 450 mg / L salicylic acid(SA)had the best protection after irradiation.It can improve the germination rate,survival rate,flowering rate and Mutation rate of Freesia under high dose radiation. |
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