Screening Of Drought Tolerance In EMS Mutants From Rape (Brassica Napus L.)

With the increase of climate change, with ecological environment becoming worse, so drought research about crop becomes more and more important. Lots of comprehensive and deeply researches on drought tolerance ability have been conducted in corn, wheat and so on, while those in rapeseed are just a little, especially in drought-tolerant mutant.Rape mutant population was constructed by treating the rapeseed "GH18"with EMS.and it conclouds 850 lines. The drought tolerance of these 850 mutants lines and GH18 were evaluated.The drought tolerance ability of the mutants was analized in two periods:seedling stage and germination period.we studied the influence of drought stress upon germination and grow of yellow rapeseed,and compared the drought tolerance ability between different mutants directly and comprehensively. Finally,we screened proper index and drought-tolerant mutants.The drought-tolerant mutants could be used in breeding and genetical research.Firstly we made a germination experiment on 850 mutants in the laboratory, and pick out some drought-tolerant material in germination period,and then identified them in seedling stage.Finally,we screened drought-tolerant materials which is both drought-tolerant in the two periods.Germination period:Drought stress is simulated by polyethylene glycol 6000 (PEG-6000).Five traits (plant height, fresh weigh, Relative vigor index, germination rate, germination viability) together with Index of Drought Resistance of all the traits were investigated and analyzed. The drought tolerance of these 850 mutants lines and GH18 were evaluated. The result showed that:3 traits (plant height, fresh weigh, Relative vigor index) changed significantly after the drought stress compared with the control in the experiment. The three indexes of rapeseed under drought stress reduced significantly. There were significant difference of drought tolerance ability among different lines of the mutant population. plant height, fresh weigh. Relative vigor index could be used as available evaluation indices for drought tolerance. Membership function was used as the main index of drought tolerance. Lines L3128,L3165,L3029,L3154,L3117,L3025,L3160,L3013,L3031,L306,L3030,L3097 screened from the population are the most drought-tolerant lines.Seedling period:Drought treatments in seedling stage were done in greenhouse.12 traits (Relative water content, shoot fresh matter weight, shoot dry matter weight, membrane permeability, chlorophyll,MDA and proline, total root length.total average diameter,root fresh matter weight, root dry matter weight) together with Index of Drought Resistance of all the traits were investigated and analyzed during seedling stage.The result showed that:There were significant difference of drought tolerance ability among different lines of the mutant population in seedling stage. Shoot fresh matter weight, shoot dry matter weight, root fresh matter weight, dry matter weight decrease significantly, total root length,total average diameter, chlorophyll reduced a little.and membrane permeability,MDA and proline rise significantly. There were significant difference of drought tolerance among different lines of the mutant population in all indexes except for Relative water content, water-holding ability. Biomass index.fresh weight, membrane permeability could be used as available evaluation indices for drought tolerance. Membership function was used as the main index of drought tolerance Lines L3033 screened from the 103 lines are the most drought-tolerant lines.Finally,we pick out 103 mutants which are both drought-tolerant in seedling step and germination period,and them account for 12.1% of the mutants population.we screened some extreme drought-tolerant materials,and them could be used for breeding and basical genetical research.