Effects of Plant Growth Regulator Source, Rate and Timing on Brassica Carinata Agronomic Performance.

Exogenous application of plant growth regulators (PGRs) can reduce lodging in oilseed brassicas caused by adverse weather or high nitrogen fertilizer application. We tested the effects of PGRs on Brassica carinata canopy structure, lodging, seed yield and oil quality in a 2-yr field study at the North Florida Research and Education Center, Quincy, Florida during the 2015/2016 and 2016/2017 winter-spring growing seasons. The experimental design was a RCBD with four replications in a 3×3×3 factorial arrangement of PGRs [Chlormequat chloride (Cycocel), Mepiquat chloride (MEP 42), and Paclobutrazol (Paczol)] applied at 3 rates ( 0.5, 1 and 2x the labelled rates) at 3 growth stages (5 and 10 leaf stage and bolting). Paclobutrazol suppressed mainstem elongation (internode lengths) and seed productivity under controlled greenhouse environment. PGRs did not have an effect on canopy structure or yield during 2015/2016, however, PGR application at 5 leaf stage reduced plant height by 8% in 2016/2017. PGR application at 10 leaf stage increased mainstem elongation rate by 14% over 5 leaf stage and bolting during 2016/2017. Regardless of PGR source, a 2x rate increased yield by 11%. In addition, applying a PGR at 10 leaf stage increased yield by 11% in 2016/2017. Plant growth regulator applications may have potential in modifying B. carinata plant canopy structure.