Modeling Performance of Plant Growth Regulators

Growing degree day (GDD) models can predict the performance of plant growth regulators (PGRs) applied to creeping bentgrass (Agrostis stolonifera L.). The goal of this letter is to describe experimental design strategies and modeling approaches to create PGR models for different PGRs, application rates, and turf species. Results from testing the models indicate that clipping yield should be measured until the growth response has diminished. This is in contrast to reapplication of a PGR at preselected intervals. During modeling, inclusion of an amplitude-dampening coefficient in the sinewave model allows the PGR effect to dissipate with time.