Key Points:
- Appropriate irrigation management is critical to achieving high yields in perennial ryegrass seed crops.
- Water stress did not affect the yield components up until anthesis/fl owering i.e. head numbers and spikelets were unaffected.
- Changes in TSW had the largest impact on the fi nal seed yield.
- Maximum potential soil moisture defi cit explained the variation in seed yield well and could be used to manage seed crops at this site e.g. accumulated evapotranspiration minus rainfall and irrigation.
- Growers need to ensure water stress is limited throughout the growing season and should aim to avoid periods of drought, regardless of timing.