杉木营养平衡与苗木干物质的分配关系

详细研究了不同营养 (N、P、NP)条件下杉木苗木干物质在根冠的分配规律 ,结果表明 ,不同的营养条件可导致苗木光合产物在根冠发生明显再分配 ,苗木的营养状态和根冠干物质分配的关系规律可应用异速生长模型y =axk 来描述和刻划。基于营养与光合产物在根冠的再分配规律及异速生长模型参数k值对营养胁迫反应的敏感性变化规律 ,提出了新的营养平衡理论和营养诊断方法 (称之为苗木群体营养诊断法 )。营养诊断法则为 :(1)在某一营养条件下 ,如果苗木异速生长模型参数k <1时 ,表明根系相对生长速率高于冠层相对生长速率 ,苗木处于营养亏缺状态 ;(2 )当k >1时 ,表明苗木冠层相对生长速率高于根系 ,苗木处于营养过剩状态 ,一般在自然条件下 ,k >1是不会出现的 ;(3)当k =1时 ,表明根系和冠层相对生长速率相等 ,苗木处于营养平衡状态。根据新的营养诊断方法 ,制定了杉木叶片和土壤营养诊断标准 ,并通过大量的杉木幼、中、近熟林施肥试验结果验证了营养平衡理论的正确性。

STUDIES ON RELATIONSHIP BETWEEN NUTRITION BALANCE AND ALLOCATION OF PHOTOSYNTHETIC PRODUCTS IN SEEDLINGS OF CHINESE FIR

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.