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Growing Degree‐Day Models Predict the Performance of Paclobutrazol on Bentgrass Golf Putting Greens
Author(s) -
Kreuser William C.,
Obear Glen R.,
Michael Darrell J.,
Soldat Douglas J.
Publication year - 2018
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci2017.06.0395
Subject(s) - paclobutrazol , growing degree day , clipping (morphology) , horticulture , biology , zoology , growth rate , mathematics , sowing , geometry , linguistics , philosophy
The performance of plant growth regulators (PGRs) in turfgrass is closely related to air temperature. Growing degree‐days (GDD) have been used to predict the performance of a foliar‐absorbed PGR, trinexapac‐ethyl (TE), on creeping bentgrass ( Agrostis stolonifera L.). Similar models have not been attempted for paclobutrazol, a root‐absorbed PGR. This research aimed to develop GDD models (base temperature = 0°C) for paclobutrazol applied alone or in combination with TE. Models were developed on creeping bentgrass putting greens in Madison, WI (2009) and near Mead, NE, (2014 and 2015). Paclobutrazol was applied alone or with TE at various rates each year. Clippings were collected several times each week and treatments were reapplied when the PGR's effects expired. Sinewave regression models fitted relative clipping yield to GDD accumulation following the most recent PGR application. Relative clipping yield from all treatments was described by symmetric sinewave regression (adjusted R 2 : 0.409–0.862). The intensity of clipping yield suppression, expressed by the model amplitude, ranged from 0.293 to 0.621 g g −1 , depending on the application rate or the addition of TE. The application rate had less effect on the duration of the growth response, represented by the model period. The estimated reapplication intervals ranged from 269 to 302 GDD. Tripling the application rate lengthened the estimated reapplication interval by <2 d. The addition of TE did not accelerate peak suppression and had a small, inconsistent impact on the model period. Golf course superintendents should use GDD models to schedule reapplications to sustain season‐long yield suppression.