EFFECTS OF HUMIC ACIDS AND THREE BIO-DYNAMIC PREPARATIONS ON THEGROWTH OF WHEAT SEEDLINGS
G Deffune1 and AM Scofield
Allelopathic effects are biochemical interactions of both inhibitory and stimulatory nature between plants and microorganisms. Both opposites seem to be separated by quite a thin line - most organic compounds that are inhibitors at some concentrations are stimulators to the same processes at higherdilutions (Rice 1984). The mode of action of plant growth hormones such as indole-3yl-acetic acid (IAA) illustrates this phenomenon: while 10-11 M is the optimum level for roots, concentrations above 10-6 M strongly inhibit root growth (Audus 1972). In this context humus and humic acids (HA) have also been the subject of several studies related to plant growth.Bio-dynamic farming is the oldest movement for sustainable agriculture. It differs from the other movements basically by the use of the bio-dynamic (BD) preparations: mineral, plant or animal extracts, usually fermented and applied in small proportions to organic manures, the soil or directly on plants, after dilution or stirring procedures called dynamizations.