Low-biomass hybrids could mark the most significant development for oilseed rape growers in the UK since the introduction of Canberra 10 years ago, one of their breeders claims.

Dekalb‘s DK Secure was the first semi-dwarf hybrid variety on HGCA’s Recommended List, along with Pioneer’s PR45D03, and combined two of the firm’s breeding strengths, breeder Matthew Clarke told a trade launch.

“We are noted for our-low biomass conventional varieties, such as Canberra and latterly Castille, and hybrid varieties that take the pain out of growing hybrids. Now we’ve put the two parts together to make something of great interest to growers.”

Most previous hybrid varieties tended to be tall, not particularly stiff-strawed and later maturing, which took most of the yield advantages away in added management costs, he said. “Even Excalibur, which is shorter than other hybrids, is as tall as taller conventional varieties.”

But combining a female parent containing a dwarf gene with a conventional-height male parent had allowed Dekalb to breed varieties similar in height to Castille, Robert Plaice, technical support manager for Monsanto, said.

Breeders had tried breeding semi-dwarf varieties before, said Mr Clarke. “The first ones were below par on yield terms, but progress has been rapid.”

Even so, DK Secure, which scores 103 for gross output in the north, is 11 points behind top-rated Catana in the region. In the east and west it scores 98 compared with 111 for Pioneer’s PR46W21.

Part of that difference was down to a Recommended List trialling system that didn’t suit semi-dwarf varieties, particularly if the varieties were swathed prior to harvest, he said. “I would guess its yields could be 5% higher than the RL trials.”

DK Secure had had good trials results in 2008 in non-RL trials, Mr Plaice claimed. “It matches or exceeds other low-biomass options out there, and showed it overcomes some of the issues of hybrids.”

For example, yields were very consistent and lodging minimal, he said. “Farmers can also use their own equipment to spray late in the season.”

But it would need some different management to get the best from it. “It is a specialist variety.”

Establishment was no different from other varieties, but it was more suited to early drilling and highly fertile soils, where lodging of other varieties could be a problem, he suggested. “Our recommended seed rates are no different from other hybrids currently, although we are doing more trials investigating it this year.”

Disease control needed to be robust, although a growth regulatory treatment in the spring was unlikely to be necessary. “Sclerotinia is an interesting topic, though. It flowers later – it comes to yellow bud at the same time and then flowers all at once.”

That potentially lessened the risk from sclerotinia with a condensed flowering period, but the variety also branched more than other varieties, which created more risk during petal fall. “It will need treating,” he suggested.

Nutrition would also need to be investigated more. There was potential for growers to push nitrogen doses to achieve higher yields without increasing lodging risk, he said. The variety would also give growers more flexibility over timing. “Late applications will be easier.”

But potentially the biggest advantage would be harvesting efficiency, which a survey suggested was vital to growers. “We need to generate more data, but feedback from our field-scale grower evaluations rates DK Secure’s ease of harvesting as markedly better than any other variety grown alongside it.

“In one case, a 4ha block was combined at 4.5kmh compared with 3.5kmh for Excel [for similarly yielding blocks]. The grower reckoned savings in diesel and time was worth at least a 5% gross output difference.”