The experiment was set in a factorial combination of two sorghum varieties, four rates of salicylic acid (SA) and three application times. The severity of stem borer and stem lodging percentage were significantly reduced following foliar application of 0.5 or 1mM salicylic acid (SA) than the controls (distilled water). Application of 0.5mM SA after 30 days of planting resulted in 15% more grain yield than the control for Meko. Similarly, application of 1Mm SA, 15 days after planting, increased the grain yield of ESH-1 by more than 20% than control. The hybrid ESH-1 gave the highest dry biomass per plant (210.4g) when sprayed with 0.5mM SA 30 days after planting, while the lowest dry biomass per plant (154.2 g) was obtained in plants treated with distilled water at 15 days after planting. Likewise, the highest dry biomass per plant (207.5 g) was recorded in plants sprayed with 0.5mM SA, 45 days after planting, whereas the lowest dry biomass (124.3g) was recorded in plants treated with distilled water, sprayed 15 days after planting for Meko. So, foliar spray of 0.5 mM and 1 mM salicylic acid (SA), can improve the grain yield of Meko and ESH-1 sorghum varieties, at Melkassa area.
Keywords: Harvest Index, Salicylic Acid, Sorghum