Effect of Water Stress and Nitrogen Levels on Yield of Forage Sorghum

In order to evaluate the effect of water stress and nitrogen levels on yield and some agronomic traits of two forage sorghum cultivars, a field experiment was conducted at the Faculty of Agriculture, Shiraz University, during Spring and Summer 2011. The experiment carried out as split-split plot based on randomized complete block design, with 3 replications. Water stress levels of 100, 75 and 50 percent of FC was considered as main plots, nitrogen levels of 150, 300 and 450 kg urea per hectare as sub plots, and the forage cultivars of Pagah and KFS2 as sub-sub plots. Results showed that drought stress reduced plant height, leaf erea index, plant fresh weight, and leaf and stem dry weight as well as forage yield significantly and the reduction was greater at higher levels of drought stress. Conversely, nitrogen fertilizer application enhanced these all traits. Two sorghum cultivars showed significant differences in morphological characters as well as forage yield. Pegah cultivar was found superior as far as plant height, fresh weight, stem dry weight and forage yield were concerned. Leaf area index and dry weight were higher in KFS2 cultivar. The results indicated that, overall, Pegah cultivar and the nitrogen level of 300 kilogram urea per hectare and irrigation regime of 100% FC resulted to the highest yield and could be recommended as the best treatment for Badjgah and similar agroclimatic conditions in Fars province.