The effect of leaf removal on yield and cycle duration of 'Niagara Rosada' grapevines was evaluated by defoliation (0, 15, 30, 50 and 70% of leaf removal), in an experiment carried out at the Jundiaí Experimental Station (São Paulo State, Brazil). Vines with 30% of the leaves (defoliation of 70%) had 77% lower crop yields and the cycle was lenghtned by 20 days. Defoliation of 15% did not affect grape yield but increased three days in cycle duration when compared to the control treatment (no defoliation). The best curve fitness of the effect of defoliation on yield was the logistic and on cycle duration was the quadratic function.
grapes; 'Niagara Rosada'; defoliation; cycle duration; yield