Evaluating the Effects of competition among different densities of mallov (Malva parviflora) using replacement series method on the yield and yield components of canola (Brassica napus L.)

Abstract

In order to evaluate the competitive capability of rapeseed and malva towards different densities, experimental planting under vase conditions using replacement series and in perfectly random blocks was carried out in Dezfool City in 2012. Experimental treatments included rapeseed and malva plantings with different ratios (0:100, 25:75, 50:50, 75:25, and 100:0) with the density of eight bushes in each vase. The results showed that the biomass of the farm plant of rapeseed decreased due to an increase in the density of malva weed in the mixed plantations. The highest decrease in the dry mass of one bush of rapeseed comparing to its pure plantation was in the 25 percent density with 68 percent decrease. Moreover the biomass of malva experienced a significant decrease due to raising the share of rapeseed in the combination. Also by increasing the density of malva bushes the seed yields, the number of pods in a bush, the number of seeds in pods and the weight of 1000 seeds were decreased. The relative yielding of rapeseed in density ratios of 50 and 75 percent show the higher competitive capability of this crop plant, while in the lower density of rapeseed (25 percent) the relative yielding of malva was better. Relative competition coefficients of these two species also confirm that in higher densities rapeseed possesses a higher competitive strength.