Resistance Identification And Mechanism Of Drought And Salt Tolerance Of Qianyu 3 (a Hybrid Maize Variety)

Taking Nongda 108(a normal maize variety) as a comparison,the resistance to drought,salt,acid rain and nitrogen deficiency of Qianyu 3(a hybrid maize variety) were analyzed and identified at the stages of seed germination and seedling,the difference in physiological characteristics under drought and salt stressed and itsUnder simulating the drought,salt,acid rain and nitrogen deficiency stresses with different concentrations of PEG-6000(6%,12%and18%),NaCl(50,100 and 150mM),H₂SO₄:HNO₃(5:1) and incomplete nutrition solution,respectively, according to physiological indexes such as seed germination,plant height and dry mass weight,and combining the direct comparison method,the results showed that, both Qianyu 3 and Nongda 108 performed some drought and salt tolerance,and little tolerance to acid rain and nutrition deficiency,but the tolerance to drought,salt and nitrogen deficiency in Qianyu 3 was stronger than Nongda 108.After treated with PEG-6000 and NaCl solutions with different concentrations for 14d,the relative electrolytic leakage,MDA content both increased significantly in seedlings of two maize varieties,the relative water content in aboveground parts, leaf chlorophyll content all decreased,and the changes in Nongda108 were higher than those in Qianyu 3.The osmotic potential in roots and leaves,and the water loss rate of cutting leaves of both stressed seedlings were all reduced,and the drop in Qianyu 3 was much more obvious than those in Nongda108.In addition,the increase in contents of Na⁺ and Cl^-,and decrease of K⁺ in both salt-stressed seedlings were observed,and the changes in Nongdal08 were Iarger than those in Qianyu 3. However,the increase in SR_K,Na value in Nongda108 under salt stress were smaller than those in Qianyu 3.Under the stresses of PEG-6000 and NaCl solutions with different concentrations for 14d,the net photosynthetic rate(Pn),intercellular CO₂ concentration(Ci),stomatat conductance(Gs),transpiration(Tr),maximum quantum yeild of photosystemâ…¡(Fv/Fm) and maximum fluorescence(Fm) of two maize variety seedlings were all declined significantly as compared to their control,while the stomatai limitation value(Ls) and initial fluorescence(F_o) increased remarkably,and the obvious changes were observed in Nongda 108.By the comprehensive evaluation under the above results,we can conclude that,although the similar physiological effects of drought and salt stress on the two experimental maize seedlings,smailer damage or stronger tolerance was showed in Qian Yu 3 when compared with Nongda 108.