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Response of maize population “Longe5” to two cycles of modified S1 recurrent selection for resistance to maize weevil

Kasozi, Lwanga Charles, Derera, John, Tongoona, Pangirayi
Euphytica 2015 v.204 no.3 pp. 587-598
Sitophilus zeamais, corn, crops, foliar diseases, genotype, grain yield, grey leaf spot disease, leaf blight, plant breeding, recurrent selection, rust diseases, self-pollination, storage pests, subtropics, weight loss, Uganda
The maize weevil (Sitophilus zeamais Mostch.) is one of the most damaging storage pests causing significant reductions in grain weight and quality in tropical and subtropical regions. The current study determined the effectiveness of two cycles of modified S₁ recurrent selection towards the improvement of weevil resistance in the maize variety “Longe5”. Grain yield and resistance to Turcicum leaf blight, grey leaf spot and rust diseases, which occurred naturally at the time of experimentation, were also evaluated to enhance the overall worth of the maize variety. Selections were made by identifying and self-pollinating the foliar disease resistant and vigorous plants, with potentially big well-placed ears from the base population of the Longe5 (the original cycle i.e., C₀), grown at the National Crops Resources Research Institute, Namulonge, in Uganda. Over 540 selfed ears were obtained from the C₀ and were screened for maize weevil resistance under controlled conditions in the laboratory, after which 162 weevil resistant genotypes were selected and recombined in an isolated field to generate the C₁. The second cycle (C₂) was generated from the C₁ in a similar procedure, by recombining 190 weevil resistant genotypes. The C₀, C₁, and C₂ were evaluated for grain yield and reaction to foliar diseases at three locations, and the ensuing seed was screened for maize weevil resistance in the laboratory. Significant gains were obtained for maize weevil resistance. There was a reduction in grain weight loss due to maize weevil damage of 65 % in C₂ and 15 % in C₁. There was a 33 % reduction in the number of weevil progenies emerging in C₂ and 19 % in C₁ grain. Similar positive trends were realized for grain yield and resistance to foliar diseases in C₁ and C₂ compared to C₀. The results indicate that the modified S₁ recurrent selection was effective in improving Longe5 for maize weevil resistance.