Abstract

In Kenya, at national policy level to the individual household level, food security is synonymous to maize productivity and availability. However, the productivity of maize is affected majorly by maize lethal necrosis disease (MLND) that was first reported in Kenya in 2011. MLND results from co-infection between maize chlorotic mottle virus (MCMV) and any cereal-infecting viruses in Potyviridae family particularly sugarcane mosaic virus (SCMV). Majority of maize germplasm are susceptible to MLND. This study was therefore carried out to identify potential germplasm for breeding for MLND resistance. A total of 38 maize germplasm (5 temperate lines with inherent resistance to maize-infecting viral diseases, 32 assorted tropical lines and one Kenyan hybrid) were artificially inoculated with MCMV and SCMV in the green house at the University of Nairobi Field Station and screened for two seasons between April 2020 and October 2021. Based on the Area Under Disease Progress Curve (AUDPC) and final severity score, germplasm KS23-6, 18, KS23-5 and 19 were identified as the most promising sources of MCMV resistance with disease severity scores of 2, 2.3, 2.3 and 3, respectively while germplasm 50, 19, and 22 were identified as source of SCMV resistance with scores of 2.0, 2.3 and 3, respectively. These germplasms could serve as potential donors for introgression of the resistance genes into locally adapted maize background to combat yield losses due to MLND.

Key words: Maize lethal necrosis disease, sugarcane mosaic virus, maize chlorotic mottle virus, resistance, maize germplasm.