National study highlights modern OSR trait value

Reliably vigorous establishment, rapid autumn development and pod shatter resistance are the three OSR characteristics most sought after alongside yield potential by growers of one of the UK’s most popular varieties, reveals the latest national study.

What’s more, the Agrii study of DK Exsteel growers from Essex to Aberdeenshire with more than 2000 ha of winter oilseed rape in the ground shows these traits to be noticeably higher-up the list of today’s priorities than traditional attributes like robust disease resistance and strong standing ability (Figure 1).

Figure 1: What particular characteristics were you looking for in your variety choice?

“This clearly reflects the changing pressures on OSR growing,” comments Agrii seed technical manager, David Leaper who co-ordinated the study. “Traits that help the crop deal with autumn pest challenges – slugs and pigeons as well as flea beetle – are, understandably, in particular demand these days. And there’s a growing appreciation of the importance of reducing losses in the run-up to and at harvesting.

“It’s also probably testament to the great progress made by breeders in recent years,” he adds. “Agronomic characters like strong phoma and light leaf spot resistance and standing power that once distinguished varieties from one another have now become widely-available essentials, allowing growers to look beyond them in their variety choice.

“The secret to the crop consistency that has become so much more important to growers than out-and-out yield is to build on these essentials in breeding rather than losing any in pursuit of additional traits.  Reliability in a variety, after all, comes from all-round agronomic strength.”

As well as highlighting the importance of vigorous establishment and rapid autumn development to growers, the early spring study has confirmed four years of Agrii variety trials showing DK Exsteel to be one of the most capable varieties in both respects and the most consistent all-round performer.

Around 70% of growers in each case report the variety as performing better than those grown alongside it, with half of these considering it noticeably better and only a very small minority seeing it perform less well. And every single one of those growing it for more than a year rated it as better than other varieties for both traits (Figure 2).

Figure 2: How has DK Exsteel performed compared to other varieties?

Rapid autumn development was, indeed, identified as one of the best things about the variety by the highest proportion (61%) of those growing DK Exsteel for the first time, with two thirds professing themselves pleased with its performance to date.

A slightly higher proportion of growers with more than a season’s experience of the variety (63%) rated rapid autumn development as one of its best attributes alongside high yield and pod shatter resistance. In terms of its overall performance last season, 75% considered it either their best variety or better than most while none saw it do less well than other varieties being grown.

While around 20% of all the growers involved are reserving their decision until harvest, almost 80% consider they are likely to grow the variety again this coming autumn with half of these planning to make it a major part of their mix or their main variety.

“It’s very heartening to see farm experience echoing our own variety trials so well,” says Mr Leaper. “As well as the usual characters, we record both autumn and spring vigour across all our sites and verticillium tolerance wherever we have noticeable levels of infection. This allows us to assess varieties well beyond information from Recommended List trials.

“In addition to RL data showing DK Exsteel is second-to-none for its combination of phoma and light leaf spot resistance and has first class lodging resistance and stem stiffness, we recognise it as one of the most vigorous autumn developers of the 40-plus varieties we trial across our sites. It also stands out in our work as one of the most verticillium tolerant.

“Together this combination of characters have put its gross output at or near the top of our trial set every year since we started including it in 2017. It stands out as the most consistent modern variety, with a combination of verticillium tolerance and pod shatter resistance proving especially valuable in minimising seed losses. The fact that, unlike most of the rest of the top performers these days, it does so without the advantage of Turnip Yellows Virus resistance speaks volumes for its strength-in-depth. This, in turn, explains why it is being so well thought of amongst our growers.”