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NATIONAL OSR RESULTS REVEAL SERIOUS VARIETY PERFORMANCE DISCREPENCY
Date added: 16/05/05 |
Last season’s oilseed rape production results from across the country reveal a
serious discrepancy between individual variety rankings in commercial practice and small plot trials. In so doing, they underline the danger of placing too much emphasis on trial yields alone in variety selection.
Detailed performance comparisons of hundreds of separate crops of the two varieties making-up 60% of the oilseed rape area recorded in ProCam’s powerful 4cast agronomy system, indeed, turn the current Recommended List rankings firmly on their head.
Despite being fully 6% below Winner in official gross output terms on the 2005/6 list, the second most popular variety with ProCam growers, Canberra outperformed it in every respect. Not only did the modestly-rated low biomass type outyield the market leader, it produced a greater financial output at a lower input cost to generate an average gross margin advantage of nearly £24/ha.
Canberra clearly proved a better bet for many of our growers last season, “ observed ProCam technical agronomist, Nick Myers responsible for the 4cast system.
“Almost certainly because its low biomass characteristics enabled it to cope relatively better with the more challenging oilseed rape growing season.
”The results also suggest worthwhile input savings may be possible with lower biomass types. After all, they do appear to have an inherent advantage in biological efficiency – requiring less plant material to produce each tonne of seed. And, providing they also have Canberra-like levels of robust disease resistance, may allow some economies in fungicide treatment for disease control as well as growth regulation.
”Had we been able to effectively account for the extra value of its easier overall management and very much faster harvesting, I’m sure we’d being seeing an even greater financial advantage for Canberra,” he added.
“Especially so, given the particular lodging problems experienced by tall varieties like Winner last year.”
Whatever the precise reasons for the disparity between the 2004 commercial results revealed by the 4cast figures and the RL ratings, they sound a clear warning for growers in future variety selection.
In particular, Nick Myers is adamant that variety choice must be based on far more than headline RL figures. He insists that growers need to look into the RL data in far more depth than many may have done to date as well as making the very most of local experience.
”The detailed RL data tells a very much more complete story than the headline yield ratings,” he pointed out. “We have to accept that small plot trials will always over- estimate commercial yields. And they are also likely to under-estimate the production value of shorter varieties, because of shading from taller varieties in surrounding plots.
But overall they can still give a very good comparative idea of a variety’s capabilities.
“Looking at a variety’s performance in individual trial years rather than merely its average across several years will give a good idea of its ability to cope with different growing conditions,” he advised.
“Some varieties vary far more widely from year to year than
others. The overall yield rating also hides variations between performance in different regions which can be very wide too.
”A high stem stiffness score and a high resistance to lodging also means more security when combined with a short stem. And given the extent to which stem canker can cause lodging problems too, a high resistance score here will indicate all-round robustness.
”Having said that, I really don’t believe there’s anything to beat a good measure of local experience in OSR choice,” insisted Nick Myers. “Whatever the trial plots show, there’s nothing quite like the challenge of broad acres production to sort out the wheat from the chaff.
Many of our growers stuck with Apex in the past just as they’ve been sticking with Canberra more recently to great effect, while other varieties came and went.
”As oilseed rape becomes a more and more important crop in the rotation, knowing it will perform for you consistently year-in, year-out will become even more vital.
“Apparent advantages in small plot trials run under the same agronomic regime regardless of varietal differences are all very well, but the real value has to lie in what a variety earns for you when you grow it under your own commercial regime.
In this respect, the extra£23.5/ha our Canberra growers earned, on average, on their crop margins over an officially higher output variety last season was certainly well worth having,” he concluded. |
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