A field experiment was conducted at the experimental fields in the College of Agriculture, University of Baghdad during spring and autumn seasons of 2016 to study the effect of humic acid concentrations (0, 1, 2 and 3 cm3.L-1) and three stages of foliar application (vegetative growth, booting and 25% flowering) on grain yield and its components of Sorghum (CV. Bohooth.70). The experiment was applied using RCBD arranged in split plots with three replications. Foliar application stages were used as main-plot, while humic acid concentrations were used as sub-plot.
The highest grain yield in both season was 4.395 and 5.213 ton.ha-1 respectively when plants were sprayed at the concentration of 3 cm3L-1. Foliar application at the stage of vegetative growth gave highest mean in plant height, leaf area, biological yield, grain weight head-1, number of grain.head-1 and grain yield (ton.ha-1).