ارزيابي رقابت در اجتماع گياهي سويا - سورگوم با استفاده از آزمايشهاي هدف

Assessment of Soybean-Sorghum Competition with Target Experiment

To study the soybean(Glycine max L.) and sorghum (Sorghum bicolor L.) interference and influence of plant density and distance of one species on performance of other species, a field experiment at three different designs was conducted at the research station of Faculty of Agriculture, University of Tabriz at 2000.The experimental designs were performed as target experiment based on randomized complete block design with three replications. At the first experiment , the distance between target species( soybean) and competitor species ( sorghum ) was studied at 5,20,35,50 and 65 centimeters .At the second experiment sorghum was used as a target plant and soybean as competitor. The third design include 2,4,6 and 8 plants of sorghum (competitor) at the fixed distance from target plant (soybean). Soybean grain yield at distances below 50 cm was affected by negative competitive effects of sorghum . The inter-specific competition coefficient (ISCC) of sorghum on soybean linearly decreased as the distance of competitor plants increased and at 65 cm decreased to zero. The soybean had maximum competitive effects on sorghum at 5 cm distance, whereas , ISCC of soybean on sorghum at distances beyond of 20 cm was equal to zero. When the competitor plants( sorghum) density at constant distance from target plant (soybean) increased, the ISCC of sorghum on soybean increased. The number of leaf and branch per plant in soybean decreased at distances below 35 cm, significantly.