Escontria chiotilla(Cactaceae): fruit development, maturation and harvest index

Abstract

Introduction . The edible fruit of jiotilla (Escontria chiotilla (Weber) Rose), a cactus endemic to Central Mexico, mature asynchronously and are characterized by the presence of bracts in the fruit peel (pericarpel). In order to establish a harvest index, a series of physical, chemical, and morphological classical parameters coupled with histological observations were determined at four different stages of fruit development from anthesis to mature fruit (S1–S4). Materials and methods. Flowers and fruit samples at each stage were collected for analysis from randomly selected plants from the desert shrub. Results and discussion. The single sigmoid growth curve exhibited major and minor changes between S2 and S3, S3 and S4, respectively. Growth cessation and maturation began at S3, the maximum concentration of total sugars occurred in S3, and the maximum value of firmness decreased in S3 and S4. A thinning of the fruit peel due to aerenchyma compression occurred in the transition period S3-S4 and fruit firmness was the mechanical parameter more closely associated with it. Poor relationships with ripening stages were shown by the other physicochemical parameters measured. Conclusions. We propose two morphological-histological indicators of harvest: 1) Fruit peel thickness, and 2) Color and texture changes of the bracts. The infundibuliform flower adapted to confine, protect and improve the aqueous reserves in the ovary of the cactus species becoming a special berry with a successful strategy for saving water during fruit development and ripening. This strategy involves structural and physiological adaptive traits to survive in arid lands.