An Assessment of the Allelopathic Impact of Sunflower on Seedlings of Spring Cereal Species Through Germination and Photosynthetic Performance

The effect of sunflower extract on the germination and development of weeds is investigated. However, knowledge about the effects of extracts on target plants is equally important. Investigations into the allelopathic relationship between sunflowers and cereals, which often make up 50-70% of crop rotations, still have many unanswered questions. This experiment aimed to investigate the allelopathic impact of sunflower (<i>Helianthus annuus</i> L.) as a donor plant for spring barley (<i>Hordeum vulgare</i> L.) and spring wheat (<i>Triticum aestivum</i> L.) through their germination and morphological parameters. The following three factors were studied: factor A-two growth stages of the donor plant; factor B-three parts of the donor plant; factor C-five concentrations (0%, 25%, 50%, 75% and 100%) of aqueous extracts of the plant donor. The extract concentration was the strongest factor influencing the germination of spring barley and spring wheat compared to the other two factors. The flowering sunflower extract inhibited the germination of the spring barley and spring wheat by 33-44% and 33-41%, respectively, more strongly than the ripe sunflower extract. According to the SE values, the allelopathic impact of extracts of sunflower parts on spring barley and spring wheat was as follows: L + S < R ˂ H and L + S < H ˂ R, respectively. The inhibitory effect of increasing concentration was determined on the SG, root/shoot length ratio, and SPAD values of both receptor plants.