Varietal Screening of Durum Wheat Varieties for Resistance to (Tan Spot) under Field Conditions.

Tan spot disease caused by was becoming more bred in Tunisia during the last decade. The search for resistant varieties against the increased virulence diversity of is presently considered as a priority. Seven of the most commercialized durum wheat varieties in Tunisia (cvs. Maâli, Salim, Razzak, Monastir, Khiar, Inrat100, and Sculptur) were inoculated with five characterized fungal strains under field conditions, during two seasons. The variance analysis revealed that strains Ech8F and B4.8 used in inoculation are the most virulent ones. These strains hosting gene caused chlorosis symptom on the tested varieties. The other strains induced necrosis with yellow halo and host gene were less virulent. The area under disease progress curve values revealed that Maâli is the most vulnerable genotype compared to the new selected varieties Monastir and Inrat100. A variable tolerance rate of the varieties to tan spot disease was also highly visible on yield components. The losses were about 22.2% of the thousand kernel weight in Maâli variety, 35% of spikes/m in Inrat100 variety, 32.5% of kernel number/spike, and 25.2% of yield grain in Monastir variety. This effect evaluation of the strains harbouring and genes could be responsible for the identification of potentially susceptible genes and representing resistance sources for breeding programs.