intercropping wheat (triticum aestivum l.) with canola (brassica napus l.) and their effects on yield, yield components, weed density and diversity

in order to evaluate the effects of yield and yield components and weed diversity and density in row intercropping for wheat and canola, a field experiment was conducted based on a complete randomized block design with three replications at the agricultural research station of ferdowsi university of mashhad, iran during two growing seasons of 2008-2009 and 2009-2010. treatments included four patterns of row intercropping of wheat and canola (one row of wheat + one row of canola (1:1), two rows of wheat + two rows of canola (2:2), three rows of wheat + three rows of canola (3:3) and four rows of wheat + four rows of canola (4:4)) and their monoculture. results indicated that the row intercropping patterns affected weed dry matter and shannon index. the maximum and the minimum weed dry matter were observed in monoculture of wheat and 3:3 of wheat and canola, respectively. the highest and the lowest relative frequency were obtained for common knotgrass (polygonum avicular l.) and flixweed (descurainia sophia l.) with 42.86 and 3.57, respectively. the maximum values of shannon index were observed in monoculture as the highest and the lowest shannon index were obtained in monoculture of wheat (with 0.86%) and 2:2 combinations of wheat and canola (with 0.66%). the highest biological yield and grain yield were obtained in monoculture and then 3:3 pattern of wheat (12894.47 and 4230.72 kg.ha-1 for biological yield and grain yield, respectively) and canola (9231.07 and 3333.49 kg.ha-1 for biological yield and grain yield, respectively). the highest amount of wheat and canola harvest index were observed in 1:1 and 4:4 patterns with 58.34 and 53%, respectively. row intercropping of wheat with canola improved crop diversity and decreased number of weed species, density and population. in general, combination of three rows of wheat and three rows of canola was the most promising intercropping treatment.