story to find out more.
When several wheat varieties are planted in a
field, one variety may be susceptible to a particular airborne fungal disease
(shown as yellow, infected by fungal spores), while another may be resistant to
the disease (shown as green, thriving). Fields are unpredictable environments,
so combining varieties that have complementary strengths can help stabilize
Planting Wheat Blends Means Higher Yields
By Rosalie Marion
May 8, 2007
A two-year comparative study of wheat
plantings has shown that blends of complementary wheat varieties out-yielded
single varieties, or nonblends, by an average of 2.3 bushels per acre. The
blendsmixtures of two or three varieties with carefully matched
traitsshowed a 3.2-percent yield advantage over the single, or
"pure," variety stands.
The study was conducted by plant pathologist
Cowger with the Agricultural Research Service (ARS), the U.S. Department of Agriculture's chief
scientific research agency. Cowger works in the
Plant Sciences Research Unit, Raleigh, N.C.
Environmental stresses such as disease and drought occur unpredictably year
in and year out. And wheat varieties have their own inherent weaknesses that
cause fluctuations in yield under suboptimal conditions. For example, a variety
may be resistant to some diseases, but susceptible to others. Or a variety may
yield well in the absence of disease, but fall short of its yield potential
when an epidemic occurs.
From eight pure varieties, Cowger developed 13 blends, matching
complementary features for best advantage. Each blend was made with equal
numbers of seeds of each variety used. She planted the 13 wheat mixtures, and
eight pure stands, in three different North Carolina counties representative of
the state's sandy, organic and clay soil environments. All 21 entries were
planted in a two-year, replicated experiment in each of the three
Cowger studied the blends' response to powdery mildew, leaf rust, soilborne
viruses and other diseases. She also evaluated yield, test weight, and quality
factors at all three test sites. For the analysis, Cowger averaged the data
over the 2-year period of 2005 and 2006.
more about the research in the May/June 2007 issue of Agricultural