Physiology of mungbean [Vignaradiata(L.)Wilczek] under salt and high temperature stress condition
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Date
2018
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Dr. Rajendra Prasad Central Agricultural University, Pusa (Samastipur)
Abstract
Many agricultural lands affected by salinity, the influence of salt stressis aggravated by the simultaneous action of high temperature. Recent studies revealed that the response of plants to a combination of two different stresses is specific and cannot be deduced from the stresses applied individually. Here, we report on the respons1e of mungbean seedlings to individual and combination of salt and high temperature stress.
The present study entitled “Physiology of mungbean [Vigna radiata (L.) Wilczek] under salt and high temperature stress condition” was conducted with three objectives (1) Screening of mungbean genotypes for combined salt and high temperature stress to identify contrasting sets of mungbean genotypes on the basis of physiological traits(2) To study physiological and biochemical mechanisms of tolerance of mungbean genotypes subjected to independent, and combined salt and high temperature stress condition.(3) To study the ionic and nutrient homeostasis in contrasting sets of mungbean genotypes subjected to independent, and combined salt and high temperature stress condition. Entirestudies were performed in 8 days old mungbean seedling grown in petriplate.
For screening of contrasting sets of genotypes, experiments were performed with thirty one mungbean genotypes. Germination percentage and growth parameters (seedling dry weight, root length & seedling length, seedling vigour I & II, germination relative index) and physiological traits (chlorophyll contents measured in terms of SPAD units), were recorded in 8 days old mungbean seedling, and on the basis of growth performance under combined stress condition, two sets of contrasting mungbean genotypes were identified (TMB-37 & Pusa 1501, relatively tolerant for combined stressand MH-1314 & MH- 1315, relatively susceptible for combined stress).
Second experiment was conducted to compare the changes occurred due individual and combined stress on physiological and biochemical traits.Results showed that combined stress severely reduced the photosynthetic pigment contents, carotenoids contents, SPAD value, chlorophyll stability, relative water contents, membrane stability compared to individual stress. Reduction was more in susceptible group compared to tolerant group of genotypes. In tolerant group the levels of antioxidant enzyme activity (peroxidase, CAT and SOD) and proline were higher compared to susceptible group both under individual and under combined stress conditions. Compared to individual stress the antioxidant enzyme activity (peroxidase, CAT and SOD) and proline were higher under combined stress conditions. Lipid peroxidation (estimated in terms of TBARS content) were also significantly high in combined stress compared to individual stress.
In third experiments ionic and nutrient homeostasis estimated by analyzing the content of Na, K, and Zn and Fe in shoot and root of contrasting sets of mungbean genotypes subjected to independent, and combined salt and high temperature stress condition. Results indicated that tolerant genotypes maintained high K-Na ratio in both shoot and root compared to susceptible genotypes under individual and combined stress conditions and produced more dry matter compared to susceptible genotypes. Reduction in K-Na ratio both shoots and roots were more in combined stress compared to individual stress. Zn and Fe mobilization was severely affected under stress condition in all genotypes under individual and combined stress conditions, however tolerant genotypes able to maintain more Zn and Fe content in their shoot and root compared to susceptible genotypes.
From Pearson Correlation Matrix it is clear that the endogenous seed Zn contents was positively correlated with dry weight, germination percentage, total chlorophyll, RWC, SPAD value, Fe & Zn content of shoot and root, and K-Na ratio. Therefore, seed Fe & Zn can also be used trait for screening of genotypes under individual & combined stress conditions during seedling stage.
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