Modelling perennial ryegrass (Lolium perenne) persistence and productivity for the Upper North Island under current and future climate

Abstract

The objective of this study was to predict the future performance of perennial ryegrass in the Upper North Island, New Zealand. The Basic Grassland model, BASGRA, was used with historic, current and future daily climate data as input, and soil water holding capacity, to predict changes in perennial ryegrass performance in space and time. The study focussed on land of ≤7° slope north of the town of Tokoroa and considered two potential warming pathways to the end of the 21st century. Persistence was defined as the time in years for the ryegrass sward to decline to 50% ground cover. The results for the two climate pathways were largely consistent with each other. Persistence should remain in the medium category (2.5-3.4 years, 10-12 t DM/ha) for the rest of this century for Bay of Islands, Whangarei, South Waikato/Tokoroa, and Rotorua. Persistence is predicted to change from medium to predominantly low (0-2.4 years, <10 t DM/ha) for Far North, Dargaville, DairyFlat/Rodney, Waiuku/Pukekohe and northern and central parts of Waikato. Coastal regions of Bay of Plenty were predicted to be poorly suited to perennial ryegrass and to remain so into the rest of the century. Large parts of the Upper North Island that are currently borderline for perennial ryegrass are predicted to become unsuitable for the species.

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

“…3 0 M a y 1 8 2 7 S e p 1 8 2 5 J a n 1 9 2 5 M a y 1 9 2 2 S e p 1 9 2 0 J a n 2 0 1 9 M a y 2 0 1 6 S e p 2 0 1 4 J a n 2 1 1 4 M a y 2 1 1 1 S e p 2 1 0 9 J a n 2 2 Total unsown species (% of total DM) There was a strong seasonal trend in perennial ryegrass performance and a loss of ryegrass persistence characterised by weed ingress, regardless of heading date. This is consistent with research in the upper North Island of New Zealand, in which perennial ryegrass populations declined and the abundance of weedy species increased as pastures aged (Tozer et al 2014;Dodd et al 2018;Beukes et al 2021).…”

The contribution of perennial ryegrass (Lolium perenne L.) breeding to whole pasture productivity under dairy cattle grazing in New Zealand. 1. Variation in yield, nutritive value and persistence‐related traits

“…Compared with the late flowering diploid group, fewer mid‐season heading diploids were commercialized in the 2000s though the release of Request in 2011 indicates renewed interest (albeit with little evidence of progress compared with older mid‐season types). This is timely, given the trend toward warmer winters and hotter drier summers in the upper North Island during the 2010s (Glassey et al, 2021) signalling possible future climates for this region under which summer and autumn pasture growth will be constrained (Beukes et al, 2021; Keller et al, 2021).…”

“…It is not known if the traits required to deal with intensifying climate and pest pressure on ryegrass in the upper North Island (Beukes et al, 2021; Mansfield et al, 2021) can be found within the accessions of Lolium and Epichloë currently being used in New Zealand breeding programmes. Other accessions that have not come through in commercial material to‐date (e.g.…”

“…The outcomes of these developments were evident in the results from the four trials reported here. Of the total 27 or 28 cultivar- North Island during the 2010s (Glassey et al, 2021) signalling possible future climates for this region under which summer and autumn pasture growth will be constrained (Beukes et al, 2021;Keller et al, 2021).…”

Organising Committee Chair's address: Resilient pastures

“…It is now indisputable that some combinations of local climate and soil type, often exacerbated by insect pest damage, present environments that are beyond the adaptive range of current perennial ryegrass cultivars (Lee et al 2017;Jagger 2021;. The specific environmental combinations, and the lethal factors operating, are still poorly defined although simulation tools are being developed to help address this knowledge gap (e.g., Beukes et al 2021). Perennial ryegrass is generally able to withstand, and recover from, single stress events like a drought, overgrazing, or insect damage (Chapman et al 2011) but multiple simultaneous stresses can collectively exceed thresholds of plant survival (Cullen et al 2006;Tozer et al 2017;Moot et al 2021).…”