Allelopathic Potential of Sunflower Genotypes at Different Growth Stages on Lettuce

Allelopathy, a biological phenomenon, is a valuable tool for weed management and minimization of synthetic pesticide use in sustainable agricultural production. The aim of the study was to evaluate the allelopathic potential of nine sunflower genotypes. Water extracts from dry sunflower leaves collected in two growth stages (butonisation and flowering) were tested in two concentrations (1 and 2.5%) on germination and growth of lettuce under laboratory conditions. The allelopathic effect of extracts was influenced by genotype, growth stage and extract concentration. The majority of extracts exhibited negative allelopathic potential with seed germination being the least affected, and root length reduced up to 85% compared to the control. A higher concentration of water extracts resulted in a greater reduction of lettuce growth parameters. On average, extracts collected in the flowering stage inhibited lettuce shoot length to a greater degree. Several genotypes showed a greater negative impact, especially on shoot length and seedlings' fresh weight. Further investigations of selected sunflower genotypes with the highest allelopathic potential on weed species and studies on phytochemical analysis are needed.