The purpose of this research was to evaluate the effects of MBTA [N,N-diethyl-2-(4-metylbenzyloxy) ethylamine hydrochloride] bioregulator applied on different times and concentrations on the yield and fruit quality of 'Pera' sweet orange. In two consecutive harvest seasons, the MBTA was sprayed in three different concentrations (8; 16 and 32 mg L-1) and in two different phenological phases (25% and 100% open flowers) in citrus mature trees, using 7 L of spray per tree added with Silwett L-77 adjuvant at 0.05%. For each cultivar, twenty fruits per tree were sampled in four different times to determine the soluble solids concentration (SS), titratable acidity (TA), quantity of soluble solids per 40.8 kg box, juice yield, "ratio" (SS/TA) and average fruit weight. The effects of MBTA varied according to the concentration and phenological phase of application. The MBTA at 8 mg L-1 concentration, sprayed on 25% of the open flowers, increased the soluble solids concentration, acidity, the quantity of soluble solids per 40.8 kg box and the yield. The same treatment also decreased the average fruit weight and did not affect the juice yield and the "ratio". The average increase was from 0.49 to 0.65% on soluble solids concentration, from 0.11 to 0.13 kg on the quantity of soluble solids per 40.8 kg box and 20.4 kg/tree on yield.
Tertiary amines; Citrus sp; Plant Growth Regulators; Soluble solids
