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1. Introduction
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The trials evaluated elite pre-release and released maize germplasm supplied by
CIMMYT, National Agricultural Research Programs, and private seed companies from
southern and eastern Africa.
CIMMYT-Zimbabwe collected the germplasm, grouped it according to vigor and
maturity, and formed six replicated trials:
EPOP99: early to intermediate maturing open-pollinated varieties (OPV's)
ILPOP99: intermediate to late maturing open-pollinated varieties (OPV's)
EIHYB99: early to intermediate maturing hybrids
ILHYB99: intermediate to late maturing hybrids
TZONE99: open-pollinated varieties (OPV's) for the transition zone (1800
2400 masl)
EAIL99: elite and advanced inbred lines
Each trial had an alpha (0,1) lattice design with three replicates. ILHYB99 contained
six dwarf maize varieties from the Africa Centre for Fertilizer Development (ACFD).
These dwarf varieties were grouped at the beginning or the end of each replicate to
prevent shading by the normal tall varieties.
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The trials were grown by CIMMYT, National AgriCUltural Research Programs, private
seed companies and non-governmental organizations in eastern and southern Africa.
Collaborators were encouraged to grow the trials under different types ofconditions:
Well-fertilized/rain-fed conditions: trials were grown using optimal sitespecific
agronomic practices
Managed nitrogen stress: trials were grown in fields that had been depleted
of nitrogen by growing unfertilized, non-leguminous crops for several seasons
and removing the crop biomass after each season. Nitrogen fertilization to
maize trials was designed so that yields under managed N stress averaged 20­
35% ofthe yield ofa well-fertilized maize crop at that site.
Managed drought stress: trials were grown during a rain-free period, with
irrigation applied at the beginning ofthe season to establish a good plant stand.
Afterwards, irrigation was withheld so that the crop suffered drought stress
during flowering and grain-filling, resulting in average yields of about 1-3 tlha.
Artificial inoculation/infestation of biotic stress factors: trials (mainly
EAIL99) were grown under artificial inoculation/infestation of leaf diseases,
stem borers, maize grain weevils and Striga hermonthica.
Acomplete list ofthe sites can be found in Section 5.
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