The aim of the work was to evaluate the allelopathic effect of water extracts from the above-ground parts of the seedlings of control buckwheat and buckwheat treated with methyl jasmonate vapours (JA-Me), as well as extracts enriched with 2-phenylethylamine (PEA) and its metabolites: phenylacetic acid (PAA) and 2-phenylethanol (PE), on the growth of the seedlings of dicotyledonous (tomato, radish and watercress) and monocotyledonous vegetables (maize). Also their effect on the level of phenolic compounds and flavonoids was determined, as well as the degree of lipid peroxidation in acceptor plant tissues. In all the cases, plant growth inhibition was noted, and the effect differed in relation to the applied extract, the studied species, and the duration of allelochemical stress. Application of JA-Me caused an increase in the content of phenolic compounds and, as an effect, the allelopathic potential of buckwheat tissues. Generally, the roots of the tested acceptor plants were more susceptible to the effect of the studied extracts than the above-ground parts. In the case of maize, the addition of PEA, PAA, and PE strongly inhibited the growth of both the roots and the above-ground plant parts. Different phenomenon occurred, on the other hand, in tomato roots, the growth of which was stimulated by PE. Buckwheat extracts also caused enhancement in lipid peroxidation in maize, although adding PEA, PAA, and PE limited the process. Buckwheat extracts also increased the biosynthesis of phenolic compounds and flavonoids in tomato and maize tissues, which may be related to the activation of the adaptation mechanism to stressful conditions.

139-151