Studies On The Physiological And Biochemical Character Of Salt Resistance And Yield In Different Wheat Varieties

In this study,11 different varieties of wheat:Dekang 961, Jaimai 22, Qingmai 6, Yannong 24, Lumai 21, Liangxing 99, Yannong 836, Qingfeng 1, Dainong 18, Shannong 21 and Yannong 21 were used to explore the germination and screening of salt tolerance indices of wheat varieties to different concentrations of salt stress. According to the germination experiment,4 wheat varieties with different salt tolerances, Dekang 961, Jaimai 22, Qingmai 6 and Qingfeng 1 were selected to study the physiological and biochemical characteristics, root activity and osmotic ion distribution of salt tolerance in seedling stage. With indoor and field production experiment, we selected the salt-resistant genotype Qingmai 6 and the salt-sensitive genotype Jimai 22 to explore the physiological and biochemical characteristics of wheat varieties to salt stress after anthesis stage. The main results were as follows:1. Effects of salt stress on the morphological and physiological characteristics of different wheat cultivars during germination strage.In this study,11 winter wheat species were selected to explore the differences of eight trait indicators under different concentrations of NaCl solution, which was chosen as the salt stress. And the relative values of the indicators were analyzed by the analysis of the Outstanding Difference. The results showed that as the concentration of NaCl salt solution increases the relative salt tolerance coefficient of each index of the winter wheat decreased during the germination. In addition, there were significant differences among the germination rate, germination potential, root length, coleoptile length, seedling height, and the growth rate of the first leaf as well as the fresh weight of seedlings between different species and different concentrations. But the effect of NaCl salt solution on the number of the wheat roots was not significant. So the seven indexes of physiological traits can be used as an effective indicator of the selection of winter wheat during the germination indoor. The study also indicated that the tested varieties of Dekang 961 and Qingmai 6 exhibit stronger salt tolerance during the germination stage, Yannong 24, Liangxing 99, Qingfeng 1, Dainong 18 and Shannong 21 showed moderate salt tolerant; Yannong 21 Lumai 21, Yannong 836 and Jaimai 22 were salt-sensitive genotype.2. Effects of salt stress on antioxidant enzymes, osmotic adjustment substances and root activity of different wheat cultivars during seedlings strage.To explore the physiological and biochemical characteristics of wheat to salt stress at seedling stage, 4 wheat varieties with different salt tolerances, Dekang 961,Jaimai 22, Qingmai 6 and Qingfeng 1 were used to analyze the Effects of salt stress on antioxidant enzymes, osmotic adjustment substances and root activity of different wheat cultivars during seedlings. The results showed that SOD activity and soluble protein content were reduced to varying degrees as salt concentration and stress time increase. The POD activity and root activity decrease after the first increase, and showed the maximum stressed after one day. The MDA content, soluble sugar and free proline content increased in varying degrees. The different salt stress time and NaCl concentration result in differences among the wheat breeds above 7 traits. The salt-tolerance capacity can be indicated efficiently by the root activity in the seedling stage.3. Effects of salt stress on absorbtion and distribution of osmotic ion in wheat seedlings.The results showed that the content of K⁺and Ca²⁺ decreased gradually, the content of Na+increased in various degree and the K⁺/Na⁺ratio decreased sharply as salt concentration and stress time increased. The decrease of K⁺and Ca²⁺ in root was higher than in shoot of all treatment. The decrease of K⁺and Ca²⁺ in salt-tolerant genotype Qingmai 6, Dekang 961 was lower than in salt-sensitive variety Jimai 22, Qingfeng 1. And the content of Na+in Qingmai 6 and Dekang 961 were lower than Jimai 22, Qingfeng 1 in shoot, which was the opposite of the Na+in root. What's more, the ability of limiting Na⁺ in Qingmai 6 and Dekang 961 was more powerful than that of Jimai 22 and Qingfeng 1. The higher K⁺/Na⁺ ratio and the ability to limiting Na⁺concentration in shoot could be one of the strategies of the wheat salt-tolerance.4. Effects of salt stress on antioxidant enzymes, osmotic adjustment substances and photosynthetic characteristics in wheat flag leaves after anthesis.To explore the different effects of salt stress on antioxidant enzymes, osmotic adjustment substances and photosynthetic characteristics in wheat flag leaves after anthesis, Qingmai 6 and Jimai 22 were cultivated in salt tank with different NaCl concentration and field stress. The results showed that SOD% POD activity and soluble protein content were reduced to varying degrees as salt concentration and stress time increase;The MDA content?soluble sugar and free proline content increased in varying degrees.The chlorophyll content, leaf area index, net photosynthetic rate, stomatal conductance, and transpiration rate were declined dramatically; In contrast, the CO₂ concentration between cells increased in varying degrees. Compared with the Jimai 22, the change of the index of the Qingmai 6 was smaller and Qingmai 6 showed higher antioxidant capacity and photosynthetic characteristics than Jimai 225. Effects of different salt stress treatments on Yield and yield components of Wheat.Different from the control, the ear number per unit, kernel number per spike, and 1000-grain weigh of the the two wheat varieties reduced under salt stress, and the increase amplitude aggravated accompanied with the increasing salt concentration levels. Although Jimai 22 maintained a higher 1000 grain weight, the grain number per spike and spike number per hectare were less than Qingmai 6, especially spike number per hectares declined greatly. The tillering rate of different wheat varieties were influenced greatly by salt stress, as a result, the yield of wheat were affected, leading to the decrease of the yield. Keeping a higher spike number per unit was the key factor to gain high and stable yield for wheats under salt stress.The following conclusions are drawn in this experiment:The physiological and biochemical indexes of different salt tolerant wheat were affected in varying degrees under salt stress. The changes of indexes in salt-tolerant wheat was significantly smaller than that of salt-sensitive genotype. Combined the indoor and field experiments,11 wheat varieties which were the main wheat varieties were divided into three grades: salt-tolerance genotype, salt-medium, and the salt-sensitive genotype based on the morphological indexes, physiological and biochemical indexes and yield indexm, meanwhile using the wheat tolerance to salt for identification and evaluation of technical specifications.The study also indicated that Dekang 961 and Qingmai 6 exhibit stronger salt tolerance, Yannong 24, Liangxing 99, Qingfeng 1, Dainong 18 and Shannong 21 showed moderate salt tolerant; Yannong 21 Lumai 21, Yannong 836 and Jaimai 22 were salt-sensitive genotype. In further study of salt tank with different NaCl concentration and Dongying salt field indicated Jimai 22 could have greatly improved yield under low salt and adequate moisture conditions, suggesting no salt or low salt were suitable for it planting. Under the salt stress, Qingmai 6 could maintain a relatively good physiological state, and obtained high and stable yield in the middle and low salt stress. Thus, Qingmai 6 should be mainly planted in the salinization in Shandong province and the surrounding areas.