PHYSIOLOGICAL CHANGES ASSOCIATED WITH SALINITY STRESS IN MASHBEAN [Vigna mungo L. (Hepper)]
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Date
2009
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Punjab Agricultural University
Abstract
In the present study mashbean genotypes were evaluated for their growth behaviour and alteration in yield contributing parameters during salinity stress. Twenty genotypes of mashbean were evaluated for salinity stress tolerance on the basis of their growth behaviour under 15 mM, 30 mM and 45 mM NaCl application in laboratory conditions. Out of these, two most salt tolerant (VU-1 and KUG 529) and two most salt sensitive (KUG 363 and KUG 539) genotypes were selected for field experiments. Reduction in growth (plant height, leaf area plant-1 and total plant dry biomass) and photosynthetic efficiency of plants measured in terms of chlorophyll content and Hill reaction activity in leaf chloroplasts was observed with increasing salinity. However, tolerant genotypes showed less reduction than the sensitive ones. All the genotypes also showed a decrease in number of nodules plant-1, fresh/dry weight, weight of nodules plant-1 and leghaemoglobin content, with sensitive genotypes showing more decrease than tolerant ones and also the decrease was NaCl dose dependent. Activity of nitrate reductase and carbonic anhydrase was also reduced as a result of salt applications with effect being more prominent in salt sensitive genotypes as compared to salt tolerant ones. The level of total proteins and different protein fractions (globulins, glutelins, albumins and prolamins) in seeds increased with increasing salinity. The genotypes KUG 529 and VU-1 (salt tolerant) showed more accumulation of proteins than KUG 363 and KUG 539 (salt sensitive) genotypes under the influence of salt stress. Reduction in yield under saline stress was more in salt sensitive genotypes. However, VU-1 and KUG 529 (salt tolerant) genotypes were able to tolerate high salinity probably by adjusting osmotically through higher proline accumulation in comparison to sensitive genotypes.
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salt sensitive, genotypes