The effects of crop density and post-emergence herbicides usage on grain yield and yield components of broomcorn (Sorghum vulgare var. technicum)

To evaluate the effect of crop density and post-emergence herbicides usage on grain yield in broomcorn, an experiment was carried out in 2011 based on randomized complete block design in factorial with three replications in Miyaneh region. The treatments were crop density of 17, 24 and 31 plant/m2 and herbicides including 2,4-D〣 and bromoxynil〣 with recommended, 20 and 40% reduced doses along with hand weeding. Results showed that increasing density leaded to higher racemes numbers and floret number per m2, grain number in racemes. The higher values of studied traits were obtained in density of 31 plant/m2, such as 1541.7 of racemes, 179.92 of florets and 18.132 of grain.Hand weeding had superior effect on traits compared to other treatments but in some cases herbicide treatments were placed in the same group with it.Yield and harvest indexwithdensity increased, significantly.The highest increasing in yield was obtained in grain density of 31 plant/m2 with 59.23%. Also,application of 2,4-D〣 and bromoxynil〣 with recommended doses, leaded to increasing of 52.05 and 40.62% of grain yield.