'Tahiti' lime fruit set related to gibberellic acid application on out-of-season flowering and the accumulation of degree days.

摘要

The production of 'Tahiti' limes in southern Brazil has increased in the last 20 years and has become a good alternative for citrus growers in regions where Citrus Variegated Chlorosis has affected sweet orange groves. One of the main goals to insure success in growing 'Tahiti' limes is to apply the right techniques to induce out-of-season flowering and winter fruit harvest when the fruit prices are the highest. This experiment evaluated the effects of gibberellic acid application on fruit set of 'Tahiti' lime trees related to out-of-season flowering and accumulated degree days. Materials and methods. Eight-year-old plants were treated with five concentrations of gibberellic acid [(0, 10, 25, 50 and 100) mg centre dot L~(-1)] applied during anthesis of out-of-season bloom. Accumulation of degree days for fruit set and fruit development in the conditions of Sao Paulo State, Brazil, were calculated. The percentage of fruit set determined by weekly counts of the number of flowers from anthesis to the maturation of the fruits were determined on each previously marked branch. Data were submitted to regression analysis. Results and discussion. In regard to fruit set, it was observed, that 10 mg gibberellic acid centre dot L~(-1) was enough to retain more than 10 percent of fruits in relation to the number of formed flowers. Starting from anthesis, (837.7 and 1115.2) accumulated degree days were necessary for the stabilization of the fruit set and fruit maturation, respectively.