The
Nigerian National Variety Release Committee (NVRC) has released the first
generation of maize hybrids, resistant to metsulfuron methyl herbicide, that
are also endowed with resistance to the noxious
parasitic weed Striga hermonthica.
The
hybrids were developed by the International Institute of Tropical Agriculture
(IITA) in partnership with DuPont Pioneer Seeds using conventional breeding
with funding from IITA and the Integrated Striga Management in Africa (ISMA)
project as part of strategies to control S. hermonthica
in maize.
The hybrids were
released as P48W01
and P48W02 and are recognized as IITA IR-Maize Hybrid 2 and IR-Maize
Hybrid 4. The hybrids have a yield potential of up to 5 t/ha under Striga infestation in comparison with
local varieties that produce less than 1 t/ha in such conditions.
“These hybrids are the
product of introducing a single nuclear gene that confers resistance to
imidazolinone herbicides, including metsulfuron methyl (MSM), into inbred lines
with known
field resistance to S. hermonthica,”
Dr Abebe Menkir, IITA Maize Breeder, said.
Recent baseline studies conducted under the
ISMA project showed that farmers ranked Striga
as the number one constraint to maize production in northern Nigeria, with 50
to 100% of the households reporting Striga
incidence in their farms. The parasitic
weed infests more than 9 million ha planted to millet, maize, and
sorghum in Nigeria and severely lowers the production capacity of these crops.
Dr Menkir said yield losses in maize from
damage by S. hermonthica varied from
20 to 80% among subsistence farmers, but 100% loss could occur in susceptible
cultivars under severe infestation in marginal production conditions.
The
released herbicide-resistant hybrids allow seeds to be planted that have been
treated with low doses of metsulfuron methyl herbicide. This targets S.
hermonthica before or at the time of its attachment to the maize root,
killing the parasite underground before it inflicts damage on the crop.
These hybrids can thus be used to
deplete the Striga seed bank in the
soil and minimize yield losses in subsequent cereal crops. MSM-reated seeds of
these hybrids can be integrated into the diverse farming systems in Nigeria
because the herbicide effectively controls the parasite at a low rate of
application.
The ISMA project
works with the private sector to catalyze the process of producing and
marketing treated seeds of herbicide-resistant maize hybrids to smallholder
farmers in Nigeria to control S. hermonthica.
Other collaborating
partners engaged in extensive testing of these hybrids include the Institute
for Agricultural Research (IAR) and Agricultural Development Programs in Bauchi
and Kano States.
The ISMA project is being implemented by IITA in partnership with CIMMYT, icipe, BASF Crop Chemical, AATF and national partners in Kenya and Nigeria.
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