Identification Of Salt-tolerance Peanut Varieties And Exploration Of The Salt-tolerance Mechanism

Peanut is an important commercial crop in our country, and it has more gross production value than soybean. Becoming the greatest oil crop across the country. We don’t have sufficient cultivated fields severing for our population, resulting in a constant threat to grain and oil insecurity. Even worse, looking through the factor influencing the land productivity, we can’t ignore the soil salinization. We must make good use of the potential of the high-yield, and improving the production of medium and low-yield lands especially the saline-alkali fields. Improving the product of peanut and growth structure, then boosting farmers’ income and securing the supply of grain and oil to our country. The experiment selected the peanut recombinant inbred lines named Huayu Num.28 and Num.76 as the testing materials, and has studied and analyzed the salt tolerance and their mechanism in peanut seedling stage. We has obtained salt-tolerance group through serious screening. The results are as follows:1. Screening process of the optimum salt concentration in peanut seedling stageParents of recombinant inbred lines-R8257 and R8258 had greater effects on the development of seedlings with the increasing salt stress concentrations, and under the stress concentrations of 0.5%, 0.75%and 1%, parameters of seedlings characters were significantly or extremely significantly lower or higher than those of control groups.But the degree of 0.25% had no effects on peanut morphological while the seedlings developed well. Then 0.5% and 0.75% concentrations signed violently fluctuated indexes of morphology and material accumulation though we got similar salt tolerance indexes of stable trend. When the concentration rose to 1.0%, there would be the hugest fluctuation and peanut seedlings died gradually. So we concluded that the optimum concentration was in the range of 0.5% to 0.75%, and the recombinant inbred lines group of that would be the ideally tolerant to salt. As a result, we used 0.75% saline solution to select the recombinant inbred lines of peanut RIL groups.2. Identification of salt tolerance of recombinant inbred linesWe chose 10 indicators, chlorophyll, seedling height, and hypocotyl length main root length, biomass-aboveground fresh, dry weight, underground fresh weight, and dry weight, hypocotyl fresh and dry weight, to systematically identify the salt tolerance of 148 groups of recombinant inbred lines.The result showed that there were generally obviously significant correlation between the 10 indicators, and a certain overlapping of information mirroring the salt intolerance of recombinant inbred line groups.And then Principal Component Analysis has been taken to the 10 indicators to several factors to identify the salt intolerance.Finally, we find that the group salt intolerance was greatly affected by aboveground fresh weight, dry weight,、underground fresh weight、dry weight、 hypocotyl fresh、dry weight, which means the three indicators could be preferable to indicated the comprehensive salt intolerance.the result showed the chlorophyll, seedling height, hypocotyl length and main root length were relatively smaller, which could be secondary indicators.In the study, groups of recombinant inbred line under the stress concentration of 0.75% have been divided into 4 parts:the variety of highly salt intolerance, the variety of salt intolerance, variety of salt sensitivity and variety of highly salt sensitivity.3. Identification of fat contentThe identification above lay the foundation of determining fat content of each group. According to previous researches, the mainly used peanut’s average fat content is about 51.0%,while 62 recombinant inbred group’s fat content exceeding this average, accounting for 41.9% of the experiment materials,,which could be available for selecting and breeding the groups regarding high fat content.The correlation analysis between fat content and salt tolerance showed that though fat content correlated with some indicator, its correlation with the three indicators from the Principal Component Analysis was not significant, so there was no significant correlation between fat content and salt tolerance.4. Determination of aliphatic acidAccording to the indienrification of salt tolerance above, we had selected the groups of highly salt tolerance and salt sensitivity to determine the aliphatic acid.The experiment mainly test 5 kinds of aliphatic acids, named stearic acid, plasmatic acid, linoleic acid, linoleic acid, as well as archaic acid, among which the amount of oleic acid is the most, in some groups its content can reach 80%. Like R8018 that has oleic acid of 82% portion, so we can select materials of the targeted content of aliphatic acids in groups of the recombinant inbred lines.According to the correlation analyses of highly salt tolerance and salt sensitivity from principal component analysis of recombinant inbred lines, we found linoleic acid and plasmatic acid showed a positive correlation to the three main components, while oleic acid showed negative correlation to the three main components.