A DYNAMIC MODEL OF THE ACCUMULATION AND DISTRIBUTION OF DRY MATTER FOR BLACK WALNUT (JUGLANS HINDSII) SEEDLINGS

One-year-old black walnut (J. hindssi) seedlings were used to set up a dynamic model of dry matter accumulation and distribution. During the period of canopy development, the dry matter accumulation in the canopy conformed to logistic curves. However, the accumulation of both total biomass and dry matter of stem+root could be divided into two phases: the first phase showing exponential increase, and the second linear increase. All three factors, the total biomass of the plant and the dry matter of the canopy and the stem+root were affected by the environmental factors. The ratio of daily increase of dry matter in the canopy and the stem+root (dw_l/dw_s) was dependent on the growth period and environmental factors. In the initial stage of canopy formation, dw_l/dw_s was larger, about 2.0 on average, which indicated that the photosynthetic product was mainly used to develop leaves. During the middle stages it was about 1.5, which indicated that the distribution of dry matter in the canopy and the stem+root was relatively balanced. When the plant was in its final growth stages, dw_l/dw_s decreased linearly, and the main distribution of dry matter moved to the roots.