Demand-Driven Technologies for Sustainable Maize ... - IITA

308geo-referenced data from a farm-level survey conducted from 1993(Frost 1995). Using a survey conducted from 1992 (Hassan et al.1995), crop loss was calculated from farmer estimates. Agriculturalstatistics obtained from the Ministry of Agriculture, mostly district leveldata, and agricultural statistics at the division level, compiled by theInternational Livestock Research Institute (ILRI), were intersected withthe map to calculate the maize production area and the expectedcrop loss. Similarly, population data from the 1999 population census(Central Bureau of Statistics 2001) were added to the map to calculatethe number of households affected. Finally, data from a 2001 surveyof 123 farmers, randomly selected using a two-stage sampling design,were used to determine farmers’ interest and willingness–to–pay.Results and DiscussionEffect of IR-maize on StrigaAs expected, the number of Striga plants/m 2 was signifi cantly higherin the sites with artifi cial infestation, with a higher Striga emergence inAlupe than in Kibos. On average, susceptible checks produced 198Striga plants/m 2 in Alupe whereas most of the IR-OPVs producedonly 0-3 Striga plants/m 2 , with 2 exceptions that produced 8 and18 Striga plants/m 2 (data not presented). Averaged across 7 sites, theIR-OPVs produced 3 Striga plants/m 2 versus 71 plants/m 2 producedby the checks (Table 1). The slight variation in the number of Strigaplants produced by the IR-maize cultivars could be attributed to theheterogeneity of the fi eld which led to water logging in some parts. Insuch spots, some of the herbicide could have been leached or washedaway before it killed all the Striga seeds around the planted maizeseeds. In some cases, very low grain yield was observed even wherethe number of Striga plants was zero, indicating that yield reductionwas due to other factors such as drought and low soil fertility, orphytotoxicity of the Striga attack (Kanampiu et al. 2001a,b; Ransomet al. 1996).Yield gains from IR-maizeData on grain yield and some other agronomic traits are presented inTable 1. Across sites, 6 IR-OPVs yielded 5.3-5.8 t/ha under optimumconditions, whereas the best check, hybrid H623 yielded 5.9 t/ha. The2 other checks, KSTP94 (Striga tolerant OPV) and WS202 (normalOPV) yielded 5.1 and 4.6 t/ha. Under artifi cial infestation, the selectedIR-OPVs yielded 2.5-3.4 t/ha whereas the checks yielded 0.8-1.7 t/ha.The Striga tolerant check yielded as much as the Striga susceptibleOPV (1.7 t/ha), 100% less than the best IR-OPV (3.4 t/ha). Theaverage yield of the selected IR-OPV was 93% higher (2.7 t/ha) thanthe average yield of the checks (1.4 t/ha). The IR-OPVs and the checks