INTERFERENCE OF PURPLE NUTSEDGE (CYPERUS-ROTUNDUS) POPULATION-DENSITIES ON BELL PEPPER (CAPSICUM-ANNUUM) YIELD AS INFLUENCED BY NITROGEN

Additive series studies were conducted under greenhouse conditions to determine the effects of nitrogen (N) rate and purple nutsedge densiti es on the yield of 'California Wonder' bell pepper. Initial densities of purple nutsedge were 0, 100, 200, and 300 plants/m(2). Nitrogen was applied at 70, 140, and 210 kg/ha. Plants were allowed to interfere f or 10 wk. There were significant purple nutsedge population density by N rate interactions on bell pepper fruit yield. At 70 kg Nka, no sign ificant effect of weed population densities was found on fruit yield, whereas at the rates of 140 and 210 kg N/ha there were significant nut sedge density effects. As N rates and nutsedge densities increased, so did purple nutsedge biomass. Linear regression models described the i nterference. Bell pepper fruit yield reduction was 73% at 210 kg N/ha with an initial nutsedge population density of 300 plants/m(2).