Tropentag, October 6 - 8, 2009 in Hamburg "Biophysical and Socio-economic Frame Conditions for the Sustainable Management of Natural Resources"

Weed Control in Maize Crop Using Leucaena leucocephala

¹Brazilian Agricultural Research Corporation (EMBRAPA), National Maize and Sorghum Center Research (CNPMS), Brazil
²Brazilian Agricultural Research Corporation (EMBRAPA), National Rice and Beans Research Center (CNPAF), Brazil

Abstract

Leucaena (Leucaena leucocephala (Lam.) de Wit) has been observed to control weeds when used as soil mulch. It contains mimosine, which, among other allelochemicals, is responsible for the allelopathic effect. In this work, the effects of leucaena shoots were assessed in field experiments against weeds of maize crop. A field experiment was carried out at National Maize and Sorghum Center Research located in Sete Lagoas, Minas Gerais State, Brazil, with four treatments: 1) 40 t ha^-1 of fresh leucaena shoots material used as mulch in soil; 2) 20 t ha^-1 distributed at the stadium of 3 leaves and the other 20 t ha^-1 distributed at the time of flowering maize; 3) manual weeding control and; 4) no weed control. The maize was sowing with spacing of 0.80×0.20 m², corresponding to a population of 60,000 plants ha^-1. Each month, phytotoxicity evaluations were made of leucaena on maize using a scale of notes of the European Council of Research on weeds (EWRC); as well as the identification and counting of weeds in a square metre in each plot. The values obtained for weed counts were converted to √x. In the plot with 40 t ha^-1 of leucaena as mulch the weed population was controlled without any damage to the maize grain yield. Was also observed that all treatments with leucaena showed reductions in amounts of weeds (grasses and broad leaves) compared to the control without weeding. The treatment whichreceived 40 t ha^-1 of leucaena showed fewer weeds than the treatment with repeated application of leucaena (20 +20 t ha^-1). It was observed that the use of leucaena as mulch did not cause phytotoxic effect on the maize development favouring an increase of nitrogen and phosphorus content in the leaves. This probably influenced the higher grain yield of maize in treatments with the addition of leucaena.

Keywords: Allelopathy, mulch, Zea mays

Contact Address: Jose Carlos Cruz, Brazilian Agricultural Research Corporation (EMBRAPA), National Maize and Sorghum Center Research (CNPMS), Sete Lagoass, Brazil, e-mail: zecarloscnpms.embrapa.br