Intraspecific variability of Quercus suber L. acorn morphology in Northwestern Tunisia

Abstract: This article deals with the morphology (length, diameter and weight) of the acorns of Quercus suber L. collected from seven sites chosen according to an altitudinal gradient in north-western Tunisia. The study looked at 31 trees and 2327 acorns. The comparative study showed that there are significant differences between trees at the station scale and between stations in terms of length, diameter and weight. Indeed, the highest length was observed in the Bellif population (41.05 ± 7.41 mm). However, the weakest was detected in the Ain Drahem population (26.38 ± 3.71 mm). The largest diameters were measured in the Ouchtata population and the smallest in the Ain Drahem population. As for the weight, it is also the Ain Drahem population which presented the lowest weights. The acorns of the Ouchtata population, on the other hand, presented the highest weights. The statistical study has shown that the correlation is negative and very highly significant between altitude and length, diameter and weight. Indeed, at low altitude, the acorns are more tapered than those at high altitude stations. Indeed, their acorns are more round approaching the diameters of those of Quercus canariensis Willd. This study should serve as a guide for the selection of fruit-producing trees with desirable morphological characteristics for the regeneration of natural forests of cork oak forests.