Morphological Diversity, Germplasm Characterization, and Selection Index Analysis of Husk Tomato (Physalis ixocarpa Brot.) from Oaxaca, Mexico

Husk tomato (Physalis ixocarpa Brot.) is a crop of major economic, cultural, and nutritional importance in Mexico and exhibits substantial genetic and morphological diversity. Characterizing this variability is essential for both germplasm conservation and breeding programs. During the spring–summer 2024 growing season, 28 husk tomato populations were evaluated at the Bajío Experimental Station (INIFAP), Guanajuato, Mexico, using a completely randomized design with 12 replications. Forty-one traits were assessed following UPOV and IPGRI descriptors. Cluster analysis, canonical discriminant analysis, and the ESIM selection index were applied. A total of 77 morphotypes were identified, exhibiting variation in 33 of the 41 evaluated traits, mainly related to growth habit, leaf morphology, fruit traits, and calyx attributes. Correspondence analysis revealed a close relationship between vegetative growth and fruit size. Cluster analysis clustered the morphotypes into six clusters with no clear geographic structure, suggesting extensive gene flow. Canonical discriminant analysis explained 94.65% of the total variation, identifying seed size, leaf dimensions, and number of anthers as key discriminant traits. The ESIM index highlighted six morphotypes with favorable agronomic and morphological combinations. These results provide a practical basis for the selection of parental materials in husk tomato breeding programs under diverse agroecological conditions.