Long-term trend in perennial ryegrass (Loliumperenne L.) delineator cultivar heading dates from 1984 to 2016

摘要

The annual variability in the temperate climates of Ireland, Northern Ireland and the UK is well recognised. The timing of heading (flowering) in crop species within a season is largely determined by responses to early season temperature and photoperiod. Numerous studies in Europe have shown earlier flowering across crop types (cereals, white clover and natural plant communities). During the last 33 years, the AFBI Plant Testing Station has evaluated forage perennial ryegrass cultivars as spaced plants under strict protocols to determine ear emergence (heading date). Examination of the mean date of ear emergence of perennial ryegrass delineator cultivars over the last 33 years provides evidence of phenology changes with earlier heading by 1.8 days per decade. The effects were evaluated using correlation and regression models for monthly mean temperature and heat sums (growing degree days). Differences in the distribution of plant heading date pre- and post-2000 were evident but not significant. Thevalue of long term data sets on phenology and climate change are discussed.