SYNTHETIC AUXIN 3-5-6 TPA INCREASED FRUIT SIZE AND RETENTION OF 'BENGAL' LYCHEE IN BRAZIL

Abstract

Fruit size is a key parameter for quality and dictates the profitability in lychee production in Brazil. Auxin stimulates cell division and enhances cell enlargement thereby affecting fruit size. Research in Australia, China, Israel and South Africa has shown that synthetic auxin applied as foliar sprays can reduce fruit drop and increase fruit size in different lychee cultivars. The aim of this study, therefore, was to evaluate the efficacy of the synthetic auxin, 3-5-6 trichloro-2-phridyl-oxyacetic acid (3-5-6 TPA) to increase fruit size and fruit retention in lychee, cv. 'Bengal', in Brazil. The experiments were conducted in a commercial orchard at Paraiso Farm in Rio Parnaiba-MG. Thirty six bearing trees used in the trial were approximately 12-years-old, clonally propagated by air layering and were planted at a spacing of 8 x 6 m (208 plants/ha). 3-5-6 TPA was applied at the 2, 4 and 6 g fruit mass stage at 0, 20, 40 and 60 mg/L, and the effect on fruit size and retention was determined. All treatments significantly increased fruit size and retention. However, the applications at the 2 g fruit mass stage at 40 and 60 mg/L resulted in the highest increases in fruit size and retention, respectively. Thus, a 3-5-6 TPA application in the range of 40 to 60 mg/L at the 2 g fruit mass stage can be recommended for ‘Bengal’ lychee to improve fruit size and retention.