美国黑核桃实生苗干物质积累与分配过程的数值模拟

Mathematically Modeling of Ecophysiological Process Response to Environmental Factors for American Black Walnut Seedlings (IV):Dynamic Models of the Accumulation and Distribution for Black Walnut's Dry Matter

以1年生美国北加州黑核桃实生苗为试材,以群体冠层的光合作用机理模型为基础,依据物质守恒及浓度梯度等理论,建立了干物质积累与分配的动态模型。在水肥适宜的条件下。对于1年生北加州黑核桃,在叶幕建造时期内,冠层干物质积累大体呈现Logistic曲线增长,而生物总量及根茎干物质的增长大体可分为两个阶段,第一阶段为指数增长阶段,第二阶段为线性增长阶段,而且无论是生物总量,还是冠层、根茎干重都呈现出波浪式增长的态势,这种波动是环境因子影响的结果。dw_l/dw_s(冠层、根茎干物质日增量之比)不仅随生育期变化,还随环境因子变化,在叶幕建造初期,dw_l/dw_s较大,平均值约为2.0,这时的光合产物主要用于叶片的生长和发育;在夜幕建造中期,dw_l/dw_s的平均值约为1.5,该时期干物质在冠层、根茎内的分配较均衡;在叶幕建造后期,dw_l/dw_s呈直线下降,干物质的分配中心主要转移到了地下部,叶子生长趋于停止。

One-year-old black walnut (J. hindssi) seedlings are employed as plant materials for setting up a dynamic model of dry matter accumulation and distribution, based on mechanistic models of photosynthesis, matter conservation and concentration gradient. Under optimum conditions of water and fertilizer, during the period of the canopy forming construction, the dry matter accumulation of the canopy conformed to Logistic curve; but the accumulation of both total biomass and dry matter of root-stem could be broken into two phases: the first phase was exponential increase, the second was linear increase. The total biomass, dry matter of canopy and root-stem all presented a fluctuant increase, which was affected by the environmental factors. dwl//dws (Ratio of daily increase of dry matter in the canopy and the root-stem) was changeable with growth periods and environmental factors. At the initial stage of the canopy forming, dwl/dws was larger, about 2.0 on average, which indicated that the photosynthetic product was mainly used to develop leaves; in the midterm, it was about 1.5, which indicated that the distribution of dry matter in the canopy and the root-stem was relatively balanced; when tended to stop growing, dwl/dws decreases linearly, and the main distribution of dry matter moved to root.