Effects of heading date and <i>Epichloë</i> endophyte on persistence of diploid perennial ryegrass (<i>Lolium perenne</i>). 1. Heading date.

<p dir="ltr"><b>Context</b>: Data are lacking on the effects of heading date of perennial ryegrass (<i>Lolium perenne</i> L.) on ryegrass persistence.</p><p dir="ltr"><b>Aim</b>: We aimed to determine the impact of heading date on perennial ryegrass persistence.</p><p dir="ltr"><b>Method</b>: Two mid-heading (Samson, Bronsyn) and two late-heading (One50, Rohan) cultivars, infected with <i>Epichloë</i> endophytes (AR37, nea2/6 or standard toxic), were established in a replicated plot study grazed by cattle in a subtropical environment of the upper North Island of New Zealand. Persistence characteristics were quantified at least five times per annum, over 4 years.</p><p dir="ltr"><b>Key results</b>: Late-heading cultivars had higher yield, nutritive value, perennial ryegrass content in pasture dry matter, ground cover and tiller density than mid-heading cultivars. There were large seasonal impacts on all ryegrass characteristics, with a major decline over summer and recovery during late autumn into early spring, with less recovery in the final year. Overall, there was a strong linear decline in ryegrass content measured during spring (2018–21).</p><p dir="ltr"><b>Conclusions</b>: The two late-heading cultivars were more persistent than the two mid-heading cultivars, although persistence declined over 4 years for all cultivars.</p><p dir="ltr"><b>Implications</b>: Results support industry recommendations of choosing late-heading cultivars for improved pasture quality and persistence.</p>