Effects of drought stress on seed germination and seedling growth of Platycodon grandiflorum (Jacq.)A.DC
[Objective] The research investigated the effects of drought stress on seed germination and seedling growth of Platycodon grandiflorum (Jacq.)A.DC.[Method] Indexes such as germination ratio,germination vigor,germination index,and vigor index of Platycodon grandiflorum seed and free proline content,soluble sugar content,activities of antioxidant enzymes,and mass fraction of MDA in Platycodon leaves were determined and compared by treating the seeds with PEG-6000 at different concentrations of 5％,10％,15％,20％,and 25％.The effects of drought stress on seed germination and seedling growth were also studied.[Result] With drought stress,initial germination time of seeds was delayed.Germination ratio,germination vigor,germination index and vigor index of seed as well as radicle length,embryonic bud length,root/shoot ratio,and fresh weight of seedling were significantly lower than the control.With the increase of drought stress,these index reduced fatherly.Drought stress could more clearly inhibit the growth of radicle than the growth of embryonic bud.With the increase of drought stress level,the Platycodon grandiflorum seedling leaves gradually turned into dark green,leaf curled,and stomatal closed.The mass fraction of free proline with 10％ PEG-6000 stress was slightly higher than the control while the fractions of other PEG-6000 stress levels were lower than the control.The content of soluble sugar was decreased by low mass fraction PEG-6000(≤5 ％) stress while it was improved by high mass fraction PEG-6000(＞5％) stress.Compared with the control,activity of SOD in seedling leaves was significantly increased with different drought stress degrees,while activity of POD was significantly decreased.Activity of CAT was slightly enhanced by low mass fractions,but it was reduced by high mass fractions (≥10％).Content of MDA was higher than that of the control.[Conclusion] Drought stress significantly inhibited seed germination and growth of radicle and bud.The inhibition of radical growth by drought stress could be one of the reasons why the germination ratio of Platycodon grandiflorum seeds in field was low.
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万方数据
维普
