Effect of Planting Patterns on Grain Yield and Morphological Characteristics of Soybean (Glycine max L.) in the Competition with Weeds

To investigate the effect of planting patterns on morphological characteristics of soybean (cv. Villiam) in the competition with weeds, an experiment was carried out in summer of 2010 at the field of Agriculture Research Station of Yasouj University. In this study a split factorial was used based on Randomized Complete Block Design with three replications. The main factors were (weedy and weed control) and subplots were row spacing (30, 45 and 60 cm) and soybean plant density (40, 50 and 60 plants m -2). The results showed that plant density and row spacing of soybean had significant effects on plant height, leaf area index, stem diameter and grain yield of soybean. With increasing of density and reduction of row spacing, increased grain yield of soybean, so that among the density different treatments the highest grain yield (240.6 gr m-2) was obtained from density of 60 plants m-2 and among the treatments of row spacing different the most grain yield (236.8 gr m-2) was obtained from 30 cm row spacing. Weed morphological characteristics (Lambsquarters and Amaranthus) was significantly affect by the plant density and row spacing of soybean, so that increasing of plant density and reduction of row spacing led to reduction of 22.7 and 29.8 percent dry weight of Amaranthus of weeds, respectively. The results, totally showed that changes in soybean planting patterns (plant spacing and row spacing) via effects on plant competitive ability against weed can be used as an cultural and non-chemical method for weed control.