- Ryegrass variety - perennial, short rotation, Italian or annual
- Endophyte choice - insect control, performance and persistence
- Ploidy choice - diploid or tetraploid cultivar
- Heading date - early, mid or late.
Ryegrass varieties
Ryegrass varies from the most persistent (perennial ryegrass) to the least persistent (annual ryegrass) and can be broadly categorised by how long they live or persist.
Annual - Less than one year
Italian - 1-2 years
Short rotation - 2-5 years
Perennial - 5 years
Ploidy
Ploidy refers to the number of chromosomes per cell in a plant, a diploid ryegrass has two sets of chromosomes while a tetraploid ryegrass has four sets. These differences create differing plant characteristics with associated advantages and disadvantages for each type.
Endophyte
An endophyte is a naturally occurring fungus that is found in ryegrass and tall fescue pastures. They are essential for persistence in most New Zealand pastures.
The endophyte protects plants from a range of insects but can be associated with animal health problems, especially ryegrass staggers. There are different types of endophyte and each varies in persistence, yield, and insect protection.
Heading date
A heading date is when 50% of the plants have emerged seedheads. Heading date is an important consideration as seedhead development reduces feed quality in late spring and heading date determines when this occurs.
Heading dates are defined relative to the cultivar Nui (approximately 22 October), heading at day 0.
Heading date definition | Days relative to Nui |
Nui | 0 |
Early-season | -21 to -8 |
Mid-season | -7 to +7 |
Late-season | +8 to +21 |
Very late-season | +22 days or later |
- Early heading date (up to about +7 days) means better early spring growth
- Late heading date means better late spring and summer feed quality.
Heading dates vary between ryegrasses, and these should be understood to ensure the cultivar mix on a farm is most appropriate to its pasture production requirements and soil characteristics.
Late and very late heading cultivars provide a significant advantage in late spring quality, so make pasture management easier, and help maintain the cows pasture intake through this period.
Do not mix early and late heading cultivars in the same paddock as:
- The higher feed quality of late heading paddocks in late spring is diluted
- It is easier to strategically graze or mow to control seeding of a pasture with a more uniform heading date.
Sow no more than 50% of the farm in late or very late cultivars to minimise early spring feed pinches.
High sugar grasses
High sugar grasses are diploid perennial ryegrass bred for elevated levels of water soluble carbohydrates (WSC).
There has been considerable research and debate about water soluble carbohydrate, with a review of 21 animal experiments concluded that there was no consistent response of intake, milk yield or liveweight gain to feeding high WSC pastures.
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