| The area of saline-alkaline land in the western part of Jilin Province is large,Muskmelon is cultivated in a large area in Jilin Province.However,the excessive salinity causes the melon seedlings to be susceptible to salt-alkali stress.Studies have shown that NO plays an important role in improving the resistance of plants and alleviating environmental stress.Therefore,the study of exogenous NO on the physiological characteristics of muskmelon seedlings under the threat of soda salinity has certain significance.In this experiment,melon was used as the research object,and the soda saline-alkali soil extract from the Da’an Alkali Land Ecological Experimental Station of the Chinese Academy of Sciences was used to simulate the salt-alkali stress conditions.Sodium nitroprusside（SNP）was used as the exogenous NO donor,and the pH was 8.19.Under the stress conditions of the soda salt-alkali extract,different concentrations of exogenous NO were sprayed:（1）50μmol/L,（2）100μmol/L,（3）150μmol/L,（4）200μmol/L.Measure the physiological and growth indexes of muskmelon seedlings on the 4th,8th,12th,16th,and 20th days after spraying,and study the mitigation effect of muskmelon under soda salt-alkali stress after spraying with exogenous NO.The main findings are as follows:Spraying different concentrations of exogenous NO can relieve the growth and physiological characteristics of cucumber seedlings under soda salt-alkali stress with a pH of8.19 to a certain extent.On the 20th day of spraying with 50μmol/L,100μmol/L,150μmol/L and 200μmol/L,the plant height increased by 11.4%,22.1%,30.4%and 16.5%respectively compared with the stress control group.The overall chlorophyll content showed a trend of first increasing and then decreasing.The root vigor of muskmelon seedlings was improved,and there was a certain significant difference between the treatments,and the root vigor reached the highest value of 77.31μg/（g·h）on the 12th day under the treatment of 150μmol/L.Compared with the control,spraying with exogenous NO increased the soluble sugar,soluble protein,and proline content in melon seedlings,and the highest spraying concentration of 150μmol/L reached 51.2mg/g and 5.06mg/g,respectively,34.2μg/g,which are higher than other spraying concentrations and are significantly different from other concentration treatments.At the same time,the accumulation of malondialdehyde was significantly reduced in the treatment of spraying exogenous NO.The malondialdehyde content was 17.81μmol/g at the20th day at a concentration of 150μmol/L,which was 16.5%lower than that of the B control.Spraying with exogenous NO increased the resistance.The activities of oxidative protective enzymes POD,SOD,and CAT also showed that the spraying concentration of 150μmol/L had the best treatment effect,and the activity reached the maximum on the 20th day.POD activity was 1983.34μmol·g-1·min-1,SOD activity It was 278.28 U·g-1,and the CAT activity was1796.70μmol·g-1·min-1,which was significantly different from the non-spraying control and spraying other concentration treatments.In summary,this experiment and this study show that:under soda salt-alkali stress with a pH of 8.19,spraying exogenous NO at 150μmol/L is the optimum spraying concentration,which has the best effect on alleviating the salt-alkali stress,and the physiological and biochemical indexes are all It is superior to other concentration treatments and there are significant differences.When the spray concentration exceeds 150μmol/L,the degree of relief will be slightly reduced. |
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