Limited research has been focused to know how a water deficit affect the size and sugar accumulation of the grape fruit. We don't have either, information to relate this two parameters with cluster and leaf water status. During 1994, a study was conducted which main objective was to know cluster and leaf water relations under different soil water conditions and its relation with fruit growth and sugar accumulation. This work was enhanced in a vineyard of 18 years old, planted with the Grenache cultivar, which was subjected during the phase III of the fruit growth to three evapotranspiration (ET) levels which were 0, 30 and 70 %. Three times per week, volume and sugar fruit were measured, so that, leaf (Ψ_t) and cluster (Ψ_c) water potential.
It was found that, the values of volume and sugar accumulation of the fruit under the 70 % of ET, were higher than in the 0 and 30 % of ET. Ψ_c showed a better response and sensibility to the treatments applied than Ψ_t. It seems that, when Ψ_c reach values of −1.1 MPa, fruit growth and sugar accumulation ceased.