influences of soil solarization and barley straw mulch on weed density and biomass

today, due to the problems caused by herbicide application, there is a strong interest in developing alternative methods of weed control. to study the effects of soil solarization, barley straw mulch on weed flora, a field experiment was conducted at research station of faculty of agriculture, ferdowsi university of mashhad during the growing season of 2007-2008. this experiment was based on a randomized complete block design arranged as a split plot with three replications. soil solarization treatment (clear and black polyethylene and non-solarized control) and various straw mulch rates (0, 300 and 600 gm-2) were arranged on the main plots and sub plots, respectively. seventeen weed species was identified by studying weed population which were mainly annual broad-leaves species. results indicated that solarization with clear and black sheets reduced weed density and biomass after removing polyethylene sheets. solarization with clear sheets reduced weed density and biomass, after application of straw mulch. straw mulch had no significant effect on weed density, but in last sampling date it reduced biomass up to 44.15% and 52.90% in 300 and 600 gm-2, respectively. the interaction effects of solarization and straw mulch on weed biomass was significant but only at 90 days after application of straw mulch. the lowest weed biomass observed in solarized bared plots with applying clear sheets.