Reproduction dynamics and thermal requirement of dragon fruit species in northern amazon

Abstract

The objective of this work was to assess the reproductive phenology and thermal requirements of two dragon fruit species grown under the climate conditions of northern Amazon. The experiment was carried out in the municipality of Boa Vista, Roraima, Brazil, during two production cycles (2020-2021 and 20212022). Two dragon fruit species were used: Hylocereus costaricensis, which produces cylindrical fruits with a red skin and purple pulp; and Hylocereus polyrhizus, which produces elongated fruits with red skin and pulp. Ten plants of each species were selected and divided into four quadrants; ten cladodes were selected per quadrant and two flower buds were selected per cladode, totaling 800 flowers for each species. The plants were monitored from the beginning of flower bud intumescence until fruit harvest. Phenological periods were evaluated from production pruning to fruit harvest, based on the phenological stage descriptions of the Biologische Bundesanstalt Bundessortenamt and Chemical Industry (BBCH) scale. Climate conditions affected the species over the years, mainly due to variations in air temperature preceding phenophases. Variations between years increased the production cycle in 20 days for H. costaricensis and 34 days for H. polyrhizus from the first (2020-2021) to the second (2021-2022) production year. Organoleptic properties of species showed excellent results, including soluble solids (SS), titratable acidity (TA), and SS to TA ratio. Complete physiological maturity of H. costaricensis and H. polyrhizus fruits occurred at 31 and 38 days after anthesis, respectively, when the fruits presented an intense red skin and pulp.