How to choose the best ryegrass

They tend to avoid the important matter of which is the best for you, so here are some options to look at when choosing a perennial ryegrass.  

Consider these four main points: 

1. Endophyte strain (relative to insect pressure) 

2. Flowering/heading date 

3. Ploidy (tetraploid or diploid)  

4. Lineage/breeding 

Endophyte strains 

Insect pressure is a key reason perennial ryegrasses don’t persist.  The further north you are in New Zealand, the more protection against insects your ryegrass will need.  

Black beetle, porina, Argentine stem weevil, grass grub and field crickets all have a huge effect, stripping valuable dry matter and even killing ryegrass pastures. 

Choosing and understanding the correct endophyte strain is very important for the longevity of your pastures. AR1, AR37 and NEA2 are all novel endophytes, developed by plant breeders to help protect grasses from insect attack.

 Getting the timing right  

 A heading date is when 50% of the plants have emerged seed-heads. This is key because seed-head development reduces feed quality in late spring and the heading date determines when this occurs. Heading dates are defined relative to the cultivar Nui (about 22 October) heading at day 0.  

Heading/flowering time is important here as it controls the extent of early spring production and late spring quality The standard heading/flowering ryegrasses are good for late August-early spring growth as this is when the quality is best, and will carry the farm through the typical spring feed pinch.

 By mid-spring (October), growth rates are often high and the feed supply often changes to a surplus; here pasture quality may deteriorate if grazing management is not precise. At this point, late flowering ryegrasses such as Ultra and Matrix (+20- +23 days after Nui) come into their own as the earlier flowering ryegrasses lose their quality.

Ploidy 

 Ploidy is a term referring to the number of chromosomes per cell. The two main ploidies are tetraploid and diploid.  

• Diploids are the most common, normally found on sheep and beef farms, due to ease of management, and have two sets of chromosomes per cell.  

• Tetraploids have four sets of chromosomes per cell, which are larger, and generally grow bigger darker leaves, with larger but fewer tillers. They have a higher ratio of water soluble carbohydrate (cell contents) to fibre (cell wall) e.g. higher ME and are preferred by livestock.  

However, tetraploids take greater management as they are easily over-grazed, so persistence can be an issue.  Lineage/breeding 

As for top quality breeding stock, it is important to understand the bloodlines or parentage of your grasses. 

It’s pointless trying to grow a plant that doesn’t belong in your environment. 

Most of the breeding lines of grasses in NZ come from northwest Spain where the conditions closely resemble NZ’s. The difference is that the germ plasm is millions of years old so the perennial ryegrass has evolved over centuries to be able to survive those conditions.   

• Jeremy Klingender is Ravensdown seed product manager.