Glycine betaine and sugar beet extract ameliorated salt stress adverse effect on green bean irrigated with saline water

Abstract

To investigate the effects of glycine betaine and sugar beet extract (molasses) on ameliorating the adverse effect of salt stress and enhancing growth, yield, chemical composition and enzymes activity of green bean plants (Phaseolus vulgaris L.) cv. Valentino, an experimental study was carried on green bean plants irrigated with four levels of saline water (1000, 2000, 3000 and 4000 ppm) combined with three anti- salinity foliar application (pure glycine betaine (GB) 50 mM, Sugar beet extract (molasses) 5cm3L-1 and water as a control).The obtained results showed that green bean plants irrigated with 1000 ppm saline water in general gave the most vigorous vegetative growth and had the highest yield compared with those grown under higher salt stress conditions .All anti-salinity applications improved vegetative growth when compared with unsprayed plants (control). Green bean Plants sprayed with glycine betaine or sugar beet extract (molasses) showed better vegetative growth and shoot biomass, chlorophyll, antioxidant content (enzymatic activity) and proline concentrations at all tested salinity levels compared with control plants (without anti-salinity application) which showed severe growth retardation particularly under the higher salt level (4000 ppm). The maximum leaf relative water content and lowest values of membrane permeability were markedly observed with glycine betaine and sugar beet extract with no significant difference between both of them. Plants irrigated with lower saline water (1000 ppm) had better antioxidant enzyme activity and accumulated higher K and lower Na and Cl than plants grown under high salinity irrigation water (4000ppm). The Anti-salinity application positively enhanced the yield components under all salinity stress levels and the highest yield was significantly detected with glycine betaine application followed by molasses and lastly coming untreated plants.