Physiological and Molecular Studies of Salinity Tolerance in Cotton (Gossypium herbaceum L.)

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Date
2006
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UAS, Dharwad
Abstract
Investigation on salt tolerance in cotton was made with four genotypes viz., Rahs-14, Dhumad, Jayadhar and Kumta under five salinity levels in lab and pot experiments. The objective was to study the changes in physiological, biochemical, molecular characters and their relationship under varying salinity levels. The results showed that germination percentage, root length, shoot length, seedling dry weight decreased relatively lower in genotypes Dhumad and Rahs-14 compared to Jayadhar and Kumta. In general, the root:shoot ratio increased, while SVI decreased with increase in salinity levels. Higher increase in root:shoot ratio and decrease in the seedling vigour index at higher salinity level was noticed in the Kumta and Jayadhar. The genotypes Rahs-14 and Dhumad showed higher level of antioxidant enzyme i.e., SOD, catalase and peroxidase activity at all salinity levels. Though, the genotypes Kumta and Jayadhar showed increase in activity with increase in salinity but it was relatively less indicating the susceptible nature of these genotypes. The genotypes Rahs-14 and Dhumad accumulated higher soluble sugars at all salinity levels denoting the preferential osmotic adjustment. The solute leakage and relative leakage ratio were higher in genotypes Jayadhar and Kumta indicating higher membrane damage due to salinity in susceptible genotypes. The genotypes showed different patterns of isozyme profiles for the enzymes SOD, catalase and peroxidase with higher activity under salinity stress over control. Based on the investigation, the genotypes Rahs-14 and Dhumad were found to be efficient in salt stressed environments because of lesser reduction in germination, root and shoot length, SVI, seedling dry weight, solute leakage, relative leakage ratio and maintenance of higher total soluble sugars and higher SOD catalase and peroxidase activity at higher salinity levels with their varied isozyme profiles which could serve as selection criteria for identification of salinity tolerance at early stages of crop growth in cotton.
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Crop Physiology
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