Asian Research Thesis Index

Abstract

The genotypic differences regarding Na + accumulation and transport in plant along with physiological response to improve salt tolerance were studied in bread wheat genotypes. Four wheat genotypes; Kharchia-65, SARC-3, S-9476 and S-8189 were grown under salt stress (75 and 150 mM NaCl) in nutrient solution with five replications. Shoot dry weight, relative growth rate (RGR), chlorophyll index, leaf water relations, Na + content and transport in plant were measured. The increase in NaCl stress decreased all growth parameters, however, variations were observed among genotypes. Kharchia-65, S-9476 and SARC-3 had better growth and water relations compared to salt sensitive genotypes S-8189. The low rate of Na + transport and better ability to restrict Na + in the root was main reason of genetic variation among different genotypes, especially, when growth characteristic did not vary significantly under salt stress. Na + partition was also recorded in wheat genotypes as salt sensitive genotypes had higher Na + accumulation in shoot while it was reverse in tolerant ones. The differences in root Na + were not significant among all genotypes. In many crop plants, over-accumulation of Na + in shoot is the main cause of yield reduction due to toxicity. In this study, wheat genotypes differed mainly because of low rates of Na + uptake and transport from root to shoot. Therefore, in this study, it was concluded that wheat genotypes with contrasting leaf Na + uptake rates and transport from root to shoot had resulted in differences in salinity tolerance. The wheat genotypes having ability to reduce Na + accumulation in shoot by retaining it at root level had better salt tolerance. The genotypes with the highest Na + uptake had lower chlorophyll, more electrolyte leakage, and a slightly lower RGR. Keywords: Genotypes, ion partition, salinity stress, sodium, wheat

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