Silicon-mediated alleviation of salt stress in pinto and green bean varieties (Phaseolus vulgaris L.)

In the present study the effects of Si (0. 5 and 1 mM) have been investigated in two varieties of Phaseolus vulgaris (pinto bean and green bean) subjected to salinity (50 mM). Two series of experiments were separately arranged in completely randomized design for each of bean varieties and 12-day-old seedlings were introduced to the treatments which lasted for four weeks. The evaluated parameters were dry matters of the shoots and roots, total chlorophyll contents, membrane electrolyte leakage, proline and relative water content of leaves, Na+ and K+ concentrations in the shoots and roots. The results indicated salt stress significantly decreased biomass, K+ level, total chlorophyll and relative water content of leaves, whilst the concentration of Na+, proline and membrane electrolyte leakage increased. Si nutrition caused a marked increment in percentage of biomass in pinto bean which it was more than that of in green bean. Data analysis suggests Si increases salt tolerance in pinto bean by relatively blocking of Na+ entrance along with increasing relative water content of leaves and decreasing membrane electrolyte leakage in the leaves.