Da Silva David, Qin Liangchun, DeBuse Carolyn, DeJong Theodore M
Ann Bot. 2014 Sep;114(4):643-52. doi: 10.1093/aob/mcu033.
Developing a conceptual and functional framework for simulating annual long-term carbohydrate storage and mobilization in trees has been a weak point for virtually all tree models. This paper provides a novel approach for solving this problem using empirical field data and details of structural components of simulated trees to estimate the total carbohydrate stored over a dormant season and available for mobilization during spring budbreak.
The seasonal patterns of mobilization and storage of non-structural carbohydrates in bark and wood of the scion and rootstock crowns of the trunks of peach (Prunus persica) trees were analysed subsequent to treatments designed to maximize differences in source-sink behaviour during the growing season. Mature peach trees received one of three treatments (defruited and no pruning, severe pruning to 1·0 m, and unthinned with no pruning) in late winter, just prior to budbreak. Selected trees of each treatment were harvested at four times (March, June, August and November) and slices of trunk and root crown tissue above and below the graft union were removed for carbohydrate analysis. Inner bark and xylem tissues from the first to fifth rings were separated and analysed for non-structural carbohydrates. Data from these experiments were then used to estimate the amount of non-structural carbohydrates available for mobilization and to parameterize a carbohydrate storage sub-model in the functional-structural L-PEACH model.
The mass fraction of carbohydrates in all sample tissues decreased from March to June, but the decrease was greatest in the severely pruned and unthinned treatments. November carbohydrate mass fractions in all tissues recovered to values similar to those in the previous March, except in the older xylem rings of the severely pruned and unthinned treatment. Carbohydrate storage sink capacity in trunks was empirically estimated from the mean maximum measured trunk non-structural carbohydrate mass fractions. The carbohydrate storage source available for mobilization was estimated from these maximum mass fractions and the early summer minimum mass fractions remaining in these tissues in the severe treatments that maximized mobilization of stored carbohydrates. The L-PEACH sink-source carbohydrate distribution framework was then used along with simulated tree structure to successfully simulate annual carbohydrate storage sink and source behaviour over years.
The sink-source concept of carbohydrate distribution within a tree was extended to include winter carbohydrate storage and spring mobilization by considering the storage sink and source as a function of the collective capacity of active xylem and phloem tissue of the tree, and its annual behaviour was effectively simulated using the L-PEACH functional-structural plant model.
为树木年度长期碳水化合物储存与调动过程建立概念和功能框架，实际上一直是所有树木模型的薄弱环节。本文提出了一种新方法，利用实地经验数据和模拟树木结构组成部分的细节，来估算休眠季节储存的、可供春季芽萌动时调动的总碳水化合物量，以解决这一问题。
在旨在最大化生长季源 - 库行为差异的处理之后，分析了桃树（Prunus persica）树干接穗和砧木树冠的树皮及木材中非结构性碳水化合物的调动和储存季节性模式。冬末芽萌动前，成熟桃树接受了三种处理之一（疏果且不修剪、重剪至1.0米、不疏果且不修剪）。每种处理选择的树木在四个时间点（3月、6月、8月和11月）进行采收，去除嫁接部位上下的树干和根冠组织切片用于碳水化合物分析。分离并分析了从第一到第五年轮的内皮和木质部组织中的非结构性碳水化合物。然后利用这些实验数据估算可供调动的非结构性碳水化合物量，并为功能 - 结构L - PEACH模型中的碳水化合物储存子模型设定参数。
所有样本组织中的碳水化合物质量分数从3月到6月下降，但在重剪和不疏果处理中下降幅度最大。11月时，除重剪和不疏果处理中较老的木质部年轮外，所有组织中的碳水化合物质量分数恢复到与前一年3月相似的值。根据测得的树干非结构性碳水化合物质量分数的平均最大值，凭经验估算树干中的碳水化合物储存库容量。根据这些最大质量分数以及在使储存碳水化合物调动最大化的重度处理中这些组织在初夏剩余的最小质量分数，估算可供调动的碳水化合物储存源。然后将L - PEACH库 - 源碳水化合物分配框架与模拟的树木结构一起用于成功模拟多年来的年度碳水化合物储存库和源行为。
通过将储存库和源视为树木活跃木质部和韧皮部组织的集体能力的函数，将树木内碳水化合物分配的源 - 库概念扩展到包括冬季碳水化合物储存和春季调动，并且利用L - PEACH功能 - 结构植物模型有效地模拟了其年度行为。
