Screening and Selection of Synthetic Hexaploid Wheat Germplasm for Salinity Tolerance Based on Physiological and Biochemical Characters

Salinity is one of the major abiotic stresses affecting plant growth and development as salinization of cultivated land is increasing globally. There is considerable variation in salinity tolerance of wheat genotypes and selection of salt tolerant genotypes is of great interest in salt affected regions. An experiment was conducted to evaluate the salt tolerance of 13 newly developed synthetic hexaploid wheats (2n=6x=42; AABBDD) along with two check varieties Kharchia-65 and Shorawaki. Thirteen-day-old seedlings, grown in a hydroponics system, were subjected to 0, 75 and 150 mM NaCl in Hoagland's nutrient solution for five days. Increasing salt stress generally affected all physiological aspects of the plants; however, various enzyme activities, proline content, soluble sugars and protein content increased with increased salt concentration. Exposure to salt stress affected plant dry biomass of all the genotypes; however, there was a difference in response of wheat genotypes to salinity stress. Among the tested genotypes, Kharchia-65, Shorawaki, N-7, N-9 and N-13 showed better performance in terms of plant biomass, K+: Na+ ratio, chlorophyll content, net assimilation rate (A), transpiration rate (E) and stomatal conductance (g(s)). There was a strong correlation between K+:Na+ ratio, chlorophyll, proline, SOD, CAT and g(s) against shoot dry biomass. Based on overall performance, the tested wheat genotypes were grouped as tolerant, moderately tolerant and sensitive. Wheat genotypes N-7, N-9 and N-13 were grouped as tolerant, N-33 and N-12 as moderately tolerant and the remaining genotypes were found sensitive to salt stress. In this regard K+:Na+ ratio, chlorophyll, proline, SOD, CAT and g(s) may be used as potential biochemical and physiological selection criteria for screening of salt tolerance in wheat genotypes. (C) 2014 Friends Science Publishers