ON LABORATORY BIOASSAYS IN ALLELOPATHY

Allelopathy involves the complex chain of chemical communications among plants, including microbes. Laboratory bioassays constitute a significant part of allelopathic research, and various bioassays have been proposed to demonstrate allelopathy under controlled lab conditions. However, many lab bioassays have little or no correspondence to field interaction, which may be due to dissimilarity of the conditions of lab bioassay to natural conditions, lack of standardized techniques, or absence of critical controls. Here we discuss several lab bioassays presently used in allelopathic research for their suitability to demonstrate allelopathy of ecological relevance. We recommend avoiding certain practices, such as grinding plant material to evaluate allelopathic potential and isolation of allelochemicals, using seed germination as the only criterion of growth response, using sand, agar, or autoclaved soil, using organic solvents as extractants in allelopathic bioassays, and eliminating microbial involvement. Care should be taken in the lab to simulate natural conditions and attention should be given to habit, habitat, and life cycle pattern of the allelopathic plants during designing of lab bioassays.