Competition Effects of Major Weed Species at Various Densities on Yield and Yield Components of Barley (Hordeum vulgare L.)

Abstract

A study on the competitive interactions of food barley, cultivar HB-42, with four dominant weed species [Avena fatua L., Erucastrum arabicum Fisch. & May., Guizotia scabra (Vis.) Chiov. and Snowdenia polystachya (Fresen.) Pilg.] at different plant density levels (0, 10, 20, 40, 80, 160 and 320 plants/m2) was made at Ambo Plant Protection Research Center, Ambo, during 2000, 2002 and 2003. The competition effect of the major weed species at various densities on yield and yield components of barley and the relative competitiveness of the weed species were determined. Both weed species and weed densities showed significant differences against most parameters considered. However, weed species by density interaction was not significantly different for all parameters. Weed density significantly decreased barley grain yield mainly through reducing number of tillers, number of productive spikes and biomass yield of barley. Barley grain yield decreased linearly with the increasing weed density (r2 = -0.59). The lowest yield was obtained at the maximum density (320 weed plants/m2). Grain yield reduction due to weed competition ranged 22-50%. S. polystachya was the most competitive causing 50.3% reduction, while E. arabicum was the least (22.4%). Averaged over the species, the number of weeds that caused a significant yield loss in barley was more than 10 weed plants/m2.