Abstract:

The allocation of the photosynthetic products in Chinese Fir seedlings was studied in this paper. Experiments were arranged under different N and P concentration and different NP compound nutrition levels in the soil. Results showed that the variation of nutrition in soil could affect the allocation pattern of photosynthetic products between root and shoot in seedlings .The relationship between the nutrition status in soil and the allocation pattern of photosynthetic products between root and shoot could be described by a Allometic model: y=ax^k. Based on the relationship between the nutrition status and the allocation pattern of photosynthetic products between root and shoot and the change patterns of the parameter k of Allometic model caused by the sensitivity of seedlings to the nutrition stress, a new nutrition equilibrium theory and a new nutrition diagnosis method were proposed in this paper. The diagnosis method could be expressed as: (1) If the parameter k of Allometic model was lower than 1 (k<1), the relative growth rate of root was higher than that of shoot, and seedlings fell in the status of nutrient deficiency. (2) If k>1,the relative growth rate of root was lower than that of shoot, and seedlings were over nutritious . But this situation had never occurred in nature. (3) When k=1, the relative growth rate of root was equal to that of shoot, and seedlings were in the status of nutrition equilibrium. According to the new diagnosis method, the nutrient diagnosis standards about the soil and the leaf of Chinese Fir were framed, and had been proved to be feasible by a great number of fertilization experiments on the young stands, the half mature stands and the near mature stands.

Key words: Chinese Fir, Allometic model, Allocation of photosynthetic products, Nutrient equilibrium