Study Of Osmotic And Ion Effects Of Winter Eheats With Different Genotypes & Nitric Oxide Signalin Salt Stress Conditions

In this paper, hydroponic experiments were conducted and using a split-root system to investigate the osmotic and ionic effects, shoot Na~+ absorption, shoot Na~+ accumulation and Na~+ recycled through the plant of salt stress on seedlings of four winter wheat in different canopy temperature genotypes (include NR 9405(warm),Xiaoyan 6(medium incline to cold),Shan 229,and RB 6(cold)etc). Response to the osmotic and ionic effects of endogenesis and exogenous nitric oxide of winter wheat in different canopy temperature genotypes were discussed. The main research results as follows:1. Osmotic and ionic effects of 4 winter wheat in different canopy temperature genotypesSalt stress(200 mM) had both osmotic and ionic effects on the seedlings. The osmotic effect was rapid and occurred in 1 or 2 days, but the ionic effect developed more slowly, occurring after about 3 to 4 days when Na~+ accumulation reached a threshold level. In the split-root system, half of the root system was treated with Hoagland solution containing 200 mM NaCl while the other half of the root system was in Hoagland solution without salt stress. The results showed that salt stress had no significant effect on the wheat seedlings. There was no significant inhibition of leaf growth when Na~+ levels within the shoots were below toxic levels. The Na~+ concentration of the solution in the cell with no NaCl increased significantly during the experiment, which indicated that part of the Na~+ absorbed by the plants could be recycled through the roots. The recycling rate reached from 76% to 89%. The recycling rate was slower when plants were under water stress. Comparisons among the winter wheat genotypes showed significant differences in Na~+ accumulation, Na~+ recycling rate, the time to the onset of osmotic and ionic stress, and the degree of osmotic and ionic stress. The Na~+ accumulation in NR 9405 and Xiaoyan 6 was less than in Shaan 229 and RB 6, but Na~+ recycling was greater in NR 9405 compared to Shaan 229 and RB6. In summary, these results indicated that NR 9405 and Xiaoyan 6 had greater salt tolerance than Shaan 229 and RB 6.2. Response to the osmotic and ionic effects of exogenous nitric oxide of winter wheat in different canopy temperature genotypes on salt stressTreated with NO donor SNP obviously relieved osmotic stress and ironic stress. In the split-root system, half of the root system was treated with Hoagland solution containing 150mM NaCl while the other half of the root system was in Hoagland solution without salt stress, the relieving effect to shoot biomass accumulation of exogenous nitric oxide were vanished, and effect to the content of Na~+ at ironic phase were also not significant. In the osmotic phase, the recycling rate reached from 52% to 70%. and added in NO donor SNP increased the recycling rate of Na~+ in a certain extent, which increased from 6% to 15%. In the ionic phase, the recycling rate decreased from 19% to 24%, this may related to ion toxic effect. Treated with SNP were not increased the recycling rate, but decrease. In the osmotic phase, the recycling rate of NR 9405 were significantly higher than RB 6. The Na~+ absorption of NR 9405 and RB 6 were increased and the recycling rate were decreased in the ionic phase. The recycling rate of RB 6 were lower than NR 9405, this suggested the ability of exudation were higher than RB 6.3. Effect of endogenesis exogenous nitric oxide on Na~+ accumulation of winter wheat in different canopy temperature genotypes of salt stressExogenous nitric oxide relieving grouth inhibition and Na~+ accumulation of 4 winter wheat genotypes of salt stress. The relieving effect vanished when NO donor was added. There were no more serious stress on 4 winter wheat genotypes when added NOS inhibitor L-NAME and NR inhibitor NaN3. This suggested there were some other pathway in vivo, and their functions were complaementing with NOS and NR. The salt resistance of warm rype wheat NR 9405 and middle type wheat Xiaoyan 6 were higher than cold type wheat Shaan 229 and RB 6. The response of warm type wheat were greater than cold type wheat.