1 December 1995

Composite among the winter rape additions

SIX new winter oilseed rapes, all offering yield lifts over current market leader Apex, join the 1996 recommended list. Five are conventional types the other a composite hybrid – listed separately.

NIAB reports plenty of grower interest in hybrids but offers a note of caution. It is true that the top two performers "by some way" in trials last season were both hybrids, says John Ramsbottom. But yields from other hybrids tested were scattered fairly well across the range of all varieties, he notes.

Most oilseeds breeders are involved in composite or fully restored hybrids, he adds. "But dont assume that because it is a hybrid you will automatically get a high yield."

But the composite hybrid Synergy is "quite outstanding for yield", says NIABs Simon Kightley. With a rating of 113 it is 7% ahead of the most promising conventional newcomer, Capitol, which itself outstrips Apex by 3%.

The hybrid trial sowings, however, were at normal seed rates and the plots surrounded by plenty of potential pollinators. NIAB acknowledges that "specialised husbandry" is likely to be needed to exploit Synergys full potential. And a list note advises growers to "proceed with caution", as the risks associated with field production have not been fully assessed.

"So far there is nothing to challenge Apex for standing power at the early lodging stage or on stem stiffness at maturity," says Mr Kightley. Most of the new material, although high yielding, tends to be fairly tall and medium- to late-maturing, he adds. "So there could be a slot for an early variety."

Capitol has very good light leaf spot resistance but is weak stemmed at harvest.

Alpine, Arietta, Jazz and Lizard all have similar yields, only a point down on Capitol. Alpines oil content, the highest listed at 45%, could mean it matches Capitol on crop value, says Mr Kightley. It flowers very early but has only medium-early maturity.

Despite being tall, Arietta has moderately good lodging resistance (rated 7) and very good light leaf spot defences (8). It is also very low in glucosinolates.

Jazz is shorter, resists lodging moderately well (5) and merits a 7 for light leaf spot resistance.

Lizard is medium to late maturing, has very good light leaf spot resistance (8) and matches Arietta for stem stiffness and lodging resistance.

New winter OSR

&#8226 Conventional types: Alpine, Capitol, Arietta, Jazz, Lizard.

&#8226 Composite hybrid: Synergy