Screening of sunflower varieties for their herbicidal potential against common weeds of wheat

Sunflower is a putative source of bioactive allelochemicals, especially phenolics and terpenoids. Because qualitative and quantitative variation is well documented in sunflower types, we screened three commercially grown varieties of sunflower (Hybrid Supper-25, Gulshan-98 and Hybrid Suncross-42) through aqueous extract bioassays against five selected weeds of wheat (i.e., Chenopodium album, Rumex dentatus, Coronopus didymus, Phalaris minor, and Medicago polymorpha). Sunflower proved to be a potential source of allelochemicals as natural herbicides for weed management of selected weeds. The allelopathic effect was found to be dosage dependant, as it gradually increased as the concentration use from 30% to 50%. The lower concentrations of 10% and 20% showed stimulatory effects or insignificant weed reduction. C. album and R. dentatus were found to be the most sensitive to various treatments. The studies were extended to pot trials to determine the ecological significance of the laboratory findings.