Tolerance of red bean cultivars to weed competition in various planting densities

Bean cultivars with various morphological features and genetic backgrounds show different responses to weeds that eventually may decrease the yield. This research was carried out during two years (2006-2007) to assess the ability of red bean cultivars to compete with some weeds. The experiment was performed as a split plot factorial based on randomized complete block design with three replications. Main plot included two levels (with and without) of weed. Sub plots had factorial combinations of different bean cultivars (Sayyad, Derakhsan and local cultivar of Zanjan province) and various plant densities (20, 30, 40 and 50 plants per square meter). included cultivars Sayyad, Derakhshan and local cultivar of Zanjan and planting densities were 20, 30, 40 and 50 plants per square meter. The space between planting rows was 30 cm. The number of weeds and thier dry weight per plot were determined three times in: third trifoliate leaf, 50% flowering and physiological maturity stages. The biomass of bean was measured in three stages as described above. Number of pods per plant, number of grains per pod, plant height, yield and one hundred grain weight for each plot were measured. Statistical analyses were performed using SAS, SPSS and EXCEL softwares and mean comparison of data was carried out using Duncans multiple range test. Results showed that Sayyad cultivar at densit of 40, Derakhshan cultivar at densit of 50 and local cultivar at densit of 30 and 40 plants per square meter had the highest biomass, yield and impact on reduction of weeds biomass.The results also showed that 40 bean plants per in the presence of weeds produced the highest bean biomass and yield and had the highest impact on reduction of weed biomass and density.