Clusters of commercial varieties of cactus pear and xoconostle using UPOV morphological traits
Keywords:Opuntia, UPOV, grouping, multivariate analysis.
Twenty nine cactus pear varieties and four xoconostle varieties were evaluated using 24 quantitative traits. Measurements of cladodes, flowers and fruits were performed according to the International Union for the Protection of New Varieties of Plants (UPOV) guidelines for tests of distinctness, uniformity and stability of cactus pear and xoconostles. Database conformed by 29 varieties and 24 traits was used in order to carry out a cluster analysis based on the Euclidian distance and the Ward?s method, and a discriminant canonical analysis. Three well–defined groups were evidenced and confirmed by the cubic criteria of clustering. Four xoconostle varieties formed an independent group, and the rest of varieties were divided in the other two groups. The second group included nine varieties used mainly for “nopalitos” production and cactus pear production („Burrona?, „Cristalina?, „Naranjón Legítimo?, „Fafayuca?, „Pico Chulo? and „Torreoja?). The third group included 16 varieties: 9 and 7 varieties with yellow and green fruits, respectively. The first canonical function (CF1) accounted for 88% of the total variation, and the two estimated functions together explained all the variation. CF1 was related with peel thickness, pulp weight, fruit weight/peel weight ratio and maximum fruit diameter; meanwhile CF2 structure was defined mainly by receptacle diameter and peel weight. Thus Opuntia spp. fruit characters, and to a lesser extent, the receptacle diameter could be the most discriminating characteristics. Our results suggest at least one group of cactus pear varieties are closely related to the degree of human use or domestication.