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

Context: Data are lacking on the effects of heading date of perennial ryegrass (Lolium perenne L.) on ryegrass persistence.

Aim: We aimed to determine the impact of heading date on perennial ryegrass persistence.

Method: Two mid-heading (Samson, Bronsyn) and two late-heading (One50, Rohan) cultivars, infected with Epichloë 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.

Key results: 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).

Conclusions: The two late-heading cultivars were more persistent than the two mid-heading cultivars, although persistence declined over 4 years for all cultivars.

Implications: Results support industry recommendations of choosing late-heading cultivars for improved pasture quality and persistence.