Resumo

GARCIA, Oskar Javier et al. Fruit set response of pineapple guava (Acca sellowiana (O. Berg) Burret) to potassium nitrate, potassium phosphate and ethephon. Agron. colomb. [online]. 2008, vol.26, n.2, pp.217-225. ISSN 0120-9965.

In the El Cortijo farm, La Vega municipality, Cundinamarca, Colombia (2,350 m altitude, temperature 17 °C, precipitation 1,423 mm·year^-1, relative humidity 85%), the effects of three chemical products were studied on fruit set of six years old feijoa trees, Clon 41 ('Quimba'). The products, also used in floral induction, were foliar fertilizers KNO₃ (potassium nitrate 13-0-46® 1.0%, at 1.5% and 2.0%), KH₂PO₄ (potassium phosphate; Cosmofoliar 0-32-43®; at 0.5%, 0.75% and 1.0%), and phytohormone ethephon (Ethrel® 48 SL; at 100, 150 and 200 mg·L^-1). Applications were made (each 15 days) starting from 50 days after pruning. There were evaluated (1) the number of formed flowers, (2) number and (3) percentage of fruits set, and (4) levels of efficacy of applied products. KH₂PO₄ at 0.5% had highest values (P<0,05) compared to the control (0 applications) in each of the four variables, which increases in the number of formed flowers of 447.6% and in the number of fruits set of 465.4%, emphasizing the importance of P in the reproductive process of pineapple guava. The second best treatment was ethephon at 100 mg·L^-1 showing a positive efficacy (96.55%) in fruit setting. The number of fruits set in the different KNO₃ concentrations did not exceed this one in the control presenting a negative efficacy and also phytotoxicity when KNO₃ concentrations of 2% were applied. Percentage of fruit set in pineapple guava (66% in control plants) was relatively high compared to other fruit trees.

Palavras-chave : ethrel; floral induction; Clon 41; 'Quimba'; forced production.

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