Abstract: A hydroponic experiment was carried out to study the influence of Cu and Zn on water spinach growth and the antidotal effect of Se. Physiological indexes, yield, Cu and Zn contents in two water spinach varieties (wideleaf and narrowleaf water spinach), and the antidotal effect of Se were investigated. The results indicated that lowconcentration Cu and Zn accelerated the growth of water spinach, and highconcentration Cu and Zn restrained the growth by decreasing root activity, antioxidative enzyme activities and net photosynthetic rate (P_n) and increasing MDA content. The yield of water spinach decreased significantly when Cu concentration was 4.00 mg·L^-1 and Zn concentration was 8.00 mg·L^-1. Cu was more harmful to water spinach than Zn. The narrowleaf water spinach had a higher antioxidation ability than the wideleaf variety. Cu and Zn contents in the two water spinach varieties increased with the increasing concentrations of Cu and Zn in nutritive medium. SOD, POD, CAT and proline played a cooperative role in alleviating lowlevel Cu and Zn toxicity. Highconcentration Cu and Zn restrained the antioxidant enzyme system, while the alleviation was dominated by the nonenzymatic system. Se improved the resistibility of water spinach under Cu and Zn stress, resulting in the decrease of MDA content and increases of proline and phytochelatins (PCs) content, yield, root activity, P_n and antioxidant enzyme activity. When water spinach was slightly affected by Cu or Zn, 5.00 mg·L^-1 Se could increase the yield of water spinach and provide Seenriched production. However, excess Se could exacerbate the toxicity of Cu and Zn.

Key words: soil respiration, experimental warming, adaptability