Efecto de las fitohormonas sobre el control de la fructificación en manzanos

Two experiments were done in apples cv. Royal Gala to evaluate different hormones for fruit thinning. In one of them, the cultivar was grafted over rootstock M9 and in the other one on M4. Treatments applied in both experiments were: 1: Benzyladenine (BA) 100 ppm when mean fruit diameter (FD) was between 8 to 12 mm; 2: Naftalen Acetic Acid (NAA) 10 ppm at 5 mm FD; 3: NAA 10 ppm at 5 mm FD + BA 50 ppm when FD was between 8 to 12 mm; 4: NAA10 ppm at 5 mm FD + BA 75 ppm when FD was between 8 to 12 mm; 5: NAA 10 ppm at 5 mm FD + BA 100 ppm when FD was between 8 to 12 mm; 6: Control: hand thinning. Response variables were: number of fruit per cm2 Branch Cross Sectional Area (BCSA) and per 100 flower clusters; and fruit set distribution (percentage of spurs where fruit set was 0, 1 or +1). At commercial harvest fruit weight, mayor and minor diameter and length of each fruit were measured and classified according to commercial sizes of the standard box (18 kg). Data were analyzed using the procedure of analysis of Variance (ANOVA); Chi-square test and principal component analysis. All the combinations of NAA + BA were effective for fruit thinning and resulted in similar fruit set and fruit sizes, thus applications of NAA at 10 ppm + BA at 50 ppm were a good alternative to thin fruits with lower costs and less environmental impact due to lower doses. Apples treated with BA had higher commercial sizes than control ones.