8 August 1997

Harvest throws status of hybrid OSR in question

By Andrew Blake

HYBRIDS contribution to this years generally good oilseed rape output is under debate.

A leading co-operative claims hybrid variety Synergy is providing 15% more yield than the number one conventional variety Apex. But official trials and grower reports suggest there is often little difference in performance – in the south at least.

A Wilts-based United Oilseeds survey covering about 5000ha (12,400 acres), mostly so far from the south, puts overall average output, including both conventional double-low and hybrid types at 3.75t/ha (1.51t/acre). "Thats slightly ahead of where we were at the same time last year and the final 3.6t/ha average," says director Martin Farrow.

Top yield of conventional Apex is 5t/ha (2t/acre) whereas the best from hybrid Synergy is 5.75t/ha (2.32t/acre) on the same unidentified farm, he claims.

Early Varplan results from NIAB (see page 65) and more recent findings indicate a different picture with hybrids previous edge over conventional types considerably trimmed.

"The story with eight trial sites now harvested is that Apex is still the leading conventional variety, 1% ahead of Contact, its possible successor," says NIABs Simon Kightley. Synergy has recovered to register a marginal advantage over Apex with fully restored newcomer Pronto doing slightly better still.

"Synergy has come up but it is still only 1% above Apex which reinforces concern about reliability of pollination," says Mr Kightley.

Interestingly, he notes, Synergys yield advantage over Apex has only come in trials sown at twice the breeders recommended rate, in other words as conventional types. Sown as commercially advised it gave 4% less.

Not enough growth

The result suggests that the drought-stressed thinner stands did not make sufficient compensatory growth to maximise the hybrids yield potential, he says. Late frosts may also have played a part.

A notable feature this season is the relatively good performance of Bristol in nearly matching Apex. "It is a clear indication that light leaf spot pressure receded almost completely this year." However it would be very unwise to forget the poor untreated performance of the variety in untreated trials in previous seasons, he warns.