Title : Effect of the crossing on the characterization of new Tunisian olive oil varieties
The most cultivated oil variety in Tunisia “Chemlali Sfax” has a moderate rate of oleic acid (55-64 %) and is relatively rich in palmitic acid (17-22 %), which makes its oil stiff at low temperature. To resolve this problem, a genetic improvement program by controlled crosses between Chemlali Sfax and other Tunisian and foreign varieties was started in 1993 and generated a collection of 1200 hybrids. Five new olives (Olea europaea L.) variety issued from this Tunisian breeding program were released in 2017.
The aim of this study is to characterize the morphological parameters about leaf, fruit and stone; also, the olive fruits characteristics (weight, pulp/stone ratio and maturity index) and the oil quality of the five new olive progenies. These five new olive trees obtained through controlled crosses between Chemlali Sfax and other Tunisian and foreign varieties are as follows: Janouby Mwaref is obtained from an unknown cross, Chemlali Mhassen from Chemlali Sfax self-pollinated, Zeitoun Allyssa from Chemlali Sfax * Chemchali Gafsa, Zeitoun Ennwader from Chemlali Sfax * Lucques and Zeitoun Ennour from Chemlali Sfax * Chemchali Gafsa.
A wide genetic diversity was observed within the new cultivars which differ from the typical cultivar. The morphological characterization of the hybrids related to the leaf, the fruit and the stone show that the characters of the fruit and the stone present a rather wide variability especially for the stone morphology. Hybrids keep the same morphological characters of parental varieties with the appearance of new characters after crossbreeding. The pomological parameters show that all the hybrids have an average weight of the fruit higher than Chemlali Sfax. The biochemical study of oils has shown a variable rate of oil yield between individuals. The oils tested are classified as extra virgin and have a fatty acid composition in accordance with the International Olive Council's standard, with high levels of oleic acid and low palmitic and linoleic acid, as well as high levels of polyphenols.