An optimal control model of crop thinning in viticulture

Abstract

Abstract.We develop an economic model of cluster thinning in viticulture to control for grape quantity harvested and grape quality, applying a simple optimal control model with the aim to raise grape quality and related economic profits. The model maximizes vineyard owner profits and allows to discuss two relevant scenarios using a phase diagram analysis: (1) when the initial grape quantity is sufficiently small, thinning grapes will not be optimal and (2) when the initial grape quantity is high enough, it is optimal to thin grapes from the beginning of the relevant planning horizon and to reduce the quantity over time until the stock of grapes arrives at its optimum. Depending on the model's parameters, the "stopping time" for thinning grapes is reached sooner or later. After the stopping time, grape quantity evolves solely according to natural decay. The results relate to observed dynamics in viticulture and for other horticultural crops.

A Mathematical Model for Vineyard Replacement with Nonlinear Binary Control Optimization

“…Logically, since grape growing is a subset of the agriculture endeavour, it is expected to see at least a few studies of OC dedicated, exclusively, to vineyard challenges. Surprisingly, to the best of our knowledge, Schamel and Schubert [31] presents the lonely attempt to bundle OC and vineyard/grapevine systems. They develop an OC model to attain the ideal crop thinning in viticulture, maximizing grape quality and quantity [31].…”

“…Surprisingly, to the best of our knowledge, Schamel and Schubert [31] presents the lonely attempt to bundle OC and vineyard/grapevine systems. They develop an OC model to attain the ideal crop thinning in viticulture, maximizing grape quality and quantity [31]. Moreover, they give a brief overview of optimization methods, noting the broad range of applications to the several subsets of the agricultural entrepreneurship.…”

Summer pruning in Mediterranean vineyards: is climate change affecting its perception, modalities, and effects?

“…The following physiological principle ( Figure 7 ) should drive the cluster thinning operation: if the anomalous values in the LA/Y ratio (e.g., lower than 1 m 2 /kg) or the Ravaz index (e.g., higher than 8–10 kg/kg) warn about a likely overcropping status, then cluster thinning should lead to the expected results of significantly improving grape and wine quality while helping to remain within yield limits imposed by law. However, when cluster thinning is performed in vines with adequate crop load, the advantages of these technique significantly diminish, resulting in reduced economic return due to the additional cost required to implement the technique ( Berkey et al., 2011 ; Preszler et al., 2013 ; Schamel and Schubert, 2016 ).…”

Influence of crop load on the yield and grape quality of Merlot and Vranac (Vitis vinifera L.) varieties in Trebinje vineyard

“…Crop loads also impacts chemical grape composition and thus the wine quality. From an economic point of view, grape growers must find the correct balance between quantity, fruit quality and long-term vine health when determining appropriate crop levels on their vines (Čuš, 2004;Schamel and Schubert, 2016). Accordingly, permanent necessity for achieving optimal crop loads is always present, especially in regions where the connections among pruning practices and grape production are poorly understood.…”