Laboratory Bioassays Seedlings and Microbes

3 Plant-Plant Allelopathic Interaction. Phase II Field/Laboratory Experiments 

The last three statements (i.e., e., f., and g.) are all consistent with the observation in Section 3.5.4.3 d. that other factors (e.g., the physiochemical and biotic environments and other organic and inorganic compounds) modulate/regulate the effects of phenolic acids. Additional support for the role of physicochemical and biotic environmental factors in determining the effects of phenolic acids was also provided by our model system studies with phenolic acids (see Section 2.5). 

If both are driven by phenolic acids from the tissues, then the simultaneous effects could occur whenever transport of phenolic acids by gravitational flow, capillary action, or transpirational pull (mass flow) to seedling root surfaces is faster than can be utilized by microbes present (i.e, phenolic acid concentrations or rate of supply are sufficient to impact both microbes and roots independently). 

However, if phenolic acid from tissues are primarily utilized ( used up ) to stimulate phenolic-acid utilizing microbes within the bulk soil and/or the rhi-zosphere/rhizoplane, then the inhibition of cucumber seedlings could be due to a promoter/modifier/inhibitor complex dominated by other inhibitors and any remaining phenolic acids and phenolic acid breakdown products, and 

Anderson RA, Todd JR (1968) Estimation of total tobacco plant phenols by their bonding to polyvinylpyrrolidone. Tob Sci 12 107-111 

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