A MODIFIED METHOD FOR THE IN VITRO ROOTING AND SUBSEQUENT GROWTH OF STRAWBERRY MICROCUTTINGS

Low quality of micropropagated plants is mostly related to low survival rates of the plantlets during acclimatization and poor performance of weaned plants. The purpose of this work was to examine the possibility of a rooting medium to enhance these quality traits. Unrooted plantlets, derived from in vitro proliferated microshoots of two commercial strawberry cultivars, 'Elvira' and 'Selva', were grown for 3 weeks on four different media. The rooting ability, the acclimatization of rooted plantlets and the performance of weaned plants were tested in order to choose the most economic and effective medium. The media tested were: (a) MRA, Murashige and Skoog agar medium with 30gL-1 sucrose and plant growth regulators, (b) MRXA, Murashige and Skoog liquid medium with 30gL-1 sucrose and plant growth regulators, (c) MSYA, Murashige and Skoog agar medium with 15gL-1 sucrose without plant growth regulators and (d) ENSHI, Enshi liquid medium, which contains only inorganic salts. Rooting and acclimatization were not significantly different in all four media tested. Fresh and dry weight of rooted plantlets did not differ either. Rooting on MSYA and ENSHI media showed that 'Elvira' and 'Selva' did not need growth regulators for root development. Weaned plantlets rooted on ENSHI medium had a significantly better performance two months after the acclimatization period, as long as leaf and root formation was concerned. Moreover, plantlets rooted on ENSHI medium gave a significantly higher number of daughter plants. Though the ENSHI medium contained no organic substances, it enhanced photo-autotrophic development which resulted to the development of more functional roots.