Effects Of Exogenous Nitric Oxide On Oenothera Drummondii Of Seed Germination And Seedling Growth

The seed and seedling of Oenothera drummondii was treated by NaCl concentration gradients(0.00,150.00,200.00 and 250.00mmol L-1)combined with adding 6 levels of donor sodium nitroprusside(SNP)concentrations(0.00,0.05,0.10,0.50,1.00 and 2.00mmol L-1)at each NaCl concentration.The seed germination index,and morphological and physiological index of seedling were determined and analyzed after treatment to explore the effect of NO on seed germination and seedling growth under the salt tolerance of Oenothera drummondii and provide some theoretical data for making more widespread planting in coastal areas.The main results are as follows:(1)The germination rate,germination potential,germination index and vigor index of Oenothera drummondii were significantly decreased with the increase of NaCl concentration as a single factor.when treated by adding 6 levels of SNP concentrations at each NaCl concentration,the germination rate,germination potential and germination index of Oenothera drummondii increase at 0.05 mmol · L-1 or 0.10 mmol · L-1 SNP,which suggests a certain concentration of SNP can mitigate the salt damage to some extent.(2)The fresh weight,dry weight,water content and stem length of Oenothera drummondii were significantly decreased with the increase of NaCl concentration as a single factor,the root length increased first and then decreased with the increase of NaCl concentration.When treated by adding 6 levels of SNP concentrations at each NaCl concentration,the fresh weight,dry weight,root length,stem length increased first and then decreased,0.05 mmol · L-1 SNP or 0.10 mmol · L-1SNP had the best effect on salt stress.Treated by different salt concentration combined with SNP concentration,water content changes little.Compared with other treatments,the water content was significantly increased when treated by 0.50 mmol · L-1NaCl and 250.00 mmol · L-1 NaCl added with 0.50 mmol·L-1SNP.(3)The net photosynthetic rate,transpiration rate,stomatal conductance of Oenothera drummondii were significantly decreased with the increase of NaCl concentration as a single factor,while the intracellular carbon dioxide concentration increased with the increase of NaCl concentration.When treated by adding 6 levels of SNP concentrations at each NaCl concentration,net photosynthetic rate,transpiration rate and stomatal conductance increased first and then decreased,while the intracellular carbon dioxide concentration decreased first and then increased.When added with 0.10 mmol · L-1SNP at each NaCl concentration,the net photosynthetic rate,transpiration rate and carbon dioxide concentration in the cell gap of Oenothera drummondii seedlings have highest values,which suggests 0.10 mmol · L-1SNP has best mitigation effect on salt stress.(4)The Chla,Chlb,Car,Chla+b contents of Oenothera drummondii seedlings were significantly decreased with the increase of NaCl concentration as a single factor,the Chla/b ratio increased with the increase of NaCl concentration,Car/Chl ratio varied little in different treatment.When treated by adding 6 levels of SNP concentrations at each NaCl concentration,Chla,Chlb,Car,Chla+b increased first and then decreased.SNP concentrations that had best mitigation effect on different concentration of salt stress varied.Fm,Fv,Fv/Fm,Fv/Fo,OPS ?,qP decreased with the increase of NaCl concentration,and Fo and qN were increasing.When treated by adding 6 levels of SNP concentrations at each NaCl concentration,Fm,Fv,Car,Fv/Fm,Fv/Fo,?PS ?,qP increased first and then decreased,Fo decreased first and then increased.0.10 mmol · L-1 SNP had the best mitigation effect on salt stress.(5)The soluble sugar content,MDA,SOD,POD,CAT of Oenothera drummondii seedlings were significantly decreased with the increase of NaCl concentration as a single factor,the Pro content increased with the increase of NaCl concentration,soluble protein increased first and then decreased.When treated by adding 6 levels of SNP concentrations at each NaCl concentration,the Pro increased first and then decreased,While other physiological indicators decreased first and then increased,adding 0.05 mmol · L-1SNP at some NaCl concentrations had the best mitigation effect on salt stress,while adding 0.10 mmol · L-1SNP at the other NaCl concentrations had the best mitigation effect on salt stress.(6)The determination results of morphological and physiological indexes of Oenothera drummondii seed and seedling growth showed salt stress could not be alleviated or even be intensified when adding 1.00 mmol · L-1SNP or 2.00 mmol · L-1SNP at each NaCl concentration.