The Use of gibberellic acid in citriculture

an overview of experimental results in Uruguay

Abstract

Main experimental results about the effect of gibberellic acid (GA₃ ) on the reproductive behavior of different varieties under Uruguayan conditions are summarized in the present review. GA₃ (20 - 40 mg.L^-1) sprayed during ecodormancy period (in Autumn-Winter) significantly reduced flower number in “Ellendale”, “Nova”, “Ortanique” hybrids, ‘Montenegrina’ mandarin and “Washington” navel sweet orange. GA₃ efficiency associates with the flowering intensity of the cultivar in each year and with the product concentration. Only in few cases this reduction increases fruit number harvested or moderate alternate bearings. No efficient anthesis application (15 to 50 mg.L^-1), to direct improve fruit set on hybrids of low partenocarpy ability, has been confirmed. Additionally, a trend of fruit size reduction has been found. A reduction of creasing incidence and severity was found with the application of GA₃ (10 - 20 mg.L^-1) sprayed between 90 and 120 days after flowering in “Washington” navel sweet orange. Results are discussed considering the international information.