No abstract

A new species of Manihot has been collected from Fortaleza, Ceará state, Brazil. It was grown at the living collection in the experimental station, University of Brasilia since 1980 and left for natural reproduction. It bred true during all these years giving rise to identical typical plants of the ancestor one. The closest species to it is M. glaziovii. Apparently this new species was formed by sporadic hybridization between M. glaziovii and cassava itself in its natural habitat, Ceará. It possesses morphological marker gene of the latter one which is ribbed fruit that is found only in cassava. Interspecific hybrids produced experimentally between M. glaziovii and cassava showed similar morphological markers. Exam of its ovules revealed formation of multiple embryos, an indicator of apomixis. Grafting it with common cassava was compatible, giving increased root size up to seven times.

ABSTRACT. A molecular, anatomical and cytogenetic study of an interspecific hybrid between Manihot esculenta (cassava) and the wild species M. oligantha was carried out. Cytogenetics revealed relatively complete chromosome pairing and high viability of the pollen grains. Ovule structure examined by the clearing method showed polyembryony in 2.7% of the ovules. Doubling of the chromosome number resulted in an increase in polyembryony of up to 18% and a reduction in pollen viability. Multivalent formation was also observed. An anatomical study of stems of diploid and tetraploid hybrids showed a larger number of vascular bundles in the tetraploid type.

Effect of sucrose, kinetin, isopentenyl adenine and zeatin on the development of embryos of Heliconia rostrata in vitro Embryos from mature fruits of Heliconia rostrata were excised and cultured in basal medium containing MS salts, vitamins and sucrose. Sucrose was essential for embryo development. In meclium without sucrose the embryos died in culture. Sucrose concentrations of 1%, 2% and 3% (w/v) were beneficial for embryo development. Sucrose concentrations of 6%, 9% and 12% (w/v) inhibited embryo growth. The addition of kinetin, isopentenyl adenine and zeatin did not improve embryo growth and development.

Resumo -O objetivo deste trabalho foi avaliar os efeitos da adição de benzilaminopurina (BAP), em combinação com o ácido naftalenoacético (ANA), e dos períodos de subcultivo, na formação de brotações in vitro de abacaxizeiro ornamental. O meio básico líquido consistiu de sais minerais MS e vitaminas. O delineamento experimental utilizado foi o inteiramente casualizado, em esquema fatorial 6x2x4, com seis concentrações de BAP (0, 0,125, 0,25, 0,5, 1 e 2 mg L -1 ) e duas de ANA (0 e 0,1 mg L -1 ), e quatro períodos de subcultivo (30, 60, 90 e 120 dias). Os explantes consistiram de brotações individuais de 1 cm de comprimento, oriundas da cultura in vitro. A formação de novas brotações foi observada em meio suplementado com BAP, em todos os períodos de subcultivo. O maior número médio de brotos por explante foi obtido em meio com a concentração de 1,2 mg L -1 de BAP e 120 dias de subcultivo.Termos para indexação: Ananas comosus, cultivo in vitro, micropropagação. Adventitious shoot of ornamental pineapple under benzylaminopurine, naphthalene acetic acid and subculture period effectAbstract -The objective of this work was to evaluate the effect of benzylaminopurine (BAP)