This study aimed to to evaluate the effect of plant growth regulators on the fruit set of atemoya 'Gefner'. Three experiments were carried out in the municipality of Matias Cardoso, North of Minas Gerais. In the first experiment four types of auxins, indol-butyric acid (IBA), indol-acetic acid (IAA), naphthaleneacetic acid (NAA) and dichlorophenoxyacetic acid (2,4-D) were evaluated combined in three concentrations (150, 300 and 450 mg L-1). The giberellic acid (GA3) also was used in the dosage of 1 g L-1, at 14 and 21 days after the first application of the auxins. In the second experiment the IAA, IBA and NAA were tested combined in two concentrations (450 and 600 mg L-1). In the third experiment, the use of NAA was evaluated in the dose of 450 mg L-1 associated with number of applications: weekly up to 35 days; weekly up to 70 days; weekly up to 105 days and every 2 weeks. The GA3 was used in the dosage of 1 g L-1, in four applications, to 13, 27, 41 and 54 days after the first application of NAA. In all of experiments, the control was the artificial pollination. The NAA was the synthetic auxin that presented the greatest averages of fruit setting, with 8% up to the 148 days after the first application. The use of 2,4-D showed the lowest percentages of fruit setting, on the 14th day of application no more fruit was observed. Independent of the type of plant regulator used, none of the treatments allowed the development of commercial fruits of atemoya.
auxins; gibberellins; fruit set; Annona squamosa x Annona cherimola
