Allelopathy of velvetbean [Mucuna pruriens]: Its discrimination and identification of L-DOPA as a candidate of allelopathic substances
1992
Fujii, Y. (National Inst. of Agro-Environmental Sciences, Tsukuba, Ibaraki (Japan)) | Shibuya, T. | Yasuda, T.
A series of the studies conducted through the laboratory bioassays and field tests to search for allelopathic plants indicated that among the 70 plant species tested, velvetbean (Mucuna pruriens var. utilis) was the most promising candidate. It is recognized that velvetbean, which is a tropical legume grown for green manure, has a special ability to smother weeds. The studies placed emphasis on evaluation of allelopathic properties of velvetbean. The field test showed the smallest weed population in the velvetbean stand plots as compared with the stand plots of tomato, eggplant, upland rice and fallow conditions. By means of HPLC and bioassay on germination and seedling growth tests, the substance inhibiting plant growth was identified as L-3,4-dihydroxyphenylalanine (L-DOPA). L-DOPA is a well-known substance biologically active in animal physiology, such as a precursor of neurotransmitter dopamine, and an intermediate of many alkaroids. The present studies revealed that L-DOPA contained in a large amount (about 1% of the fresh weight in leaves and roots of velvetbean) inhibited the growth of some companion plants, and that it probably contributed to its allelopathy. L-DOPA suppressed the growth of some broad leaf weed, while little effect was observed on gramineous plants. In addition to its effectiveness as a green manure, velvetbean could be utilized as an allelopathic crop to control weeds
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