Effect of NaCl Stress on Seed Germination and Seedling Growth of Pepper
To explore the physiological response mechanism of pepper seeds and seedlings on salt stress,3 differ-ent genotype pepper varieties were identified as experimental materials,and the effect of different concentrations of NaCl stress on seed germination and growth of pepper seedlings were identified in this study.Besides,a com-prehensive evaluation of salt-tolerance properties of pepper varieties and different treatment stages was performed by weighted subordinate function method.The result showed that with the increase of NaCl concentration,the ger-mination rate,germination potential,germination index and root length of 3 pepper varieties decreased gradually,while the bud length and fresh weight appeared a trend of firstly increased and then decreased.The germination of the 3 pepper varieties was significantly inhibited at the NaCl concentration of 200 mmol/L,indicating that the pep-per seeds can only be adapted to the salt stress of less than 200 mmol/L NaCl during germination,and 200 mmol/L can be used as a reference concentration for salt-tolerant screening of pepper seed.The comprehensive evaluation of salt-tolerance indicated that'Wanyu'and'Liu58'varieties show preferred salt-tolerance properties under low salt conditions,while'HJ01-1'has better salt-tolerance under high salt conditions.The physiological indicators of pep-per seedlings have a response to salt stress.With the increase of NaCl concentration,the content or activity of mal-ondialdehyde(MDA),proline(PRO),catalase(CAT),superoxide dismutase(SOD)increased,while the activity or content of peroxidase(POD),chlorophyll,root length and root area increased first and then decreased.The content or length of chlorophyll,root length and root area reached peak at NaCl concentration of 100 mmol/L,but the ac-tivity of the POD reached the peak at the NaCl concentration of 200 mmol/L.The study results not only contribute to the analysis of physiological response mechanisms under salt stress,but also provides a scientific basis for the breeding on salt-tolerance of pepper varieties.
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