Allelopathic potential of sunflower on weed management in safflower and wheat

Allelochemicals have the potential to create friendly-eco products for weed management. Because synthetic herbicides pose worldwide risks to health and the environment, the need for alternative methods for weed control has become acute. This study evaluated the allelopatic potential of different sunflower cultivars on several crops and associated weeds at different concentrations. Factorial experiments were performed based on a completely randomized block design with three replications. The first factor included eight sunflower cultivars. The second factor was the concentration of the extracts (25, 50 and 100%). The third factor was the type of target plant (Amaranthus retroflexus, Portulaca oleracea, Lolium rigidum, Hordeum spontaneum, wheat and safflower). The results showed that Amaranthus retroflexus was the most sensitive to sunflower allelopathy, and P. oleracea was the most resistant. As extract concentration increased from 25 to 100%, the inhibitory effect on germination indices increased, while with 25% extract concentration was observed to have stimulating effects on wheat and Portulaca oleracea germination. The Megasun sunflower cultivar had the most effect and Hysun36 had the least effect on the target plants. Megasun extract at 100% concentration effectively suppressed over 80% of selected weeds. The results indicate that the allelopathic properties of some sunflower cultivars can affect noxious weed species such as H. spontaneum and L. rigidum in wheat and A. retroflexus in safflower.