اثرات رقابتي علف هرز تاج خروس بر عملكرد و اجزاء عملكرد ذرت دانه اي

Effect of redroot pigweed (Amaranthus retroflexus) interfrence on corn (Zea mays) yield and yield components

To study the effect of competition of redroot pigweed on corn yield, an experiment was conducted in 2002 at Research Station of College of Agriculture Ferdowsi University of Mashhad. Factorial experiment based on randomized compelete block deign with three replications was used as factorial of weed density (0,2,4,6 and 12 plant mʹ2) and corn density (7,9 and 11 plant m-2) were arranged in additive series.Three parameters rectangular hyperbolic model was fitted to biomass and seed yield of com.The highest crop biomass yield loss of 82%,47% and 32% was obtained as weed density approaches infinity at 7,9 and 11 plant m^-2 corn density,respectively.Maximum biomass yield loss decreased by 60% when corn density increased from 7 to 11 plant m^2 . Similar to biomass maximum percentage of seed yield loss as weed density approaches infinity was 52%,34% and 26% at 7,9 and 11 plantm^-2 corn density ,respectively. When corn density increased from 7 to 11 plant m^-2 maximum biomass yield loss decreased by 49%.Increasing redroot pigweed density significantly reduced ear-fill duratron, ear diameter, ear weight, rows /ear and kemel / rows .However, 100 seeds weight and harvest index were not affected signiflcantly.The results of this study showed that increasing redroot pigweed density reduced biomass and seed yield of corn across all densities of com.The highest density of redroot pigweed and lowest corn density, resulted in the lowest yield averaged over all treatments.