Effects of Infection with Septoria Leaf Blotch (Septoria tritici Rob ex Desm.) at Different Growth Stages on Yield and Yield Components of Wheat Cultivars in Gorgan

Septoria leaf blotch of wheat (Septoria tritici) is one of the most important diseases of wheat in the world. To detemine yield reduction caused by this disease and the effects of infection in different growth stages on yield and yield components in three wheat cultivars, a field experiment for two years (2003-2004) was carried out using a factorial design in form RCBD with four replications. Artifical inoculation at different growth stages including tillering, stem elongation, flag leaf opening and ear emergence were levels of a factor and cultivars Tajan, Zagros and Kouhdasht were levels of other factor. A treatment without infection was considered as check. Grain yield, number of ears per squar meter ,number of kernels per ear and 1000 kernels weight were measured. The results showed that the effects of different stages of infection on grain yield, 1000 kernels weight and number of kernels per ear was significant, but on number of ears per square meter was not . The extent of yield reduction differed on wheat cultivar and infection at different stage. In this experiment, yield reduction were recorded from 9.07 to 28.95 percent .Daily yield reductions in cultivars Tajan ,Zagros and Kouhdasht assessed 0.30, 0.24 and 0.25 percent and total yield reductions were 28.95, 26.67 and 24.69 percent, respectively.