ABSTRACT
This chapter describes the bioassay systems of historical and current use for a specific group of chemical substances known as the naturally occurring plant growth regulators (PGRs). The development and use of these bioassay systems are intrinsically related to the discovery and characterization of the major classes of plant hormones. The chapter provides particular bioassay depended upon the degree of its characterization and evidence of reproducibility within the appropriate scientific literature. It also generally describes as simply log-linear and linear-linear relationships. The use of bioassays for the characterization of PGRs has been subjected to increasing criticism during the past decade. There are at least two major reasons for this criticism. The first lies in the substantial improvements in physicochemical methods of detection and quantitation of PGRs made during this period. The second reason for the current disenchantment with bioassays lies in the inherent limitations of the technique per se and its frequent misuse.
