Varietal difference and genetic analysis of field resistance to northern leaf blight in maize [Zea mays] inbred lines
2000
Takamiya, Y. (Hokkaido. Tokachi Agricultural Experiment Station, Memuro (Japan)) | Sendo, S.
Varietal differences of field resistance to northern leaf blight (Setosphaeria turcica: NLB) were evaluated with maize inbred lines by artificial inoculation in the isolated field of Hokkaido Prefectural Tokachi Agricultural Experiment Station. Genetic analysis of field resistance was also conducted with seven inbred lines and 21 F1 combinations from half diallel crosses. All vivid leaves were classified into six grades by the ratio of NLB area (0: No-disease - 5: over 50%). The degree of NLB(X) was calculated by the following formula: X=sigma (the grade of the disease * number of the leaves that were classified into the grade)/(5 * total number of the leaves that were investigated) * 100. Great varietal differences of the field resistance to NLB were observed among these inbred lines. There were some resistant lines that were bred from land races in Hokkaido. Five inbred lines, To45, To 15, W401, RB262 and To50 were considered the resistant line. Analysis of variances in the diallel table showed that the resistance to NLB was caused by both an additive and dominant gene effect. General combining ability and specific combining ability were statistically significant. The results showed that the resistance was incompletely dominant. The number of effective genes was estimated at 2.369. Heritability was estimated at 0.806 (narrow sense) and 0.986 (broad sense). It was considered that individual selections in early generations were effective in breeding inbred lines. Also, it was possible to improve the resistance of F1 hybrid by using one resistant inbred line at least
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