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Tetraploid, Diploid, Endophyte

Tetraploid, Diploid, Endophyte

Which to Sow – Tetraploid or Diploid?

By the natural order of nature, ryegrass is referred to as a Diploid. By introducing the chemical compound colchicines, plant breeders have found they can double the number of chromosomes that occur naturally from 14 to 28.  The result of this process creates a new breed of ryegrass called Tetraploids.  These Tetraploid ryegrasses are generally darker in colour and carry much higher water content. These new characteristics are generally associated with increased palatability and in some cases have been linked with greater animal performance.

Tetraploids are generally considered to be suited to conditions of –

  • Higher fertility
  • Moist or irrigated conditions
  • Relaxed grazing management (leaving a residual after grazing 5 – 7cm)
  • Grazing rotations of between 21 – 30 days approximately
  • Ideal sowing rate between 20 – 30kg/ha
  • Approximately 350,000 seeds per kilogram

Diploids are generally considered to be suited to conditions of –

  • Lower fertility
  • Drier, unpredictable seasonal conditions
  • Shorter grazing intervals of 14 – 25 days
  • Closer grazing (Leave a residual of 2 – 5cm)
  • Recommended Sowing Rate of 15 – 20kg/ha
  • Approximately 500,000 seeds per kilogram

As a rule of thumb, in the South East Region, Diploid varieties have been the preferred option for top quality hay mixes.  They are finer in the stem and usually dry quicker.  They are more erect growing, tend not to out compete their clover companions and give higher quality hay as a result.  Through local trials at our research farm we have found Diploids can be slower to establish when sown late in the season compared to Tetraploid varieties.

Quick Rundown on Endophyte

Endophyte is a fungus which occurs naturally in many grasses. Endophyte is carried in the seed of grasses and will not pass from one plant to another.  The endophyte within a plant produces chemicals called alkaloids and these alkaloids can have negative effects on stock health.  However, the alkaloids also give the plant special traits such as:

  • Drought tolerance
  • A measure of pest and disease resistance
  • Maximising plant persistence
  • Increasing plant production and growth rates

The alkaloids produced in the plant by the endophyte include –

  • Peramine (Deters insect pests)
  • Lolitrem B (Causes Ryegrass staggers)
  • Ergovaline (Limits blood flow and causes poor animal production)
  • Epoxy Janthitrem – Breakthrough in insect pest resistance, offering resistance to Argentine Stem Weevil Larvae, Pasture Mealy Bug, Root Aphid, Black Beetle.

The following table is a summary of the types of alkaloids produced by the endophyte for quick reference to give you a guide as to what you currently have in your pastures as well as what may suit your purposes in the future.

Contact us at Naracoorte Seeds to discuss your endophyte options and requirements.