| In order to improve the drought resistance of Bletilla ochracea Schltr and Bletilla striata（Thunb.）Reichb.f.The study used aseptic/artificial cultured seedling of Bletilla ochracea Schltr and Bletilla striata（Thunb.）Reichb.f.as test materials.Through the method of the simulated-drought culture with different concentrations（0%,5%,10%,15%,20%）of PEG-6000,morphological and physiological indexes of the tissue cultured seedlings were measured at the 0,2,4,6 and 8 days during the experimental period,and drought resistance was evaluated by principal component analysis and membership function analysis.Then,the selected best osmotic stress exercise mode was used to treat Bletilla ochracea Schltr and Bletilla striata（Thunb.）Reichb.f.at the age of three and a half months.Continuous determination of four months of the indexes and sucrose metabolism related enzyme activity（SS、SPS、AI and NI）,on the other hand in Bletilla ochracea Schltr and Bletilla striata（Thunb.）Reichb.f.Drought stress treatment after two months,the determination of its shape index,chlorophyll content,root activity,osmotic regulation substances and the change of antioxidant enzyme activity,the effects of osmotic stress training on growth and drought resistance of Bletilla ochracea Schltr and Bletilla striata（Thunb.）Reichb.f.was analyzed.The following conclusions are drawn:1.Drought resistance training of Bletilla ochracea Schltr and Bletilla striata（Thunb.）Reichb.f for a better method: PEG-6000 osmotic stress for 4 days.After several combinations of PEG-6000 at different concentrations and different times,the tissue culture seedlings of Bletilla ochracea Schltr and Bletilla striata（Thunb.）Reichb.f.was subjected to osmotic stress training.Using principal component analysis and membership function analysis,it was concluded that the tissue culture seedlings were under osmotic stress with 10% PEG-6000.Exercise in solution for 4 d had the highest comprehensive evaluation value among all treatments,indicating that 10% PEG-6000 osmotic stress exercise for 4 d was a better way to carry out drought-resistant exercise on Bletilla ochracea Schltr and Bletilla striata（Thunb.）Reichb.f.tissue culture seedlings.2.Exercise is beneficial to the growth of seedlings and the accumulation of pseudobulb weight.During the test period,compared with the untrained control seedlings of Bletilla ochracea Schltr,except for the chlorophyll content lower than the control,the plant height,leaf number,root number,root length,root vigor,plant fresh and dry weight,Pseudobulb fresh weight and dry weight were higher than the control.Compared with the untrained control,the exercised seedlings of Bletilla striata（Thunb.）Reichb.f.had higher plant height,leaf number,root number,root length,chlorophyll content,root vigor,plant fresh weight and dry weight,Pseudobulb fresh weight and dry weight were higher than the control,indicating that exercise is beneficial to the growth of Bletilla ochracea Schltr and Bletilla striata（Thunb.）Reichb.f.In addition,the activities of sucrose phosphate synthase,sucrose phosphatase,acid invertase and neutral invertase were all higher than those of the control during the test period,and the fresh and dry weights of pseudobulbs were also higher than those of the control.It indicated that exercise was beneficial to the accumulation of polysaccharides in the pseudobulbs of Bletilla ochracea Schltr and Bletilla striata（Thunb.）Reichb.f.3.Exercise improved the drought resistance of Bletilla ochracea Schltr and Bletilla striata（Thunb.）Reichb.f.With the increase of drought time,except that the plant height of Bletilla ochracea Schltr and Bletilla striata（Thunb.）Reichb.f.did not change significantly,and the root length of Bletilla ochracea Schltr was lower than that of the control seedlings,compared with the control seedlings,the exercise slowed down the number of leaves,roots,and root of Bletilla ochracea Schltr and Bletilla striata（Thunb.）Reichb.f.The fresh weight and dry weight of plant,the fresh weight and dry weight of pseudobulb,the number of leaves,number of roots,root length,fresh weight and dry weight of plant,fresh weight and dry weight of pseudobulb decreased,indicating that exercise enhanced Bletilla striata,and the ability of Bletilla striata tissue culture seedlings to resist drought.In conclusion,the method of applying 10% PEG-6000 solution to the tissue culture seedlings of Bletilla ochracea Schltr and Bletilla striata（Thunb.）Reichb.f.for 4 days is beneficial to the growth of the seedlings and improves the ability of the seedlings to resist subsequent drought. |
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