From strength to gluten strength
By Donna Fleury
New durum wheat variety brings higher quality and better agronomics.
With a directive from industry to increase the gluten strength of the Canada
Western Amber Durum class, researchers at Agriculture and Agri-Food Canada (AAFC)
in Swift Current have met the challenge with the release of a new variety, Strongfield.
Using the variety AC Morse as a target, Strongfield easily meets or exceeds
this gluten strength goal. Stronger gluten is desirable in many markets because
of its influence on cooking texture and quality.
|A demonstration plot of AC Strongfield.|
Stronger gluten strength provides advantages in pasta manufacture and a firmer
cooked texture in food products. Strongfield comes from a cross with the variety
AC Avonlea, which has been available for a few years. "In comparison with
AC Avonlea, Strongfield yields about five to seven percent more, while maintaining
the same high protein content," explains Dr. John Clarke, research scientist
in Swift Current. Strongfield is similar in maturity and straw strength to AC
Avonlea, but stronger than some of the older varieties such as Kyle. It yields
12 to 14 percent higher than Kyle under most conditions and it has better leaf
spot resistance than Kyle, possibly a bit better than AC Avonlea.
"The other major feature of Strongfield is its low grain cadmium levels,"
says Clarke. "We've been working for the past 13 years to convert Canadian
durum varieties to a low cadmium uptake characteristic because of changes in
some markets such as Europe, which have put an upper limit on cadmium concentration
in food products." There is an expectation that cadmium limits may be reduced
even further in some markets in the future. "The cadmium levels currently
found in durum are below the recommended levels, but through plant breeding
we know we can reduce those even further to help reduce the total amount people
consume in diets." Durum wheat tends to accumulate more cadmium in grain
than other wheat classes.
Cadmium is a naturally occurring toxic heavy metal found in prairie soils and
around the world. It may cause health problems in people exposed to high concentrations
over a long period. It accumulates mostly in the liver and kidneys, and can
cause kidney problems later in life. Cadmium can also be toxic to livestock.
High levels in the diets of poultry have caused egg production to cease, and
in young animals can cause anemia. In most classes of livestock, reproductive
problems related to cadmium have been observed.
Strongfield is the second variety developed with low cadmium levels. The first
low cadmium variety was Napoleon, which was released in 1999. "However,
Napoleon isn't as well adapted to the main durum growing areas in western Canada,
so it hasn't really taken off," says Clarke. "We expect Strongfield
to be well accepted because of its high yield, exceptional agronomics and good
adaptation to the durum growing areas." Strongfield was made commercially
available in the fall of 2005. The Canadian Wheat Board will offer production
contracts for the variety to encourage quick adoption by producers. Secan has
the marketing rights, so Strongfield will be widely available to growers.
Clarke notes that another strong gluten variety has just been registered, called
Commander. It is an extra strong gluten type variety that would be seen as a
replacement for AC Navigator, which is one of the parents. Similar to AC Navigator,
Commander is a semi-dwarf variety. "However, Commander has substantially
increased gluten strength, while keeping all of the other desirable quality
features of AC Navigator including a very high yellow pigment content and very
good milling properties." AC Navigator and Commander will be grown under
contract Identity Preserved (IP) programs. Limited commercial production is
expected in 2006.
Commander also has a bit better leaf spot resistance than AC Navigator. "None
of these varieties are where we want them for leaf spot resistance, so over
the long-term we will be working on improvements for leaf spot, fusarium resistance
and other factors," adds Conner. "These varieties have inherited the
susceptibility for leaf spot from their desert durum relatives."
Over the past few years, durum acreage in western Canada has been around six
million acres, with about 80 percent grown in Saskatchewan, 15 percent in Alberta
and the remainder in Manitoba. "In the future, growers will continue to
see the development of more varieties of durum wheat in this class with stronger
gluten strength, lower cadmium levels and a high quality agronomic package,"
says Clarke. -30-
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