the effect of sowing date and weed interference on growth indices of different red bean (phaseolus vulgaris l.) cultivars

abstract to evaluate the effect of sowing date and weed interference on growth indices of red bean cultivars with different growth habit, a field experiment was carried out during the spring 2009 at university of zanjan as a factorial split plot on the basis of randomized complete block design, with three replications. main plots included factorial of three red bean cultivars (derakhshan (standing cultivar), sayyad (half-standing cultivar), and goli (prostrate cultivar)) and sowing date at two levels, (30th of may and 13th of june) and subplots included weed interference (complete weed control and without control). according to the results, the earlier sowing date respect to later sowing date, increased total dry matter and crop growth rate about 1.3 and 1.2 folds, respectively, because of its longer growth duration. the effect of sowing date and weed interference on the leaf area index of cultivars was significant. weed interference significantly decreased leaf area index (about 40%), total dry matter (about 60%) and crop growth rate (about 48%) of red bean cultivars in both sowing dates. goli cultivar had the highest (1222 kg.ha-1) and sayyad cultivar had the lowest (928 kg.ha-1) grain yield, respectively. it was concluded that the goli cultivar respect to other cultivars had good performance in both sowing dates and weed interference and the best candidate for cultivation in zanjan conditions.