Light and IBA on microcuttings rooting of Rabbiteye and Southern highbush blueberries/Luminosidade e IBA no enraizamento de microestacas de mirtileiro dos grupos Rabbiteye e Southern highbush

The objective of this work was to evaluate the effect of different concentrations of indolebutyric acid (0-control; 500; 1000; 1500 or 2000 mg [L.sup.-1]) on microcuttings rooting of different blueberries species (Southern Highbush 'O'Neal', Vaccinium sp., and the Rabbiteye 'Aliceblue', Vaccinium ashei Reade), associated with the effect of light on the initial phase of the microcuttings rooting (14 days of darkness or natural light). After the treatment with IBA, the microcuttings were put into polystyrene trays which contained as substrate perlite + Plantmax® (1:1) and maintained in greenhouse equipped with an intermittent mist system. In 60 days after the microcutting placement, it was evaluated the percentage of both rooted and surviving microcuttings, roots number, roots length and the percentage of callus formation. Microcuttings of 'O'Neal' and 'Aliceblue' root well without IBA application. The light presence on the initial phase of rooting does not affect the rooting capacity of the microcuttings. The treatment with darkness in the initial rooting phase reduces callus formation, promoting a decrease of microcuttings survival and rooting percentage. Index terms: Vaccinium spp., vegetative propagation, darkness, IBA. O objetivo deste trabalho foi avaliar o efeito de diferentes concentracoes do acido indolbutirico (0-controle; 500; 1.000; 1.500 e 2.000 mg [L.sup.-1]) no enraizamento de microestacas de mirtileiro de especie e grupos distintos (cultivar O'Neal, Vaccinium sp., grupo Southern highbush e cv. Aliceblue, Vaccinium ashei Reade, grupo Rabbiteye), associado ao efeito da luminosidade na fase inicial do enraizamento das microestacas (14 dias de escuro ou luminosidade natural). Apos o tratamento com IBA, as microestacas foram colocadas em bandejas de poliestireno expandido contendo como substrato perlita + Plantmax® (1:1) e mantidas em telado equipado com nebulizacao intermitente. Aos 60 dias apos o estaqueamento, avaliaram-se a porcentagem de microestacas enraizadas, porcentagem de microestacas sobreviventes, numero medio de raizes, comprimento medio de raizes e a porcentagem de formacao de calo. Atraves dos resultados obtidos, concluiu-se que, para o enraizamento de microestacas de mirtileiro das cultivares O'Neal e Aliceblue, nao e necessaria a aplicacao de IBA. A presenca de luz na fase inicial do enraizamento nao interfere na capacidade de enraizamento das microestacas. O tratamento com escuro na fase inicial do enraizamento reduz a formacao d