Response of okra based on electrophysiological modeling under salt stress and re-watering

Abstract

In this study, two okra cultivars, Chinese green and Chinese red were used to assess the water status and growth parameters subjected to salt stress by adding NaCl and CaCl₂ with same proportion in Hoagland culture solution at levels of 0%, 0.6%, 1.2%, 1.8% and re-watering at levels of 0.6-0%, 1.2-0.6%, 1.8-1.2%. The measured water potential and physiological capacitance values were used to calculate leaf tensity. Salt stress significantly reduced growth and water status parameters. Chinese green showed more reduction as compared to Chinese red but at 1.8% salt stress reduction of both cultivars were almost same. Re-watering had given a positive response for both cultivars to recover from higher salt stress. Dry weight, physiological capacitance, leaf tensity and salts concentration levels models gave predicting re-watering levels in percentage, also gave values of dilute irrigation point for Chinese red 9.05 or 10.00 ds m^-1 and Chinese green 6.67 or 5.66 ds m^-1. At resulted dilution points, plants of both cultivars were under high salt stress, which emphasized the need to re-water or dilution of salts for the survival of plants. The most effective predicting re-watering level and dilute irrigation point of both cultivars were found in same regime, so these models findings were very credible and meaningful. Higher dilute irrigation value of Chinese red indicates its more tolerance ability than Chinese green. Model's equations also gave direct irrigation point of Chinese red 1.32 or 1.62 ds m^-1 and Chinese green 2.07 or 0.38 ds m^-1. It was concluded that predicting re-watering levels, dilute and direct irrigation point help to get maximum production using saline water resources.