Two factorial experiments, with three replicates, were conducted in a glasshouse during the summer of 2005 at Faculty of Agriculture. Peanut (Arachis hypogaea L. cv. NC-7) was grown as mono and mixed culture with maize (Zea mays L. cv. Hamidiye) and barley (Hordeum vulgare L. cv. Tokak 157/37) plants in non-draining PVC pots. The numbers of peanut, maize and barley were 6, 4 and 8 in their monoculture. The ratios of peanut:maize were 6:4 in higher density and 6:2 in lower density mixed cropping (Experiment I), and the ratios of peanut:barley were 6:8 in higher density and 6:4 in lower density mixed cropping (Experiment II). Experimental soil, typic