The Effect of Weeding and Plant Density on Yield and Yield Components of Forage Sorghum Cultivars

In order to study the effects of weeding and plant density on forage yield of two sorghum cultivars، an experiment was conducted in 2011 at Bahonar University of Kerman Research field station. The experiment was designed as a randomized complete block with a factorial-split treatment arrangement and with three replications. Treatments were included four levels of weeding (whole season wedding، whole season interference، twice and three times weeding) and three levels of sorghum density (20، 25 and 30 plants per m2) and two forage sorghum cultivars (Pegah and Speedfeed). The results showed that the competition of weeds with forage sorghum significantly influenced all of the measured parameters. The maximum reduction in yield was observed in weed-infested treatment (full season competition). Increasing in plant density led to the reduction of stem diameter، and increased plant height. The highest fresh fodder، dry matter and leaf to stem ratio was obtained in the density of 30 plant per m2. The maximum dry matter of 6. 352 ton per hectare was obtained in Speedfeed which was a superior hybrid over Pegah cultivar. Increasing plant density enhanced yield and yield components and competition power of crop plant which led to decreased weed dry matter production.