Biochemical and Mineral Responses of Okra Seeds (Abelmoschus esculentus L. Variety Marsaouia) to Salt and Thermal Stresses

The present research has studied the effects of NaCl and temperature on germination and emergence of okra. Studies were carried out with seeds of a local okra variety (Marsaouia) subjected to 0 and 100 mM NaCl, performed in the dark at 10, 15, 25, 35 and 40°C at germination stage and by 12 h light at emergence stage. The cumulative germination percentage, the cumulative emergence percentage, starch content, the reducing sugars levels, total amylase activity, sodium and potassium accumulation were quantified in germinated seeds at 15°C, 25 and 35°C. Temperature presented a significant effect on salt sensitivity of this species at germination and emergence stages. Germination of okra seeds was completely inhibited at 10 and 40°C. The best germination and emergence temperature was recorded at 25°C. The adverse effect of salt was more pronounced at low and high temperature. During the salt stress treatment, the level of starch reserves was higher at 25°C and lower at 15 and 35°C, an increase in reducing sugars content in cotyledons was observed. The activity of total amylase was most intensive at lower temperature in control seeds and at higher temperature in salt treated seeds. The sodium concentration on germinated seeds increased significantly at 15 and 35°C, but potassium amount did not change regularly within thermal and salt stress interaction.