THE EFFECT OF EXPLANT TYPE AND NUTRIENT MEDIUM ON THE IN VITRO PROLIFERATION OF OLIVE (OLEA EUROPAEA L. 'CHONDROLIA CHALKIDIKIS')

Abstract

The effect of explant type and nutrient medium on in vitro proliferation of olive (Olea europaea L. ‘Chondrolia Chalkidikis’) was studied. The explants, taken from shoots of olive plants grown in a greenhouse, were divided into three groups: young shoot tips, uni- and bi-nodal explants. Furthermore, half of the explants maintained part of their leaves while the rest were defoliated. The explants were established in the OM nutrient medium containing BA (1.0 mg L-1) and IBA (0.5 mg L-1). After a 4-week period, it was observed that the type of explant affected significantly the in vitro proliferation of olive. Specifically, the bi-nodal explants without leaves had the highest proliferation rate and developed the greatest number and the longest new shoots. The young olive shoot tips died as a result of the disinfection process conducted before the establishment of the in vitro culture. Afterwards, three types of nutrient media were used for the in vitro multiplication of olive: the Olive Medium (OM), the Murashige and Skoog (MS) and the Woody Plant Medium (WPM). The concentration of the macronutrients of the above media was the normal or reduced to half or doubled (OM, ½OM, 2OM, MS, ½MS, 2MS, WPM, ½WPM, 2WPM). In all treatments BA (1.0 mg L-1) and IBA (0.5 mg L-1) were included. The experiment lasted 4 weeks. Not only the nutrient medium but also the macronutrients’ concentration affected the in vitro proliferation of olive. The highest proliferation rate was observed when the full strength OM nutrient medium was used, while the MS medium presented the smallest rate, independently of the salt concentration. The greatest number of new shoots was developed in the 2WPM medium, while the longest ones in the full strength OM medium. Finally, hyperhydricity was observed in all the treatments but it was more severe in the cases of the explants cultured in the MS culture medium.