Abstract:
On-farm evaluation of downy mildew resistant (DMR) maize varieties was carried out in 32 locations of
downy mildew (DM) endemic areas of South-western Nigeria covering Ogun, Osun, and Oyo states, for two
years. Mean grain yield of improved DMR varieties varied between 2222 to 3578 kg ha'1 as against 1022 to
18822 kg ha'1 in downy mildew susceptible (DMS) varieties. In genera! DMR maize varieties significantly
outyielded the DMS varieties by about 200% while the G x E interactions showed that varieties, and yield x
variety were highly significant for yield. DM severity rating varied between 1.56 to 1.64 in the DMR
materials compared with 4.51 and 4.7 in the DMR varieties. In fact, cultivars 'Ibadan local' and 'western
yellow' exhibited total susceptibility to DM pathogen in almost all states. DMR varieties were also seen to
have responded differently to varied agro-ecologies as well as varied seasons of the year. The advantages of
the use ofDMR varieties in these agro-ecologies are discussed.
