Evaluating of Forage Yield Increase of Sorghum (Sorghum bicolor L.) and Weed Control by Its Intercropping with Forage Legumes

This experiment was conducted to study yield increase of forage sorghum by its intercropping with forage legumes and weed control. This study was carried out in a factorial experiment based on a randomized complete block design with 3 replications at the Research Station of University of Zanjan in 2015. In this experiment, a different proportatios of sorghum with forage legumes including pure culture of sorghum plants, lathyrus and hairy vetch, increased percent of sorghum by 33%, 66% and 100% of hairy vetch and lathyrus, and different weed control management, including full weed control during season, single weed control and no weeds control, were examined. The results showed that the highest and lowest fresh and dry yields of sorghum were obtained in intercropping of sorghum with 33% vetch and 100% lathyrus, respectively. The highest chlorophyll content and leaf area belonged to sole cropping of sorghum and full weed control. The highest height of sorghum and cover crops was observed in 100% sorghum+ 100% lathyrus and weed-infested. On the other hand, in the sole culture of vetch and lathyrus and full weed control treat, the cover crops had the highest dry weights. The results of this experiment also showed that the highest dry weights and density of weeds were obtained under sole culture and weed-infested condition. As a result, it can be said that by selecting the appropriate intercropping ratios and forage legumes, we can control weed population to a large extent also improve the quantitative yield of sorghum forage.