Effects of Water Deficit Stress and Biological and Chemical Fertilizers on Yield and Yield Components of Two Sorghum Cultivars

Sorghum (Sorghum bicolor Moench) is one of the most important forage crops in the cereal family. Due to its adaptation to arid condition and high-water use efficiency, it may produce satisfactory seed yields in arid conditions. The present study was conducted in Khorramabad province during two crop years of 2016 - 2017. The experiment was conducted in a randomized complete block design with split-factorial arrangement with four replications. The stress factor was assigned to main plots through three levels of irrigation, normal irrigation, and irrigation at vegetative and reproductive stages, and sub-factor to subplots, consisted of three levels of biofertilizer, soil NPK application, soil vermicompost application, and vermicompost and chemical fertilizer combining with Sepideh and Kimia cultivars. Initially, combined analysis of variance was performed. Due to the lack of significant year effect and its interaction effects by different factors, analysis of variances was performed on two years data. The effects of stress and the interaction effects of cultivar by stress and fertilizer on some traits were measured. It was found that the quantitative, qualitative and phonological indices of sorghum were directly negatively affected by stress at the reproductive stage. On the other hand, the effect of vermicompost fertilizer on the studied traits was significant and positive. Sepideh possessed the highest vahues for those traits except for protein percent, in comparison to Kimia. Grain yield was about 8 ton at irrigation-interrupt during vegetative stage for Sepideh and 4.36 t.ha-1 for Kimia, but grain yield at irrigation-interrupt during reproductive stage was 7.67 and 4.45 t.ha-1 for Sepideh and Kimia, respectively.