Effects of Exogenous Ascorbic Acid(AsA)on Seed Germination of Rheum Tanguticum(Polygonaceae)Under Simulated Drought and Salt Stress
To investigate the effects of PEG-6000 and NaCl on seed germination of Rheum tanguticum,as well as the alleviating effects of exogenous AsA on drought and salt stress,this study used PEG-6000 with mass fractions of 5%,10%,15%,20%,25%and 0.05,0.10,0.15,0.20,0.25 mol/L NaCl solution to simulate drought stress on R.tanguticum seeds,and screened out the PEG-6000 and NaCl concentration with the strongest inhibitory effect on seed germination.Subsequently,different concentrations of AsA were applied under this condition,and the germination rate,germination potential and germination index of the seeds were measured to reveal the effects of exogenous AsA on the germination of R.tanguticum seeds under simulated drought and salt stress.The results showed that as the concentration of the PEG-6000 and NaCl simulating drought and salt stress increased,the germination rate,germination potential and germination index of R.tanguticum seeds gradually decreased and the 25%PEG-6000 and 0.25 mol/L NaCl solution had the strongest inhibitory effect on seed germination(P<0.05).After treating the seeds under 25%PEG-6000 solution drought stress with 0.2,0.5 and 1.0 mmol·L-1 AsA,it was found that the germination rate,germination potential and germination index of the seeds treated with 25%PEG-6000 and 1.00 mmol·L-1 AsA were 53.33%(P<0.05),37.78%(P<0.05),and 88.82%(P<0.01)higher,respectively,compared to the control group(treated with 25%PEG-6000 only).After treating the seeds under 0.25 mol/L NaCl solution salt stress with 0.2,0.5 and 1.0 mmol·L-1 AsA,it was found that the germination rate,germination potential and germination index of the seeds treated with 0.25 mol/L NaCl and 1.00 mmol·L-1 AsA were 40.00%(P<0.05),34.45%(P<0.05),and 27.51%(P<0.01)higher,respectively,compared to the control group(treated with 0.25 mol/L NaCl only).This indicates that PEG-6000 and NaCl simulating drought and salt stress has a significant inhibitory effect on the germination of R.tanguticum seeds,and exogenous AsA can promote the germination of seeds under PEG-6000 and NaCl simulated drought and salt stress,playing a good role in alleviating drought and salt stress.This provides technical support for the introduction,domestication and artificial cultivation of R.tanguticum in drought and salt environments in the future.
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