Partial Resistance to Septoria Glume Blotch Analyzed in Winter Wheat Seedlings

Abstract

A diallel analysis was conducted to investigate gene effects for six components of partial resistance of wheat, Triticum aestivum (L. em Thell.), to Septoria glume blotch, which is caused by Leptosphaeria nodorum E. Muller, anamorph Septoria nodorum (Berk.) Berk. Information obtained in this study will allow plant breeders to select parents to allow combining resistance genes for different components. The recorded components were incubation period, latent period, percentage of diseased leaf tissue, initial spore production at the end of the latent period, total spore production at 100% necrosis, and maturation period. Maturation period was defined as time between the first appearance of disease symptoms and the completion of a single life cycle, as indicated by the appearance of the first mature pycnidia. The analysis of variance showed significant differences among the crosses for incubation period, latent period, maturation period, and total spore production. No significant differences were found for percent necrosis or for initial spore production, as high variability within each genotype caused least significant differences for these traits to be inflated. General combining ability (GCA) exhibited significant variability, indicating additive gene action. Specific combining ability also was significant indicating some nonadditive (i.e., dominance and epistasis) gene effects.