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

Phytotoxic effects of Cyanamide on seed germination ans seedling growth of weed crop species

We examined the response of plants of various crop and weed species to cyanamide in order to evaluate allelochemical- mediated interactions between the species. We studied germination and seedling growth in the common weeds Galium aparine L. and Amaranthus retroflexus L., and the crops Zea mays L., Triticum aestivum L., Lactuca sativa L., Solanum lycopersicum L. and Sinapis alba L. as acceptor plants. Concentration-dependent phytotoxic effects of cyanamide were noted during seed germination and in the root and shoot growth of the tested plants. The monocotyledonous plants generally were less sensitive to cyanamide treatment. Seed germination and seedling growth of the dicotyledonous plants were strongly inhibited by the allelochemical at both tested concentrations (1.2 mM, 3 mM). We conclude that cyanamide has potential for use as a natural herbicide only in specific field systems of cyanamide-tolerant monocotyledonous crops accompanied by cyanamide-sensitive dicotyledonous weeds