THREE YEARS THINNING TRIALS ON 'ROCHA' PEAR WITH 6-BENZYLADENINE AND 1-NAPHTHALENE ACETIC ACID
During three consecutive years (2011-2013) the thinning agents 6-benzyladenine (BA) (100 and 150 ppm) and the combination BA 80 ppm + 1-naphthalene acetic acid (NAA) 8 ppm and BA 100 ppm + NAA 10 ppm were evaluated on 6- to 9-year-old Rocha pear trees grafted onto BA29 in a commercial orchard. Trees were sprayed at 10-12 mm fruit size and hand thinning was done after June drop. In 2013, BA at 150 ppm resulted in a significantly lower fruit number (P≤0.05) and a higher average fruit mass (P≤0.05) when compared with the other treatments and the percentage of the production with <60 mm fruits was significantly (P≤0.05) higher in hand thinned trees, stressing the importance of chemical thinning in this situation and the crop load interaction. This effect was also observed in the fruit growth pattern, when the diameter of individual fruitlets was fortnightly measured, the BA treated fruits at 100 or 150 ppm had a higher slope. In 2011 and 2012 the sprayings were as effective as hand thinning and did not result in a lower crop level, except in 2012 where the combination BA 100 ppm + NAA 10 ppm resulted in a higher yield and a higher fruit number compared with BA at 100 ppm. Hand thinning done after June drop comes too late to increase fruit size as effectively as BA or BA+NAA. BA 80 ppm + NAA 8 ppm may be a better choice comparing with BA due to its lower cost and less dependence of temperature. Comparing hand thinning cost with these chemical alternatives a cost reduction of about 40% is possible with the advantage of less smaller fruits in an on year. Return bloom was not affected negatively by BA or BA+NAA.
Maurício, A., Fernandes, C., Mota, M. and Oliveira, C.M. (2015). THREE YEARS THINNING TRIALS ON 'ROCHA' PEAR WITH 6-BENZYLADENINE AND 1-NAPHTHALENE ACETIC ACID. Acta Hortic. 1094, 395-401
crop load, fruit chemical thinning, fruit size, hand thinning, plant growth regulators, Pyrus communis