Study on fruit and seed morphology and morphometry, seed phytochemicals, and germination characterization in three populations of Echinocereus stramineus (Cactaceae) at Ciudad Juárez Municipality, Chihuahua, Mexico

In this study, the fruit and seed morphological and morphometric parameters, the seed phytochemical content, and the germination process were analyzed for three populations of Echinocereus stramineus located at Juárez Municipality, Chihuahua, Mexico. The morphometric variables were measured for each fruit and seeds obtained from each one. The seeds were subjected to three times of immersion in H2SO4 as scarification treatment, allowing the seed development for 21 days for the characterization of the germination process. The germination percentage, mean germination time, germination speed, and mean germination speed were calculated. The seedling morphometry was also measured for all treatments. The concentration of reducing sugars, total phenols, tannins, flavonoids, and antioxidant activity (DPPH and FRAP) were determined for seeds under basal conditions. The fruits from the three populations showed significant differences in length and width, with the Sierra of Ciudad Juárez (SCJ) population having the longest and widest fruits. The SCJ seeds had the highest mass values, while those from the Sierra of Presidio (SP) and SCP populations showed the highest length, length/width ratio, area, and perimeter. Immersion in H2SO4 improved the germination percentage in SCJ and SP seeds. This treatment also caused a gradual decrease in the mean germination time and a progressive increase in the mean germination rate and germination speed index across seeds from all three populations as the immersion time increased. Similarly, the seedling stem length and area in SP seeds increased with immersion time. The seeds from the SP population had the highest reducing sugar content, while those from the Sierra of Samalayuca (SS) population showed the highest levels of flavonoids, phenolics, tannins, and antioxidant activity.