Submitted to: Allelopathy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2006
Publication Date: 4/5/2007
Citation: Williams, R.D., Hoagland, R.E. 2007. Phytotoxicity of mimosine and albizziine on seed germination and seedling growth of crops and weeds. Allelopathy Journal. 19(2):423-430. Interpretive Summary: Mimosine and albizziine are two toxic, non-protein amino acids found in several legume species. Mimosine has phytotoxic, insecticidal, and mammalian toxicological properties, while albizziine has phytotoxic and insecticidal properties. Both have been identified as potential allelochemicals, but their phytotoxic potential has not been compared. Here we examine both compounds in seed germination, seedling growth, and cotyledon greening bioassays. Both compounds delayed, but did not reduce, seed germination of hemp sesbania, sicklepod and winter wheat at 10-5 M to 10-3 M concentrations. These concentrations did inhibit shoot and root elongation of all three species, with the greatest inhibition occurring at 10-3M. Dark seedling growth of ten-day-old sesbania and sicklepod seedling were also reduced by 10-3M mimosine, while minor effects were noted for albizziine at 10-3M. Cotyledon greening of sesbania and sicklepod were significantly reduced by 10-5 to 10-3 M concentrations of both compounds. The cotyledon greening bioassay appeared to be the most sensitive assay used in the study. Overall mimosine seemed to be the more phytotoxic of the two compounds.
Technical Abstract: Mimosine and albizziine are two toxic, non-protein amino acids found in several legume species. Both compounds have been shown to inhibit seed germination and seedling growth, but no comparative study of the two compounds has been conducted. In the present study the 10-3 M concentration of both compounds delayed germination of hemp sesbania, sicklepod and winter wheat at 48 h, and by 72 h the treatments were similar to the controls. Shoot length of all three species was inhibited by 10-3 M application of mimosine, while albizziine (10-3 M) only inhibited sicklepod and winter wheat shoot elongation. Radicle length was more inhibited by mimosine (10-3 M) than albizziine (10-3 M). A mist application of mimosine and albizziine (both at 10-3 M) did not show a significant biological affect on the shoot length of dark grown seedlings. However, root application of mimosine (10-3 M) inhibited the shoot elongation in dark grown seedlings of hemp sesbania and sicklepod, while the albizziine (10-3 M) stimulated shoot elongation of hemp sesbania and inhibited the elongation in sicklepod. Cotyledon greening seemed to be the most sensitive bioassay. Mimosine and albizziine at 10-5 to 10-3 M concentrations reduced the chlorophyll content of both hemp sesbania and sicklepod. However mimosine appeared to be the most toxic compound in this bioassay. Throughout the study mimosine displayed more phytotoxic ability than albizziine, and as suggested in the literature concentrations of 10-3 M or greater are required to see significant delay in seed germination or inhibition of seedling growth. No other study has observed the effects of these two non-protein amino acids on cotyledon greening.