Reproductive growth stages according to the extended BBCH-scale and physical-chemical changes of yellow pitahaya fruit (Hylocereus megalanthus)

The yellow pitahaya ( Hylocereus megalanthus ), native to Central and South America, has high nutritional and commercial value; however, its reproductive phenology and associated physicochemical changes remain poorly characterized under tropical growing conditions, limiting the establishment of precise management and harvest criteria. The aim of this study was to establish phenological growth codes and stages for its reproductive phase according to the extended BBCH scale (Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie) and to evaluate the physicochemical changes during fruit growth and maturation. Eighteen secondary growth stages were described, grouped into four main stages: bud development (5), flowering (6), fruit development (7), and maturation (8). Weight, volume, mesocarp and endocarp content and thickness, length, diameter, dry matter, total soluble solids, titratable acidity, and maturity index increased during growth; in contrast, epicarp content and thickness, as well as firmness, decreased. Fruit growth followed a double sigmoid pattern, and physiological maturity was reached approximately 17 weeks after anthesis, representing the most suitable stage for harvest under the studied conditions. The proposed BBCH-based scale and the integrated physicochemical indicators provide a practical framework to support decision-making in crop management, pest, nutrient, pollination, and optimal harvest timing, contributing to improved production efficiency and fruit quality in yellow pitahaya cultivation. The scale could also be applied to define the vegetative and reproductive growth stages of other crops.