Seedlings of a
hypoxia-resistant cultivar, Lübachun No.4, and a
hypoxia-sensitive cultivar, Zhongnong No.8, were applied by feeding roots. The effects of exogenous
24-epibrassinolide (EBR) on lipid peroxidation, activities of major
antioxidant enzymes and anaerobic respiratory
enzymes and their time courses were investigated in cucumber seedling roots under
hypoxia stress. Root growth was significantly inhibited under
hypoxia stress, which was improved by exogenous EBR application (Figs.1,2). O(-*)(2) and H(2)O(2) level and lipid peroxidation were significantly increased in the roots upon exposure to
hypoxia stress, which were inhibited by exogenous EBR application (Fig.3). EBR treatment increased SOD and POD activities under
hypoxia stress (Fig.4).
Hypoxia enhanced the activities of
lactate dehydrogenase (LDH),
alcohol dehydrogenase (ADH) and
pyruvate decarboxylase (PDC) whereas EBR treatment significantly increased ADH activity, but decreased LDH activity (Fig.5). There was no significant difference in CAT and PDC activities between the
hypoxia stress treatment and "hypoxia+EBR" treatment (Fig.4,5). From the results obtained in this work it can be concluded that oxidative damage on seedling roots by
hypoxia stress can be considerably alleviated, and alcohol fermentation can be enhanced by EBR treatment.