Is it the beginning of the end for conventional open-pollinated oilseed rape varieties? It certainly could be, with most breeders confirming to Crops that hybrid varieties have progressively taken a larger share of the R&D budget in recent years.
Indeed some breeders, such as DSV, are only developing hybrid varieties, while there is a good case for believing that many of the others are mainly using conventional varieties as the source of parental lines for hybrids, and commercialising only those pure lines that look extremely promising.
The main justification the breeders give for the gradual switch to hybrid varieties in breeding programmes is yield. They are convinced, in the long run at least, that hybrid varieties will yield more than conventional ones.
So far the evidence in oilseed rape doesn’t back that belief; yield improvements haven’t been sustained over time. While hybrid varieties occupy four of the top five slots in the HGCA’s Recommended List for the east and west region, six of the top seven candidate varieties before this year’s trials were conventional varieties, including the hotly-tipped DK Cabernet.
In the mid-term that pattern is likely to remain in place, admits Nigel Padbury of Syngenta Seeds, although he points to other crops where hybrids have brought higher yields.
Among the reasons why hybrids haven’t jumped ahead in oilseed rape yet is because the development of double-low varieties came from single varieties creating a genetic bottleneck for breeders, he says. “When creating a hybrid the greatest level of heterosis or hybrid vigour is generated when the parent lines are as genetically disparate as possible.”
Breeding varieties with a low erucic acid and glucosinolate oil profile forced breeders into using parent lines with similar genetics, and while firms such as Syngenta are now working on developing genetically diverse gene pools for parent lines, in breeding terms the exercise has only just begun, Mr Padbury says.
Another drag on hybrid yield, at least for Syngenta, has been that the extra focus on developing new restorer systems has meant that some of the focus on performance characteristics, such as yield, has been lost. “In the conventional programme these were always the primary focus. Now we have the Safecross system providing stable, reliable hybrids we can turn our attention to performance characteristics in hybrids.”
Hybrid breeding programmes will also allow bigger leaps forward in characteristics, such as quality, establishment and vigour, as well as yield, than in conventional varieties, Monsanto‘s Anne Williams says. “We can work faster in hybrids to bring more useful improvements using molecular marker technology.”
That should allow breeders to deliver new traits to the market faster, such as those already being seen with semi-dwarf hybrids and different oil profiles.
“We also see better consistency with hybrids, with often a better tolerance to adverse environmental conditions like stress,” Ms Williams says.
But a switch to hybrids isn’t without controversy. Hybrid seed tends to be more expensive, as it is more expensive to produce and, of course, you cannot farm-save hybrid seed.
That is something most growers wouldn’t be happy about, Keith Dawson of SAC stresses. “Home-saving is useful, for example, when taking a risk on fields in marginal conditions.”
Lincolnshire farmer Mark Ireland is worried that without the competition of home-saved seed, hybrid seed costs could go up. “And on those fields which may not be suited to ultra-low seed rates, the cost of the seed may become prohibitive, if you are faced with cobbly seed-beds, slugs and chopped straw.”
Another concern is if breeders concentrate on hybrids then conventional varieties will slip away more by default than anything else, says Richard Fenwick, an independent variety consultant. “I think the wise breeder would continue to breed both types because I think there will always be grower demand for conventional varieties.”
- Nickerson OP and hybrid programmes, but increasing emphasis on hybrids
- Elsoms Both, balance weighted to UK market
- DSV 100% hybrid
- Syngenta Seeds Both, but increased spend on hybrids
- Monsanto Targets both OP and hybrids, but see future primarily as hybrids
Top hybrids and conventional varieties
RL east and west
PR46W21 111% (Hybrid)
Dimension 108% (Hybrid)
Vision 106% (Conventional)
Candidates east and west
DK Cabernet 115% (Conventional)
Krypton 112% (Conventional)
Compass 110% (Hybrid)
Catana 114% (Conventional)
Flash 112% (Hybrid)
Cuillin 111% (Hybrid)
Krypton 108% (Conventional)
Compass 107% (Hybrid)
Bizzon 107% (Conventional)