Abstract:

【Objective】The aim of the work was to study the effects of 24-epibrassinolide (EBR) added to nutrient solution on carbohydrate metabolism of cucumber (Cucumis sativus L.) under root-zone hypoxia. 【Method】Seedlings of a relatively hypoxia-resistant cultivar, ‘Lübachun No.4’, and a relatively hypoxia-sensitive cultivar, ‘Zhongnong No.8’, were hydroponically grown for 8 days in normoxic and hypoxic nutrient solutions with and without addition of EBR at 1 μg L-1. And the effects of EBR on contents of carbohydrates in leaves and roots and activities of glycolytic enzymes in the roots were investigated. 【Result】Application of EBR to normoxic nutrient solution promoted the accumulation of total soluble sugars in leaves and roots, but had no effects on activities of glycolytic enzymes in the roots. Changes in contents of starch and glucose, and activities of acid invertase and ATP-dependent phosphofructokinase enzymes in the roots showed obviously different between two genotypes cucumber in response to root-zone hypoxia. EBR added to hypoxic nutrient solution caused an increase in the concentrations of fructose and sucrose and activities of major glycolytic enzymes in the roots, but exerted little influence on carbohydrate concentrations in the leaves. 【Conclusion】These results suggest that EBR added to hypoxic nutrient solution may stimulate the photosynthate allocation down to roots and activities of major glycolytic enzymes, and eventually enhanced tolerance of cucumber plants to root-zone hypoxia.