Abstract
Monoterpenes, the main constituents of essential oils, are known for their many biological activities. The present work studied the potential biological activity of twenty-seven monoterpenes, including monoterpene hydrocarbons and oxygenated ones, against seed germination and subsequent primary radicle growth of Raphanus sativus L. (radish) and Lepidium sativum L. (garden cress), under laboratory conditions. The compounds, belonging to different chemical classes, showed different potency in affecting both parameters evaluated. The assayed compounds demonstrated a good inhibitory activity in a dose-dependent way. In general, radish seed is more sensitive than garden cress and its germination appeares more inhibited by alcohols; at the highest concentration tested, the more active substances were geraniol, borneol, (±)-β-citronellol and α-terpineol. Geraniol and carvone inhibited, in a significant way, the germination of garden cress, at the highest concentration tested. Radicle elongation of two test species was inhibited mainly by alcohols and ketones. Carvone inhibited the radicle elongation of both seeds, at almost all concentrations assayed, while 1,8-cineole inhibited their radicle elongation at the lowest concentrations (10−5 M, 10−6 M).
Highlights
Environmental constraints of crop production systems have stimulated interest in alternative weed management strategies
The germination of radish seeds is more affected by monoterpenes than garden cress seeds
The germination of garden cress was less sensitive to inhibition by monoterpenes
Summary
Environmental constraints of crop production systems have stimulated interest in alternative weed management strategies. The use of synthetic herbicides may threaten sustainable agricultural production and has resulted in serious environmental problems, such as the enhanced incidence of resistance in weeds to important herbicides and the increased environmental pollution and health hazards [1]. There is an increasing interest in the development of natural products as bio-herbicides. The plants offer a remarkable potential for selective biological weed management and starting point for the development of biodegradable compounds [2] through the production and release of substances from the leaves, flowers, seeds, stems, and roots of living or decomposing plant materials. Inhibition of plant growth by other plants in their neighborhood has been known for a long time and the possible use of natural compounds in weed management has been well documented [3,4]
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