Induction of genetic variability of maize genotypes through radiation revealed mutants resistant to maize streak disease

Abstract

The absence of genetic variability among crop genotypes is an impediment to breeding progress, hence mutagenesis could serve as a useful tool to create genetic variation to obtain desirable traits of interest. In this study, four maize genotypes, Obatampa, Dapango, Pann 54 and Honampa which were susceptible to maize streak disease (MSD) were acutely irradiated at 254.3 Gy, using a cobalt 60 (⁶⁰Co) at a rate of 300 Gy/hr. The irradiated seeds were planted with their parental controls at streak disease highly endemic environment. Field trials for the selected maize genotypes were conducted from the M₁ to M₄ generations to screen for MSD resistance and improved grain yield. Sixteen putative mutants and four individual parental controls were selected across the four maize genotypes at the end of the M₄ generation based on disease severity score and yield indices. Detailed morphological screening and field evaluation of putative mutants showing improved plant architecture, increased grain yield and resistance to maize streak disease were tagged and selected. Obatanpa-induced-genotype was the best mutant identified with a grain yield of 6.8 t ha^-1. Data on days to 50% flowering indicated that all 16 putative mutants were maturing plants.