evaluation of seed yield and competition indices of corn (zea mays l.) intercropped with different bean (phaseolus spp.) types

in order to evaluate the intercropping of corn (zea mays l.) and bean cultivars (phaseolus spp.) an experiment was carried out in a randomized complete block design with three replicaties at sari agricultural sciences and natural resources university during growing season of 2010. the experimental treatments consisted of sole cropping of corn, white bean, bush bean, red bean, pinto bean and sword bean and 50:50 ratio of corn and bean types. in this experiment, the corn-bush bean and corn-pinto bean intercropping had the highest seed yield (5734.4 and 5674.3 kg/ha-1, respectively) and land equivalent ratio (ler=1.13 and 1.21, respectively). evaluated intercropping indices indicated that red bean (k= 1.85), pinto bean (k= 2.41) and sword bean (k= 2.80) had the highest crowding coefficient whereas the maximum aggressivity value was belonged to pinto bean intercropped with corn (a= -0.02). also, both the red bean and pinto bean (cr=0.75 and cr=0.98, respectively) had the maximum competitive ratio. furthermore, the most corn crowding coefficient (k=1.15) was belonged to corn and sword bean intercropping and maximum corn aggressivity value was observed in corn intercropped with white bean (a=+0.60) and bush bean (a=+0.69). in conclusion, according to competition indices, intercropping of 50% corn + 50 % red bean and pinto bean plants were superior as compared to other combinations.also, both the red bean and pinto bean (cr=0.75 and cr=0.98, respectively) had the maximum competitive ratio. furthermore, the most corn crowding coefficient (k=1.15) was belonged to corn and sword bean intercropping and maximum corn aggressivity value was observed in corn intercropped with white bean (a=+0.60) and bush bean (a=+0.69). in conclusion, according to competition indices, intercropping of 50% corn + 50 % red bean and pinto bean plants were superior as compared to other combinations.