How high can we get? High-yielding and winter hardy perennial ryegrass cultivars for higher latitudes

Comparing to other temperate fodder grass species, perennial ryegrass specie is superior in yield, regrowth after harvest and fodder quality. Unfortunately, it is also one of the least winter-strong fodder grass species, which limits the cultivation area in Norway. However, the consequences of climate change are expected to expand the cultivation area of ryegrass towards higher latitudes and more continental climates and increase the importance of this species to our Norwegian livestock. HighGrass project has formally started on January 1, 2022 and will run until Dec 31, 2025. The project will be carried out via a collaboration between the industry partners Graminor AS, Felleskjøper Agri SA and Strand Unikorn SA; and the research institutions NMBU; and farmer advisor Norsk Landbruksrådgiving; and international research institutions in Belgium and Denmark. The primary objective of HighGrass project is to advance the development of persistent, high yielding, perennial ryegrass cultivars that possess higher feed quality and are better adapted to Nordic climate than existing cultivars. This main objective will be reached through several secondary objectives; (1) characterize the performance of ryegrass breeding material and cultivars (2X and 4X) under Norwegian field conditions. In this project, we will utilize ryegrass populations that have been developed though our Nordic project «Public-Private-Partnership (PPP) for pre breeding in perennial ryegrass». (2) Develop high throughput phenomic protocols for accurate prediction of dry matter yield, regrowth and feed quality measures in perennial ryegrass. (3) Quantify correlation of water-soluble carbohydrates with winter survival and feed quality. The project also designates specific working package to develop strategies for application of genomic tools (i.e., Genomic Selection – GS) in Graminor’s ryegrass breeding program. Field trials of 33 populations were established at six different locations in 2021. In 2022, 2023, and 2024, these fields were harvested three times and recorded for tiller shooting, harvested crop, regrowth, and spring and autumn cover. The same 33 populations were established as row experiments at Bjørke (Graminor) and Ås (NMBU) in 2021. These fields were harvested three to four times in the season in 2022, 2023, and 2024 and also recorded for the same characteristics mentioned above. In addition to visual field recording, the use of drones with mounted multispectral cameras has been tested, which have taken pictures of the fields at Ås and at Bjørke throughout the season. The processing of these image data is complete and the first analyses were completed by master student Hedda Charlotte Haugland, who also completed her master's degree in the project. The master's thesis focused primarily on the development of regression models to be able to predict yield and regrowth for the first two harvests at Bjørke and Ås. The master thesis was completed in the summer of 2023. The analysis of water-soluble carbohydrates for the first half of the plants from single-plant trials in Ås has been completed. In 2024, the second half of this experiment was established and tissue from the crown and leaf material will be harvested in the winter of 2024/25. This material will again be sent to KU Leuven for further fructan analyses. GBS genotyping was completed in the spring of 2024 and genotypic data is now being used to develop genomic prediction models and update them with phenotypic data from all trial years and locations.

Sammenlignet med andre tempererte fôrgrasarter er flerårig raigras overlegen i avling, gjenvekst etter høsting og fôrkvalitet. Dessverre er det også en av de minst vintersterke fôrgrasartene, noe som begrenser dyrkingsområdet i Norge. Konsekvensene av klimaendringene forventes imidlertid å utvide dyrkingsområdet av raigras mot høyere breddegrader og mer kontinentale klima, og øke betydningen for norsk husdyrhold av denne arten. Vårt hovedmål i dette prosjektet er å utvikle robuste flerårige raigrassorter som gir høy avling, har god fôrkvalitet og er tilpasset de ulike framtidige vekstforholdene i Norge. For å nå dette målet må norsk foredling av raigras bli mer effektiv ved å ta i bruk moderne foredlingsmetoder og teknikker. Vi vil bruke en rekke populasjoner og breie diploide og tetraploide avlspopulasjoner som er utviklet i det Nordiske prosjektet «Public-Private-Partnership (PPP) for pre- breeding in perennial ryegrass». Vi skal teste tilpasningsevnen til 50 raigraspopulasjoner som er utviklet i i PPP prosjektet til ulike klimatiske forhold i Norge, bruke høy-oppløselig og høyintensiv fenotyping med moderne imagingteknikker, studere hvordan innhold og sammensetning av vannløselige karbohydrater (WSC), spesielt innhold og sammensetning av fruktan, korrelerer med vinteroverlevelse og fôrkvalitet, teste om genomiske prediksjonsmodeller etablert i PPP-prosjektet er gyldige for forskjellige norske lokaliteter og om de kan brukes til å forutsi avling til blandinger av diploide og tetraploide sorter. Genomisk seleksjon og høyopppløselig fenotyping vil bli implementert i foredlingsprogrammet til industripartneren Graminor. Dette vil muliggjøre en raskere produksjon av nye forbedrede og robuste sorter, med forbedret økonomisk bærekraft ved at fôr med bedre kvalitet kan dyrkes lokalt og redusere behovet for kraftfôr.