31 May 1996


Continued from page 42

OILSEED rape growers have been favoured by two seasons with very little lodging. But this has allowed NIAB only a very limited view of the agronomic characters of new varieties.

Nagging doubts about the standing power of some additions to the recommended list leave Apex well placed to retain a fair share of the market this autumn.

Hybrids aside, it is difficult to see any of the provisionally recommended varieties making major inroads, says NIABs Simon Kightley.

All have outputs 2-3% above Apex, but as a group they provide no real agronomic advantages, he explains. "They have got the yield but dont appear to offer anything exceptional in terms of standing ability or maturity.

"We have also had two pretty dry seasons with very little lodging in the national crop." A wetter year could see some of the newcomers potential yield advantage eroded, he suggests.

All round reliability is a key varietal feature for most growers, he says. So sowing some of the newer types requires an element of faith.

"Growers must spread their risks by growing a range of varieties, and the Recommended List contains plenty both in terms of agronomic characters and disease resistance. In the final selection only they will know the types that do best on their farms."

Hybrid focus

Only one hybrid, Synergy, has so far been listed. But in future most attention will focus on them, he believes. Other "composite" types have been less impressive than Synergy in trials, often performing no better than conventional varieties. But "fully restored" hybrids coming through the system show distinct promise with yields nearly 20% above current conventional controls last season.

Synergy did exceptionally well in 1994 but was less impressive last year which was notable for late frosts and drought. Capitol, on 107% of controls against Apexs 102%, was within a couple of points of Synergy, he notes.

"There were signs that a number of conventional varieties were better or equal to other composites in first year trials."

Certified and farm-saved seed statistics suggest that Apex, a short, stiff and easy to manage variety will continue to be widely sown this autumn. "It is not immune to light leaf spot, but responds well to fungicide."

Express, the only other variety fully recommended for all regions, has a yield rating six points below Apex, but remains listed because of its good combination of agronomic characters and disease resistance. "It could be useful for low-input systems, explains Mr Kightley.

Capitol, like older varieties Envol and Idol, is relatively weak stemmed. This can provide the sort of interlocking tight canopy that some growers who cut direct find attractive to prevent seed shedding, he suggests.

Nickel has given high yields on many sites, but its potential for lodging in a wet year remains a threat, he adds.

Arietta is nearly as stiff as Apex. "But it is rather tall. However it has better light leaf spot resistance, though it is slightly poorer against stem canker."

Jazz matches Apex on shortness, but is the weakest of the newcomers on overall disease resistance.

Dry conditions

"Lizard did very well in 1994 but less so last year. As a tall, medium to late-maturing variety it possibly ran out of steam in the very dry conditions."

Alpines main attribute is its good oil content – 0.5% higher than Apex.

Amber is yield-rated two points below Apex. "As the latest-maturing variety on the list it will certainly have been hit by the drought, says Mr Kightley. "This may have taken the shine off an otherwise good all round variety."

Among regionally recommended types, Falcon remains listed mainly for its late flowering and early maturity which is valued in the north, where Gazelles earliness is also appreciated. Both are joined by Inca which is relatively late but stands very well.

"Bristol has been retained for the south-east and central regions where it continues to do reasonably well. But the emphasis has to be on controlling light leaf spot," he warns.

Commanches combination of earliness and high yield sees it provisionally recommended for the north. Cobra, first listed in 1988, keeps its place, albeit as an outclassed variety. "It continues to throw up occasional high yields in trials, and its resistance to light leaf spot seems to have im-proved," he explains.n

Despite the arrival of hybrids, conventional oilseed rape varieties will continue to hold their own for some time to come, according to NIABs Simon Kightley. But fully restored hybrids show promise, he adds.