Changes in the fruits and seeds morphometric, germination, phytochemicals content, and antioxidant capacity in seed ripening of Echinocereus stramineus

Within the cacti family, most studies have focused on the physicochemical characterization of the stems, fruits, and seeds from Mammillaria, Opuntia, Hylocereus, and Stenocereus genera. However, few information is focused on the morphological and physicochemical characterization of the stems, fruits, and seeds of other genera widely distributed in the arid and semiarid zones of the Chihuahuan desert, such as the genus Echinocereus. The objective of this study was to analyze the fruit morphology, morphometry, germination process, and phytochemical content in four stages of seed in fruit ripening from E. stramineus. Morphometric parameters were measured by picking ten fruits and sixty seeds for each ripening stage. The characterization of the germination process included the germination percentage, mean germination time, germination speed, and mean germination speed which were computed 21 days after germination. The quantification of total phenols, flavonoids, tannins, reducing sugars, protein, and antioxidant activity of seeds was determined using colorimetric approaches under basal conditions. The morphometric results revealed a negative correlation between the fruit ripening stage and total mass (r= -0.980, p = 0.020), shell mass (r= -0.986, p = 0.014), pulp mass (r = -0.979, p = 0.021), fruit length (r = -0.978, p = 0.022), fruit width (r = -0.968, p = 0.032) and fruit area (r = -0.960, p = 0.04). The germination characterization process showed a negative association between the fruit ripening stage and the seed germination percentage (r = -0.979, p = 0.021) and between the seed mean germination time and the mean germination speed (r= -0.986, p = 0.014). The content of flavonoids, reducing sugars, proteins, and antioxidant capacity showed significant differences among the four stages of fruit ripening; however, no association was found between seed phytochemical content and the ripening stage. This study provides the first data on seed phytochemicals and information on the germination process of E. stramineus seeds.