EFFECTS OF SEPTORIA LEAF BLOTCH ON SOFT PIED WINTER-WHEAT MILLING ANDBAKING QUALITY

Septoria leaf blotch causes economic yield losses in wheat worldwide. Research on the impact of septoria leaf blotch on grain quality, howev er, has been limited to its effect on test weight. The objectives of t his study were to determine the effect of septoria leaf blotch severit y on soft red winter wheat quality in cultivars with varying levels of resistance and to assess the impact of disease pressure on selection for improved quality in breeding programs. Twelve cultivars expressing a range of genetic resistance were grown in a split-plot design with four replicates in two Missouri environments. Cultivars were considere d main plots. Five experimental subplot treatments, including a nonino culated unprotected control and plots with fungicide protection as wel l, as plots inoculated at tillering, jointing, and flag leaf, were use d to establish a range of septoria leaf blotch severity. Increased dis ease pressure resulted in linear reductions in test weight (r=0.97*), milling quality (r=0.98*), adjusted flour yield (r=0.97**), and a li near increase in water absorption in the flour (r=0.95*). Increased d isease severity also resulted in an increase in flour protein and a de crease in baking quality, however, the linear correlation coefficients were nonsignificant. The role of resistance genes for maintaining qua lity was important for milling quality but was negligible for baking q uality. Cultivar by treatment interactions were due primarily to chang es in magnitude and not in cultivar rank, which suggested that selecti on for milling and baking quality would be effective even when septori a leaf blotch disease pressure is high.