Original Contribution STUDY OF LATENT PERIOD AND INTERACTIONS BETWEEN DIFFERENT SEPTORIA TRITICI GENOTYPES AND DIFFERENT WHEAT CULTIVARS AND LINES IN GREENHOUSE

In this study, the interaction of four genotypes of Septoria tritici-the causal agent of Septoria blotch- which were collected from Khuzestan (Safiabad), Ardebil (Moghan) and Golestan (Gorgan) provinces with (Tajan, Zagros, Koohdasht, Shiroodi, Shanghai, Falat and Darab-2) cultivars and two ( N-80-6 and N-80-19) lines of wheat were examined. The factorial experiment was carried out in a compeletely random design with four replications in the greenhouse. Disease severity was measured using double digit scale from disease appearance to heading. The Area Under Disease Progress Curve (AUDPC) and disease severity was calculated and used in analysis. The results showed that there is a significant difference between these cultivars and lines, four isolates and interaction between cultivars and isolates. Also, cultivars Falat and Darab-2 had maximal and cultivar Shanghai had minimal AUDPC. Golestan province isolates had the highest AUDPC in all tested cutivars. Statistically Significant interaction of isolate-cultivar showed that virulence of each isolate (pathogen genotype) on each cultivar or line is different from other cultivars and lines. This showed that, there is a host- pathogen specificity in S. tritici-wheat pathosystem. The results showed that the length of latent period was varied between 16 and 20 days in different cultivars and lines and it showed a significant difference between cultivars and lines. This is the first study on length of laten