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

307and planted into 10-row plots, each row being 10 m long. The mostpopular commercial hybrid H513 was included in the trial, which wasconducted in 15 farmers’ fi elds under natural Striga infestation inwestern Kenya.Artificial Striga infestationFor the artifi cial infestation, an inoculum was prepared by mixing about5 g Striga seeds (25% purity and 25% viability) thoroughly with 5 kgfi ne sand. The inoculum was then added to an enlarged planting holeat a depth of 7-10 cm (directly below the maize) to ensure that eachmaize plant was exposed to a minimum of 5,000 viable Striga seeds inaddition to those already in the fi eld [applied in an area of 75 m -2 (121hills: 11 rows, each 10 m-long, 11 hills per row)]. About 50 kg N and128 kg P 2O 5/ha were applied at the time of planting in form of di-ammoniumphosphate (18-46-0) to ensure vigorous maize development.Data collection and analysisGrain yield at 15% moisture under both Striga-free and Striga-infestedconditions were recorded as well as the most important agronomiccharacters and foliar diseases. Analysis of variance was performedusing combination of the following softwares: Microsoft ® Offi ceExcel 2003, SAS® 9.1, and Fieldbk 5.1/7.1(CIMMYT 1999).Economic analysisFor the economic analysis of agronomic trials of a new technology,the results are usually compared with the control, which is usuallythe current farmers’ practice. In this study, two methods were used:partial budget analysis and marginal analysis. In partial budget analysis,different options or technologies were compared in terms of theirnet benefi ts (NB), defi ned as the gross margin (yield times outputprice) minus the variable costs (VC). In marginal analysis, the extra netbenefi t (the yield gain times the output price) was compared tothe extra variable costs (in this case, the cost of the herbicide), bycalculating the marginal rate of return (MRR); that is:This ratio represents the return a farmer receives from his investmenton a new technology. During the last 5 years in East Africa, maizeprices have more or less followed international prices; an average of160 US$/ton was, therefore, used for the economic analysis.Impact assessmentTo estimate the potential impact of the herbicide resistant maize inWestern Kenya, the area infested by Striga was determined using