Proline accumulation, water status and chlorophyll content in leaf in relation to salt tolerance in soybean

An experiment was conducted to study the effect of salinity on proline accumulation, water status and chlorophyll content in leaf of a salt - tolerant (AGS 313) and a salt - susceptible (Shohag) soybean (Glycine max L) genotypes. The plants were grown in pots inside a vinylhouse with 50 and 100 mM NaCl solutions and tap water as a control. Leaf proline accumulation, water uptake capacity (WUC) and concentration of chlorophyll a, b and total chlorophyll of the two genotypes were compared at 15, 30, 45 and 60 days after treatment imposition. Marked variation in accumulation of proline was found between the two genotypes differing in salt tolerance. Proline accumulation was increased with the increasing salinity levels and with duration in both the genotypes. AGS 313 accumulated higher amount of proline under salt stress condition than that of Shohag at all the growth stages. Salinity also increased WUC in both AGS 313 and Shohag. The relative increase in WUC (% of the control) was greater in Shohag than that in AGS 313, which indicated that Shohag suffered more with water deficit than AGS 313. The chlorophyll a, b, and total chlorophyll in leaves of the two genotypes were decreased greatly with the increase in salt concentrations and with duration of exposure to salinity. The relative reduction (% of the control) of chlorophyll content was higher in Shohag than that in AGS 313. It was concluded that relatively higher amount of proline in AGS 313 had a greater osmoregulatory role in maintaining relatively lower WUC and higher leaf chlorophylls than those of Shohag.