Effects of Sowing Date and Plant Density on Forage Yield of Sorghum

This study was conducted to evaluate the effects of sowing date and density on forage sorghum yield in 2006 at Agricultural Research Centre of Jahad-Keshvarzi, Ardabil. The factorial set of treatments was arranged by a randomized complete block design with three replications. Factors consisted of sowing date at three dates of 8, 15, and 22 May, and density at three levels of 6, 12, and 18 plants/m2. Results showed that sorghum can be harvested twice in the environmental conditions of Ardabil during growth season. Sorghum forage yield was significantly affected by harvest, time sowing date, density, and harvest time × density. Forage yield at the first harvest was more the second harvest than. The highest and the lowest forage yields were related to 15 May with 12plants/m2, and 22 May with 6 plants/m2. It canbe probably attributed to suitable seed germination and seedling emergence in 22 May, and less intraspecific competition and more produced tillers at 12 plants/m2 as comparied to 18 plants/m2. Plant height was increased as Plant density increased. At the first harvest, it was more than the second. As sorghum density increased, % stem weight and stem diameter were inceased and reduced, respectively. Also, % leaf weight was decreased by increasing sorghum density.