A methodology for the modelling of the triggering of the vine flowering

Abstract

The effect of temperature on the biological rythm of the vine is well known. Flowering is triggered when the thermal requirement is met, expressed in the form of an accumulation of daily temperature over a given threshold as from a precise date. The purpose of this study is to propose a methodology for the modelling of the triggering of flowering, that has since been applied in 5 vineyards, enabling the definition of the most suitable model for each site. This work can easily be transferred to other vineyards by the development of a computerized tool. These results confirm the value of the « thermal requirement » approach, from which the following comments can be drawn : - it is better to take account of the maximum rather than of the mean temperatures; - given the level of the « effective » thresholds, the bud-burst stage is not always the best starting point. In certain cases, the models are better adjusted with a fixed date; - the variability in thermal requirements can almost always be explained by an adaptation of the vine to the climate, even if occasionally the influence of climatic conditions at the actual time of flowering can perturb this effect. Such cases, however, occur relatively infrequently.

Keywords

• thermal requirement
• flowering
• modelling