Abstract

SILVA, José Antonio Alberto da et al. Doses of gibberellic acid in the production and quality of ‘Natal’ sweet orange in São Paulo, Brazil. Rev. de Ciências Agrárias [online]. 2021, vol.44, n.4, pp.71-80.  Epub Nov 09, 2021. ISSN 0871-018X.  https://doi.org/10.19084/rca.25056.

The growth and importance of the Brazilian citrus industry in the world involves the introduction of technologies such as the use of plant growth regulators such as gibberellic acid (GA3). The effects of doses of 0, 5, 10 and 15 mg L-1 of GA3 (Pro-Gibb®) associated with the surfactant Silwett L-77® at 0.5 mL L-1 were evaluated in an experiment by spraying the plants of a ‘Natal’ orange orchard in the Northern region of the state of São Paulo, Brazil. The treatments were applied annually, for two years, when the fruits were still fully green, but before the flowering of the next crop. The results showed, at the picking period, that the treatment of ‘Natal’ sweet orange trees with gibberellic acid associated with silicone surfactant, reduced fruit abscission due to the higher force needed to detach the fruits from the plants and significantly increased the peel resistance to puncture; The maintenance of the greener color of the orange peel, evaluated using a colorimeter, make them less attractive to fruit flies and make it possible the delay on insecticides treatments for flies control. Additionally, it allows the delay on harvesting by storing the fruits on the plants, with staggered harvest beyond the normal period for the variety. It is suggested doses of 5 to 10 mg L-1 GA3 always associated to silicone surfactant (0.05% L77) to obtain the best responses in oranges of Natal cultivar. Treatments with GA3 did not affect the productivity of the ‘Natal’ sweet orange orchard, neither the maturation and nor the technological quality of the fruits.

Keywords : citrus; colorimeter; GA₃; plant regulators; surfactant.

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