Salt (NaCl)-Induced Modulation in some Key Physio-Biochemical Attributes in Okra (Abelmoschus esculentus L.)

Salt (NaCl)-induced regulation of some key physio-biochemical characteristics in two okra (Abelmoschus esculentus L.) cultivars (Nirali and Posa Sawni) was examined under greenhouse conditions. Plants of both cultivars were subjected for 30 days to sand culture salinized with four salt levels [0 (control), 50, 100 and 150 mm NaCl] in Hoagland's nutrient solution. Salt stress significantly reduced the shoot and root fresh weights, transpiration rate, chlorophyll b content, net CO2 assimilation (A), transpiration rate (E), while enhanced leaf and root Na+ and Cl- concentrations in both cultivars. In contrast, chlorophyll a content, stomatal conductance (g(s)), leaf internal CO2 (C-i), C-i/C-a ratio, water-use efficiency (A/E) and fluorescence characteristics such as photochemical quenching (qP), non-photochemical quenching (NPQ), efficiency of PS-II (F-v/F-m), proline contents, and leaf and root K+, Ca2 + and N contents remained almost unaffected in both lines due to salt stress. The efficiency of PSII (F-v/F-m), A, chlorophyll b, root fresh weight and root N were higher in relatively salt tolerant cv. Nirali, whereas leaf Na+ and root Cl- were higher in cv. Posa Sawni. The relatively more reduction in growth in the cv. Posa Sawni was found to be associated with higher accumulation of Na+ in its leaves and Cl- in roots.