Natural flowering in pineapple: inhibition by growth regulators

Abstract

-Introduction. Natural flowering is an obstacle for the management of pineapple production. This phenomenon is at the origin of considerable and increasing fruit losses on an international scale. The objective of this work was to determine, at various times of the year, the role of substances inhibiting the vegetative growth of the plant to prevent, reduce or delay the natural pineapple flowering of the variety 'Perola', most planted in Brazil. Materials and methods. Two trials were conducted in the experimental field in Cruz das Almas, Bahia, Brasil, during the years 1996 to 1999. Various growth substances were tested at various concentrations: propionic acid 2-(3-chlorophenoxy) (ACP) at (45, 90 and 120) mg⋅L -1 , paclobutrazole (PBZ) at (77.4, 155.8 and 320) mg⋅L -1 , mepiquat chlorure (MC) at (60 and 120) mg⋅L -1 , gibberelic acid (GA 3 ) at (30 and 60) mg⋅L -1 , tebuconazole (TBZ) at (60 and 120) mg⋅L -1 and propaconazole (PPZ) at 120 mg⋅L -1 . The treatments were applied onto two, three or four split applications, every 15 days, from 7:00 to 9:00 a.m. and from April to July (the critical period for natural flowering in the region). Results and discussion. The results obtained show that ACP and PBZ are capable of inhibiting, reducing and delaying the natural flowering of pineapple with the concentrations of (90 to 240) mg⋅L -1 . The best results were obtained when the growth regulators were applied during April and May. The other products did not have an effect on the natural flowering of pineapple. Conclusion. The variation observed in the effects and efficiencies of the growth regulators used indicates the necessity of validating the best treatments under different environmental and cultural conditions. The selected growth regulators can be a valuable tool for physiological studies on the mechanisms of flowering initiation in pineapple. Brazil / Ananas comosus / flowering / precocity / growth inhibitors / triazolesFloraison naturelle chez l'ananas : inhibition par les régulateurs de croissance.