Modern
Maize Hybrids
Respond
in Tough Environments
New evidence from the remote Polochic watershed of Guatemala—a low-input farming area similar to many marginal maize production zones in Central America and southeastern Mexico—contradicts the notion that farmers’ local maize varieties perform better than scientifically improved hybrids in such circumstances. In experiments at 75 sites during 1997–98 and under three levels of fertilization, from none (farmers’ normal practice) to high, the white-grained hybrid HB-83 outyielded local, non-hybrid varieties by an average of more than 20%.
“These results and several studies elsewhere in the developing world seem to refute the concern that the superior yield potential of modern hybrids is expressed only when they receive adequate fertilization and other inputs,” says Jerome Fournier, a CIMMYT research associate who conducted the work in fulfillment of his PhD requirements. “In fact, at the site where maize yields tend to be lowest, hybrid HB-83 yielded 65% more than the local varieties.”
The higher grain yields of the hybrid resulted from several traits, including a greater number of grains per plant, less lodging, and a higher ratio of grain to above-ground vegetation.“HB-83 yielded better than the local varieties at high-yielding sites and seemed better adapted in low-yielding environments,” says Fournier. “On both hillsides and moist flatland, HB-83 also seemed to respond better to fertilizers than the local varieties. On dry flatland its yield superiority was greater under no fertilization. Thus investing in seed would represent only a small risk for most farmers, if they could use even a minimal amount of fertilizer.”
“Promotion packages such as ‘kilo-for-kilo’ (whereby farmers receive improved seed for planting and repay with an equal weight of grain at harvest) would probably go very far in promoting adoption of new cultivars.”
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 Maize grain yield of local varieties and HB-83 without fertilizer (F0) and at recommended (F1) and high levels of fertilizer (F2), Polochic, Guatemala. |
An Isolated, Subsistence World
Fournier did his study in a 1,800-square-kilometer zone of the Polochic River basin in three types of environments: dry flatbeds, moist flatbeds, and the hillsides typical of many remote maize cropping zones in Central America. Nine-tenths of the people in the region belong to Mayan Indian ethnic groups, and many do not even speak Spanish. Most private seed companies have little interest in markets in remote locations like Polochic, and many farmers continue to grow lower yielding varieties of maize, using their own seed.
Hybrid HB-83 is based on CIMMYT materials and was released in Guatemala in 1983. According to CIMMYT agronomist Jorge Bolaņos, who worked for many years in Central America, it is among the most productive hybrids across a range of environments in the region.“HB-83 has been a difficult hybrid to surpass,” he says.
Demand for Seed, but Few Suppliers
According to Bolaņos, most “farmer” seed in Polochic is actually descended from improved, open-pollinated varieties. “Improved materials have somehow reached the place and come to stay,” he explains. Bolaņos says the lack of adequate seed production and distribution services has stopped the adoption of new varieties. “Promotion packages such as ‘kilo-for-kilo’ would probably go very far in promoting adoption of new cultivars.” In kilo--for-kilo programs, farmers receive improved seed for planting and repay with an equal weight of grain at harvest.
According to Fournier, in addition to sowing hybrids, farmers in Polochic and similar areas should be encouraged to adopt soil-conserving practices. “Among other things, they should avoid burning crop residues and increase the use of mulches to protect soils from erosion and conserve organic matter.”
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For more information: Shivaji Pandey (s.pandey@cgiar.org) |
Published on October 2001
August, 2004