This Herbage Update summarises findings from three seasons of irrigation on browntop trials in Canterbury, New Zealand.
Key Points:
- Browntop seed yield on Templeton Silt Loam soils increased with irrigation across three seasons, with optimal results achieved from 334 to 486 mm of water applied.
- On average, crops required around 400 mm of irrigation from September to harvest reflecting the higher water demand associated with browntop's late maturity.
- Seed yield consistently dropped once the critical soil moisture deficit (Dc) of 54 mm was exceeded, regardless of when drought occurred, indicating that browntop seed crops are less drought-tolerant than ryegrass, wheat or cocksfoot (critical deficit ≥70 mm at the same site).
- Continuous irrigation is essential throughout the season, particularly during hot, dry periods, to prevent stress at any growth stage and maintain seed yield.
- Higher seed yields were associated with greater seed head numbers and branching, resulting in more seeds per square metre.