Inhibitions of cotton seedling growth by volatile ketones emitted by cover crop residues

Low-input, sustainable agriculture (LISA) systems can include soil incorporation of residues of weeds and legume cover crop species. However, both seed germination and seedling growth of crops, including cotton (Gossypium hirsutum L.), are inhibited by volatile organic compounds emitted by these residues during decomposition. A cotton seedling-growth assay was used to demonstrate that C₄ through C₉ ketones released by decomposing legume residues significantly inhibited root and shoot elongation, root and shoot fresh and dry weight gain, and cotyledon expansion. Seedling root and shoot water relationships were relatively insensitive to those components of plant residue volatile emissions. Concentration (0.0, 0.5, 1.0, 1.5, or 2.0M/cm³ sterile greenhouse soil mix) and root-zone temperature (20 or 30°C) altered the activity of the more inhibitory ketones. Molecular weight (carbon chain length), carbon chain branching, and position of the carbonyl group also influenced ketone inhibitory activity.Mention of a commercial or proprietary product does not constitute an endorsement by the U.S. Department of Agriculture.