Abstract
The olive is a tree that has adapted very well to the Tunisian climate. Thus, olive cultivation has been in practice in Tunisia for millennia. Now, the cultivation of the olive tree occupies about 1.600 00 ha. Two main varieties of oil olives, namely, Chetoui in the north and Chemlali in the rest of the country, dominate olive plantations. The Chemlali variety is far more widespread. The gouvernorats of the Sahel, namely, Sousse, Monastir and Mahdia, and Sfax, count as the traditional areas where this variety is cultivated. From there, it has spread to occupy more than two-thirds of plantations, producing more than 60% of national oil produce.
Recent researches in identification, cloning, and genetic amelioration by crossing, have been undertaken for twenty years by Khlif, Trigui and collaborators on the Chemlali variety in Sfax. The study of this variety in the other regions of its traditional habitat constitutes a logical follow-up to the aforementioned regions. The aim of this work is to make observations that constitute a first step in the already ongoing process, whose objective is to be able to know about the capacities and potentialities of this variety.
A parcel of land has been chosen in each gouvernorat, where three Chemlali trees, aged 60 or more, have been marked as having approximately the same charge of small olives.
The method followed consists in taking two samplings of two kg of olives per tree at the beginning and end of discolouring. Part of this work consists in determining the mean weight of olives and the yield in oil and fat content per fruit have been done by NMR (nuclear magnetic resonance). The polyphenols content of oils has been done according to the Folin-Denis method.
The results have revealed that the mean weight of olives, the yield in oil, the oil content of olives, and the polyphenols content differ from one tree to another in the same parcel and vary from region to region.
These results confirm that the Chemlali variety is characterised by variability of its clones as has been demonstrated by research done on this variety in the Sfax region.