THE INTERACTION OF FERTILIZER TREATMENT WITH TOLERANCE TO POWDERY MILDEW IN SPRING BARLEY

Tolerance to fungal disease in cereals has been reported but rarely co nsidered important in field studies. We tested a wide range of spring barley genotypes identified from previous field trials as potentially tolerant or non-tolerant. These included cultivars, breeding lines and segregants from crosses. Genotypes were put into trial over two years and different fertiliser levels to test for environmental interaction in yield response to disease. Mildew was assessed as either the area under the disease progress curve (AUDPC) from visual scores, or as a b iomass measurement using enzyme-linked immunosorbent assay (ELISA). En vironmental effects, expressed as differences between years, and asses sment method had major interactions with tolerance expression, whilst the effect of fertiliser was expressed mostly in the second year only. Despite these interactions, some genotypes overall expressed a strong tolerance or non-tolerance trait to disease, indicating a heritable c omponent. (C) 1998 Elsevier Science B.V.