NIAB TAGhas been running a 3 year, multi-site experiment looking at different sowingdates for a set of diverse winter oilseed rape varieties and as part of thisresearch has been measuring vigour using three specific criteria plantheight, number of leaves and ground cover. Simon Kightley of NIAB TAG explainsthat is important for crops to be vigorous so that they can get big enough tosurvive pigeon damage and the winter weather. In most situations, includingthe HGCA Recommended list, vigour has been a subjective characteristic, but inthis research it is actually measurable.
Thesemeasurements show that vigour is something that varies tremendously fromvariety to variety and it also shows that conventional rape varieties are justas, and in some cases more vigorous, than hybrid varieties. Results illustratethat you have to look at the individual variety itself, not just whether it isa conventional or a hybrid.
Oneof the varieties that we have included in this project is Es Alienor, aconventional type. In all three years, it has shown autumn vigour as good as orbetter than any of the hybrids. Even in the difficult 2012 autumn this camethrough well whilst the hybrids in general showed no significant advantage overthe rest of the conventional pack. Alienor is a prime variety with good earlyvigour. It did impress in these trials, by getting away well both in the autumnand spring.
Healso concludes that the project indicates no particular argument to say thathybrids are more suited to the later sowings.
Simonpoints out that conventional varieties offer other practical advantages whichcould be more advantageous this coming autumn. Conventional varieties have more flexibility in their seed rates. Seedis less expensive and, especially if faced with difficult seed bed conditionsand no seed insecticidal treatments, this gives the grower more leeway toincrease the seed rate to allow for potential field losses.
Howeverhe warns that using high seed rates means growing a variety with good standingability. If your worst fears dont cometrue and all the seed germinates, you may be running into a lodging risk.Choosing stiff-strawed vigorous varieties is a vital part of this autumnsstrategy.
Withthe loss of the major seed dressing products, a shift back towards higher seedrates could well be part of growers strategy, too. I would say thatresearchers and growers will need to make a rapid assimilation andunderstanding of how crops perform this autumn without seed dressings. It couldbe a steep learning curve but good establishment of the crop remains importantwhatever the season brings.
NeilGroom, Technical Director of Grainseed, says the loss on neonicotinoids willcertainly increase the importance of autumn vigour and the need for higher seedrates. Autumn vigour could make surethat the rape out runs any insect damage from flea beetles or aphids and theimpact of viruses – real threats to this autumns crops. Seed vigour isessential to ensure rapid germination and good development of the root systemand seedling growth. Rapid germination and vigour are going to be keyrequirements now that seed treatment options are limited.
Whenoilseed rape seed was treated with Chinook many growers drilled at 6 kg/ha ofseed, which is approximately equivalent to 120 seeds/m. With a betterunderstanding of seedbed requirements, tillage trains, consolidation andimproved placement of seed, I think many growers will opt for increased seedrates this season, but maybe not as high as 120 seed/m.
Alienorhas been proven in trials and in commercial use to have these characteristicsin spades. It also is a low biomass conventional variety that performsconsistently well, as do all our other autumn rape varieties, Es Alegria, EsCubic and Es Astrid. All these varietieshave top stem stiffness, resistance to lodging and multigene resistance to stemcanker. Being low biomass means that they are easily managed and harvested,which is what growers are looking for.