Quantitative analysis of phenolics in selected crop species and biological activity of these compounds evaluated by sensitivity of Echinochloa crus-galli

The purpose of this study was to determine the content of selected phenolic compounds in white mustard, buckwheat, spring barley, oat and rye grown under field conditions. Moreover, the allelopathic efficiency of these compounds was evaluated by sensitivity of Echinochloa crus-galli. The aromatic acids: transcinnamic, salicylic, ferulic, chlorogenic, p-hydroxybenzoic, protocatechuic, p-coumaric and vanillic were separated from crop plants by TLC and determined spectrophotometrically. Differences in concentrations of analysed compounds were observed for most of the examined plant species. The highest concentration was noticed for cinnamic acid and ranged from 360 gg-g⁻¹ DW in rye to 2770 gg-g⁻¹ DW in spring barley. The relatively high concentration was noticed for ferulic acid (from 73.8 gg-g⁻¹ DW in buckwheat to 1046 gg-g⁻¹ DW in spring barley) and p-coumaric acid (from 50 gg-g⁻¹ DW in oat to 1499 gg-g⁻¹ DW in buckwheat). The observed differences in the phenolics content between two successive vegetation seasons can reflect the effect of abiotic and biotic environmental factors on the phenolics level in studied plants.In the greenhouse experiment the effect of particular compounds on the growth of Echinochloa crus-galli was also studied. It has been found that the examined phenolics, and especially transcinnamic acid and mixiure of phenolic compounds, significantly inhibit the growth of Echinochloa crus-galli. The obtained results may contribute to the explanation of the biological activity of some phenolic compounds.