Physiological Responses Of Maize Seedlings To Mixed Saline - Alkali Stress And Regulation Of Exogenous Spermidine

This test corn budding and seedling stages were used Na Cl and Na HCO₃ stress screening process proceeds salinity, salinity and salinity on seedling give two sensitive species, and then the two were combined stress saline and spermidine amine ease, study their physiological response mechanism, salinity stress and relieve a clear mechanism for salinity tolerance identification of maize varieties, improvement and utilization of saline soil salinity breeding and provide a theoretical basis. Identification by salinity concentration screening results, 50 mmol·L-1Na Cl and 25 mmol·L-1 Na HCO₃ Stress on seed germination promoted; 200 mmol·L-1Na Cl as corn budding and seedling resistance identification of ideal concentration 100mmol·L-1Na HCO₃ as corn budding and seedling alkali resistance screening; identification over the salt concentration of the screening. Bud fresh weight could be identified as the main indicator of corn germination salt tolerance screening; root length could be identified as the main indicator of corn sprout alkali resistance screening; root dry weight could be identified as the main indicators of maize seedling screening of salinity.After the evaluation results of the resulting salinity of the tested varieties were as follows:1. In Germination both salt（Na Cl） and alkali（Na HCO₃） maize varieties were Zhengdan 958, Dan 8201, Ningyu 524, Ningyu 525, Yufeng 619, DK517, Limin 33, Yufeng 19, Jiangyu 417, salt-sensitive varieties were Zhenjin 8 and Xianyu 335.2. Under Na Cl stress corn seedling Ningyu 309 and Jiangyu 417 of test material were highly tolerant varieties, DK159, Yinhe 32, Tianfa-05, Ningyu 525, DK517, Yufeng 619, Zhengdan 958, Denghai 618 were tolerant varieties; Xianyu 335, Limin 33, Qingdan 3,Zhenjin 8, Dongfanghong 1, Ningyu 524, Lianchuang 808 were salt-sensitive varieties; Dongfanghong 2, Dan 8201, YF16, Nonghua 106, Qingdan 7, Nonghua 101 were highly sensitive species.3. In corn buds salt and sensitive species and in seedling salt and sensitive varieties, under seedling Na HCO₃ stress Zheng 958 was alkali-resistant type; Yufeng 619 and Xianyu 335 were intermediate type; Zhenjin8 and Jiangyu 417 were sensitive.4. In corn buds and seedling both salt and alkali-resistant varieties was Zhengdan 958, Zhenjin 8 was sensitive.In seedling Zhengdan 958 and Zhenjin 8 of Na Cl, Na2SO4, Na HCO₃ and Na2CO₃ four kinds of complex salt stress, obtained the following results:1. Saline under combined stress, 50mmol·L-1 in group B（Na Cl: Na2SO4: Na HCO₃: Na2CO₃ = 1: 2: 1: 0） to promote accumulated Zhengdan958 and Zhenjin8 shoot and root growth; 50mmol·L-1 a group of（Na Cl: Na2SO4: Na HCO₃: Na2CO₃ = 1: 1: 0: 0） promote the accumulation of Zhenjin8 and Zhengdan958 chlorophyll a and total chlorophyll content; Zhengdan958 and Zhenjin8 in 50mmol·L-1 when less accumulated H₂O₂,02- and OH^- oxygen product activity, promote the growth of roots and leaves of the two varieties.2. Under salinity stress complex, 150 mmol·L-1 Zhengdan958 group B（Na Cl: Na2SO4: Na HCO₃: Na2CO₃ = 1: 2:1: 0） and 200mmol·L-1Zhenjin8 group E（Na Cl: Na2SO4: Na HCO₃: Na2CO₃ = 9: 1: 1: 9） CAT activity of the strongest blade; 100 mmol·L-1 Zhengdan958 group E（Na Cl: Na2SO4: Na HCO₃: Na2CO₃ = 9: 1: 1: 9） and 200mmol·L-1 Zhenjin8 group D（Na Cl: Na2SO4: Na HCO₃: Na2CO₃ = 1: 1: 1: 1） of POD activity, the strongest Zhenjin8 activity is greater than Zhengdan958.3. Under Saline combined stress, the degree of victimization is greater Zhenjin8 than Zhengdan958, a basic salt stress stronger than the neutral salt stress. Exogenous substance spermidine to 150 mmol·L-1 group D（Na Cl: Na2SO4: Na HCO₃: Na2CO₃= 1: 1: 1: 1） and 200mmol·L-1 group E（Na Cl: Na2SO4: Na HCO₃: Na2CO₃ = 9: 1 : 1: 9） Seedling saline complex of Zhenjin8 and Zhengdan958 mitigation test results are:Exogenous substance spermidine concentration of Zhengdan958 optimum ease of 0.015mmol·L-1, the concentration of Zhenjin8 optimum ease is 0.5-0.75 mmol·L-1; spermidine Zhengdan958 and Zhenjin8 POD activity mitigation best. Exogenous substance spermidine on salinity stress mitigation Zhenjin8 is stronger than Zhengdan 958.