Effects of Gibberellins A4+7 and 6-Benzylamino Purine on Fruit Set, Fruit Characteristics, Seed Content, and Storage Quality of ‘McIntosh’ Apples1

Spraying trees of ‘McIntosh’ apple ( Malus domestica Borkh.) with gibberellins A 4+7 (GA 4+7 ) + 6-benzyIamino purine (BA) plus 1000 ppm daminozide 17 days after full bloom increased fruit set as GA 4+7 + BA concentrations increased from 0 to 100 ppm, but did not alter fruit size, shape, or quality at harvest. Increased poststorage development of senescent breakdown with increasing concentration of applied GA 4+7 + BA was attributable to increased occurrence of seedless fruit. Responses to treatments appeared to be due primarily to the GA 4+7 component and did not occur when GA 4+7 + BA combination was applied after “June drop.” Fruit flesh calcium concentration declined as GA 4+7 + BA concentration increased.