Take-all resistance of Lithuanian winter wheat breeding lines.

Take-all, caused by Gaeumannomyces graminis var. tritici, is one of the most important root diseases of wheat around the world. Previous research has suggested that winter wheat varieties pose no effective resistance. The e xperiment was carried out in the winter wheat mono-crop nursery during 2006-2009. In total, 324 accessions, including standard cultivars, were tested during 3 vegetation seasons. The accessions were grown in 2.0 m 2 plots. The disease severity was assessed as ear discoloration symptoms from early to late milk stages in scores, using the scale 1 to 9 points, where 1 is t he lowest value. Disease severities were high during all three seasons and ear symptoms developed from just visible to full discoloration during 3 to 5 weeks depending on the accessions' re sistance and year. Take-all severity on the accessions tested was estimated from 4.75 to 9.0, 5 .38 to 8.95, and 4.00 to 8.53 points in 2007- 2009, respectively. Varieties 'Flair' and 'Dream' w ere the most frequent in the pedigree of the most resistant lines, occurring in 23.3% pedigrees of the lines. The thousand kernels and hectolitre weight showed no or low correlation with disease severities. Lines resistance showed weak correlation with yield when all plot data were used for calculation. However, correlation coefficients considerably increased when ten percen t of each minimal, mean and maximal yields values were used. A mean yield of resistant and susceptible lines differed about 1 t ha -1 in 2007 and 2008, whereas a lower difference (0.54 t h a -1 ) was found in 2009. Some susceptible