Institute of Biological Production Systems, Leibniz Universität Hannover, Herrenhäuserstr. 2, 30419 Hannover, Germany.
Ann Bot. 2011 Oct;108(6):1075-84. doi: 10.1093/aob/mcr150. Epub 2011 Jun 28.
Growth imbalances between individual fruits are common in indeterminate plants such as cucumber (Cucumis sativus). In this species, these imbalances can be related to differences in two growth characteristics, fruit growth duration until reaching a given size and fruit abortion. Both are related to distribution, and environmental factors as well as canopy architecture play a key role in their differentiation. Furthermore, events leading to a fruit reaching its harvestable size before or simultaneously with a prior fruit can be observed. Functional-structural plant models (FSPMs) allow for interactions between environmental factors, canopy architecture and physiological processes. Here, we tested hypotheses which account for these interactions by introducing dominance and abortion thresholds for the partitioning of assimilates between growing fruits.
Using the L-System formalism, an FSPM was developed which combined a model for architectural development, a biochemical model of photosynthesis and a model for assimilate partitioning, the last including a fruit growth model based on a size-related potential growth rate (R(P)). Starting from a distribution proportional to R(P), the model was extended by including abortion and dominance. Abortion was related to source strength and dominance to sink strength. Both thresholds were varied to test their influence on fruit growth characteristics. Simulations were conducted for a dense row and a sparse isometric canopy.
The simple partitioning models failed to simulate individual fruit growth realistically. The introduction of abortion and dominance thresholds gave the best results. Simulations of fruit growth durations and abortion rates were in line with measurements, and events in which a fruit was harvestable earlier than an older fruit were reproduced.
Dominance and abortion events need to be considered when simulating typical fruit growth traits. By integrating environmental factors, the FSPM can be a valuable tool to analyse and improve existing knowledge about the dynamics of assimilates partitioning.
在黄瓜（Cucumis sativus）等不定型植物中，个体果实之间的生长不平衡很常见。在这种植物中，这些不平衡可能与两个生长特征的差异有关，即果实达到给定大小的生长持续时间和果实败育。这两个特征都与分配以及环境因素和冠层结构在其分化中的作用有关。此外，还可以观察到一个果实在先前果实之前或同时达到可收获大小的情况。功能结构植物模型（FSPM）允许环境因素、冠层结构和生理过程之间相互作用。在这里，我们通过引入用于在生长中的果实之间分配同化产物的优势和败育阈值，测试了考虑这些相互作用的假设。
使用 L-系统形式主义，开发了一种 FSPM，该模型结合了结构发育模型、光合作用生物化学模型和同化产物分配模型，后者包括基于与大小相关的潜在生长率（R(P)）的果实生长模型。从与 R(P)成比例的分布开始，模型通过包括败育和优势进行扩展。败育与源强度有关，优势与汇强度有关。两者的阈值都被改变以测试它们对果实生长特征的影响。模拟针对密集行和稀疏等距冠层进行。
简单的分配模型无法真实地模拟单个果实的生长。引入败育和优势阈值可以获得最佳结果。果实生长持续时间和败育率的模拟与测量结果一致，并且再现了一个果实比一个旧果实更早可收获的事件。
在模拟典型果实生长特征时，需要考虑优势和败育事件。通过整合环境因素，FSPM 可以成为分析和改进关于同化产物分配动力学的现有知识的有价值工具。
