Influence of Woody Species in the Dynamics of Weeds in Agroforestry Systems in the Yucatan, Mexico
The factors that limit maize production in Yucatán, México are decreasing yields and a constant increase of weedy species. A strategy to deal with these problems is to develop diversified productive schemes, such as agroforestry systems (SAF). This study determined the cover dynamics and biomass of weeds in an SAF composed of forage trees and maize during two cropping cycles (CC). Leucaena leucocephala, Guazuma ulmifolia, and Moringa oleifera, associated with maize, and a plot of maize monocrop were evaluated with a complete random block design with three replications. Weed cover, biomass, diversity and density were measured at the beginning, middle and end of the two CC. The weeds were collected in squares delimited by 50´50 cm frames distributed randomly in each experimental unit, separated by species and dried. With this data, an ANOVA was performed, and when significance was detected, the Tukey test (p£0.05) was used. At the beginning of the first CC, the SAF Guazuma + maize had lower weed cover (41 %), while Moringa + maize was higher at the middle and end (71 and 49 %). At the beginning of the second CC, the Guazuma + maize SAF had less weed cover, and Guazuma + maize and Leucaena + maize were lower (54 and 48 %). In both CC, weed biomass in the SAF was almost half that of monocropped maize. At the end of both CC, the Guazuma + maize system had less weed diversity than the maize monocrop. At the beginning and end of the two CC, weed density was greater in the monocrop. Eighteen botanical families were identified and, of these, 21 % were leguminous. The suppression of weeds in the SAF was 23 to 36 %. Woody species in SAF reduce weed cover and biomass, relative to maize monocrop.