Rev. Bras. de AGROCIÊNCIA, v.2, nº 1, 17-20, Jan.-Abr., 1996 17 MICROPROPAGATION OF BLACKBERRIES (Rubus sp.) CULTIVARS BOBROWSKI, Vera L. 1 ; MELLO-FARIAS, Paulo C. 2 & PETERS, José A. 1 1 UFPEL/IB/Laboratório de Cultura de Tecidos de Plantas - Campus Universitário - Caixa Postal 354 - Tel. (0532) 757316 - CEP 90010-900 - Pelotas/RS, Brasil. 2 UFPEL/FAEM/Deptº de Ciencia e Tecnologia Agroindustrial - Campus Universitário - Caixa Postal 354 - Tel. (0532)757258 - CEP 96010-900 - Pelotas/RS, Brasil. (Recebido para publicação em 20/12/95) ABSTRACT Experiments were carried out aiming to develop techniques for in vitro propagation of blackberries (Rubus spp.) plants. Multiplication were done from axillary buds wich were placed in MS (MURASHIGE & SKOOG, 1962) medium, supplemented with BA (benzylaminopurine), NAA (naphthaleneacetic acid) and GA 3 (gibberellic acid) in different concentrations and combinations. Subsequently, studies were done to determine the influence in rooting of the MS medium with all the salts reduced to 1/3, and with different concentrations of IBA (indolbutyric acid). Results indicated that the best multiplication of shoots was obtainned with BA (1.0 and 2.0 mg/l). The addition of NAA and GA 3 in media in these experiments didn't improve the multiplication rate. Rooting was succesfully achived with 100% rooted plants in all cultivars, with no differences significant differences among rooting media. Key words: Rubus, blackberry, fruit, micropropagation RESUMO MICROPROPAGAÇÃO DE AMORA PRÊTA (Rubus spp.). Com o objetivo de desenvolver técnicas de propagação in vitro de plantas de amora-preta (Rubus spp.), foi realizada a multiplicação de brotos com gemas axilares, os quais foram excisados e inoculados, em meio MS (MURASHIGE & SKOOG, 1962), suplementado com diferentes combinações e concentrações de BAP (benzilaminopurina), ANA (ácido naftalenoacético) e AG 3 (ácido giberélico). No enraizamento, utilizou-se meio MS reduzido a 1/3 da sua concentração de sais minerais, adicionado com AIB (ácido indolbutírico) em diferentes concentrações. As avaliações permitiram concluir que a multiplicação de brotos foi mais estimulada por BAP (1,0 e 2,0 mg/l). A presença de ANA e AG 3 nas concentrações utilizadas não melhorou as taxas de multiplicação. A taxa de enraizamento foi de 100% para todas as cultivares testadas, não havendo diferença significativa entre os meios utilizados. Palavras-chave: Rubus, amora-preta, fruta, micropropagação INTRODUCTION Blackberry belongs to the Rosaceae family, Rubus (Tourn) L. genus and Eubatus subgenus. Blackberry is a shruby tree with erect, semierect or creep grown habit, and most cultivars have thorny stems. Thornless blackberries are comercially propagated by tip layers or stem cuttings (BROOME & ZIMMERMAN, 1978; CALDWELL, 1984). According to Moore and Clark (1989), mentioned by FERNANDEZ & CLARK (1991), shoot emergence from root cuttings of the erect thornless blackberry "Navaho" has been poor, setting of rooted plants or closely spaced root cuttings was suggested to achieve adequate stands. Tip layering propagation requires a sizeable planting for the layering bed, few tips are avaiable per plant, and weed control among the layers is a problem. Propagation by hardwood stem cuttings is simple but rooting is not always satisfactory. Softwood cuttings root readily, but require considerably more care for successful plant production (BROOME & ZIMMERMAN, 1978). The use of tissue-cultured plants would eliminate the need for root pieces and allow uniform spacing of plants in the field (FERNANDEZ & CLARK, 1991). Nowadays, the tissue culture have been used in scions propagation, supplying thousands virus-free and genetically uniforms plants, and in a reduced time. However according to SKIRVIN et al. (1981), successful tissue cultures have been reported for many members of the genus Rubus involving callus cultures, shoot tips growth, parthenocarpic fruit and roots development. Despite these studies, no good system for the rapid proliferation of the trailing blackberry has been developed. Tissue culture may be the only practical method of a quickly redistributing virus-free material if strict certification programs for Rubus are put into effect. Tissue culture also offers additional opportunities for the rapid dissemination of new cultivar releases. Furthermore, plants can be produced during the entire