28 July 1995

Poor weather fails to defeat hybrid rape

SCOTTISH crops of hybrid oilseed rape Synergy seem to have produced enough pollen to safeguard yield despite poor weather at flowering.

There has been some doubt over the varietys yield potential in wetter, cooler climates due to its limited pollen supply. Unlike conventional types, only 20% of the plants produce pollen – most are male sterile.

That is no problem in the warm French climate where Synergy outyields conventional rapes by up to 30%. It has taken nearly a third of that market as a result. But it still needs to prove itself further north, says the SACs oilseed rape specialist Kerr Walker.

Last year Synergy yielded well in Scotland, he says. It averaged 18% more than the mean of Falcon and Apex at Edinburgh, and 12% more at Aberdeen. But the weather at flowering was good. This season has provided a much sterner test, he notes.

Cold, wet and miserable

"It was cold, wet and miserable all the way through flowering – not what you would think of as good pollen weather." But he remains cautiously optimistic.

"Pollination was not quite as good as last year, but I think there will be enough. Some pods have aborted and others have a low seed number, but rape has good powers of compensation. The crop has produced a very large biomass, but we wont know until harvest whether it lives up to this potential."

But trials do not necessarily reflect a field situation, he adds. "There is plenty of pollen blowing about from conventional varieties in neighbouring plots. That is not the case in the field."

Three fields of Synergy are being grown in Scotland for agent CPB Twyford to test commercial performance. "They dont look that different from the plots, which is encouraging," says Dr Walker.

Rapeseed consultant Mike Pickford is more optimistic. "Two of the field crops are among the best weve seen in the UK. Yields should be very good and will probably beat the record for the two farms. All that is needed is good pod-fill in the remaining weeks before harvest." The third crop was sown on gravelly soil and is drying out fast. Yield is expected to suffer as a result, he admits.