EFFECT OF FOLIAR-APPLIED PLANT BIOREGULATORS ON ´JUNE FRUIT DROP´, YIELD AND FRUIT SIZE OF ´HASS´ AVOCADO
Research was conducted to evaluate the effectiveness of foliar-applied plant bioregulators (PBRs) to reduce June fruit drop and increase yield and fruit size of Hass avocado under rainfed conditions in Nayarit, México. Treatments were applied approximately 1 month before the expected start of June fruit drop in 10 ± 1 L aqueous solutions per tree to achieve full canopy coverage. The surfactant Silwet L-77® at 1 mg×L-1 was added to all treatments, including the control. In Year 1, the following treatments were applied in June, when fruit were about 5 to 7 cm long: (T-1) 25 mg×L-1 2,4-D (66 mg×L-1 Citrus Fix®), (T-2) 45 mg×L-1 aminoethoxyvinylglycine (300 mg×L-1 Retain®), (T-3) 0.45 mg×L-1 6-benzyladenine (25 mg×L-1 Accel®), and (T-4) control (surfactant only). For Year 2, treatments were modified and applied when fruit were 3-4 cm long (20 May) or 5 to 7 cm long (15 June): (T-1) 10 mg×L-1 2,4-D (26.3 mg×L-1 Citrus Fix®) in May and June, (T-2) 12.5 mg×L-1 2,4-D (23.9 mg×L-1 Citrus fix®) in May and June, (T-3) 20 mg×L-1 2,4-D (52.6 mg×L-1 Citrus Fix®) in June, (T-4) 22.5 mg×L-1 aminoethoxyvinylglycine (150 mg×L-1 Retain®) in May and June, and (T-5) 45 mg×L-1 aminoethoxyvinylglycine (300 mg×L-1 Retain®) in June, (T-6) control (surfactant only). A randomized block design with 10 single-tree replications was used. Intensity of June fruit drop in control trees was 47% to 66%. A reduction of 19.4% to 17.3%, in the intensity of June drop was achieved by tree canopy sprays in June of 20 mg×L-1 2,4-D (52.6 mg×L-1 Citrus Fix®) or 45 mg×L-1 aminoethoxyvinylglycine (300 mg×L-1 Retain®), respectively. In addition, these treatments increased by 17% to 18% the kg of large size fruit (170 to >266 g per fruit) per tree. These results will be of great economic benefit to the avocado grower.
Salazar-Garcia, S., Gonzalez-Duran, I.J.L., Cossio-Vargas, L.E., Medina Torres, R. and Lovatt, C.J. (2006). EFFECT OF FOLIAR-APPLIED PLANT BIOREGULATORS ON ´JUNE FRUIT DROP´, YIELD AND FRUIT SIZE OF ´HASS´ AVOCADO. Acta Hortic. 727, 197-202
Persea americana, fruit abscission, fruit set