EFFECTS OF CLIMATE CHANGE ON DATE OF EAR EMERGENCE IN VARIETIES OF PERENNIAL RYEGRASS LOLIUM PERENNE L.

摘要

The availability and nutritional value of grass for grazing or silage production in spring depends largely on weather, location, the perennial ryegrass (PRG) varieties chosen and their dates of ear emergence (EE), which vary annually with meteorological conditions. A total of 213 varieties of PRG, each with at least 10 years of ear emergence data in the period 1991-2017 were mined from a database and used to determine strong associative relationships with a range of published Met Office regional temperatures. Further EE data recorded between 1935 and 1974 in Northern Ireland, England, Scotland and Wales from four previous publications were re-examined with their respective regional Met Office data and strong, significant correlations were determined.Varieties recommended in Northern Ireland in 2014 were found to mature 1-2 weeks earlier on average compared with their counterparts in 1974. Significant correlations (p<0.001), differentially related to maturity group, were found between annual dates of ear emergence and Met Office temperature data. Dates of PRG ear emergence and therefore timing for optimal nutritional value were found to become earlier in general but less predictable from one year to the next. Cognisance of this trend will be advantageous when choosing PRG varieties for reseeding.