ASSESSMENT OF MORPHO-PHYSIOLOGICAL FEATURES OF TWO OKRA (ABELMOSCHUS ESCULENTUS L.) CULTIVARS AND THEIR HYBRIDS UNDER INDUCED SALT STRESS CONDITIONS

Salinization is an enormous problem affecting the horticultural crops. Salinity alters plant metabolism, reduces the endogenous water potential, and inhibits plant growth. Okra (Abelmoschus esculentus L.) is the most important annual vegetable, with high nutritional and medicinal values. It exhibits large genetic variation amongst cultivars, which shows better breeding material for improved crop production. Four concentrations of NaCl (0, 25, 50, and 75 mM) were applied to Japanese and Egyptian parents of okra and their F1 hybrids (Egyptian x Japanese) and (Japanese x Egyptian). Salt stress significantly enhanced the reduction of shoot length, root length, dry weight, and fresh weight in Egyptian cultivars and both hybrids. The efficiency of photo system two [PSII (Fv/Fm)] in the Egyptian mothers showed a significant decrease. Increasing NaCl concentrations significantly reduced protein content in the Japanese (J) and Egyptian (E) cultivars. While both hybrids (JxE and ExJ) showed a significant increase (P value < 0.05) in protein content from 249 to 310.9 and 240 to 312.5 mg/g DW (dry weight). Also, there was an increase in total phenolics, proline, and steroids in hybrids compared to their parents under high salt concentrations (75 mM), reaching (15, 14.75, and 82.44 mg/g DW, respectively) for the JxE hybrid and (22.5, 8.98, and 64.45 mg/g DW, respectively) for the ExJ hybrid. These results clearly indicated the successfully higher salt-tolerant nature of hybrids, which correlated with a higher level of protein, proline, steroid, and total phenolics at high salt concentrations. Cross-breeding between Japanese and Egyptian okra cultivars improved the okra salt tolerance.