Differential responses to timing of defoliation in perennial ryegrass (Lolium perenne L.) grown under silage management

摘要

Plant breeders and testing authorities place increasing importance on enhancing herbage quality but some evidence exists that management interactions can alter evaluations. This study compared yield and herbage quality (digestibility, D-value; neutral-detergent fibre, NDF; acid-detergent lignin, ADL) in perennial ryegrass when test protocols differed in the timing of the first silage cut by up to 28 days, with a fixed regrowth of six weeks to the second cut. Increasing and decreasing trends in yieldand quality with delayed cut were largely reversed at the second cut for all but ADL, which had a more novel response pattern. The effects of timing of defoliation were shown to be greatly reduced or eliminated by combining the first and second silage cuts and offered a better assessment of genetic potential, except for ADL. These findings also have implications for cultivar evaluation programmes and pose questions regarding ryegrass physiology relating to the observed differential responses in herbagequality parameters.