Mimosine in Leucaena as a potent bio-herbicide.
Mimosine [α-amino-β-(3-hydroxy-4-oxo-1,4-dihydropyridin-1-yl)-propanoic acid] is a major constituent of Leucaena leucocephala and is responsible for the strong allelopathic potential of the legume tree. Mimosine showed strong herbicidal activities on six plants, namely Brassica rapa [B. campestris], Phaseolus vulgaris, Bidens pilosa, Mimosa pudica, Lolium multiflorum and Leucaena leucocephala, in a bioassay. All plant parts of L. leucocephala contain mimosine. The quantity of mimosine in the young leaves and mature seeds was the greatest, 2.66 and 2.38% of dry weight, respectively, while the quantity in the root xylems and xylems was the lowest: 0.18 and 0.11% of dry weight, respectively. Younger plant parts of L. leucocephala contained greater amounts of mimosine than the mature parts. Mimosine released from young parts and the seeds was proportional to the quantity of soaking water. Compared with the mature seeds, other mature parts of the plant did not exude any mimosine. In soil to which mimosine was added, ∼60% of the mimosine was adsorbed in 1-5 days, and only a minor volume of mimosine was decomposed: 5.30 and 0.16% after 1 and 5 days, respectively. Using a mixture of FeCl3 and mimosine in a 4:6 ratio may be the most effective and economical method of lowering the toxicity of mimosine in L. leucocephala leaves, giving a safer cattle feed and decreasing the soil toxicity caused by mimosine in areas where L. leucocephala is grown. On the other hand, the incorporation of mimosine leaves into cultivated soils may be helpful for the biological control of weeds. The findings of this research reveal that mimosine may be useful for the development of bioherbicides.