Phenotypic diversity of cactus pear (O. ficus-indica (L.) Mill.) populations in Tigray, northern Ethiopia, based on qualitative traits

Cactus pear (Opuntia ficus-indica) is a common plant in Ethiopia/Tigray and is known for its various uses, but the diversity of the cactus pear population in Ethiopia varies according to farmer accounts. Therefore, this study was conducted to determine the genetic diversity of the cactus pear population. Descriptive statistics were applied to the qualitative data using SPSS software to calculate frequency distributions. Principal component analysis (PC) was also performed to analyse the qualitative characteristics. The degree of morphological diversity was expressed as the Shannon–Weaver index (H’). Most of the cultivars in this study exhibited ovoid fruit shapes with shape indices ranging from 0.65 to 0.79. Judging by eigenvalues greater than 1, the total deposit rate for the first four PCs was 76.71%. PC1 was positively associated with the cladode shape, fruit shape, fruit shape index, and cladode shape index. Differences in the frequency distributions of morphological parameters among the districts were detected. The orange pulp colour type of cactus pear was dominant in the lower altitudinal areas while the red pulp colour type was dominant at middle altitudes. At lower altitudes, the shape of the cladodes was more elliptical. The number of glochids per fruit decreased with increasing altitude. The H’ for qualitative features ranged from 0.80 to 1.00. The average H’ values for the six traits were greater in the Tsirae-Womberta collection (0.76) but lower in those of the Saesie district (0.64), followed by the Enderta (0.65) and Gulo-Mekeda districts (0.65). The total H’ values across the altitudinal classes varied from 0.60 for pulp colour and glochids to 0.88 for peelability.