Allelopathic effect of crotalaria (Crotalaria juncea L.)and coquito (Cyperus rotundus L.) extracts on weeds and annual crops

Efecto alelopatico de extractos de crotalaria (Crotalaria juncea L.) y coquito (Cyperus rotundus L.) sobre malezas y cultivos anuales

The present work was done during the second semester of 2001 and the objective was to determine the allelopathic effect of crotalaria ( Crotalaria juncea L.) and coquito ( Cyperus rotundus L.) extracts on the emergency and growth of several weeds and crop species using a randomized block design. The extracts were obtained from adult plants of coquito and Crotalaria by maceration of leaves in the presence of 96% cold ethanol, and were sprayed in pre and post-emergency on coquito, meloncillo (Cucumis melo L.), caminadora (Rottboelia cochinchinensis L.), mentolada ( Stemodia durantifolia ), maize ( Zea mays L.), cotton (Gossypium hirsutum L.), rice ( Oryza sativa L.), bean ( Phaseolus vulgaris L.). The results in pre-emergency showed allelophatic effects of crotalaria extracts on the emergency of coquito, mentolada and cotton, while the emergency of caminadora was affected by the coquito extract. Dry matter, leaf area and number of leaves were not affected by the extracts. In post-emergency, it was observed that plant height of maize, cotton and bean was affected by the coquito extract, while plant height of meloncillo, coquito and caminadora was affected by crotalaria extracts. Leaf number of mentolada and dry matter of meloncillo, coquito and maize were affected by coquito extract while the same variables were affected in mentolada and caminadora by crotalaria extracts. The leaf area was affected in all species but rice sproyecl with coquito extracts.

1. CONALGODON. 1998. Principales indicadores del cultivo del algodón en Colombia, 1996-1997 y estimación para 1998, p.
2. Cousens, R. y M. Mortimer. 1995. Dynamics of weed populations. Cambridge Univ. Press, Cambridge, p.??
3. Francis, I. y Ortega, A. 1986. Estudio alelopático de tres especies de maleza sobre tres cultivos en el valle del sinú medio. Tesis Ingeniero Agrónomo. Universidad de Córdoba, Montería. Hoyos, F. y García, E. 1999.
4. Estimación de la variabilidad genética en una población criolla de berenjena en el departamento de Córdoba. Tesis Ingeniero Agrónomo. Universidad de Córdoba. Montería.
5. Muller, C. 1966. The role of chemical inhibition (Allelopathy) in vegetational composition. Bull. Torrey Bot Club 93: 332-351.
6. Tirado, G. 1999. Estudio del efecto bioherbícida de extractos vegetales para el manejo sostenible de malezas en el cultivo del algodón en el caribe seco. Tesis Ingeniero Agrónomo, Universidad del Magdalena, Santa Marta.