Seed germination and seedling growth of sweet pepper under NaCl stress.

The effects of NaCl stress on germination and growth of sweet pepper were investigated by water culture method.The results showed:the seed germination was promoted under the treatment of 50 mmol·L-1 NaCl.While the seed germination was inhibited when the concentrations of NaCl were higher than 50 mmol·L-1.At the 18th day after NaCl stress,except that 250 mmol·L-1 NaCl stress caused the seedling's death,the height,leaf area,fresh weight and dry weight of seedlings decreased under 50 mmol·L-1 and 150 mmol·L-1 NaCl stress relative to the controls.However,the root growth was promoted by 50 mmol·L-1 NaCl stress.The content of chlorophyll was mild changed when NaCl concentration ≤150 mmol·L-1 NaCl,as well as carotenoid to improve the capacity of sweet pepper to salt stress.During the 7 d NaCl stress under 50 and 150 mmol·L-1 NaCl stress,the content of MDA,activity of SOD and the content of soluble sugar significantly increased with higher NaCl concentration,and the contents of proline significantly increased except for 50 mmol·L-1 NaCl.Under 250 mmol·L-1 NaCl stress(only 3 d),the contents of MDA,proline and soluble sugar significantly increased.The activities of SOD increased under low concentration and declined under higher concentration.These results indicated:the higher NaCl concentration,the more obvious inhibition.Under 50 mmol·L-1 and 150 mmol·L-1 NaCl stress,SOD was important in scavenging active oxygen species,and proline and soluble sugar were main osmoregulation substances,as well as carotenoid played a role.That membrane lipid peroxidation was serious under 250 mmol·L-1 NaCl stress suggested that normal metabolism of reactive oxygen species and osmoticum were disturbed under such stress.