Make the most of variety genetics to help de-risk OSR – Arable Farming

“In this way, it is possible for varieties to better withstand environmental challenges that play an important role in maintaining yield security and fulfilling the yield potential of the variety.

“While it is relatively easy to identify varieties with the genetic traits recognised on the RL, vigour, pod shatter and stem health are not measured, so it is key to understand how these can be quantified and the role these valuable characteristics play in terms of delivering the crop on farm,” he says.

Mr Bouch believes hybrid varieties offer the best case for establishment, and are loaded with valuable genetic traits.

“There is a reason why 65-70% of the market is down to hybrids, genetic traits such as TuYV, Rlm7 and clubroot resistance, as well as characteristics such as vigour – both autumn and spring – stem health and even the ability to scavenge nitrogen. All play a part in securing that important final yield.

“Vigour is all important forgetting the crop up and away, both in the autumn and in the spring, and shouldn’t be underestimated in value. Vigour is the characteristic that provides some security in helping the crop to grow enough biomass in the autumn to fight against adult CSFB attack and then to drive growth again in the spring to stand up to larval pressure.”

Liam Wilkinson, oilseed rape manager at breeder Limagrain, points out that while the AHDB carries out early vigour scores which are recorded on the one year harvest results, it is not a value that is carried over onto the Recommended List (RL).

“The basis of this scoring is on a sliding scale of 1-9, where 1 is a very weak variety and 9 representing the most vigorous variety on a field by field basis. Clearly this is open to a large amount of interpretation and variation between varieties, fields and locations.

“However, in the absence of official vigour scores on the RL, there are various methodologies that have been adopted to measure vigour across the industry. Remember however, no-one knows a variety as well as the breeder, he says.

The next characteristic to consider is pod shatter resistance and choosing to grow a variety with built in pod shatter resistance is one of the most important things a grower can do, says Mr Bouch.

“A variety that offers robust pod shatter resistance over one that doesn’t can be the difference between a decent and average crop. There is no point in taking a variety all the way to harvest with all the associated costs, to then lose it unnecessarily.”

Pod shatter is a natural process for seed dispersion in oilseed rape; however on farm it can result in significant seed loss caused by heavy wind, rain, hailstones, or the combine passing through the crop.
“We haven’t had a major weather event over the last few years to impact crops, so it may have been slightly forgotten, but it is important to engage with it.”

Mr Wilkinson points out that while not all varieties carry the pod shatter trait, all Limagrain hybrids carry pod shatter resistance which is reflected in their high yields.

He highlights the hybrid variety Attica, which is the highest yielding variety on the RL offering pod shatter resistance.

“At Limagrain, we precisely quantify pod shatter resistance using lab-based techniques, where the force required to shatter the pod is measured, and this clearly shows that not all POSH resistant varieties offer the same level of resistance,” he says.

“POSH resistance can also help to provide some flexibility in the timing of the harvest, which can be as much as 14 days extra in our tests,” he adds.

Stem health is the latest area of focus for oilseed rape breeders as they come to realise the impact of three main stem-based diseases of OSR – phoma, cylindrosporium (light leaf spot) and verticillium.
“By having healthy green stems longer into the growing season we often see higher yields and oil content,” says Mr Wilkinson.

“For a Limagrain variety to hold the Stem Health tag it has to offer high levels of disease resistance to all three diseases – one single weakness leads to exclusion from the Stem Health list, or the right to carry the Stem Health claim.

“We select plants with good strong stems that stand well – we know the genetics will hold up,” says Mr Wilkinson.
Newly recommended variety Attica offers Stem Health – adding to an already trait-loaded offering -and this is reflected in its consistently high gross output of 107%.

Mr Bouch believes that good stem health scores go some way to allowing a variety to deliver consistently across seasons.
“However as verticillium is not currently scored on the RL it would be useful for breeders to come together with a universal scoring system.”
Clubroot is another example of where genetics play out on farm to bring added yield security, he adds.

“Clubroot is becoming increasingly widespread and is now found in areas historically not known to be infected, such as the West Midlands. Early drilling into warmer, wet soils can also increase the risk.”

However, genetics has once again given growers a get out of jail card, as there are now clubroot varieties that offer additional traits and therefore do not carry a yield penalty. For example, LG Scorpion is a high yielding clubroot resistant variety that also offers TuYV resistance, pod shatter and very good vigour.

To protect the genetics, it is imperative that clubroot varieties are only grown where land is infected and are not used as preventative measures.

“After all of this, the biggest single consideration remains the conditions at time of planting. If soils are warm and more importantly there is sufficient moisture, then oilseed rape still provides a very viable option in the crop rotation,” says Mr Bouch.