Genotypic variation in tolerance to salinity in Pakistani okra (Abelmoschus esculentus L.) varieties as assessed at seed germination, seedling growth and biochemical characters

Salt stress is one of the major abiotic stresses that causes reduction in crops yield. Okra (Abelmoschus esculentus L.) is a high-value nutraceutical vegetable because its various parts are used for different purposes. This study was conducted to calculate the salt tolerance among thirteen okra varieties. Different salt (NaCl) levels: 0, 50, 75 and 100 mM were selected to measure the response of the okra varieties to stress. The experimental data showed that all varieties were affected by salt level with a differential variation in their stress response, demonstrating the presence of genetic variability. Five varieties: "NAYAB-F1", "Arka anamika", "MALAV-27", "Sarhad Green" and 051-F1 showed germination at all stress levels (0, 50, 75 and 100 mM), six varieties: "Feveeri Green", "Punjab Selection", "Local Multani", "Shehzadi", "Green Star" and "Hunza" showed germination at (0, 50 and 75 mM) and two: "Anmol" and "Sabz Pari" showed germination at (0 and 50 mM). As a result of salt stress, germination percentage (PG), leaf fresh and dry weight (LFW and LDW), shoot fresh and dry weight (SFW and SDW), root fresh and dry weight (RFW and RDW) were significantly reduced with increasing stress level. Based on the performance of variety to salt stress, five varieties were selected for biochemical analysis, concentrating on the determination of osmolytes. The values of sugar and proline were affected both by the varieties and salt levels. Variety "NAYAB-F1" showed higher sugar and proline content at all stress levels compared to varieties "Arka anamika", "MALAV-27", "051-F1" and Sarhad Green. Correspondingly, in the stressed seedling a decreasing trend in chlorophyll "a" and "b" were noted depending on the varieties and stress concentrations. After a series of experiment, it has been concluded that varieties "NAYAB-F1", "Arka anamika", "MALAV-27", "Sarhad Green" and "051-F1" were recommended as salt tolerant varieties and could be utilized in the breeding program of salt tolerant okra.