Growing grapes on a virtual plant

The growth of a fleshy fruit is greatly affected by the carbon and water status of the parent plant. Here, we developed an integrated functional-structural grapevine (Vitis vinifera L.) model that can simultaneously simulate berry growth and whole-plant carbon and water status based on hourly environmental conditions.The model was tested on fruiting-cutting Cabernet Sauvignon system. It was calibrated and validated with weekly berry dry weight and fresh weight with contrasting leaf number per cluster. The model captured the negative effects of leaf-to-fruit ratio on the rate of water and dry matter accumulation in berries. Furthermore, the model revealed that a greater proportion of carbon was allocated to the berries under the low leaf-to-fruit ratio.This integrated model is a useful tool for predicting and understanding plant and environmental impacts on fleshy fruit growth. However, further work still needs to be done to understand the detail of the berry sugar unloading process, e.g. the relationship between turgor pressure and sugar uptake.