Salt-induced changes in the growth, key physicochemical and biochemical parameters, enzyme activities, and levels of non-enzymatic anti-oxidants in cauliflower (Brassica oleracea L.)

Salt-induced changes in the growth, leaf chlorophyll contents, water relations, inorganic nutrient contents, activities of some anti-oxidant enzymes, and levels of non-enzymatic anti-oxidants in cauliflower (Brassica oleracea L.) were examined under greenhouse conditions. Fifteen-day-old seedlings of two cultivars of cauliflower ('FD1' and 'FD2') were exposed to four different levels of saline stress [0 (control), 50, 100, or 150 mM NaCl] for 30 d, applied through the rooting medium. Increasing levels of NaCl significantly decreased shoot and root dry weights (DWs), relative water contents (RWC), leaf and root K+ ion contents, total soluble proteins, total phenolic compounds, malondialdehyde (MDA) levels, and root K+/Na+ and Ca2+/Na+ ratios. Increasing salinity increased leaf water contents, leaf and root Na+ and Cl- ion contents, leaf free proline, glycinebetaine (GB), and ascorbic acid (AsA) contents, as well as the activities of superoxide dismutase (SOD), peroxidase (POX), and catalase (CAT) in both cauliflower cultivars. However, no significant effects of NaCl were observed on chlorophyll a and b contents, relative membrane permeability (RMP), and leaf or root Ca2+ ion contents in either cauliflower cultivar. 'FD2' was relatively less-affected by salt stress. The relatively improved growth performance of 'FD2' under saline conditions was found to be attributable to its higher RWC, as well as increased levels of proline, root Ca2+ ions, total phenolic compounds and AsA, as well as elevated SOD activity, and lower levels of MDA compared to 'FD1' plants under salt stress.