Research Highlights of the CIMMYT Wheat Program 1999-2000

New Bread Wheats for High Rainfall
Environments: The Package
M. van Ginkel and L. Gilchrist
High rainfall environments make up the second
major mega-environment where bread wheat is
grown in the world, after irrigated production
areas. Particularly in developing countries, regions
receiving more than 500 mm of rainfall during the
cropping cycle suffer retarded economic
development and the associated curses of
unemployment, poverty, ill health, and high
infancy death rates. Such areas include parts of
Eastern, Central, and Southern Africa, the Andean
Region of South America, China, and pockets in
South Asia.
Enormous progress has been achieved in
disseminating so-called modern varieties in
irrigated regions around the world. Key wheat
ideotypes, such as the Veerys and, more recently,
the new wheats Kauz and Attila, have
demonstrated their wide adaptation and stable
performance across this irrigated agro-ecological
zone. Adoption of modern wheats has reached
almost 100% in high rainfall areas in the last
decade. However, few genotypes have shown to
contain the complete “package” of requirements for
that zone. The Bobwhites constituted an impressive
advance some 20 years ago, but with evolving
diseases and market demands, new varieties are
continuously needed. Usually varieties do well for
a certain period and then succumb to diseases, or
their quality characteristics remain poor, and local
mills import most of the wheat they require,
negatively impacting local wheat producers.
There are several reasons for production instability
in high rainfall areas. For example, more diseases
thrive under higher humidity conditions than in
irrigated or rainfed areas with low humidity, and
nutrient imbalances (both deficiencies and
toxicities) are more pronounced in regions where
leaching associated with high rainfall is prevalent.
In many of these areas, wheat has been imported in
large amounts, for a variety of reasons, including
famines, political mismanagement of food
resources, lack of support for agricultural research,
immigration/emigration pressures, cost/benefit
considerations, and the high industrial quality of
imports. Imported wheats generally come from one
or more of the top four wheat exporters in the
world: USA, Canada, Argentina, and Australia.
Since these countries grow wheat mostly under
rainfed conditions and produce the low yields (1.5-
2.5 t/ha) associated with elevated protein levels,
imported wheat is generally of superior quality.
Traits for High Rainfall Wheats
If a nation in a high rainfall area aims to satisfy
some, most, or all of its domestic wheat needs, its
breeders must address an extensive list of traits.
Wheats targeted towards high rainfall areas should
have some or, ideally, all of the following key traits:
1. Yield
a. High*
b. Stable*
2. Disease resistance
a. Stripe rust*
b. Leaf rust*
c. Stem rust*
d. Septoria tritici*
e. Fusarium spp. (head scab)*
f. Barley yellow dwarf virus
g. Soil-borne pathogens
h. Tan spot
i. Powdery mildew
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