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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