Phenological Stability, Fruit Growth and Fruit Quality Responses of Red Pitahaya Under Contrasting Live and Inert Stake Systems in the Ecuadorian Amazon

Live-stake systems used in red pitahaya (Hylocereus undatus) cultivation in the Ecuadorian Amazon represent a sustainable alternative for crop production; however, their effects on phenological development and fruit quality under humid tropical conditions remain poorly understood. This study evaluated phenological timing and fruit quality of red pitahaya cultivated under two live-stake systems (Spondias mombin and Erythrina sp.) and inert concrete stakes was evaluated over two consecutive production years. Phenological development was characterised using the Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie (BBCH) scale, while physical and chemical fruit quality attributes were assessed across different ripening stages. The duration of the principal phenological phases was highly consistent among stake systems, with only minor differences detected during reproductive bud development (BBCH 510–519), whereas flowering, fruit development, fruit ripening and the complete reproductive cycle did not differ significantly among systems. Analysis of covariance further showed that neither canopy shade (%) nor soil organic matter (OM), used as an indicator of soil fertility, significantly explained variation in the duration of the principal BBCH phenological phases. The complete reproductive cycle lasted approximately 56–57 days. Fruit quality was predominantly determined by ripening stage. Fruits harvested at BBCH 817 exhibited the highest fruit weight, pulp percentage and soluble solids content, while firmness declined progressively with ripening. Differences among stake systems were comparatively limited and trait-specific, with variation detected mainly in fruit weight, diameter and soluble solids content. Based on ripening-related changes in fruit quality, BBCH sub-stages 811–815 were more suitable for markets requiring greater firmness and postharvest potential. Contrastingly, sub-stage 817 was more appropriate for markets prioritising higher pulp percentage and soluble solids content. Reproductive phenology remained stable across the contrasting stake systems, while fruit quality responded primarily to ripening stage and, to a lesser extent, to the conditions associated with the different support systems. These findings provide practical criteria for harvest planning and support the use of live stakes as a viable agroforestry-based alternative for red pitahaya production under humid tropical conditions.