Bioclimatic Impact on the Carob Seeds Morphological Diversity in Morocco

Abstract

The carob tree, Ceratonia siliqua L., a typical thermophilic sclerophyllous species, is a multipurpose tree (agronomic, silvicultural and pastoral) with aromatic and medicinal properties. Due to its geographical distribution, it occupies different countries of the Mediterranean. In Morocco, this species spreads over the different bioclimatic from the arid in the south to the humid in the north. The present work, study the morphological diversity of the seeds of five carob tree ecotypes distributed along a rainfall gradient (from the arid in the south to the humid one towards the north of the country). The shape parameters studied are the length, width, thickness, weight, volume and density of the seeds.The results obtained show that the carob tree ecotypes are characterized by significant differences in the different morphological parameters of the seeds among the five ecotypes studied. Indeed, dry land seeds are generally reduced in length, volume and weight, while those in humid regions are larger in weight and size. Those of the dry sowing areas have moderate parameters. The variance analysis shows that the origin of the ecotypes hada significant effect on the various shape parameters. Moreover, the multiple comparison of averages revealed different distinct groups. ACP analysis revealed that seed weight and volume is strongly correlated with the first component (the bioclimatic origin and the annual rainfall of the site of origin). While the second component corresponds to the parameters of length, width and thickness of the seeds. As for the factor 3, it corresponds to the density of the seeds which is not dependent on the other variables.In terms of conclusion, it is deduced that in Morocco, the carob tree seeds are characterized by a large morphological diversity which varies according to the rainfall gradient.