Abstract To find out how maize and potato can grow and develop in an intercropping system rather than each grown alone in a sole cropping system the following factorial experiment was performend in the frame-work of a randomized complete block three replications in the experimental farm of the faculty of agriculture, Zanjan University in year 2004. Different potato to maize ratios of (1:0), i.e. sole potato;(3:1) meaning 75% potato plus 25% maize; (1:1), that is half and half of each crop; 25 percent potato together with maize of 75% (1:3); and finally sole cropping of maize (0:1) were employed. Two plant population treatments of 3.8 and 5.3 plants/ m2 were assigned to each crop. There was an increase observed in the radiation absorption and in Leaf Area Index (LAI) with an increase in plant density from 3.8 to 5.3 plant per square meter. Maximum potato yield (20390 kg/ha) was obtained from 3:1 crop ratio and maximum yield of maize (8898 kg/ha) from the 1:1 ratio of intercropping system. In the case of potato the new cropping system (intercropping) there were significant (? = 0.05) observed in yield, mean number of branches per plant, as well as in mean weight of potato tubers. In maize, the cropping system revealed a significant effect on yield, mean number of ears per plant as well as on mean number of seeds per year. Land Equivalent Ratio (LER) was shown to be more than one for all the treatments indicating more profitability and superiority of intercropping to sole cropping system. The highest LER for either one of the crops in intercropping system was 1.58. This was obtained for potato in the 3:1 ratio treatment while for maize it was obtained for the treatment of 1:1 ratio. Key Words: Sole cropping; Intercropping; Land Equivalent Ratio (LER); Dominance; Substitutio
