here are few models considering the effects of both water and carbon (C) availability on sink and source organs growth under stressful environments. The simulation model QualiTree is an integrated plant-fruit model mainly developed as a C driven model linking organ growth to C assimilation and allocation. It has been used to study the within-tree variability of vegetative growth, fruit yield and quality as well as the effect of different cultural practices such as tree training and fruit thinning. It is well known that vegetative growth is impacted by the plant water status, not only through a reduction of the leaf photosynthesis, but through a reduced growth linked with the shoot water potential as well. Therefore, a radiative balance and a simplified water transfer model was integrated in QualiTree in order to estimate the leaf transpiration, the shoot and leaf water potential and their variations within the tree. Thus, we were able to study the effect of water stress not only on the C acquisition but also on sink limitations through a reduced growth. The model was parameterized and assessed for a late maturing peach cultivar (‘Elberta’) under semi-arid weather conditions, and under different irrigation treatments. The model was able to simulate properly the effect of the water deficit on both the photosynthesis (leaf scale) and vegetative growth (shoot scale). The water deficit impact is first through a direct reducing effect on the vegetative growth and second through an indirect reducing effect on the leaf photosynthesis. As a consequence, the fruit yield and fruit traits are greatly affected by the water deficit.

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