Investigating the Impact of Intercropping Time of Soybean ( Glycine max ) and Haricot Bean ( Phaseolus vulgaris L.) With Sorghum on Striga ( Striga hermonthica ) Control and Crop Productivity in Kobo, North Wollo Zone, Ethiopia

Striga weed infestation severely limits sorghum productivity in Ethiopia, particularly in North Wollo. A field experiment at the Sirinka Agricultural Research Center during the main cropping season evaluated the effects of intercropping sorghum with soybean and haricot bean at three legume sowing times: 2 weeks before, 1 week before, and simultaneous with sorghum planting. The experiment, laid out in a randomized complete block design with three replications, used the local sorghum variety “Jigurity,” soybean “Wollo,” and haricot bean “Lehode.” Data on growth, yield, and Striga infestation were analyzed, alongside land equivalent ratio (LER) and monetary advantage index to assess biological and economic benefits. Results showed that haricot bean significantly reduced Striga counts more than soybean. The highest sorghum grain yields (2405.4 kg/ha) and LER (1.45) were achieved when legumes were planted two weeks before sorghum, with soybean intercropping yielding the greatest economic return (monetary advantage index = 21,804). Sorghum phenology, including days to 50% flowering and days to physiological maturity, was not significantly affected by the treatments, but plant height, grain yield, and biomass were significantly influenced by legume type and sowing time. In conclusion, intercropping sorghum with soybean or haricot bean, especially when legumes are sown 2 weeks prior to sorghum, can enhance yield and control Striga in North Wollo and similar areas. However, results should be validated through multiseason trials before broad recommendations.