Abstract: By the method of solution culture, this paper studied the effects of D-arginine on the seedling roots polyamine content and anaerobic respiration metabolism of two cucumber (Cucumis Sativus L.) cultivars Zhongnong No.8 and Lübachun No.4 differed in hypoxia tolerance. The re-sults showed that under hypoxia stress, the putrescine (Put), spermidine (Spd) and spermine (Spm) contents in the seedling roots of test cultivars increased significantly, and anaerobic respira-tion accelerated. The ethanol fermentation activity was higher in the seedling roots of hypoxia-tolerant cultivar Lübachun No.4 than in those of hypoxia-sensitive cultivar Zhongnong No.8, while lactate fermentation activity had an opposite trend. Comparing with treatment hypoxia, hypoxia plus D-arginine decreased the Put, Spd and Spm contents in roots significantly, enhanced the activities of alcohol dehydrogenase (ADH) and lactate dehydrogenase (LDH) and the contents of ethanol and lactate, and inhibited plant growth. Exogenous Put application lessened the effects of D-arginine. Higher level of polyamines in roots could have great benefits for cucumber seedlings to improve their resistance to hypoxia stress.

Key words: Nutritional resource, Anagrus nilaparvatae, Longevity, Parasitic ability, Survival rate