Effects of wheat residue and different densities of sunflower on weed biomass and sunflower (Helianthus annus L.) yield.



Field experiment was conducted to assess the efficacy of wheat residues and different densities of sunflower in weed control during 2007 growing season. The experimental design was a randomized complete block with three replications. The experiment was set up in factorial arrangement, amount of 0, 1250, 2500, 3750, 5000 Kg ha-1 of wheat residue and burning of residue (5000 kg ha-1) were the levels of factor A and three densities of sunflower consisting of 50000, 70000 and 90000 plants ha-1 were factor B. During growth season measurement of weed biomass and weed height in 3, 6 and 9 week after planting was conducted. Increasing amounts of wheat residue and sunflower density decreased weeds biomass and height. 71.8, 73.17 and 87.48 percent of weed biomass reduction occurred with increase in wheat residue at 3, 6 and 9 weeks after planting, respectively. Also increasing sunflower density from 50000 to 90000 Plants ha-1 decreased the weeds canopy height. Sunflower grain yield increased 29.86 and 31.73 percent with increasing wheat residue and sunflower density, respectively. Applying 2500 kg.ha-1 wheat residue integrated with sunflower planting at density of 90000 plants ha -1 can give an effective control of weeds and can be an alternative to cut herbicide use.