ffect of Sowing Date on Yield and Yield Components of Three Grain SorghumCultivars

In order to study the effect of sowing date on yield and yield components of sorghum cultivars, a field experiment was conducted at experimental field of agriculture factuly, Tarbiat Modares University which is located in 17 km Tehran-Karaj freeway. In this research effect of two factors, sowing date and cultivars of sorghum bicolor, was studied in split-plot based on randomized complete block design with 4 replications. Main plots were sowing date with three levels (8th June, 28th June and 18th July) and sub plots were cultivars with three levels (Payam, Sepideh and Kimia). Investigated traits include biological yield and its component, panicle weight, grain yield, percent and yield of protein, harvest index and grain yield component. Result showed that total biomass and vegetative biomass were not affected by any of factors. panicle dry weight and harvest index was significantly affected by cultivars (p≤0.01) although in grain yield was significant in 95 percent level. Weight of 1000 seeds was also affected by sowing date and cultivar (p≤0.05) and was affected by sowing date × cultivar interaction (p≤0.01). In spite of non significant effect of sowing date on grain yield, the highest grain yield was obtained by Sepideh in 28th June. In the result for higher grain yield in this region and other places with similar conditions, sowing Sepideh cultivar in mid June is recommended.