مطالعه و پيش بيني اثرات رقابتي تاج خروس بر عملكرد و اجزاءعملكرد لوبيا با استفاده از سطح برگ نسبي و مدل سه پارامتري كراف

Study and prediction of competitive effects of redroot pigweed (Amaranthus retroflexus) on yield and yield components of dry bean by using of relative leaf area and three parameters Kropff model

To predict the competitive effects of redroot pigweed on dry bean yield and yield components by using redroot pigweed relative leaf erea an experiment was conducted at the Ferdowsi University of Mashhad Experimental Station during 2000-2001 growing season. The type of design was completely randomised block in which redroot pigweed at the densities of 0, 4, 8 and 12 plant/m2 grew among bean planted at the density of 20 plant/m2 .The 3 parameters biological model of kropff and collaborators was used to analyse and predict the results. The results indicated severe sensivity of bean to compete with redroot pigweed so that biological and economical yields reduction was 74.05% and 76.48% respectively. The relative damage coefficient prediction of model (q) indicated the superiority of pigweed competitiveness over bean and indicated the rapid expantion of pigweed leaf area than bean. This competition chracteristics in pigweed make it an effective competitor. On the other hand, comparing yield under weed free conditions and maximum yield loss parametres with experimental data indicated high accuracy in predition of pigweed compettitive effects. Based on the results of this experiment, pigweed imposed its maximum effect on yield by reducing the number of pods and branches per plant. The competition of pigweed did not affect on the number of 100 seeds weight and harvest index.