以耐低氧性具有明显差异的两个网纹甜瓜(Cucumis melo var. raticulalus)品种为试材，研究了根际低氧胁迫下幼苗生长、根系活力及根系呼吸关键酶活性的变化。结果表明，根际低氧胁迫下，两品种幼苗生长均受到明显抑制，而根系活力升高；根系PDC活性两品种均显著提高，品种间无显著差异； MDH活性两品种均显著降低，且耐低氧性弱的‘西域一号’下降幅度较大；根系ADH和LDH活 性两品种均显著提高，耐低氧性强的‘东方星光’ADH活性增加的幅度显著高于耐低氧性弱的 ‘西域一号’，而‘西域一号’LDH活性增加幅度显著高于‘东方星光’。说明‘东方星光 ’在低氧胁迫下能保持较高的有氧呼吸水平，无氧呼吸的主要途径为乙醇发酵，而‘西域一 号’在低氧胁迫下无氧呼吸的主要途径为乳酸发酵。
In this paper, two muskmelon cultivars, `Xiyu 1‘ with low hypoxia_resistance and `Dongfangxingguang‘ with high hypoxia_resistance, were used to study the changes in the activities in PDC, ADH, LDH and MDH under hypoxia stress. (DO at 2±0.20 mg•L-1). When seedlings grew to 3rd euphylla, they were cultured in a Hoagland nutrient solution and divided into two sets. One set of seedlings was exposed to normal dissolved oxygen levels (DO) using vigorous aeration to main tain DO levels at 8.0-8.5 mg•L-1, and the other set was treated with hypoxia stress using a DO analyzer (QUANTUM_25) to keep levels at 2.0±0.2 mg•L-1. The results showed that seedling growth of both cultivars were significantly inhibited and the root activity increased under hypoxic conditions. The PDC activity i n roots of both seedlings increased significantly under hypoxia stress, but there were no obvious differences between the two cultivars. The MDH activity in roots of both seedlings decreased significantly under hypoxia stress and the decrease of activity of `Xiyu 1‘ was much more than that of `Dengfangxingguang‘. The activities of ADH and LDH of both seedlings increased significantly under hypoxia stress. The increase in the activity of ADH in `Dongfangxingguang‘ was more than that of `Xiyu 1‘, while the increase of the activity of LDH in `Xiyu 1‘ was more than that of `Dongfangxingguang‘. The results suggested that `Dongfangxinggua ng‘ could maintain high levels of aerobic respiration, and ethanol fermentation was the primary pathway of anaerobic respiration under hypoxic stress whereas lactate fermentation was the leading pathway of anaerobic respiration under hyp oxia stress in `Xiyu 1‘.