Nguyen Phu V., Dickmann Donald I., Pregitzer Kurt S., Hendrick R.
Department of Forestry, Michigan State University, East Lansing, MI 48824-1222, USA.
Tree Physiol. 1990 Dec;7(1_2_3_4):95-105. doi: 10.1093/treephys/7.1-2-3-4.95.
Two hybrid Populus clones, Tristis and Eugenei, which had been grown from cuttings in 114-liter pots sunk in the ground, were sequentially harvested during the latter part of the first growing season. Pots were supplied with water and nitrogen at two different rates. Starch and sugar concentrations were determined in samples taken from stems, branches, cuttings, and five diameter classes of roots. Concentrations of starch and sugar in all components of the trees were significantly affected by time of harvest and clone. Water and nitrogen treatments, however, did not significantly affect carbohydrate concentrations. From August to November, as plants developed cold hardiness, starch concentrations declined and sugar concentrations increased in stems and branches, especially in Tristis. In both clones, the large roots (> 1 mm diameter) were major repositories of starch and sugar late in the season. By the end of September, 80% of total-tree nonstructural carbohydrates in Eugenei were located in the roots. Even the fine-root fraction (< 0.5 mm diameter) showed substantial carbohydrate loading in late season, contradicting the hypothesis that starch deposition in fine roots occurs only when they are being formed.
两个杂交杨树无性系，即Tristis和Eugenei，它们是从扦插苗培育而来，种植于埋在地下的114升花盆中，在第一个生长季后期按顺序进行采收。花盆以两种不同的速率供水和施氮。测定了取自茎、枝、插条以及五个直径级别的根的样本中的淀粉和糖浓度。树木所有组成部分中的淀粉和糖浓度都受到采收时间和无性系的显著影响。然而，水和氮处理对碳水化合物浓度没有显著影响。从8月到11月，随着植株形成抗寒性，茎和枝中的淀粉浓度下降，糖浓度上升，尤其是在Tristis无性系中。在两个无性系中，大根（直径>1毫米）在生长季后期是淀粉和糖的主要储存部位。到9月底，Eugenei无性系中全树非结构性碳水化合物的80%位于根部。即使是细根部分（直径<0.5毫米）在生长季后期也显示出大量的碳水化合物积累，这与细根中淀粉沉积仅在其形成时发生的假设相矛盾。
