PEREIRA FILHO, I. A.

PIRES, N. de M.

PRATES, H. T.

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ISCE 2000 - Poços de Caldas Poster POIOEFFECT OF LEUCAENA ON GERMINATION AND GROWTH ON WEEDSPECIES OF SAVANAS (CERRADO) MAIZE CROP.Hélio Teixeira Prates1, Nádja de Moura Pires', Israel Alexandre Pereira Filho".Leucaena is a legume found in tropical region and has been used as protein source for animal food andrecovery of degraded areas. Leucaena shoot as mulch or incorporated to the soil can liberate substances producedin its secondary metabolism, such as mimosine (b-[N-(3-hydroxi-4-oxopyridil)]-a-aminopropionic acid), whichhas the ability to influence the growth of other plants. The use of those compounds as alternative to syntheticherbicides has been the focus of research to prevent environmental contamination. Bioassays were conducted todetermine the potential effect of leucaena (Leucaena leucocephala) on the germination and growth of threeweeds occurring in the savanas maize crop, namely Amaranthus deflexus, Bidens pilosa, Siegesbeckiaorientalis. Two aqueous extracts from fresh and dry shoots were prepared in a concentration of 20% (w/v),using either hot (80 DC) and cold water. Different concentration (2.5; 5.0; 10.0 and 20.0%) of the aqueousextracts have not shown significant reduction on the germination of the species tested. However, the growth ofseedling of those species decreased with the increasing amounts of the aqueous extracts, specially with theextract obtained with hot water. RadicJe elongation was the most sensitive indicator of the effect of extracts.HPLC analysis showed mimosine in high concentration (-1400 mg ml,") in the hot cru de extract, but lowerconcentration (-530 mg mL-I) was found in the cold extract. It is supposed that mimosine is the substanceresponsible for the effect on the growth of the species tested.IPesquisador Embrapa Milho e Sorgo. C.Postal151, 35701-970, Sete Lagoas, MG.E-mail: htprates@cnpms.embrapa.br.2Bolsista Recém-doutor CNPq/Embrapa Milho e Sorgo.

Effect of Leucaena on germination and growth on weed species of savanas (cerrado) maize crop.

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