1 March 2002

HYBRIDRYEGRASSOVERPERSISTENCY PROBLEMS

By Robert Davies Wales correspondent

NEW hybrid ryegrass with exceptionally high water soluble carbohydrate content should see it overcome the persistency problems of the past.

Genetic blends of Italian and perennial ryegrasses are no longer unstable or lack persistency and medium-term yield potential, says researcher Llinos Jones.

She has bred ryegrass hybrids at the Institute of Grassland and Environmental Research for more than three decades and believes modern tetraploid varieties can remain economically productive for five years. They produce quality herbage all year and are compatible with legumes, she says.

AberEcho, which is still being evaluated, is the latest in a long line of bred varieties that have transformed the way hybrids are perceived by producers.

The breeding programme has produced varieties with a range of flowering times, which allows more flexible cutting and grazing management. Across the range, ground cover, digestibility and sugar levels have all been enhanced.

"Hybrid ryegrass seed sales are still a modest 600t/year, but improved varieties are pushing up demand."

AberLinnet and AberExcel behave in a similar way to Italian ryegrass up to ear emergence. They then tend to display perennial traits, such as high tillering and leafy regrowth.

Producers see the benefit of a combination of excellent early spring production and the potential to extend the autumn grazing season, says Ms Jones.

Visitors to IGER Aberystwyth this year will get the last chance to see a hybrid evaluation trial sown in 1996. Early, intermediate and late flowing per-ennial, Italian and hybrid ryegrass varieties were sown in separate groups based on flowering date.

A seven cut management system was imposed – equivalent to spring grazing in March, two silage cuts, followed by four aftermath grazings between August and early November. Total whole season dry matter yields were measured and ground cover was used to indicate persistency (see table).

By the third year perennials were out yielding Italian ryegrass varieties. By the fifth year perennials were out-yielding hybrids. But hybrids, in particular AberLinnet, were still giving high silage yields over two cuts and maintaining their ground cover.

After five years, the tetraploid perennial Merlinda retained 65% ground cover, AberLinnet achieved 56%, diploid Italian Atalja 24% and tetraploid Italian Roberta 5.5%.

"Taking two silage cuts from the latest hybrid variety can produce enough dry matter to make a third expensive cut unnecessary."

This should be demonstrated clearly when the long-term trial is repeated using the newest Aber hybrids, Ms Jones believes. &#42

Hybrids can combine early spring production and extend grazing into autumn, says Llinos Jones.


Grass variety DM yields

Total Silage only

t/ha t/ha

(t/acre) (t/acre)

Merlinda (P) 16.4 9.3 (6.6) (3.8)

AberLinnet (H) 15.8 9.0 (6.4) (3.6)

Atalja (I) 12.9 7.9 (5.22) (3.2)

Roberta (I) 11.3 7.3 (4.6) (2.6)

P = perennial, &#42 = hybrid, I = Italian.

&#8226 Persistency problem overcome.

&#8226 Yields hold well.