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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.
We examined the response of common buckwheat (Fagopyrum esculentum Moench) seedlings, as a nontarget plant, to various doses of glyphosate applied to the root zone or to the shoots. Glyphosate was used at 0.1, 0.5, and 1.0 mM concentrations. The study was conducted on seedlings grown in hydroponic cultures under controlled growth conditions. Primary root and shoot growth, anthocyanin and photosynthetic pigment contents were measured to assess the effects of exposure to glyphosate. Glyphosate applied to shoots had a considerably higher impact on the growth of primary roots and shoots of seedlings. Low glyphosate concentrations produced an increase in anthocyanin content of hypocotyls, regardless of the mode of its application. Increasing the concentration of glyphosate applied to the root zone resulted in a gradual increase in anthocyanin content in cotyledons. Our overall results show that in hydroponically grown common buckwheat seedlings, glyphosate is less phytotoxic when applied to the root zone than when applied to the shoot. Low doses of glyphosate applied to the root zone stimulate root and shoot growth and increase the anthocyanin levels in cotyledons. The phytotoxicity of glyphosate was decreased in the absence of mineral nutrients in the root zone of buckwheat seedlings.
The response of radish seedlings (Raphanus sativus L. subvar. radicula Pers.), as non-target plant, to various doses of glyphosate applied to root zone was studied in the experiment. The glyphosate was used at concentrations 0.1, 0.5 and 2.0 mM, and the study was conducted on seedlings grown in hydroponic cultures in controlled light and temperature conditions. In the experiment, roots of seedlings were exposed to glyphosate for 4, 7 or 14 days. In order to evaluate the effect of glyphosate, length and biomass of the seedling organs, as well as contents of anthocyanins in hypocotyls and cotyledons have been measured. Glyphosate applied to root zone had considerably higher impact on the growth of the primary root than shoot of radish seedlings. Short-term exposure to glyphosate led to the stimulation of growth and biomass organs of the radish seedling, but such treatment had no effect on the contents of anthocyanins in the cotyledons and hypocotyl. However, after longer exposure to glyphosate a decrease of anthocyanins content in the hypocotyl and its increase in the cotyledons was noted.
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.
The effect of methyl jasmonate (MJ) vapors on the composition and peroxidation of major fatty acids in the organs of common buckwheat seedlings was investigated. The composition of fatty acids in the hypocotyl and cotyledons of seedlings changed significantly under exposure to MJ vapors in closed jars. Four-day exposure to MJ led to a significant reduction in the concentrations of stearic, linoleic, and linolenic acids in the hypocotyl, whereas oleic acid levels increased approximately 3.5-fold. A decrease in stearic acid levels and an increase in the content of linolenic acid were noted in cotyledons, whereas oleic acid levels decreased in roots. Seven-day exposure to MJ vapor caused a further reduction in stearic acid content and an increase in oleic acid and linoleic acid levels in the hypocotyl. At the same time, the linoleic acid content of roots and linolenic acid levels in cotyledons were doubled, but a 5-fold reduction in linolenic acid concentrations was observed in roots. Methyl jasmonate intensified fatty acid peroxidation in cotyledons after 4 and 7 days and in roots after 4 days of exposure. Peroxidation was inhibited in the hypocotyl and roots after 7 days. The noted changes in the composition and peroxidation of fatty acids are probably indicative of senescence in buckwheat seedlings under the influence of MJ. Senescence seems to proceed faster in cotyledons than in other organs of buckwheat seedlings.
The objective of the study was to assess the influence of methyl jasmonate (MJ) vapors on accumulation of 2-phenylethylamine (PEA), phenylacetic acid (PAA) and 2-phenylethanol (PE) in leaves and roots of maize (Zea mays L. subsp. mays, saccharata group, cv. Złota Karłowa) seedlings. Furthermore, we analyzed the expression patterns of eight genes (ADH1, ADH2, AO2, CAO, PDC1, PDC2, PTA and LOX, encoding alcohol dehydrogenase 1 and 2, primary amine oxidase, aldehyde oxidase 2, phenylalanine decarboxylase 1 and 2, phenylalanine (histidine) transaminase and lipoxygenase, respectively) involved in biosynthesis and turnover of PEA in maize tissues. In addition, the effect of MJ application on fresh biomass and growth of the tested seedlings was recorded. Oneday MJ exposure increased the fresh weight of aerial parts and roots of Z. mays seedlings, whereas the opposite tendency occurred after 4-day of MJ treatment. One-day application of MJ resulted in an increase in the length of roots and its fluctuations in the aerial parts of maize plants, but extended exposure declined the growth of both parts of the seedlings. Methyl jasmonate elicitation caused various changes in the contents of PEA, PAA and PE in the maize seedlings. MJ treatments led to high upregulation of most genes, with the exception of three genes (i.e., ADH1, ADH2 and AO2) whose expression was downregulated after a 4-day exposure.
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