Stimulation of Photosynthetic Pigments, Anthocyanin, Antioxidant Enzymes in Salt Stressed Red Cabbage Plants by Ascorbic Acid and Potassium Silicate

Abstract

Plants growing under saline conditions are affected in different ways: reduced water potential causing water deficit, phytotoxicity of ions such as Na+ and Cl- and nutrient imbalance. In this study, foliar application of Ascorbic acid (AsA) at 200 and 400 ppm and potassium silicate (KSi) at 1 and 2 mM were used to stimulate the tolerance of red cabbage (Brasssica oleracea L. var. capitata) “Primero” plants irrigated with three levels of saline water (320 (tap water), 2500 and 4500 ppm). Two pot experiments were carried out at the Experimental Farm, Faculty of Agriculture, Ain Shams University, during winter seasons of 2014/2015 and 2015/2016. Vegetative growth and yield parameters in addition to biochemical composition analysis were recorded. Plants irrigated with 320 ppm (tap water) showed better morphological and physiological characteristics particularly plants received 2mM KSi and 400 ppm AsA. Application of ascorbic acid and potassium silicate generally enhanced all growth parameters when compared with untreated plants. Both treatments improved vegetative growth; plant fresh and dry weight, relative water content (RWC), chlorophyll a, b, total chlorophyll and carotenoids concentrations in leaf and some biochemical properties; proline concentrations, polyphenoloxidase (PPO), peroxidase (POD) activity, protein and K concentrations, in both stressed and unstressed plants. In the contrary, these treatments decreased values of membrane permeability (MP), lipid peroxidation (MDA), Na and Cl percentage. Anthocyanin concentration increased with the increase in salinity levels, meanwhile potassium silicate and ascorbic acid treatments showed another increment in anthocyanin pigment under salinity stress. Best results were noticed with the high levels of both KSi and AsA treatments. It significantly increased most recorded growth parameters and chemical composition.