Paulo Hercílio Viegas Rodrigues

Acclimatization of micropropagated Heliconia bihai (Heliconiaceae) plants

To evaluate the behavior of micropropagated heliconia seedlings during the acclimatization process using different substrates and shade levels, seedlings of H. bihai (Lobster Claw I) were planted in plastic trays using the substrates: washed sand, vermiculite (medium texture), and PlantMax® Horticultura, and shade cloths with percentages of 0% (full sun), 30%, 40%, 50%, 60%, 70%, and 80% of shade in relation to full sun. Best results were obtained for washed sand and PlantMax substrates at shade conditions starting from 50%, especially at 70% and 80%. Pre-existing roots from in vitro rootings were not functional, not presenting secondary roots, and showing root tissue necrosis. Acclimatized seedlings developed new roots. This finding suggests that this plant can be acclimatized without going through a laboratory rooting stage.

PROPAGAÇÃO DE MUDAS DE HELICÔNIA EM BIORREATOR DE IMERSÃO TEMPORÁRIA

Novas tecnicas de micropropagacao tem sido estudadas visando a otimizacao da producao e reducao dos custos de producao. Dentre elas, a tecnica de micropropagacao em biorreator de imersao temporaria destaca-se pela utilizacao do meio de cultivo liquido em um sistema automatizado. Neste experimento avaliou-se, em tres repeticoes, um biorreator artesanal de imersao temporaria, utilizando explantes de Heliconia champneiana Griggs cv. Splash, submetidos a tres subcultivos com quinze minutos de imersao em intervalos de uma hora (T1), quatro horas (T4), seis horas (T6) e oito horas (T8), em que foram avaliados o volume final de meio de cultivo, pH final, numero de brotacoes, massa da materia fresca, massa unitaria e a funcionalidade do sistema. Resultados das avaliacoes entre os tratamentos de imersao temporaria demonstraram que o melhor desempenho ocorreu no tratamento T1, sendo inviavel o tratamento T8 para esse tipo de cultura. Na comparacao com o metodo convencional (C), os tratamentos T1 e T4 foram superiores, demonstrando melhor eficiencia da imersao temporaria na producao de brotos. O prototipo do biorreator de imersao temporaria teve bom desempenho, sendo funcional, de facil manuseio e podendo ser utilizado no estudo de outras culturas.

Somaclonal variation in micropropagated Heliconia bihai cv. Lobster Claw I plantlets (Heliconiaceae)

The occurrence of somaclonal variation is described in various cultures of agronomic interest. Such variation can be of benefit in the development of new flower varieties. In this study, the occurrence of somaclonal variation in micropropagated changes of Heliconia bihai cv. Lobster Claw I was investigated. Stem apexes were introduced in MS culture media with the addition of 2.5 mg L-1 of benzylaminopure (BAP) and 500 mg L-1 of sodium cefotaxime. After selecting the apex stem, it was sub-cultivated in MS media and supplemented with 4.0 mg L-1 of BAP to induce side buds. To conduct the trial, 2,000 plants were selected and compared with plants originated from rhizomes. To calculate the percentage of the variants, the plant stature, the form and color of leaves and pseudostem were evaluated. The plants with buds presenting the same type of variation were considered as variants. The occurrence of three types of somaclonal variants was observed: Variation of the Chlorophyll in the Leaf, Low Stature Variant and Pseudostem and Petiole Color Variant, the latter with ornamental potential. The somaclonal variation rate for Heliconia bihai cv Lobster Claw I, under the proposed conditions, was 61.40%.

In vitro establishment of Heliconia rauliniana (Heliconiaceae)

The great interest for heliconias by the external market has placed this crop in a prominent position in the flower production chain. The small offer of healthy seedlings, however, the expansion of this activity. The presence of endophytic microorganisms such as Pseudomonas sp. represents an obstacle even for the evolution of heliconia tissue culture studies. Stem apices of Heliconia rauliniana were inoculated and analyzed in vitro to investigate the presence of endophytic microorganisms. An antibiotic analysis was also run for posterior microbiological control. The presence of Pseudomonas sp. and Klebsiella sp. in stem apices confirmed infection. Antibiotics such as chloramphenicol, cefotaxime and the association of both (chloramphenicol + cefotaxime) at rates of 50, 150, 250 and 500 mg L-1, were applied to the MS medium and supplemented with 3.5 mg L-1of 6-BA. After a 50 day-period, 500 mg L-1 of cefotaxime was the most efficient form to control endophytic microorganisms in this species of heliconia. The chloramphenicol, although effective for endophytic microorganism control, was inadequate for in vitro growth due to its cytotoxicity to explants.

Rooting of jade vine (Strongylodon macrobotrys A. Gray) cuttings treated with indolbutiric acid

A flor de jade e uma trepadeira da especie Strongylodon macrobotrys A. Gray, nativa das Filipinas. Possui inflorescencia pseudoracemosa de coloracao azul esverdeada, o que a torna unica e incomparavel. E considerada uma das trepadeiras mais admiradas e procuradas, apesar de rara nos jardins. Este trabalho objetivou avaliar o efeito da aplicacao de acido indolbutirico (AIB) no enraizamento de estacas dessa especie ornamental. Estacas herbaceas sem folhas e com um par de folhas cortadas ao meio, foram coletadas de ramos de uma planta adulta e bem desenvolvida de flor de jade e submetidas a imersao em solucao com AIB (0; 500; 1.000; 2.000 ou 4000 mg.L-1), durante 15 segundos. Posteriormente, a base dessas estacas foi enterrada em bandejas de poliestireno expandido, contendo vermiculita media (uma estaca por celula) e mantidas em câmara de nebulizacao intermitente por um periodo de 80 dias quando foram avaliadas quanto a porcentagem de enraizamento, numero de raizes e comprimento da maior raiz. Para a producao de mudas de flor de jade deve-se utilizar estacas herbaceas com folhas, tratadas com a concentracao de 2.000 mg L-1 de AIB

Determinação da DL 50 em explantes de Heliconia bihai (Heliconiaceae), empregando radiação gama.

A elevada importância economica das plantas ornamentais representa um estimulo para os melhoristas na obtencao de novos cultivares. Dentre as diversas tecnicas empregadas, a inducao de mutacoes utilizando radiacao gama pode apresentar resultados promissores em Heliconia . A determinacao da dose letal 50% (DL 50) no cultivo in vitro de H. bihai e o passo inicial para utilizacao desse metodo. Foram testadas as doses de 0, 10, 20, 30, 40 e 50 Gy de raios-gama em 25 apicescaulinares por tratamento. Os resultados indicam que a DL 50, para essa cultura in vitro , esta entre as doses de 30 e 40 Gy.