Quality and yield response to the control of Mycosphaerella graminicola in wheat as affected by nitrogen rate and cultivar bread-making characteristics

Abstract

Septoria leaf blotch (SLB), caused by Mycosphaerella graminicola, reduces yield and grain quality of wheat (Triticum aestivum L.) by affecting the photosynthetically active area of the crop. This might influence grain protein concentration (GPC) and affect bread-making parameters. Nitrogen (N) fertilisation is required to achieve high yields in wheat; however, it may enhance the development of foliar diseases such as SLB. The aim of this study was to evaluate the effect of fungicide and N rate on SLB severity, green-leaf-area duration, grain yield and bread-making parameters in three wheat cultivars differing in bread-making characteristics. Two field experiments were conducted during 2009 and 2010 in a split-split-plot design with three fungicide treatments (triazole, triazole-strobilurin, nil) as main plots, three N fertiliser rates as subplots and three cultivars as sub-subplots. Fungicides significantly reduced the area under disease-progress curve (AUDPC) and this was associated with increased yield, which varied among cultivars. The AUDPC was lower in the higher N-rate treatments. Fungicide applications and increasing N rates extended green-leaf-area duration. GPC increased in untreated plots and it was reduced with applications of triazole-strobilurin fungicide. GPC reduction caused by this type of fungicide tended to be lower when the rate of N increased. The two cultivars with low bread-making characteristics showed a tendency to greater reductions in GPC with both fungicide types. Regarding quality variables, only tenacity and dough strength were reduced by the triazole-strobilurin fungicide. On average, for all treatments, tenacity, water absorption and dough development time were higher in the best quality group cultivars.