Only two new varieties make it onto the HGCA Recommended List for oilseed rape in 2010. But they continue the leap in yields of the past two years.

Of the 30 candidate varieties drilled in RL trials last season just Dekalb’s DK Cabernet and Senova’s Fashion have emerged to join the east and west RL.

Trial failures in the north, where only two of four RL trials and one of two National List trials survived a difficult autumn establishment period, mean there was no new recommendations for growers north of Darlington.

“There wasn’t enough data for us to consider recommendation,” HGCA’s Jim McVittie admitted. Four of the best performing varieties, Fashion, Compass, Krypton and PR45D05, have been re-sown into this year’s RL trials for consideration next season. “They are also described in the new RL booklet.”

But oilseed rape continues to jump forward, at least in variety trials if not so much commercially, in its yield potential. “Hybrid yield leapt up from Excalibur in 2006 to Flash in 2008, and again to PR46W21 last year. We had a big jump in conventional yields last season with Vision and another one this year with DK Cabernet and Fashion,” Dr McVittie said.

At 111% of the controls, DK Cabernet’s gross output matches that of the leading hybrid variety, PR46W21.

High seed yields combined with an oil content of over 45% gave growers all-round output consistency, Anne Williams of Dekalb said about DK Cabernet. “Manageable height with good stem stiffness and lodging scores combine for practical direct harvesting on farm too.”

Disease resistance is solid, scoring sixes both for light leaf spot and stem canker resistance. But it is at the later end of maturity scale, Dr McVittie pointed out.

Fashion is 3% behind DK Cabernet in gross output, but 2% ahead of the previous best conventional variety, Vision, which also came from the Senova stable.

“It is a similar variety to Vision, although I have been told they came from different breeding programmes,” Dr McVittie said.

Its gross output is ahead of most hybrids, Senova’s Jeremy Taylor points out. “And offers a 6% improvement over Castille. This translates to added value on the farm and at a time when margins are under pressure this yield improvement will be appreciated by growers.”

Agronomically, Fashion is rated as an eight for lodging resistance, and is a five for stem canker and six for light leaf spot resistance.

Standards improving

The jump in top gross outputs from both hybrids and conventional varieties in the past two seasons meant it was difficult for more varieties to be recommended, Dr McVittie noted.

“The barrier to get onto the RL has gone up – the standards have improved.”

That’s the main reason why so few of the candidates had made the list, he said. The long list of candidates for the east and west list had been partly due to the previous year’s National List trial failures in the south, he added.

“We gave quite a lot of candidates the benefit of the doubt and included them in the RL trials.”

It did mean there were some candidate varieties not recommended with higher gross outputs than some of the current recommended varieties, he admitted. But he suggested growers would move to new varieties rather then grow older, outclassed varieties. “And why would they grow a mid-ranking new variety rather than the top one?”

The system was working, he stressed. “It is a process that has been developed over time.”

But a wider review of oilseed rape variety trials was ongoing. The speed that which oilseed rape seed could be produced was often quicker than the current system could cope with, meaning varieties could be on sale commercially before they were recommended, he said.

“It is also expensive to do oilseed rape variety trials, so we need to look at how best to use our resources. We hope to have some interim conclusions in the New Year, and it might require some changes to the trials programme.”