The competitive ability of maize (Zea mays L.)-common bean (Phaseolus vulgaris L.) intercrops against weeds

Different combinations of maize (Zea mays L.) and common bean (Phaseolus vulgaris L.) intercropping ratios were compared with the sole cropping of each crop during 2011-2012 growing season in north of Iran. The experimental plots were laid out in a randomized complete block design with three replications. Field experiment comprised five treatments including three intercropping combinations (3:1, 2:2 and 1:3) and sole culture of common bean and maize. Analysis of variance indicated that intercropping system significantly influenced bean and maize traits. The seed yields of common bean obtained from sole bean and maize:bean intercropping (1:3) was statistically similar and significantly higher than other intercropping treatments. The highest value of maize grain yield was obtained in sole cropping of maize. Total land equivalent ratio (LER) was grater to one (1.24) in two rows of common bean between two rows of maize (M50B50), indicating the increase of the yield in this intercropping treatment and advantage was equal to 24%. The highest competitive ratio (CR) for maize was obtained in M75B25. The maize sole crop and intercrops indicated a reduction in weeds, as compared with the bean sole crop. The intercrops of one row of common bean between three rows of maize (M75B25) seemed more suppressed weeds than both of maize and bean sole crops. This research indicates that maize-common bean intercropping was an appropriate method for utilizing the available resources and reducing weed infestations in organic farming systems. Bean had a proportionately low competitive effectiveness towards weeds and intercropping can be a way to produce successfully beans in organic farming.