Integrated phenotypic, biochemical and SSR-based characterization of nutraceutical diversity in guava germplasm

Guava ( Psidium guajava L.) is an important tropical fruit crop valued for its nutritional quality, adaptability, and economic significance. However, the relatively narrow genetic base of cultivated guava necessitates systematic characterization of available germplasm to facilitate effective conservation and breeding. In the present study, 15 guava cultivars were comprehensively evaluated for morphological, biochemical, antioxidant, pigment, mineral, enzymatic, and molecular traits. Substantial variation was observed among cultivars for fruit and seed characteristics, fruit quality, and nutraceutical attributes. Fruit weight varied nearly five-fold (74.02–347.04 g), while marked variation was also observed for ascorbic acid, phenolics, flavonoids, pigments, and antioxidant activity. Black Guava showed comparatively high values for several antioxidant- and pigment-related traits, whereas Arka Kiran recorded the highest lycopene content, highlighting the potential of coloured-flesh cultivars as valuable nutraceutical resources. High broad-sense heritability and genetic advance for several traits suggested potential for effective phenotypic selection under the evaluated conditions. Exploratory principal component and cluster analyses visualized broad patterns of phenotypic and multivariate variation, while SSR-based analyses revealed molecular genetic diversity among the evaluated cultivars. VNR Bihi, L-49, Arka Kiran, and Black Guava showed promising and complementary trait profiles related to fruit size, nutritional quality, pigment content, and antioxidant capacity, respectively. Overall, the study provides an integrated assessment of phenotypic, nutraceutical, and molecular diversity within the evaluated guava germplasm and offers useful information for germplasm characterization, conservation, and preliminary parental selection.