Giovana Bomfim de Alcantara

Organogenesis and transient genetic transformation of the hybrid Eucalyptus grandis × Eucalyptus urophylla

The hybrid Eucalyptus grandis x Eucalyptus urophylla presents high levels of productivity and potential for use in paper, cellulose and fiber industries. The bud organogenesis from leaf explants of two clones of E. grandis × E. urophylla was studied in order to verify the effect of several factors: subculture duration on multiplication medium, type of explants, entire and half leaves: basal and apical portions, and duration of the culture on a regeneration medium. Differences in organogenic capacity of the two clones tested were observed. The explant most recommended for organogenesis is the basal section of the leaf collected from shoot clusters subcultured every 17 days. Moreover, the leaf explants must be transferred to a fresh bud induction medium every five days. This study also aimed at evaluating factors affecting the genetic transformation of leaf explants with the uidA gene, via co-cultivation with Agrobacterium tumefaciens, such as the pre-culture of the explants on a specific medium, the duration of their co-culture with the bacteria and the addition of acetosyringone to the culture media. The best conditions for the expression of the uidA gene were two days of pre-culture of the leaf tissues, three days of co-culture with the bacteria and the addition of acetosyringone in pre- and co-culture media.

Efeito dos ácidos naftaleno acético e indolilbutírico no enraizamento de estacas de jambolão [Syzygium cumini (L.) Skeels]

Jambul usually propagates by seeds, which causes variability in the descendant plants and represents a problem in the formation of commercial orchards. The development of a protocol for vegetative propagation by cuttings would enable the reproduction of all features of the Mother plant, uniformity in populations and easy propagation. The aim of this work was to evaluate the effect of naphthaleneacetic acid (NAA) and indolebutyric acid (IBA) on rooting of jambul cuttings. Twelve-cm-long cuttings from the median region of branches were prepared through bevel cut in the base and right cut above the last axillary bud, keeping one pair of halved leaves. Cutting bases were immersed for 10s in aqueous solutions containing NAA or IBA at 0, 500, 1000 and 1500 mg L-1 concentrations. Plastic trays containing medium sand were used in the planting. The cuttings were kept in a greenhouse under intermittent nebulization and, at 120 days after planting, the following variables were evaluated: percentage of rooted, with calluses, alive (not-rooted and without calluses) and dead cuttings; length of the three largest roots (cm); and number of roots per cutting. The best rooting was observed by using 1000 mg L-1 of both tested plant growth regulators. Rooting percentage was slightly higher under NAA relative to IBA.

Substratos, concentrações de ácido indolbutírico e tipos de miniestacas no enraizamento de melaleuca (Melaleuca alternifolia Cheel)

Melaleuca alternifolia tem como produto principal o oleo essencial extraido das folhas devido as propriedades antifungicas e antibacterianas. Pouco se tem relatado sobre a propagacao desta especie, sendo a miniestaquia uma alternativa para a propagacao vegetativa de clones superiores visando a implantacao de campo de producao. Este trabalho teve como objetivo avaliar o efeito de diferentes substratos, concentracoes de AIB, e tipo de miniestaca, no enraizamento de Melaleuca alternifolia. No primeiro experimento foram testados os substratos, areia de granulometria media, Plantmax HT®, Golden-Mix® e vermiculita. No segundo experimento foram avaliadas diferentes concentracoes de AIB (0, 500, 1000 e 2000 mg L-1), em dois tipos de miniestacas (apical e mediana). As miniestacas foram confeccionadas com 5 cm de comprimento, mantidas em casa de vegetacao com nebulizacao intermitente, e, apos 45 dias do plantio, foram avaliadas as porcentagens de miniestacas enraizadas, com calos e nao responsivas, o numero de raizes formadas por miniestaca e o comprimento das tres maiores raizes (cm). O substrato Golden-Mix® e as miniestacas coletadas da porcao apical do ramo submetidas ao tratamento com 500 mg L-1 de AIB apresentaram maior porcentagem de enraizamento e melhor qualidade do sistema radicial.