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Microbial competition and soil structure
limit the expression of allelochemicals in nature
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S.K. Schmidt and R.E. Ley
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| In this chapter we review the literature on the fate of allelochemicals in soil with special emphasis on the microbial mineralization of such compounds by soil microorganisms. It is our thesis that most purported allelochemicals could not build up to phytotoxic levels under natural conditions. Recent literature indicates that even in the absence of microbial metabolism, soil renders compounds much less toxic than they are in laboratory solutions. This lessened toxicity is due to slowed diffusion rates in soil and to various complexation and sorptive reactions (discussed below and by Huang et al., this volume). Added to these abiotic checks on toxicity is the potential for microbial destruction of allelochemicals in soil. Most soil microbes are carbon limited and many soil organisms can very rapidly mineralize aromatic compounds. On a per weight basis, aromatic compounds are more energy rich than simple sugars and thus some soil bacteria prefer these purported allelochemicals to sugars. In addition,. Many soil bacteria are chemotactically attracted to phenolic compounds and can therefore intercept them at their source. We conclude our chapter by discussing possible scenarios in which allelopathy might occur in nature and what kinds of chemicals could stand up to the gauntlet of soil and cause allelopathy. | |||||||||||
In: Principles and Practices in Plant
Ecology: Allelochemical Interactions. (S. Inderjit, K.M. Dakshini & C.L.
Foy, eds.). CRC Press, Boca Raton, Florida.
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