Study of the variability, correlation and importance of chemical and nutritional characteristics in cactus pear (Opuntia and Nopalea)

Cactus pear is a widely cultivated plant in the Brazilian semiarid region that contributes significantly to the feeding of livestock, especially in times of drought. Because it has a great phenotypic variability among the varieties cultivated in Brazil, there is need to characterize the diversity of chemical and nutritional characteristics. The objectives of this study were to characterize the diversity in seven varieties of cactus pear, genera Opuntia and Nopalea, through 20 chemical and nutritional characteristics, and to determine the correlation and importance of these characteristics in the variability among genotypes, using multivariate analysis techniques. The study was conducted at the IPA (disambiguation) experimental station in Arcoverde-PE, using randomly designed blocks with three replications. The materials IPA-100003, IPA-200016, IPA-200008, IPA-100004, IPA-200021, IPA-200205 and IPA-200149 were evaluated for 20 quantitative characteristics of the plants. The collected data were analyzed by analysis of variance by F test and means grouped by the Scott-Knott test (p < 0.05). The broad-sense heritability and correlation among characteristics were estimated. The diversity was estimated by multivariate methods. Analyses of variance and diversity revealed significant differences among genotypes, with the possible formation of three or four genetically distinct groups. The heritability values ranged from 78.04 to 99.99%. The content of flavonoids and potassium were the characteristics that contributed most to the divergence among the materials. These characteristics are significantly correlated with the nitrogen-free extract and phenolic compounds. The confirmation of variability among the cactus pear varieties studied serves as potential materials in breeding programs. Multivariate analysis techniques are effective in the study of diversity of species of the genera Opuntia and Nopalea.