Mechanisms of Allelopathic Action in Bioassay
1985; American Chemical Society; Linguagem: Inglês
10.1021/bk-1985-0268.ch013
ISSN1947-5918
AutoresGerald R. Leather, Frank A. Einhellig,
Tópico(s)Weed Control and Herbicide Applications
ResumoBioassays to detect a wide range of concentrations of allelochemicals were developed to follow allelopathic activity during compound identification and to determine the biochemical mechanism(s) of plant growth inhibition by the allelochemicals. Comparison of several bioassays for sensitivity to phenolic acids, flavanoids, and coumarins showed that the growth and reproduction of cultured Lemna species was inhibited at concentrations as low as 50 µM. Other assays in order of decreasing sensitivity were: sorghum seedling growth in nutrient culture, seed germination, and radicle elongation. The Lemna assay was developed using 24-well culture dishes that provided six replications of each treatment. Beginning with three to five fronds per well, the rate of vegetative reproduction and growth rate were determined over a seven-day culture period. Lemna growing in treatments containing high concentrations of phenolic acids (1000 µM) failed to produce new fronds and lacked chlorophyll. Lower concentrations (to 250 µM) reduced the growth rate 50% over a seven-day period. Determination of chlorophyll in Lemna minor and anthocyanin in Lemna obscura, increased the sensitivity of this bioassay to 0.5 nM concentrations of allelochemicals. The Lemna assays were also useful for determining bioactive fractions extracted from allelopathic plants.
Referência(s)