A Review of Bioassay Techniques in Herbicide Investigation

Bioassay techniques used in herbicide studies are based on the response of chosen organisms, higher plants or microorganisms, to the chemical. Various means of assessment are used: seed germination, weight or size of plant parts, modification in physiological activities such as photosynthesis and transpiration, and typical symptoms. Several special bioassays are described. Does-response relations are affected by the age of the indicator plant and environmental conditions of growth. Results can be estimated visually by objective measurements; for correct interpretation appropriate controls and standards must be included in each experiment. Examples are given of bioassay procedures developed to investigate various aspects of herbicide behavior: soil effects, dissipation from soil surface, movement in soil, degradation and persistence.