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Effect of salinity on growth, oxidative damage and foliar concentration of some secondary metabolites in two bean (Phaseolus vulgaris L.) varieties

Abstract:

The yield of black bean (Phaseolus vulgaris L.) is strongly reduced on saline soils. A greenhouse experiment was conducted with the varieties 'Tacarigua' and 'Montalbán', in order to determine the impact of salinity on growth, oxidative damage and the possible role of some secondary metabolites on the antioxidant response of this crop. Fifteen days-old plants were stressed with NaCl (40 or 80mol·m-3); at 7 and 14 days after saline stress (dass), relative chlorophyll content (RCC), lipid peroxidation grade (LPG) and alkaloids, total phenols and flavonoids concentration were determined; also total foliar area, root and shoot biomass and root biomass/shoot biomass ratio (R/S) were measured at 14 dass. Concentration of 80 mol m-3 NaCl resulted lethal for both varieties, and at 40 mol m-3 all the growth variables were reduced, except R/S in Tacarigua'. Based on RCC and LPG values, 'Montalbán' showed higher oxidative damage than 'Tacarigua'. At 14 dass, concentration of alkaloid and flavonoid was increased and total phenols content decreased in both varieties, showing 'Tacarigua' a higher content of the first two metabolites than 'Montalbán'. These results showed genotypic differences in response to salinity in this crop, with advantages in 'Tacarigua' over 'Montalbán'.