Effects of Exogenous Nitric Oxide on Growth and Physiological Indexes of Pepper Seedlings Under High Temperature Stress

To investigate the effect of exogenous nitric oxide( NO) on the growth and physiological characteristics of pepper seedlings under high temperature stress,the changes of the growth and physiological indexes of pepper seedlings under high temperature stress and the mitigation effects of exogenous NO to high temperature stress was studied withSongyangpepper in nutrient solution. The results showed,under high temperature stress,the increasing rate of plant height and fresh weight decreased,the content of proline and soluble protein increased,the activity of antioxidant enzyme including SOD and POD increased,the content of MDA increased. A certain concentration of SNP could mitigate the stress of high temperature on seedling growth of pepper. Contrast to the high temperature control group( T0),the increasing rate of plant height and fresh weight increased with 85. 2% and 45. 3%,the content of proline and soluble protein,the activity of SOD and POD increased first and than decreased with the highest number when the concentration of SNP was 100 to 200 μmol·L- 1,the content of proline and soluble protein increased with 53. 8% and30. 0% respectively,the activity of SOD and POD increased with 34. 1% and 54. 4% respectively. The content of MDA decreased first and than increased,with the lowest number when the concentration of SNP was 100 to 200 μmol·L- 1.decreased with 26. 0%. Indicated that NO acted as an important signal molecule,might alleviate lipid peroxidation through activating antioxidant enzyme system and improve the osmotic adjustment substances content to improve the resistance of pepper seedlings to high temperature stress,which provide theoretical basis to clarify the physiological mechanism of exogenous NO mitigate the high temperature stress on pepper seedlings.