AR37 is an endophyte from AgResearch that is a step-change in enhancing ryegrass persistence and production.
Agronomic trialling began in the mid-1990s. In 11 trials sown over 2 years and 4 regions of the country, a range of endophytes were tested against endophyte-free and the Standard endophyte. The outstanding feature of this research was the better production and persistence that AR37 imparted on the ryegrass (see graph).
On average, these 11 trials showed that over a 3-4 year period, annual dry matter was 12% better for AR37-infected ryegrass compared with ryegrass infected with Standard endophyte. Differences were greatest in northern regions of NZ, and greater in late summer/autumn (see slideshow). This information was first published at the 5th International Endophyte Symposium in the USA in 2004 (see symposium paper and poster).
Graph showing relative ryegrass growth for 11 trials (100 = standard endophyte)
Further work with different cultivars sown in other years (see NZGA paper), has confirmed that these results are repeatable. These more recent trials show that the time for the advantages of AR37 to come through will differ between years and regions.
While the AR1 endophyte has been a success story for its high animal performance relative to Standard endophyte, these agronomic trials showed that at times its agronomic performance can be lower than that of the Standard endophyte. In such cases, AR37 should be seen as an alternative to AR1.