K. Nakahisa et al., STUDY ON THE ALLELOPATHY OF ALFALFA (MEDICAGO-SATIVA L) .1. OBSERVATION OF ALLELOPATHY AND SURVEY FOR SUBSTANCES INDUCING GROWTH-INHIBITION, Nippon Sakumotsu Gakkai Kiji, 62(2), 1993, pp. 294-299
Allelopathic effects of alfalfa (Medicago sativa L.) plants were inves
tigated using soil previously grown with alfalfa (alfalfa soil). Alfal
fa soil inhibited the emergence of alfalfa seeds and also the growth o
f alfalfa and radish. Methanol extracts from the alfalfa soil markedly
inhibited the elongation of radish hypocotyl and alfalfa radicle, sug
gesting the presence of allelopathic substances. The incorporation of
cut pieces of alfalfa shoots in the soil reduced seed emergence, hypoc
otyl elongation and dry weight in radish seedlings to 65, 73 and 81%,
respectively, compared to the control. Aqueous extracts of alfalfa pla
nts inhibited the elongation of radish hypocotyl and alfalfa radicle.
Inhibition increased with increasing concentrations. Inhibition of rad
ish hypocotyl and alfalfa radicle elongation was greater in root extra
cts than in shoot extracts. The presence of phenolic compounds as alle
lopathic substances in alfalfa soil, as well as in the alfalfa plant,
was suggested using color reaction with diazotized sulfanilic acid.