5 January 1996

Rape choice is simpler thanks to bigger yields

RAPID turnover in spring oilseed rape varieties reflects steady progress in boosting yields, according to NIABs Simon Kightley.

At first sight growers have a bewildering choice. The descriptive list includes no fewer than 26 names, 10 of which join it this year. Only three were introduced before 1993.

But with nearly half falling within the same upper potential yield range, the risk of choosing badly is reduced.

Potential imports make UK certification figures (as in the pie charts) less help in assessing seed supplies for oilseeds than in other crops. But with the growth of the spring rape market, breeders are striving to become more self-sufficient in the UK to save on import costs, says Mr Kightley.

Low input

Apart from a clear need to control both pollen beetle in rape and flea beetle in linseed, spring oilseeds are "low input" crops. So the descriptive lists concentrate on agronomic characters alone, he explains.

"Harvestability" – the combination of earliness and standing power – is the key, especially for northern growers.

One of last years newcomers, Acrobat (103)*, which has the biggest share of the UK certified seed area, is the earliest to both flower and ripen. But like most others on the list, it has only moderate standing power.

Varieties such as Aries (107), Marinka (105) and Spok (106), should all prove satisfactory performers, he says.

Solar (106) and newly added Maskot (105) are among the earliest ripeners.

Nothing apparently matches newcomer Sprinter (107) for combined standing power and speedy maturity. But Mr Kightley says the ratings are "cautious" because a seed quality hiccup led to a years gap in trials data.

Seed statistics suggest there should be plenty of Mars (104) and Starlight (102). Despite its comparable yield, 1989 introduction Global (104) does not figure in the top 10 varieties for UK seed area.

Top oil content

Ester (102) and newcomer Licosmos (103) have the highest oil contents (44%). But this barely offsets their slightly lower output against two other 1996 additions – Star (107) and top-yielder Rebel (108), for which imports should ensure plenty of seed for "enthusiasts".

Most of the other new material is "well dispersed" through the list, with no particularly strong attributes. The high erucic variety Industry (79) has disappointed. "Its very early and short but it is hard to see how its yield penalty could be offset by any premium."

Earliness to flower does not vary much across the top 14 yield-rated varieties, most meriting 6-8 on the 1-9 scale. Spok (5), Licosmos (4), and Unica (102) (2) are the exceptions.

In the north there is a difference of up to a fortnight between ratings of 8 and 4/5 (the later ones), notes Mr Kightley. "We wouldnt advise mixing varieties with different flowering dates on the same farm because it makes controlling pollen beetle harder."

*Yields relate to the 100% control mean of Mars, Starlight and Puma. Differences of less than 6% should be treated with caution, says NIAB. &#42

Harvestability, the combination of earliness and standing power, is a key agronomic character up north.