Choosing the right perennial ryegrass can be a daunting task when all sales reps say they have the best. They tend to avoid the important question of which is the best for you so I've put together some options you should look at when choosing your perennial ryegrass.

What to consider

There are four main points you have to consider when choosing the right perennial ryegrass:

1. Endophyte strain (relative to insect pressure)
2. Flowering/heading date
3. Ploidy (tetraploid or diploid)
4. Lineage/breeding

Endophyte strains

Insect pressure is one of the main reasons perennial ryegrasses don't persist.  The higher up in the country you are, 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 can even kill 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 and have been developed by plant breeders to help protect grasses from insect attack.

Getting the timing right 

A heading date is when 50 percent of the plants have emerged seed-heads. It is an important consideration as 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 (approximately 22 October) heading at day 0.

Heading/flowering time is important, 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) eg higher ME and are preferred by livestock.  However, tetraploids take greater management as they are easily overgrazed by stock, therefore, persistence can be an issue.

Lineage/breeding

Like 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 New Zealand come from North Western Spain as the conditions there are very similar to ours. The difference is that the germplasm is millions of years old so the perennial ryegrass has evolved over centuries to be able to survive those conditions.