The objective of this study was to identify a compound(s) that may
be responsible, at least in part, for alfalfa autotoxicity.
We found
that medicarpin (3-hydroxy-9-methoxypterocarpan) is a compound
produced by' alfalfa (Medicago sati~'a L.) that contributes to this.
A clay loam soil from a declining alfalfa stand with two plants per 930
cm2 and its 95% ethanol extract inhibited alfalfa emergence and
seedling growth whereas extracted soil did not.