Technical
The MARCH of the TETRAPLOIDS
New tetraploid ryegrass mixtures, due to be launched in early 2012, look set to take the chill out of winter overseeding.
To be featured in the new the turfgrass seed booklet, these new mixtures have undergone trials in The Netherlands and at Worcester
Warriors, where the results have proved very encouraging
unprecedented heights, but also pressures on groundstaff have been placed into even sharper relief given the boom in televised sports: turf quality and performance have to be better than ever and to be seen to be so. Likewise, ever-evolving turf science brings the possibility of creating more manageable groundcare year-round and making sustained high standards more attainable, especially through winter. Once upon a time, turfcare
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professionals knew which grass seed was suitable for the particular time of year, and worked accordingly within seasonal constraints to attain optimum results from it.
Ryegrass has long been a species that has undergone vast swathes of research and development in a bid to harness its hardy virtues for year-round application. After thirty years of trialing ryegrass cultivars, the industry is entering a truly revolutionary era - one where the culmination of so much research into ryegrass has created a reliable species for utilising in any overseeding programme, in any season.
New turf type tetraploid cultivars (4Turf) have been trialled at UK sites
130 PC DECEMBER/JANUARY 2012
n virtually every sphere, groundsmanship has transformed out of all recognition in just a generation. Not only have technical and scientific demands reached
Trial plots showing tetraploids resistance to snow mould
and are about to be unveiled in early 2012 in a move, it is believed, will bring a wholesale shift in the effectiveness of overseeding, whatever the season. In particular, these ryegrass cultivars are expected to address many of the issues groundstaff face when trying to overseed in winter. Winter overseeding poses one of the toughest challenges for groundstaff, who have limited hours to work, diseases to contend with, competition from unwanted species and poor conditions for germination due to low temperatures and light levels - all issues further exacerbated by modern stadia, which often allow little natural light to fall on the grass through the winter months. Despite the pitfalls, overseeding at this stage of the year is beneficial to maintain surface quality and ensure a denser sward to withstand the rigours of winter play. Good winter overseeding also helps maintain a diverse and balanced sward, repairs worn and damaged surfaces and, importantly, fights to outcompete weed species, especially Poa annua - the scourge of countless grounds professionals.
Late autumn, into winter and early spring represent some of the least productive times for growth, leading to periods where poor plant coverage and appearance can persist.
The tetraploid overseeding mixtures
being introduced are set to transform winter maintenance programmes. In trials, they have produced specifically better low temperature establishment, improved winter disease resistance, improved shade tolerance and increased winter wear tolerance.
It is the combination of the annual rye for the very fastest establishment, the low temperature germinating high wear diploids for outright long term wear tolerance, and the new tetraploid (disease resistance and fast
establishment) that deliver the high level of wear tolerance, not the tetraploids on their own.
The science behind the improvements in winter stress tolerance characteristics is simply explained. Traditional turf type perennial ryegrasses (diploids) have two sets of chromosomes - tetraploids have four sets, and 4Turf seeds are one and a half times larger than regular turf type ryegrass. Because of that characteristic, they can produce seedlings quicker, and generate a thicker sward, so turf is no longer resigned to poor growth and the characteristically thin, patchy appearance. The biggest benefit of the tetraploid is the winter disease resistance. The picture above, from a breeding plot last winter, shows a range of diploids that were all badly hit with snowmould, yet all of the tetraploids remain virtually untouched. The increased seed size also gives them
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