Evaluating the transfer and metabolism of carbon (C) in apple fruit is key to estimating the potential accumulation of atmospheric ¹⁴C in fruit near and around nuclear facilities. We developed a dynamic compartment model for apple fruit-bearing shoots, assuming that the shoots are a simple unit of source and sink for photoassimilates. Fruit-bearing shoots of Malus domestica “Fuji” at different fruit growth stages were exposed to ¹³CO₂ in situ, followed by sampling at 72 h after exposure or at harvest. The ¹³C/(¹³C+¹²C) mole ratio in fruits, leaves, and current branch were measured to construct a five-compartment model of ¹³C (fruit, each fast and slow component of leaves, and current branch). The C inventories in the compartments were presented in accordance with the measured growth curves of C in the organs. The model simulated the ¹³C dynamics in plant tissues well. Simulation results of photoassimilate distribution using the model indicated that the retention of photoassimilated C at the harvest depended on the growth rate of C in the organs at the exposure.

评估苹果果实中碳（C）的转移和代谢是估算大气中¹⁴ C在核设施附近和周围果实中潜在积累的关键。我们假设苹果芽是光吸收物质的简单来源和吸收单元，因此为苹果果实的芽开发了一个动态隔室模型。在不同的果实生长阶段，将家蝇（Malus domestica “ Fuji”）的果实枝条原位暴露于¹³ CO ₂ ，然后在暴露后72 h或收获时取样。测量水果，叶片和电流分支中的¹³ C /（¹³ C + ¹² C）摩尔比，以构建¹³的五室模型C（果实，叶子的每个快慢成分，以及当前分支）。根据测得的器官中C的生长曲线显示了隔室中的C清单。该模型很好地模拟了植物组织中的¹³ C动态。使用该模型的光同化物分布的模拟结果表明，光同化的C在收获时的保留取决于暴露时器官中C的生长速率。