Is the use of growth regulators necessary to increase pecan size?

Barton is the most cultivated pecan cultivar in Brazil even though 42 cultivars have already been registered in the country. It bears small nuts, a fact that may represent a hindrance to demands of the Brazilian market and to new markets abroad. Nuts with a large caliber are valued by both internal and external markets. To increase fruit size in fruit trees, growth regulators have been used. Thus, this study aimed at evaluating the effects of plant growth regulators on the increase in pecan size. Two experiments were carried out with the cultivar in a commercial orchard in Santa Maria, Rio Grande do Sul (RS), Brazil, from the 2021 cycle to the 2023 one. Experiment 1 comprised the combination of two plant hormones and two doses of gibberellic acid (GA3) and five doses of Benzylaminopurine (BAP), which was applied in different phenological stages. Experiment 2 consisted of five treatments conducted with a commercial product that has auxin, cytokinin and gibberellin, which were applied in different phenological stages. In general, GA3, BAP and the commercial product need further studies of increase in ‘Barton’ pecan size.