IN-VITRO ROOTING OF MICROPROPAGATED SHOOTS FROM JUVENILE AND MATURE PINUS-PINASTER EXPLANTS - INFLUENCE OF ACTIVATED-CHARCOAL

The ability for adventitious rooting of micropropagated shoots from ju venile and mature Pinus pinaster Ait. explants was assessed in vitro o n a rooting expression medium. The different rooting traits observed, namely the rooting rate, the number and the length of the adventitious roots, and the root score, were greatly influenced by the age of the donor plant: 98% of juvenile explants rooted, while only 49% of mature explants did. Addition of activated charcoal in the rooting expressio n medium improved the overall rooting capacity of the mature explants to an average of 78%. Whatever the plant material, the number and the length of the adventitious roots, as well as the root score, fluctuate d according to the sampling date.