Allelopathic potential of sorghum (Sorghum bicolor L. Moench) cultivars for weed management

Sorghum (Sorghum bicolor) is an allelopathic crop and contains numerous water-soluble allelochemicals, phytotoxic to many plant species. Nine sorghum cultivars (JS-263, Hegari, Balo, JS-2001, Kashmor, Jabbal, Sibbi, Sindhar and Sadabahar) were grown in the field. These were harvested at maturity and then dried herbage was used for the preparation of aqueous leachates. Aqueous leachate of each cultivar was analyzed qualitatively and quantitatively by HPLC for their phytotoxins composition. The quantity and number of phytotoxins varied greatly among various cultivars demonstrating allelopathy to be a genetic trait. The cultivar Balo was best for grain production (1325 kg ha^-1) and can be grown for this purpose. However, the concentration of allelochemicals in this cultivar was much lower than Hegari and JS-2001, which can be grown for fodder purpose. Cultivars also varied in their relative efficacy in suppressing seedling growth of Trianthema portulacastrum and Cyperus rotundus and response of these weeds differed, C. rotundus was more susceptible to aqueous leachates of all test cultivars. Thus sorghum is a potential allelopathic crop and its cultivars differ considerably in their allelopathic potential. Sorghum cultivars can be selected for inclusion in cropping systems for suppression of weeds and aqueous leachates obtained from mature herbage of the cultivars with higher allelopathic potential can be used as foliar sprays for weed suppression in field crops.