Cyanamide mode of action during inhibition of onion (Allium cepa L.) root growth involves disturbances in cell division and cytoskeleton formation

Cyanamide is an allelochemical produced by hairy vetch (Vicia villosa Roth.). Its phyotoxic effect on plant growth was examined on roots of onion (Allium cepa L.) bulbs. Water solution of cyanamide (2–10 mM) restricted growth of onion roots in a dose-dependent manner. Treatment of onion roots with cyanamide resulted in a decrease in root growth rate accompanied by a decrease in accumulation of fresh and dry weight. The inhibitory effect of cyanamide was reversed by its removal from the environment, but full recovery was observed only for tissue treated with this chemical at low concentration (2–6 mM). Cytological observations of root tip cells suggest that disturbances in cell division may explain the strong cyanamide allelopathic activity. Moreover, in cyanamide-treated onion the following changes were detected: reduction of mitotic cells, inhibition of proliferation of meristematic cells and cell cycle, and modifications of cytoskeleton arrangement

Rozkład liści i korzeni jabłoni w glebie

The studies have been performed to trace changes in the soil content of phenolic compounds entering from decomposing apple leaves and roots, depending on the type and pH of soil and the rate of added apple residues. In has been found that roots added to soil were a richer source of phenolic compounds than leaves. Amount of phenols entering to soil from apple leaves and roots was in proportion with the applied rates of apple residues. A gradual fall in the content of phenolic compounds was found to occur in three successive months. But root residues added to the soil at a relatively high rate delayed this process. Neither liberation of phenolic compounds from the added apple residues nor the later fall of their content depended on the type and pll of the applied soil.Celem pracy było prześledzenie zmian zawartości związków fenolowych, pochodzących z rozkładających się w glebie liści i korzeni jabłoni, w zależności od typu i pH gleby oraz od ilości wprowadzonych resztek. Stwierdzono, że korzenie dodane do gleby były bogatszym źródłem związków fenolowych niż liście. Ilość fenoli uwalniających się z liści i korzeni była proporcjonalna do ich dawki wprowadzonej do gleby. Podczas trzech kolejnych miesięcy obserwowano stopniowy spadek zawartości fenoli. Resztki korzeni wprowadzone do gleby w stosunkowo wysokiej dawce hamowały ten proces. Zarówno uwalnianie fenoli z resztek jabłoni, jak i późniejszy spadek ich zawartości nie zależały od typu i pH gleby

Response of maize, pea and radish roots to allelochemical stress

We examined whether allelochemical stress leads to increased lipoxygenase activity in roots of sweet maize (Zea mays L. ssp. saccharata), pea (Pisum sativum L.) and radish (Raphanus sativum L. var. radicula). The lipoxygenase activity of soluble and membrane-bound fractions was assessed in roots after exposure to ferulic and p-coumaric acids. Lipid peroxidation and membrane injury were determined as indicators of stress. Increased lipoxygenase activity of both studied fractions was followed by lipid peroxidation and plasma membrane injury. The results suggest the key role of lipoxygenase in plasma membrane injury during allelochemical stress caused by administration of hydroxycinnamic acids

Cytochemical localization of peroxidase activity in early developmental stages of the moss Ceratodon purpureus. Light-microscopic observations

Peroxidase activity was localized in the cell walls and minute cytoplasm granules of swollen and germinating spores and in the several-celled protonema of the moss Ceratodon purpureus kept in darkness. Kinetin in a concentration of 100 μM inhibited the protonema development and also depressed the activity of this enzyme

Aktywność cytokininowa sześciu odmian Hordeum vulgare L. [Cytokinin activity of six cultivars of Hordeum vulgare L.]

Cytokinin activity was determined in roots, crowns, ears of six varieties of the barley in the tobacco Wisconsin 38 callus tissue test. Analysis was made in early stage of ears. The order increasing values of the total cytokinin activity (the total activity of compounds fitting their mobility with zeatin, zeatin ribosid and their more polar derivatives) were for most part of varieties: younger roots < older roots < crowns < ears. Dependences between the cytokinin activity and fresh weight of analysed material were not found