A split application approach to nitrogen and growth regulator management for perennial ryegrass seed production

Eric J. Koeritz, Eric Watkins, Nancy J. Ehlke

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Experiments were conducted during 2009 and 2010 in first year perennial ryegrass (Lolium perenne L.) fields under limiting or adequate spring N. Three N application methods (single, two-split, and three-split), five growth regulators (split and single applications of prohexadione Ca or trinexapac ethyl) and two spring N rates (56 or 100 kg N ha-1) were evaluated in a split-split plot design. Under adequate spring N, all N application methods resulted in similar seed yields but when spring N was limiting, a single application of N resulted in up to 14% greater yield vs. the three-split. The three-split N application improved relative chlorophyll index (RCI) 6 to 20% late in the harvest season and reduced stem rust (Puccinia graminis Pers. subsp. graminicola) area under the disease progress curve (AUDPC) by 18 to 39% vs. the single N application. Other effects of three-split N applications observed in 2010 were 8 to 19% less biomass, 2 to 3% greater harvest index (HI), 4% greater seedling vigor, and 25% less lodging. The split prohexadione Ca treatment gave the most consistent results and when vegetative growth was greatest it resulted in a 36% increase in seed yield, a 5.5% increase in HI, 14 cm shorter plants, 70% less lodging, 30% greater RCI, 13% lower stem rust incidence, and 3% lower stem rust severity. Development of a model to optimize rates and timings for split N and growth regulator applications based on growth stage, soil N availability, and growing degree days (GDD) could improve efficacy of split applications.

Original languageEnglish (US)
Pages (from-to)1762-1777
Number of pages16
JournalCrop Science
Issue number4
StatePublished - Jul 2013


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