RELATIONSHIPS AMONG GROWTH REGULATORS AND FLOWERING, YIELD, LEAF MASS, SLIP PRODUCTION AND HARVESTING OF 'PEROLA' PINEAPPLE

Natural flowering is very inconvenient and has caused, with increasing intensity, significant losses in all pineapple producing regions around the world. The objective of this work was to determine the role of substances which inhibit the vegetative growth of the plant, in different seasons of the year, focusing on the inhibition, reduction or delay of natural flowering, and also their effects on leaf mass, yield, slip and fruit production, harvesting and quality of pineapple, cv. Perola. The study was conducted at the experimental field of Embrapa Cassava and Tropical Fruit Crops, in Cruz das Almas/Bahia, Brazil, between 1998-1999. The growth substances and concentrations (total active ingredient) were as follows: 2– (3–chlorophenoxy) propionic acid – ACP (C.P. 7,5%): 90 – 120 mg L^-1; paclobutrazol – PBZ (C.P. 21,5%): 240 – 320 mg L^-1; tebuconazole – TBZ (C.P. 20%): 60 – 120 mg L^-1 and propaconazole – PPZ (C.P.25%): 120 mg L^-1. The treatments (two to four equal split applications) were applied fortnightly (7–9 a.m.), in two seasons, April/May and May/June, a period favorable for natural flowering in the region. Despite the variation observed in the effects and efficiency of the used growth regulators, the results have shown that ACP and PBZ are capable of inhibiting, reducing and delaying the natural flowering of pineapple, in the concentrations of 90 to 240 mg L^-1, and also, influencing leaf mass, slip production, yield and harvesting period. The better results were obtained when the growth regulators were applied during the months of April and May. The other products did not affect the natural flowering or the vegetative growth and fruiting of the pineapple. ACP and PBZ can be useful in the physiological studies on the mechanisms of flowering initiation on pineapple.