Assessment of genetic diversity and cross-compatibility among pitaya (Selenicereus spp.) genotypes

New pitaya (Selenicereus spp.) cultivars can be obtained through the selection of genotypes and the development of hybrids from intra- and interspecific crosses. This research was carried out to evaluate the compatibility of intra- and interspecific crosses between S. undatus and S. monacanthus through controlled and natural pollination, and to assess the genetic diversity of the plants using SSR molecular markers. Intraspecific and interspecific diversity was assessed using 29 SSR molecular markers. Interspecific crosses between S. undatus and S. monacanthus showed compatibility, while intraspecific crosses involving the studied genotype of S. monacanthus were not viable, and those with S. undatus resulted in low fruit set rate. Controlled interspecific crosses between S. undatus and S. monacanthus ensured a higher fruit set rate and the production of fruits with larger size and a higher number of seeds. Interspecific cross-pollination of S. undatus with S. monacanthus pollen improved the quality of its fruits. The genetic diversity of the orchard favored the production of better-quality fruits. The population of S. undatus and S. monacanthus in the studied orchard was probably formed by a single clone.