Effect of halopriming on seed germination performance and early seedling establishment in okra (Abelmoschus esculentus (L.) Moench) under saline conditions

Soil salinity can severely impact okra production by disrupting the metabolic phases during seed germination and limiting seedling establishment. However, seed priming has been shown to mitigate the stress caused by salt. This study aims to identify the optimal pretreatment conditions for promoting seedling establishment in okra (Abelmoschus esculentus (L.) Moench) under salt stress conditions. We conducted the study using saline solutions with increasing concentrations of NaCl (25 mM, 50 mM, 75 mM, 100 mM) as well as a control (without NaCl) to treat seeds from two varieties of okra (Clemson spineless and Hire) for durations of 1, 3, 7, and 9 h. Our findings revealed that NaCl-induced stress conditions had adverse effects on germination, physiological parameters, and the establishment of seedlings in both varieties of okra. Interestingly, regardless of the duration of priming, osmotic pretreatments improved germination parameters and seedling establishment in okra. Notably, the variety Hire exhibited the highest germination rate (97.22%), representing an increase of up to 6% compared to the control, and the best seedling viability (99.00%). Furthermore, osmopriming significantly enhanced seedling length, with the most effective treatment observed at 50 mM NaCl. In addition, osmotic pretreatments notably enhanced the photosynthetic pigment contents in the seedlings of the okra variety Clemson spineless compared to the control. After osmotic seed pretreatment with 50 mM NaCl for 7 h, the highest chlorophyll ‘a’ (5.53 mg/g), chlorophyll ‘b’ (1.46 mg/g), and carotenoid (4.84 mg/g) contents were observed. These results demonstrate the positive impact of osmopriming with 50 mM NaCl on okra seed germination and seedling establishment under saline soil conditions.