Atomic Annual Ryegrass Logo with Atoms
Atomic Annual Ryegrass in paddock

Download Tech Sheet

Atomic Annual Ryegrass (Lolium multiflorum)

Atomic Ryegrass is exceptionally fast out of the ground and has prolific winter growth. A mid-maturing, annual tetraploid, Atomic Ryegrass produces excellent hay and silage and is a variety you can trust and rely on every time you sow it.

Key Features

  • Excellent winter production
  • Extremely rapid growth
  • Ideal for both hay and silage production
  • Highly palatable and nutritious
  • Strong vigorous seedling

Plant Characteristics

  • Broadleaf tetraploid
  • High tiller count
  • Wide leaves and dense tillers


  • Atomic is a mid-flowering variety. Days to flowering relative to Nui (0) = +4

Where can I grow it?

  • Medium to high rainfall zones
  • Suitable for irrigation

Sowing Rate

  • 25-30 kg/ha

Blend Rate

  • 5-15 kg/ha

Seed Size

  • 200,000-300,000 seeds per kg (Source: Pasture Varieties used in NSW 2006-2007, Bev Zurbo, 2006)

Frequently Asked Questions

Atomic is well adapted to a wide range of fertility levels and soil profiles, but performs best in a well-drained loam. Tetraploid annuals will cope with short-term water-logging provided the growing tip is above water. To maximise stand productivity, soil testing is advisable. Analyse soil and neutralise deficiencies with fertiliser and/or lime.

Good base rates of phosphorus are necessary for maximum DM production, especially during establishment phase. DM production is directly related to nitrogen availability. Consult your Upper Murray Seeds agronomist or fertiliser advisor for nitrogen application rates.

Sow at 25-30kg/ha alone or 5-15kg/ha when a component of a pasture blend. Sow seed no deeper than 1cm in a fine but firm seed bed. Sow into bared ground if direct drilling. Lightly harrow and roll to improve germination. Suitable for oversowing into an established stand. Pasture productivity is directly related to successful plant establishment.

During emergence it is essential to monitor regularly for damage from insects such as RLEM and lucerne flea, and spray as required. Inspect during early stand life for populations of black-headed cockchafer and slugs. Contact your Upper Murray Seeds agronomist for spray application rates.

Atomic seedlings germinate quickly and are very competitive once established. Always use a knockdown herbicide to ensure you are sowing into a clean seedbed. Monitor for post-emergent weeds and spray as required. Use options such as spray-grazing for broadleaf weeds.

Do not graze Atomic until the plant is well anchored and root depth is established. Carry out a quick in-paddock ‘grab test’ by hand to ensure stock cannot pull plants out of the ground. Atomic should be rotationally grazed to maintain 2-3 leaves per tiller. If the stand is allowed to grow beyond the three-leaf stage, it may run to head earlier and there will be a proportional reduction in quality and productivity.

Annual tetraploids, such as Atomic, have 4 sets of chromosomes per cell resulting in bigger, darker leaves. This increased cell size has higher sugar and moisture content which is more palatable and digestible than diploid varieties.

To optimise livestock weight gain and health, ensure livestock are vaccinated and drenched. To prevent nutritional problems, make gradual diet changes when introducing hungry stock to lush pastures. Contact an Upper Murray Seeds agronomist for more information.

Atomic 2020