Plant Physiology & Pathology

Biography

Biography: Rashad M. Balal

Abstract

The current investigation was carried out to assess whether the alterations in the activities of antioxidant enzymes and the levels of some non-enzymatic antioxidants could be used as potential indicators of heat-tolerance in ten commercialy important cultivars of okra (Abelmoschus esculrntus L.). The tested cultivars were exposed to three different temperatures i.e., 25, 40 and 45 °C under controlled conditions in growth chambers. Various growth, physiological and biochemcial characters in leaf or/and root tissues were analyzed. According to percent inhibition in shoot/root fresh and dry biomass at the highest temperature (45 °C) cultivars Sabaz Pari, Desi Okra and Green Wonder were ranked as tolerant (percent inhibition less than 60%), Shahzadi, Anarkali, Sarsabaz and Rama Krishna moderately tolerant (percent inhibition 60–70%), Click-5759 MF-03 and Pen Beauty heat sensitive (percent inhibition more than 70%). Heat stress caused significant reductions in photosynthesis associated attributes but didn’t affect number of stomata. High temperature-stress significantly elevated the activities of antixodiants, levels of osmolytes and decreased the MSI, and activities of GPX and CAT, while the internal levels of H2O2 remained unaffected in all tested okra cultivars. Although heat-induced oxidative stress was observed in all okra cultivars, but the response of heat-resistant and heat-sensitive cultivars with respect to the formation of enzymatic and non-enzymatic metabolites measured in the present study was not consistent. Of various gas exchange characteristics, antioxidant-enzymes and metabolites measured, only Pn, MSI and activities of GPX and CAT activity was found to be a consistent indicators of heat-tolerance in tested okra cultivars.