evaluation of growth indices of hemp (cannabis sativa l.) and sesame (sesamum indicum l.) in intercropping with replacement and additive series

in order to evaluate the effect of intercropping with replacement and additive series for hemp (cannabis sativa l.) and sesame (sesamum indicum l.), a field experiment was conducted during growing season 2006-07 at the agricultural research station of ferdowsi university of mashhad, iran. a randomized complete block design with three replications was used. treatments included different combinations of intercropping with replacement (75%sesame+ 25% hemp, 25%sesame+ 75% hemp, 50%sesame+ 50% hemp) and additive (50%sesame+ 100% hemp and 100%sesame+ 50% hemp) series and their monoculture. results indicated that the highest and the lowest leaf area index (lai) and dry matter (dm) accumulation of hemp were observed in 50% sesame+ 50% hemp (2.99 and 1921.7 g.m-2) and 50% sesame +100% hemp (1.06 and 929 g.m-2), respectively. the highest and the lowest lai and dm accumulation of sesame were observed in monoculture (1.34 and 551.27 g.m-2) and 50%sesame+ 100% hemp (0.23 and 51.73 g.m-2), respectively. the maximum crop growth rate (cgr) of hemp and sesame were observed in 50% sesame+ 50% hemp (76.58 gm-2day-1) and monoculture (22.78 gm-2day-1), respectively. it seems that the intercropped sesame with hemp reduced the growth indices of sesame due to increasing shading on it and decreasing the absorption of radiation.