Phenotypic diversity of Opuntia ficus indica (L.) MILL. in the Algerian steppe

Opuntia ficus indica (L.) is interesting; it is used as forage, medicinal plant and as food (sweet fruits). Moreover, the cacti involve the CAM photosynthetic pathway which allows great water-use efficiency. In Algeria, despite their vegetative propagation, the wild accessions of this species showed significant diversity. In order to evaluate this diversity, 20 accessions of O. ficus indica L. were collected from different bioclimatic localities in Algeria. Morphological characterization of these accessions was performed. Thirty one qualitative and quantitative morphological features of six cladodes per accession were studied (measured or observed), then subjected to one-way analysis of variance (ANOVA), the principal component analysis (PCA) and the factorial correspondence analysis (FCA). The factorial analysis of the qualitative features separates the accessions into two forms (spiny and spineless). The bioclimatic effect on these features was negligible. However, ANOVA and PCA analysis of quantitative features allowed detecting a significant diversity within and between accessions. Spiny forms showed high variation in comparison to spineless forms; thus, under bioclimatic effect, three spiny groups were illustrated. This illustration allowed detecting a gradual variation of the following features: aptitude and length of spine, number of spine per areole, number of areole per face and cladode width. A significant correlation was found between these features and the classical Emberger's pluviometric quotient (Q2). The results presented in this paper confirmed our hypothesis about the existence of a gradual variation of the spines and areoles traits, which seems to be a response to the bioclimatic effect.