IN VITRO MULTIPLICATION AND ELONGATION OF HYBRID CLONES OF Eucalyptus globulus

Os h\uedbridos de Eucalyptus globulus representam uma excelente alternativa para o setor de celulose e papel, em raz\ue3o dos ganhos em qualidade da madeira para a fabrica\ue7\ue3o de celulose. Entretanto, estes h\uedbridos t\ueam apresentado recalcitr\ue2ncia ao enraizamento advent\uedcio. Assim, a micropropaga\ue7\ue3o \ue9 apontada como a t\ue9cnica para o rejuvenescimento desses h\uedbridos adultos, viabilizando a propaga\ue7\ue3o clonal dos mesmos. O presente trabalho avaliou o cultivo in vitro de tr\ueas clones de Eucalyptus grandis x Eucalyptus globulus e de tr\ueas clones de Eucalyptus urophylla x Eucalyptus globulus, em rela\ue7\ue3o \ue0 multiplica\ue7\ue3o in vitro, no meio MS suplementado com 0,5 mg L-1 de BAP e 0,01 mg L-1 de ANA, bem como o efeito das concentra\ue7\uf5es de 0,25; 0,50; 0,75 e 1,0 mg L-1 de AIB e dos meios de cultura MS e JADS no alongamento in vitro das brota\ue7\uf5es. Os clones diferiram quanto \ue0 multiplica\ue7\ue3o in vitro das brota\ue7\uf5es e apresentaram uma taxa de multiplica\ue7\ue3o m\ue9dia dos clones de 3,0 tufos de brota\ue7\uf5es em cada subcultivo, ao longo dos 25 subcultivos realizados. No alongamento in vitro, os clones diferiram quanto \ue0s concentra\ue7\uf5es de AIB adequadas para provocar o alongamento, bem como em rela\ue7\ue3o aos meios de cultura MS e JADS. O intervalo m\ue9dio entre 0,40 e 0,80 mg L-1 de AIB proporcionou o maior n\ufamero e comprimento das brota\ue7\uf5es alongadas in vitro e com maior vigor.Eucalyptus globulus hybrids represent an excellent alternative to the pulp and paper sector, because of gains in wood quality for pulp. However, these hybrids have shown recalcitrance to adventitious rooting. Thus, micropropagation is considered the technique for rejuvenating adult genetic materials, allowing its clonal propagation. This study evaluated the in vitro culture of three clones of Eucalyptus grandis x Eucalyptus globulus and three clones of Eucalyptus urophylla x Eucalyptus globulus in relation to in vitro multiplication on MS medium supplemented with 0.5 mgL-1 BAP and 0,01 mgL-1 NAA. The effect of IBA concentrations (0.25; 0.50; 0.75 and 1.0 mg L-1) and MS and JADS culture media was evaluated on in vitro elongation. The clones differed during in vitro multiplication of shoots and they had an average multiplication rate of 3.0 shoot clusters in each subculture. The responses of the clones to different concentrations of IBA, as well as to MS and JADS culture media differed for elongation in vitro. The range between 0.40 and 0.80 mg L-1 AIB provided the highest number and length of in vitro elongated shoots and the best vigor of shoots