ABSTRACT
Department of Plant Pathology, University of KwaZulu-Natal, Pietermaritzburg, South Africa
CONTENTS
16.1 Allelopathic Influences on Plant Growth ................................................................... 232
16.1.1 Impairment of Certain Growth Processes..................................................... 233
16.1.2 Forestry Examples............................................................................................. 233
16.1.3 Cover Crop Examples ...................................................................................... 234
16.1.4 Crop Opportunities .......................................................................................... 234
16.1.5 The Case of Eucalyptus ................................................................................... 234
16.2 The Nature and Production of Allelochemicals........................................................ 235
16.2.1 Categories of Allelochemical Compounds ................................................... 235
16.2.2 Allelochemical Production .............................................................................. 235
16.3 Allelochemicals and the Soil Environment ................................................................ 236
16.4 Discussion........................................................................................................................ 238
References ................................................................................................................................... 238
Plants and microbes release various metabolites into the soil environment via leaching,
exudation, decomposing plant material, and volatilization. The study of allelopathy
is concerned with the very detrimental effects that some of these metabolites can have
on other plants growing in the same soil — what might be called “the dark side” of
plant-plant and plant-microbial relationships in the soil. Because allelochemicals are
subjected to various ecological processes in the soil, these processes affect the production
of these compounds and their impact on susceptible plants. The allelochemicals
that are produced by plant roots or soil organisms which have been identified so far
belong to at least 16 chemical groups, so this subject is chemically as well as biologically
complex.
