Abstract: To provide theoretical basis for rational nitrogen (N) fertilizer management of an endangered medicinal plant, Tetrastigma hemsleyanum Diels et Gilg, the effects of two different N forms (NO₃^--N and NH₄⁺-N) on photosynthesis, energy allocation and activities of antioxidant enzymes in the leaves of T. hemsleyanum seedlings grown under shading conditions (30% of full sunlight) were investigated. The results showed that two different N forms had no significant effects on leaf area, specific leaf weight, chlorophyll content, superoxide dismutase activity, catalase activity and energy allocation pattern. The photosynthetic parameters (net photosynthetic rate, stomatal conductance, and transpiration rate) were significantly higher and peroxidase activity and malondialdehyde content were significantly lower in the leaves of T. hemsleyanum under NO₃^--N supply than that under NH₄⁺-N supply. Our results indicated that  the application of NO₃^--N is more conducive to the growth of T. hemsleyanum.

Key words: soil conditioner, Chao soil region, nitrification inhibitor, controlled-release fertilizer, wheat-maize rotation system, N loss