effects of weed interference, sowing date and method on growth, yield and yield components of red bean (phaseolus vulgaris l.)

introduction red beans (phaseolus vulgaris l.) with 22-25 % protein and 50-60 % carbohydrates are one of the most important legumes in the world, particularly in some developing countries. it is one of the major sources of vegetable protein. with regard to increasing population and increasing the need of protein, the use of plant resources like red bean with a large amount of protein is growing. modern agriculture is highly dependent on the use of herbicides. due to increase in the number of herbicide-resistant weeds and environmental concerns, there have been considerable efforts in designing alternative weed management strategies. although the use of herbicides is the most popular method for weed control, but the use of integrated weed management (considering other methods like conservation tillage, sowing date and method) as an ecological strategy provides a suitable method to reduce herbicides and as a result, to increase the competitiveness of crops and inhibit weed growth. therefore, the objective of this research was to evaluate the effect of weed interference, sowing date and method on growth, yield, and yield components of red bean (var. akhtar). materials and methods this experiment was conducted in 2014 at the research field of college of agriculture (badjgah region), shiraz university, iran, ne (lat 29. 40˚ n, long 52.25˚ w). the soil of research area was clay with ph of 6.92. the experiment was carried out in split-split plot arrangement based on a randomized complete block design with three replications. treatments included two levels of sowing method (single-row and double-row) and three sowing dates (15 may, 1 june, and 18 june) which were performed in weedy and weed-free conditions. studied features were included leaf area at flowering stage, pod number per plant, seed number per pod, 100-seed weight, pod length, pod weight, number of branches, biological yield, and seed yield. analysis of variance of the data, correlation, stepwise regression analysis and path analysis was carried out using sas (2002) software. duncan´s test was applied to compare means at 5% probability level. excel (2007) software was used to draw figures. results and discussion the results showed that dry weight of both broad-leaf and grass weeds in single-row sowing method was higher than double-row. according to previous researches, competitiveness of weeds at single-row planting pattern was higher than double-row planting method and double-row planting method due to better weed overlap with the closure of the canopy and better competition with crops could control weeds. weed density and dry weight on 18 june were less than 15 may, and 1 june. the results of the influence of planting date and weed interference on sweet corn growth and development sweet corn was suggested high weed biomass early, which reflected resource availability to the weed community, but low weed biomass late could be the result of a more suppressive crop, lower weed growth rate, or a combination of the two factors. the effect of sowing method was not significant on all traits except for weed dry weight. also, the effect of sowing date was significant on all traits except for 100-seed weight and number of branches. all the traits on 15 may and 1 june were higher than 18 june. the results of path analysis showed that number of pods per plant, 100-seed weight and biological yield had the highest direct effect on grain yield. according to the results of this experiment, 1june and 15 may sowing date had no significant difference with each other, so these sowing dates could be offered as appropriate sowing dates for red bean in badjgah region. it should be mentioned that, the agrotis segetum and tetranychus urticae activities were higher in early and late season, respectively, and also, density and dry matter of broadleaf weeds were higher on 15 may sowing date (data not shown). conclusion generally, with regard to importance of sowing date and method to enhance the red beans yield, suitable weed control, sowing on 1 june with double-row sowing method can be recommended specially for badjgah region.