This study was conducted to determine if common buckwheat (Fagopyrum esculentum Moench) root residues (BRR) in soil are effective in limiting the growth and metabolic responses of barnyard grass (Echinochloa crus-galli (L.) P. Beauv.), wind grass (Apera spica-venti L.), cleavers (Galium aparine L.), and tiny vetch (Vicia hirsuta L.). After removal of above ground parts, BRR of 14-day-old buckwheat plants remained in soil for an additional 7 days when the weeds were seeded. After 30 days of growth, biomass of above ground parts of the weeds as well as free and bound phenolic acids and flavonoids were determined. Antioxidant capacity and peroxidase activity were measured in barnyard grass and cleavers. The biomass of 30-day-old plants of barnyard grass and cleavers grown in bare soil was approximately 5- and 3.5-fold higher, respectively, than in plants grown in the presence of BRR. BRR did not affect the biomass of wind grass and tiny vetch plants, but activate the antioxidant response, increase in peroxidase activity, and the content of phenolic compounds in weed tissues, which indicates an adaptation to the stressful environmental conditions.

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Allelopathic influence of common buckwheat root residues on selected weed species

The level of flavonoids and amines in de-etiolated and methyl jasmonate treated seedling of common buckwheat

Seed-meals of allelopathic crops may serve as an effective and environmentally friendly alternative for weed control. In this experiment, two series of a pot and one-year of micro-plot field research were conducted in southern Poland, to determine the phytotoxic impact of different seed-meals on indigenous weeds and maize (Zea mays L.) establishment. The pot experiment was performed for four meals: seed-meals of Sinapis alba L., Brassica napus L. and Fagopyrum esculentum Moench and a meal of Raphanus raphanistrum L. plants in the fruiting stage, at doses of meals 2 and 4% (w/w). As a result, the seed-meals of S. alba and F. esculentum were proved to be the most effective against the growth of tested weeds: Echinochloa crus-galli and Amaranthus retroflexus and chosen for the field experiment. In the field, the seed meals were applied into the sandy soil by the end of April 2015 at two doses, equal to 1 and 2% (w/w) per 15-cm of soil and mixed with soil by cultivator. On the same day maize cv. Wilga was sown. Weed composition was assessed at the beginning of July, and weed biomass was measured by the end of August, at the harvest time. Both doses of S. alba seed-meals and a higher dose of F. esculentum seed-meal totally eliminated Echinochloa crus-galli (L.) P.Beauv. and Erodium cicutarium (L.) L`Her. from the plots. At the same time, the number of maize plants and their vegetative biomass was significantly inhibited, as compared to the herbicide control. Interestingly, the application of seed meals stimulated the growth of maize cobs and, as a result, the yield of maize kernels from the plots treated with the seed-meals was similar to the herbicide control. Further research should address different terms and doses of seed-meals applications in the maize cultivation.

Effect of allelopathic seed meals on the weed infestation and yielding of maize

Methyl jasmonate has a strong effect on secondary metabolizm in plants, by stimulating the biosynthesis a number of phenolic compounds and alkaloids. Common buckwheat (Fagopyrum esculentum Moench) is an important source of biologically active compounds. This research focuses on the detection and quantification of 2-phenylethylamine and its possible metabolites in the cotyledons, hypocotyl and roots of common buckwheat seedlings treated with methyl jasmonate. In cotyledons of buckwheat sprouts, only traces of 2-phenylethylamine were found, while in the hypocotyl and roots its concentration was about 150 and 1000-times higher, respectively. Treatment with methyl jasmonate resulted in a 4-fold increase of the 2-phenylethylamine level in the cotyledons of 7-day buckwheat seedlings, and an 11-fold and 5-fold increase in hypocotyl and roots, respectively. Methyl jasmonate treatment led also to about 4-fold increase of phenylacetic acid content in all examined seedling organs, but did not affect the 2-phenylethanol level in cotyledons, and slightly enhanced in hypocotyl and roots. It has been suggested that 2-phenylethylamine is a substrate for the biosynthesis of phenylacetic acid and 2-phenylethanol, as well as cinnamoyl 2-phenethylamide. In organs of buckwheat seedling treated with methyl jasmonate, higher amounts of aromatic amino acid transaminase mRNA were found. The enzyme can be involved in the synthesis of phenylpyruvic acid, but the presence of this compound could not be confirmed in any of the examined organs of common buckwheat seedling.

Methyl jasmonate stimulates biosynthesis of 2-phenylethylamine, phenylacetic acid and 2-phenylethanol in seedlings of common buckwheat

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

M. Horbowicz

Papers

Allelopathic properties of extracts and some metabolites present in the tissues of common buckwheat (Fagopyrum esculentum moench) seedlings