Journal of Chemical Ecology

, Volume 20, Issue 2, pp 315-319

First online:

Allelopathy of oats. II. Allelochemical effect ofl-Tryptophan and its concentration in oat root exudates

  • Hisashi Kato-NoguchiAffiliated withDepartment of Bioresource Science, Faculty of Agriculture, Kagawa University
  • , Junya MizutaniAffiliated withMizutani Plant Ecochemicals Project, Eniwa RBP Center Building
  • , Koji HasegawaAffiliated withInstitute of Applied Biochemistry, University of Tsukuba

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l-Tryptophan caused growth inhibition of roots and hypocotyls (or coleoptiles) of cockscomb (Amaranthus caudatus L.), lettuce (Lactuca sativa L.), cress (Lepidium sativum L.), timothy (Phleum pratense L.), rice (Oryza sativa L.), wheat (Triticum aestivum L.), and oat (Avena sativa L.), increasing the dose ofl-tryptophan increased the inhibition. The concentrations for 50% inhibition of the root growth were 0.14, 0.15, 0.21, 0.79, 0.95, 1.7, and 2.4 mM for cockscomb, cress, lettuce, timothy, rice, wheat, and oat, respectively; the concentrations for 40% inhibition of the hypocotyl (or coleoptile) growth were 0.28, 0.33, 0.43, 2.7, 4.5, 7.2, and 15 mM for cockscomb, cress, lettuce, timothy, rice, wheat and oat, respectively. The levels ofl-tryptophan in oat seedlings and in its root exudates were 29.3 mg/kg fresh wt and 0.25 mM under light conditions, and 21.1 mg/kg fresh wt and 0.18 mM under dark conditions, respectively. The presence ofl-tryptophan in the root exudates coupled with its effect on growth suggested thatl-tryptophan may play an important role in the growth inhibition of other plants in nature.

Key Words

Allelopathy Avena sativa oat l-tryptophan root exudates