Morphological variability of prickly pear cultivars (Opuntia spp.) established in ex-situ collection in Tunisia

Abstract

Belonging to the succulent plants’ family, the Cactaceae, Barbary fig tree (Opuntia ficus-indica) is an excellent arid-resistant species, implicated in erosion control. In Tunisia, the Barbary fig is one of the country's main fruit species, mainly used for its edible fruits. Thus, forty-eight ecotypes belonging to four species of Opuntia genus (Opuntia ficus-indica, Opuntia engelmannii, Opuntia tomentosa and Opuntia undulata), were collected from the INRAT collection in northern Tunisia. In order to conduct a morphological study aiming to estimate the morphologic variation degree, 63 phenotypic characteristics that comprised 30 quantitative and 33 qualitative traits recorded to Opuntia trees, cladodes, flowers and fruits were detected. Based on quantitative and qualitative parameters separately, results of dendrograms were consistent with Principal Component Analysis (PCA) and Multiple Correspondence analysis (MCA) results. These analyses showed that the four quantitative variables: (the mean number of seeds per fruit, the mean number of areolas per cladode, the mean number of areolas at the cladode border and fruit mean weight) and the three qualitative variables: (cladode shape, pulp color and fruit color) are the most discriminating parameters in differentiation between the four studied species. Indeed, dendrograms showed that studied ecotypes were classified independently of their geographical origins and corresponding species. In this study, fourteen quantitative parameters were revealed using one-way analysis of variance (ANOVA). For the qualitative variables; Z test, Kruskal-Wallis test and chi-square analysis were performed and non-significant values were detected. In conclusion, our results revealed a very high level of morphological variability and a great similarity between O. ficus-indica and O. engelmannii that will be very useful for genetic breeding and conservation programs.