The effects of parthenium weed density on yield attributes and yield of maize in Ethiopia

Parthenium weed is an invasive alien species in numerous countries around the world, including Australia. It has become a major weed species in tropical and sub-tropical cropping systems, in which it causes significant crop yield losses. However, information about economic thresholds of parthenium weed in different crops is currently lacking which is imperative for sustainable management of this species. The present study was conducted to determine the effects of different densities of parthenium weed (0, 5, 10, 15, and 20 plants m−2) on growth and yield of maize in Ethiopia. A strong linear relationship was observed between density and biomass of parthenium weed. Parthenium weed biomass also had strong negative correlations with yield and yield related traits of maize. Density of parthenium weed had a significant negative effect on growth and yield of maize. The highest density of parthenium weed (20 plants m−2) caused the highest reductions in maize leaf area index (15%), ears per plant (21%), thousand grain weight (12%), biological yield (15%) and grain yield (18%) as compared with the plots free from parthenium weed. However, parthenium weed densities of 5–15 plants m−2 only caused 8–10% losses in the grain yield of maize. Therefore, it is suggested to reduce the density of this weed species to below 15 plants m−2 to avoid substantial yield losses