Gauging stability of resistance to Pyrenophora teres f. teres in barley using best linear unbiased prediction

Abstract

Data were gathered on resistance of spring barley genotypes to Pyrenophora teres Drechs. f. teres Smedeg., the causal phytopathogen of net blotch. The barleys were sown in Finnish official variety trials during two seasons and at six sites. Replicate blocks were scored for terminal disease severity and individual plants were assessed for resistance on a percentage flag leaf (F) and second leaf (F‐l) basis. These methods of assessment were compared and site by genotype interactions were investigated using mixed models and best linear unbiased predictors (BLUPs). Arve was confirmed as the universally susceptible check while Pohto and Tofta, relatively resistant varieties, rated differently over seasons, though consistently between sites. Bor88377, a two‐row barley, and Bor94007, a six‐row barley, both proved to be widely adapted relatively resistant breeding lines, but under severe disease pressure Bor94007 was the better of the two. Using a terminal severity score generally better differentiated germplasm for resistance to P. teres than the more time consuming assessment of percentage leaf area damaged. Using BLUPs allowed site‐specific interactions to be assessed within entire datasets without the need to investigate them separately.