Plant growth regulators: a success story in perennial ryegrass seed crops

The introduction of the plant growth regulator trinexapac-ethyl (Moddus) has increased seed yields in perennial ryegrass (Lolium perenne) by up to 50% in New Zealand. Application rates from ten trials have confirmed that approximately 1.6 l/ha are optimum. Yield increases are a result of increased harvest index and better dry matter partitioning to the harvested parts. The resulting changes in harvest components include increasing seed head density and seeds per spikelet (better seed retention) associated with delayed lodging. Keywords: Lolium perenne, lodging, Moddus, seeds/spikelet, trinexapac-ethyl