1USDA-ARS-GRL, Research and Extension, Langston University, P.O. Box 1730, Langston, OK 73050 USA.
2USDA-ARS, Southern Weed Science Research Unit, P.O. 350, Stoneville, MS 38776 USA.
*Correspondence Author. E. Mail: Robert.williams@ars.usda.gov
Mimosine and albizziine are non-protein amino acids produced by certain legume species that possess allelopathic activity. Although these allelochemicals have exhibited phytotoxicity in some bioassays, but all test plants were not affected. We tested these compounds at various concentrations (10−3 to 10−5 M) for allelopathic effects on seed germination, growth, and greening of weeds and crops: hemp sesbania (Sesbania exaltata) and sicklepod (Senna obtusifolia) and wheat (Triticum aestivum). We also examined in vitro effects of these chemicals on the enzymatic activity of cysteine synthase from sicklepod tissue. Mimosine at 10−3 M reduced germination (by ~ 40%) in both wheat and sicklepod. The greatest growth inhibition occurred, when these compounds were supplied via seed imbibition, but some inhibition also was noted in root feeding and sprays of the chemicals on seedlings. Mimosine and albizziine inhibited chlorophyll development in hemp sesbania and sicklepod cotyledons at all concentrations tested. Chlorophyll inhibition ranged from 25 to 40% for albizziine and from 20 to 97% for mimosine. Both compounds caused a small inhibition (10%) of sicklepod cysteine synthase activity. Generally mimosine was the more phytotoxic compound.
Allelochemical(s), cotyledon greening, inhibition, non-protein amino acid, root length, seed germination, seedling growth, shoot elongation, hemp sesbania [Sesbania exaltata (Raf.) Rydb. Ex A.W. Hill], sicklepod (Senna obtusifolia L.), winter wheat (Triticum aestivum L.)
