The Inheritance of Resistance to Septoria Glume Blotch:

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Abstract
The inheritance of resistance in common wheat (Triticum aestivum, L.) to Septoria glume blotch, caused by the pathogen Septoria nodorum Berk., was studied. Four quantitative parameters of resistance were measured: infection efficiency (IE) and disease severity (DS) on intact young plants together with legion size (LS) and length of latent period (LP) on detached leaves. The method of testing the disease reaction of wheat to S. nodorum on detached leaves was refined and standardised to minimize the non‐pathological sources of variation. Four wheat cultivars were tested for their reaction to 11 Septoria nodorum isolates. Two of the cultivars were crossed for studies on the genetics for host resistance, using a single S. nodorum isolate for inoculation; parental, F1, F2 and F3 populations were analysed.Interaction between wheat cultivars and S. nodorum isolates was significant, but its variance component was quite small compared with the main effects of cultivars and isolates, The inheritance of resistance was mainly additive, with low to moderate heritability, apparently controlled by 3 to 4 quantitative genes, with indications of gene interactions. LS and LP were highly correlated, suggesting pleiotrapy for these two parameters of resistance. IE and DS (on intact plants) were moderately correlated to LS and LP (on detached leaves), apparently due to a partial pleiotropy or linkage.