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OSR management will unlock hybrid yield potential

Bayer officially launched its new OSR hybrid variety Fencer at a trials site in Herefordshire

Bayer officially launched its new OSR hybrid variety Fencer at a trials site in Herefordshire. Dominic Kilburn reports.

The decision whether or not to select a hybrid variety when growing oilseed rape will reach the point of being a no-brainer in the future. And, while current hybrid products are exciting, their yield performance mustn’t be judged too early.

That was the view of Bayer CropScience’s UK seeds manager Adrian Cottey (left), speaking at the official launch of the company’s recently recommended hybrid oilseed rape variety Fencer. He said that hybrid and conventionally bred variety yields were still similar because of very good open pollinated breeding techniques but, through more targeted management, and more variability in hybrid germplasm in the future, hybrid variety yields would begin to improve significantly.
“It took decades to understand maize hybrids before yields really took off and, in terms of OSR, we are still early on in the development phase of hybrids and so we mustn’t judge them too early. A lot is already being expressed in hybrid vigour but perhaps not quite, as yet, in yield,” he suggested.
Adrian stressed that hybrid varieties must be managed properly if developments are to be seen. “There’s every sign that yields will go up; in Canada, where hybrids are long-established, we are seeing yearly increases in yield of between 4-5 per cent but we must talk specifically about how to manage them, just as we do with wheat.”

He questioned whether sowing OSR crops in mid-August was the right thing to do, and suggested that a very late August or early September sowing date could be more appropriate, adding that those sowing too early are also losing opportunities for grass weed control.

“Most growers probably don’t adjust their sowing dates and seed rates when they change varieties but the most progressive hybrid growers understand the importance of the crop canopy and adjust seed rates accordingly.

“We’ve seen their seed rates go down to between 30-50 seeds/m2 as well as better optimisation of nitrogen and fungicide inputs – growers getting a 5t/ha crop are feeding it with sufficient nitrogen and sulphur and managing the leaves with fungicides and PGRs.”

Flexible Fencer
Focusing on new hybrid variety Fencer, Bayer’s second recommended variety after Harper under the company’s global oilseed rape brand InVigor, Adrian said that sowing date trials at the company’s Callow trials site in Herefordshire (2013/2014) had demonstrated that when comparing three September planting dates (3rd, 16th and 30th), Fencer was less affected by later drilling times compared with other hybrid and conventional varieties.

And, in rooting depth trials staged near Peterborough and Lincoln earlier this year, Fencer achieved a greater average rooting depth compared with 16 other varieties – hybrid and conventional.

“These trials clearly demonstrated Fencer’s vigour above ground while it also had the best rooting below ground, producing thicker, deeper and more branched roots,” commented Adrian.
“It’s these characteristics that give Fencer the ability and flexibility to be sown later, without losing yield, as well as providing exceptional vigour in the autumn and spring.”

As well as pointing out Fencer’s leafy, erect growth habit and good lodging resistance, Adrian said that the variety’s excellent phoma stem canker resistance meant a reduced workload in the autumn. “Because of the strength of its resistance, Fencer is unlikely to reach the disease threshold required for a phoma treatment before November, which allows for a single treatment for light leaf spot and phoma at that stage, rather than an additional one earlier,” he explained.

“Fencer is not top of the Recommended List but with the best combination of canker resistance and oil content, it has consistently high yields and oil premium earning potential.”

Plant vigour
Also speaking at the event was ADAS crop physiology consultant Liz Hudson, who confirmed varietal differences in plant vigour between hybrids Fencer and Harper, and two conventional varieties Patron and Rinker, when sown on different dates (9th and 17th September).

An experiment near ADAS Terrington, Norfolk demonstrated that both hybrids had a higher number of plants/m2 than the conventional varieties drilled at the earlier date (when measured in February) and Fencer’s plant count was least affected by the later drilling date.

When taking Green Area Index (GAI) measurement into consideration, later drilled crops all had a lower GAI in November compared with earlier drilled, but Fencer’s was significantly higher on average (0.482) compared with Harper, Patron and Rinker (GAI 0.310, 0.367 and 0.309).

“When comparing seed yields in the same trial, Fencer was, again, least affected by the later sowing date,” added Liz.
And, in terms of oil content, Fencer had significantly higher oil on average at 47.3 per cent compared with all other varieties: Rinker (46.7 per cent), Harper (46.3 per cent) and Patron (46.1 per cent), however both Harper and Fencer lost very little oil when sown late (0.3 and 0.2 per cent).

Canopy is key
ADAS’ Dr Pete Berry said that achieving good yields in OSR was all about maximising the number of seeds/m2 and this was determined by photosynthesis during a 2-3 week period after flowering.
A GAI of 3-4 is required by flowering for an optimum-sized ‘open’ canopy to intercept the maximum amount of light for maximum seed set, he said.

“A small canopy will mean a smaller yield as light cannot be intercepted but a canopy that is too big means a higher lodging risk and light not intercepted efficiently.

“It’s important to keep the green canopy going as long as possible to fill seeds,” he added.
Dr Berry also referred to newly compiled OSR rooting data (2004-2013), produced by ADAS colleague Dr Charlotte White, across 40 different OSR crops and with a variety of cultivations.

He pointed out that across all crops average rooting was inadequate in terms of extracting water and nutrients below a depth of 40cm. “There was sufficient rooting to that depth, but below that there were simply not enough roots and if growers can maximise root growth below 40cm then they could see some real benefits.”

Why plant Fencer in 2015?
Vigorous in both the autumn and spring
Positive root development
Flexible sowing date, ease of management
Minimal risk from autumn pests
High oil content
Consistent good yields
Phoma stem canker resistant
Lodging resistance

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