Modelling virtual Riesling canopies for reducing sunburn risks in grapevine (Vitis vinifera L.) berries

葡萄藤浆果和其他水果作物的晒伤被认为是一种经常性的疾病，导致严重的产量损失和浆果质量下降。然而，近年来已观察到晒伤的出现增加。鉴于这些对晒伤发生的观察通常与热浪有关，晒伤和气候变化之间可能存在联系。葡萄藤是研究气候变化影响的理想模式作物，这是第一个旨在调查未来葡萄园浆果日灼相关性的模拟研究。葡萄园对环境条件变化的反应模拟应该为我们提供气候变化对日灼影响的答案。我们假设未来的气候条件可能会影响季节性晒伤的发生。例如，CO2（eCO2）的升高可能会降低在后期的晒伤风险，因为增加了二次侧枝的生长。然而，随着更频繁的热浪，晒伤的发生，特别是与叶子去除有关的晒伤，可能会急剧增加。由于浆果晒伤是一种需要浆果直接暴露在阳光下的疾病，它取决于葡萄藤树冠的结构。功能结构植物模型（FSPM）是将植物冠层的结构要素详细地结合起来，以捕捉冠层的变化。虚拟雷司令是这样一个FSPM葡萄品种。雷司令它模拟了包括行向在内的格架系统内冠层结构的动态生长。虚拟雷司令已被证明是有用的，在评估葡萄藤结构的温度变化的意义。我们假设，晒伤发生的葡萄藤浆果可以预测从三个关键特性的浆果：当地的阳光照射，表面温度和敏感性晒伤。所有的特性都将被集成到一个先进的虚拟雷司令模型中。为此，将开发和集成浆果和集群生长的新模型，包括浆果的光传感器，浆果晒伤模型以及先进的三维叶片形状模型。新的子模型的参数化和虚拟雷司令的进步将基于在葡萄园自由空气二氧化碳富集（FACE）设施中进行的实验。将进行一系列计算机模拟实验，以评估eCO2和温度升高对晒伤发生的形态反应的影响，并确定减少晒伤发生的最佳叶片去除方法。最后，我们将应用并比较标准的叶片去除策略和理论上有利于降低田间晒伤风险的新发现策略。项目成果将帮助我们更好地了解气候变化如何影响晒伤，从而为减轻气候变化的影响提供新的思路，基于葡萄园和其他农业系统中植物结构管理的新策略。

Sunburn in grapevine berries and other fruit crops is known as a recurring disorder causing severe yield losses and a decline in berry quality. Yet, an increased emergence of sunburn has been observed in recent years. Given that these observations of sunburn occurrence are often associated with heat waves, it is likely that there is a link between sunburn and climate change. Grapevine is an ideal model crop for studies of climate change impacts, and this is the first modelling study that aims at investigating the relevance of berry sunburn in future vineyards.Simulations of responses of vineyards to changes in environmental conditions should give us answers to the impact of climate change on sunburn. We hypothesize that future climatic conditions might affect seasonal sunburn occurrence. For example, elevated CO2 (eCO2) might reduce sunburn risks in the later season because of an increased growth of secondary lateral shoots. However, with more frequent heat waves sunburn occurrence, particularly re-lated to leaf removal, might dramatically increase. Since berry sunburn is a disorder that re-quires direct exposure of the berries to the sun, it depends on the grapevine canopy’s archi-tecture. Functional-structural plant models (FSPMs) integrate structural elements of a canopy in detail to catch the canopy’s variability. Virtual Riesling is such a FSPM for grapevine cv. Riesling. It simulates the dynamic growth of the canopy architecture within a trellis system including row orientation. Virtual Riesling has proven to be useful in assessing the significance of changing temperatures for grapevine architecture. We assume that sunburn occurrence of a grapevine berry can be predicted from three key characteristics of the berry: local sun-exposure, surface temperature and susceptibility to sunburn. All characteristics will be inte-grated in an advanced Virtual Riesling model. To this end, new models for berry and cluster growth including light sensors for berries, a model for berry sunburn, as well as an advanced three-dimensional leaf shape model will be developed and integrated. Parameterization of new sub-models and advancements of Virtual Riesling will be based on experiments con-ducted, inter alia, in a vineyard free-air carbon dioxide enrichment (FACE) facility. A series of in silico experiments will be performed to estimate the effects of morphological responses to eCO2 and increased temperature on sunburn occurrence and to identify optimized leaf re-moval practices for reducing sunburn occurrence. Finally, we will apply and compare both, standard leaf removal strategies versus the newly identified strategies theoretically favorable for reducing sunburn risks in the field.The project output will help us to better understand how climate change affects sunburn and will thus provide new ideas for mitigating effects of climate change, based on new strategies for managing plant architecture in vineyards and other agricultural systems.