Oilseed rape seeds are smaller than normal this year due to the drought during pod fill, so farmers should try to drill varieties with bold seeds, particularly where there are establishment challenges.

“Bolder seeds are proven to boost vigour at germination due to the extra energy they contain,” explains Clive Sutton at DLF Seeds. “This means crops can grow away from disease and pest challenges for more even establishment.”

Trials at the Saskatoon Research Centre in Saskatchewan, Canada, revealed that the leaf area, shoot weight and biomass of seedlings from large canola seeds were 1.3-2.0 times greater under controlled conditions than those from small seeds. “Under field conditions without insecticides, seedlings from small seeds had the highest flea beetle damage, poorest establishment, and lowest shoot weight, biomass and yield,” says the report.

“Seedlings from large seeds are more vigorous and tolerant to flea beetle damage than seedlings from medium or small seeds.” This is due to a higher initial shoot biomass and higher growth rate.

Getting rapeseed off to a vigorous start is especially important in the absence of neonicotinoids, to get the crop growing away from flea beetle damage. “At the Cereals Event this year Anglia Grain Services had a display of smaller seeded plants growing next to larger seeded ones, and the difference was really noticeable,” says Mr Sutton. “You could see the difference in rooting, and both the cotyledons and first leaves were markedly bigger.”

One advantage of using conventional varieties rather than hybrids is that it is relatively cheap and easy to increase the seed rate to account for local weather and pest conditions. “This means you can react to changing circumstances by increasing the seed rate as required.”

When farm saving seed, it is vital to get it properly dressed to obtain bold seeds with no admixture, he warns. “It’s also worthwhile choosing varieties that naturally have larger seeds through their superior genetics. Broadway and Elevation, both new to the Recommended List this year, were specifically bred for large pods, seed content and seed size.”

Elevation in particular has very bold seed, and to date it has topped the yield chart in both 2017 and 2018 official trials. “This year was very challenging for establishing and nurturing crops through the damp spring and dry summer,” says Mr Sutton. “To achieve this level of consistency is very impressive.”

As well as offering good energy stores for germination, bolder seed also boost the resulting yield at harvest. “Plants with larger pods, bolder seeds and more seeds per pod have a natural advantage when it comes to yield. Every 1g extra in thousand seed weight at harvest gives you an extra 15-20% yield for the same seed number.”