Plant growth regulator activity of soluble humic complexes.

Abstract

Auxin and cytokinin bioassays were performed to test the biological activity of soluble humic complexes (SHC). 'Pea split stem curvature' (auxin test) and 'cucumber' tests (cytokinin test) did not show any quantifiable activity of SKC. 'Cress test' and 'senescence test' offered good evidence of a hormonal-like activity 100 times lower than that of IAA (1-mg IAA.g-1 SHC) and 10 times lower than that of N6 BA (100mg N6 BA.g-1 SHC). At a high concentration of SHC, toxic effects were evident, indicating the presence of inhibitory substances which counteracted the hormone-like activity of humic complexes. -Authors