GIRDLING COMBINED WITH PACLOBUTRAZOL BOOSTED YIELD OF 'BENGAL' LYCHEE IN BRAZIL

Abstract

This study aimed to evaluate the effect of girdling and the application of paclobutrazol (PBZ) on the production of 'Bengal' lychee trees for two consecutive years (2009 and 2010). The experiments were conducted in commercial orchards at the Rio das Pedras Farm in Jundiai-SP and Paraiso Farm in Rio Parnaiba-MG. The trees were approximately ten-year-old clonally propagated by air layering and were planted with 6 m x 4 m spacing (416 plants/ha) at Rio das Pedras Farm and 8 m x 6 m spacing (208 plants/ha) at Paraiso Farm. Girdling was carried out on the trunk, main branches or trunk plus main branches. PBZ was applied at 500, 1,000 and 2,000 mg of active ingredient (a.i.) per linear meter of the canopy diameter with an average of 6 m soon after girdling in early May. Sole treatment with girdling in any position of the tree or PBZ at any concentration increased slightly the average yield but did not show a significant increase in both locations. However, girdling combined with PBZ boosted the yield with a consistent increase in two consecutive years. The best combination, trunk girdling combined with an application of 1,000 mg a.i. PBZ per linear meter of canopy significantly increased the average yield of 2009 and 2010 seasons by 6.4-fold and 5.6-fold at Rio das Pedras Farm and Paraiso Farm, respectively, compared to the control trees. Thus, girdling combined with PBZ was very effective in increasing flowering, fruiting and yield of ‘Bengal’ lychee trees.