Assessment of phenotypic diversity of local Algerian date palm (Phoenix dactylifera L.) cultivars

The Date palm is a strategic fruit crop in Algeria, which is one of the largest producers of dates in the world and contains about one thousand cultivars. However, the practice of monovarietal culture threatens the biodiversity of date palm leading to severe genetic erosion. This study aimed at phenotypic diversity assessment among 26 Algerian date palm cultivars grown in Ziban region. In total, 52 morphological markers measured separately on both vegetative and reproductive parts were treated using multivariate analysis. The results showed a great morphological variability among local cultivars. Overall, correlation matrix showed mainly high positive correlations between most of the vegetative and reproductive characters. Principal component analysis (PCA) defined the most discriminants characters responsible of the observed variability. In fact, among the 27 vegetative traits analyzed in this study, ten related to the different descriptors of the leaf, rachis, leaflet and spines allowed a reliable differentiation among cultivars out of the period of fructification. As regards to the reproductive traits, among the 25 descriptors used twelve traits, describing the fruit and bunch, were the most discriminants. The cluster analysis (CA) showed associations between cultivars with similar characteristic related to the palm or to the fruit and enabled the identification of three main phenotypic clusters for both vegetative and reproductive characters. Dissimilarity levels ranged from 0.064 to 1.148 for vegetative characters, and from 0.036 to 1.256 for reproductive characters. Similarities between PCA and CA clustering were observed in this study. Furthermore, the obtained results agree with farmers characterization oriented towards important agronomic traits. The data obtained here would help to create a phenotypic database and use the most discriminants descriptors found in this study for a large-scale phenotyping.