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PHYSIOLOGICAL AND MOLECULAR STUDIES ON SALINITY TOLERANCE IN WHEAT

KrishiKosh

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Title PHYSIOLOGICAL AND MOLECULAR STUDIES ON SALINITY TOLERANCE IN WHEAT
Ph D
 
Creator LEKSHMY S.
 
Contributor R.K. Sairam
 
Subject yields, grain, nutrients, millets, statistical methods, sets, crop residues, nitrogen, research methods, planting
 
Description T-8374
Wheat is one of the world’s major cereal crops, with an annual production of over
626 million tonnes in 2005. However both irrigated and rain-fed wheat is threatened by
salinization. Salt stress disrupts homeostasis in water potential and ion distribution. Drastic
changes in ion and water homeostasis lead to molecular damage, growth arrest and even
death. Six wheat genotypes viz. Kharchia 65, KRL19, HD2009, HD2687, HD4713, and WL
711 were raised in earthen pots of uniform size and subjected to salinity treatment with 2.5
litres of saline solutions, S1 100 mM NaCl), S2 (200mM NaCl). Actual salinity levels
expressed as electrical conductivity, ECe determined at vegetative, anthesis and harvest stages
are 1.21, 8.43 and 13.04 respectively for control, S1 and S2. Salinity stress reduced relative
water content, membrane stability index, chlorophyll, carotenoids, dry matter (root and shoot)
and yield in all genotypes; more so in salinity susceptible genotypes like HD 2687 and WL
711, which had very low grain yield per plant. Salinity tolerant genotypes like Kharchia 65
and KRl 19 had higher 1000 grain weight and maintained normal levels of grain protein
content. Salt-stress induced accumulation of reactive oxygen species measured in terms of
lipid peroxidation, hydrogen peroxide and superoxide radicals were comparatively lower in
Kharchia 65 and HD 2009, which may be due to salinity induced transcriptional activation of
anti oxidant system consisting of superoxide dismutase, catalase, ascorbate peroxidase and
glutathione reductase. Salinity stress stimulated accumulation of compatible solutes like
soluble sugars, trehalose, proline and glycine betaine. Tolerant cultivar like Kharchia 65
maintained higher levels of osmolytes by transcriptional activation of corresponding enzymes.
Soil salinity significantly reduced the potassium, calcium, nitrogen and iron content in leaf
root and seeds of all the genotypes. In contrast, the sodium, copper and zinc content was
increased in all the plant parts under salt treatment. But, the increases were lesser in tolerant
genotype Kharchia 65 which showed higher K/Na and Ca/Na ratios. Expression analysis of
genes of sodium exclusion mechanism in both roots and leaves of wheat reveals the existence
of a more efficient Salt Overly Sensitive pathway composed of SOS1, SOS2 ,SOS3 , vacuolar
Na+/H+ antiporter and Vacolar H+pyro phosphatase in tolerant genotypes like Kharchia 65 .
Kharchia 65 also possess strong salinity signaling components like MAPK, transcription
factors like NAC and bZIP, revealed by quantitative real-time PCR analysis.
 
Date 2016-10-26T11:16:36Z
2016-10-26T11:16:36Z
2010
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/82067
 
Format application/pdf
 
Publisher IARI, DIVISION OF PLANT PHYSIOLOGY