PACLOBUTRAZOL AND TIP PRUNING IN THE MANAGEMENT OF 'PALMER' MANGO TREES IN THE SEMI-ARID REGION OF BRAZIL

Paclobutrazol (PBZ), a synthetic plant growth regulator, was applied to mango trees to control vegetative growth and induce flowering. The objective of this study was to evaluate the effect of PBZ and tip pruning on flowering, yield and fruit quality of mango trees, cultivar ‘Palmer’, in irrigated conditions in a semi-arid region of Brazil. Uniform trees were selected at a commercial farm located in Jaíba County, Minas Gerais, Brazil. A randomized complete block design experiment was used with two methods of pruning and five different dosages of PBZ (0, 0.3, 0.6, 0.9 and 1.2 g (a.i.) ml PBZ), with four replicates and one plant per plot in a factorial combination. The PBZ was dissolved in 2 L of water and applied directly onto the soil. Vegetative growth parameters, reproductive characteristics, fruit quality and yield were evaluated. Differences among treatments were determined using analysis of variance at 5% of probability. Means separation among the treatments was performed using a Tukey’s test, and regression models were developed. The dosage of 0.86 g (a.i.) ml promoted a significant reduction in branch length. The different dosages of PBZ in conjunction with tip pruning produced significant flowering. Applying PBZ at 0.3 g (a.i.) ml increased the yield per branch and fruit firmness and reduced fruit length, fruit weight, pH and soluble solids. The fruit yield was not affected by tip pruning or PBZ application. INTRODUCTION The cultivation of mango (Mangifera indica L.) has great importance in the Brazilian semi-arid region in the northern region of Minas Gerais, occupying extensive planted areas primarily within the Jaíba Irrigation Project. In this region, which has a hot, dry climate, mango trees can produce fruit of excellent quality during any part of the year under irrigation conditions, provided that technology is adopted to manage the induction of flowering. Flowering management in mango trees using plant growth regulators is a practice that enables the scheduling of production for periods when the fruit value is higher (Cardoso et al., 2007). Paclobutrazol (PBZ) is widely used in mango crops, and its application inhibits the synthesis of gibberellins, alters the phloem/xylem ratio, and affects the redistribution of metabolic substances necessary for the processes of flowering and fruiting (Taiz and Zeiger, 2012). The use of plant regulators has shown great potential in the cultivation of mango in cultivars such as ‘Tommy Atkins’ (Silva and Neves, 2011), ‘Rosa’ (Cardoso et al., 2007), ‘Haden’, ‘Kensington’ and ‘Mangovar’ (Johnson and Robinson, 2000), possessing an essential function in inducing flowering in periods more appropriate for commercialization. The ‘Palmer’ cultivar displays high plant vigor yet suffers from the high temperatures and resulting high water conduction under an irrigated regime in the northern region of Minas Gerais, which tends to compromise the management of flowering. The practice of tip pruning in productive branches prevents continuous vegetative growth, which is a consequence of inappropriate climate conditions and has Proc. X Intl. Mango Symposium Eds.: J.J. Espinal et al. Acta Hort. 1075, ISHS 2015