Cool, Dry Storage Key to Maintaining Endophyte Viability in Perennial Ryegrass Seed

Anything else risks dead endophyte and weak pasture, it says.

Scientists stored perennial ryegrass seed containing two common endophytes - AR37 and NEA2 - in six bag types under different conditions for 12 months.

The results for both were almost identical.

Only cool storage (4°C, 30% relative humidity) held endophyte viability at 83-92%, matching pre-storage levels.

Ambient storage (15-25°C, 65% relative humidity) dropped it to 54-68%, with most loss in the final three months.

Bag type made almost no difference, researchers concluded.

The study was led by Lincoln University and the Seed Industry Research Centre to find out how storage conditions and packaging affect seed quality and endophyte viability.

"The results are pretty sobering," says Barenbrug sales manager Jason Gardner.

"Buying seed without knowing its storage history is a gamble, and jeopardises what should be a highly profitable, multi-year return on investment."

Elevating the risk is the fact that most seed sold for autumn pasture renewal is at least 12 months old, as the window between harvest and sowing is too brief to process it all.

The findings challenge the industry assumption that ambient storage works fine for a year in New Zealand, Gardner says.

"It doesn't - not if you want reliable endophyte protection against pests and better pasture persistence."

Over 90% of perennial ryegrass seed in NZ contains endophyte.

"The research backs up the care and effort we've made for many years to cool store seed with endophyte in both the North and South Island and continually test and check its quality. Anything other than correct cool storage puts endophyte at risk."

Farmers can protect their investment in autumn pasture renewal simply by asking about the stewardship of their intended seed purchase and making an informed decision.