50 American Academic Scientific Research Journal for Engineering, Technology, and Sciences ISSN (Print) 2313-4410, ISSN (Online) 2313-4402 http://asrjetsjournal.org/ Use of Plant Regulators in the Off-Season Flower Induction of ‘Tahiti’ Acid Lime and ‘Ponkan’ Mandarin Gilson Barbara a , Lais Naiara Honorato Monteiro b , Antonio Flávio Arruda Ferreira c , Maria Gabriela Fontanetti Rodrigues d * a,b Faculty of Engineering of Ilha Solteira FEIS/UNESP, 56 Brazil Sul Street, Ilha Solteira, 15385-000, Brazil c State University of Mato Grosso. North 2 Perimetral Rogério Silva Street, Alta Floresta, 78580-000, Brazil d Faculty of Agrarian and Technological Sciences FCAT/UNESP. 651 Comandante João Ribeiro de Barro Highway, Dracena, 17900-000, Brazil a Email: gilson.barbara@unesp.br , b Email: laismonteiiro@gmail.com c Email: arrudaferreira.af@gmail.com , d Email: maria.gf.rodrigues@unesp.br Abstract Brazil is one of the world’s largest citrus producers. To maintain the uniformity of annual production during seasonality, there is a need to apply new technologies in agriculture to enhance plant productivity. Applications of plant regulators in fruit trees are part of methods to standardize production. Thus, the aim of this study was to evaluate the use of plant growth regulators Paclobutrazol (PBZ) and Ethephon, associated with potassium sulfate and calcium nitrate foliar fertilizers, in the off-season flower induction in ‘Tahiti’ acid lime and ‘Ponkan’ mandarin crops, for off-season production. The experiment was carried out in properties located in the municipality of Aparecida do Taboado/MS, with randomized blocks design, containing 2 treatments (without/with application of plant growth regulators), 4 blocks with 50 replicates, with each plant evaluated being considered an experimental unit. At 150 days after the application of products, number of flowers per square meter of plant canopy and fruit set in both crops were evaluated, in addition to their diameter. ‘Tahiti’ acid lime plants treated with PBZ obtained average of 77.24 fruits per m²/plant canopy, while controls had 16.08 fruits m²/plant canopy. In ‘Ponkan’ mandarin, treated plants obtained 87.49 fruits per m²/plant canopy, while controls had 30.94 fruits m²/ plant canopy. The execution schedule and products used as plant regulators, especially Paclobutrazol, applied to ‘Tahiti’ acid lime and ‘Ponkan’ mandarin plants allowed significant increase in the amounts of flowers and fruits, making it possible to plan the staggering of flowering induction and production of these cultivars. Keywords: Citrus latifólia; Citrus reticulada blanco; Floral induction. ------------------------------------------------------------------------ * Corresponding author.