Ethephon increases return bloom and yield of 'Rocha' pear trees

B. Carra, M. Dini, E.S. Abreu, M.S. Pasa, C.P. Pasa, P. Francescatto, F.G. Herter, P.C. Mello-Farias
Flower induction and differentiation are complex phenomena not fully understood in pear trees. Ethylene is a plant hormone that seems to play an important role in flower induction. Exogenous ethephon (Eth) and naphthaleneacetic acid (NAA) applications have shown promising results to increase return bloom and yields in some pear cultivars. The objective of this study was to evaluate the effect of Eth and NAA on return bloom, yield and shoot length of 'Rocha' pear trees in southern Brazil. The study was performed during 2015/2016 and 2016/2017 growing seasons, using a five-year-old 'Rocha' pear orchard grafted on 'BA29' quince rootstock. Treatments consisted of untreated control, Eth 100 mg L‑1; NAA 5 mg L‑1; NAA 7.5 mg L‑1; NAA 10 mg L‑1; Eth 100 mg L‑1 + NAA 5 mg L‑1; Eth 200 mg L‑1 + NAA 7.5 mg L‑1; Eth 300 mg L‑1 + NAA 10 mg L‑1 applied at 40 + 60 + 80 days after full bloom (DAFB); Eth 150 mg L‑1 + NAA 7.5 mg L‑1 applied at 60 + 70 + 80 + 90 DAFB; and Eth 150 mg L‑1 + NAA 7.5 mg L‑1 sprayed at 40 + 60 + 80 + 100 DAFB. Shoot length in the year of application, return bloom, number of fruits tree‑1, yield (kg tree‑1 and Mg ha‑1) and average fruit weight the following season were assessed. Return bloom and yield were increased when trees were sprayed with Eth 100 mg L‑1 at 40 + 60 + 80 DAFB and Eth 150 mg L‑1 + NAA 7.5 mg L‑1 at 40 + 60 + 80 + 100 DAFB. NAA sprayed alone did not increase return bloom and yield. These results suggest that only ethephon was effective to increase return bloom, since NAA alone had no effect. Shoot length was reduced by all treatments compared to the untreated trees.
Carra, B., Dini, M., Abreu, E.S., Pasa, M.S., Pasa, C.P., Francescatto, P., Herter, F.G. and Mello-Farias, P.C. (2021). Ethephon increases return bloom and yield of 'Rocha' pear trees. Acta Hortic. 1303, 291-298
DOI: 10.17660/ActaHortic.2021.1303.41
Pyrus communis, naphthaleneacetic acid, plant growth regulators, vegetative growth, flower induction, flower differentiation

Acta Horticulturae