Effect of abscisic acid on the maturation of olive trees cv. Arbequina
Interventions which accelerate the fruit maturation of olives planted in cold climates are necessary to advance the harvest and not allow the fruit to be exposed to early freezes which may have negative effects on the quality of the oil. In Autumn (28 April) 2006 we applied 0, 100, 200, 300 and 400 mg-L-1 abscisic acid (ABA) to trees of the variety of Arbequina at the beginning of veraison in an orchard in Melipilla, Metropolitan Region, Chile, in order to evaluate its effect on the acceleration of fruit maturation. The experimental design was completely randomized; the means of the treatments were compared by ANOVA and Tukey's test (p<0.05). The application of ABA produced a strong defoliation of the trees, together with a marked fruit fall, especially at 300 and 400 mg-L-1. Fruit maturation was retarded, expressed as a delay in the development of color for trees treated with 400 mg-L-1 ABA. The treatments did not produce an effect on the oil content measured as a proportion of dry weight. The following year (2007), those trees treated with 300 and 400 mg-L-1showed a significant reduction in fruit harvested per tree, which may be due to an effect of the ABA applied on the processes of induction or initiation of bud differentiation.