EX-VITRO SURVIVAL, ROOTING AND INITIAL DEVELOPMENT OF IN-VITRO ROOTEDVS UNROOTED MICROSHOOTS FROM JUVENILE AND MATURE TECTONA-GRANDIS GENOTYPES

The influence of in vitro formed adventitious roots on acclimatization and initial ex vitro development of microshoots from juvenile and mat ure teak (Tectona grandis) genotypes was investigated. Overall, the in vitro rooted microshoots gave rise to higher survival and ex vitro ro oting rates 7 weeks after transfer than those not rooted in vitro. The age difference resulted in higher mortality rates 7 and 15 weeks afte r transfer for the microshoots of mature origin. The number of roots p roduced in vitro was observed to have a strong influence on the number of roots formed ex vitro 7 weeks after transfer and on the height of the microshoots at the time of transfer, 7 weeks later and to a lesser extent after 15 weeks. Differences in height at transfer between micr oshoots from the two origins of plant material tended to disappear dur ing the acclimatization process. Overall, more than 80% of the microsh oots that were initially transplanted from the various categories test ed were successfully acclimatized to ex vitro conditions. These result s are discussed considering mainly the influence of the maturation pro cess on the formation of ex vitro roots in in vitro-derived microshoot s and emphasizing the role of some basic exogenous factors.