Results of screening greenhouse and int vitro behaviour to evaluate some durum wiieat varieties and their F5 descendents selected in algeria for resistance to Septoria tritici.

15 genotypes of durum wheat, composed of 5 parental varities and 10 F5 lines selected in Algeria, were studied for evaluating thein behaviour to Septoria tritici Two trials were realised: one under green house conditions, where seedlings were inoculated artificially with Septoria tritici suspension, and another under in vitro conditions where detached leaves where also inoculated. Among this range of varieties, some genotypes were tolerant, others susceptible and others showed rather reactions between tolerant and susceptible. Tolerant genotypes presented a low number of necrosis in the green house trial and a reduced lesion size on the in vitro infected tissu. On the contrary. sucseptible genotypes showed a high necrosis number and an important lesion size on their detached leaves. Some observations, during the experimentation, permitted to underline the important limiting effect that could impose some biotic and abiotic factors (temperature, relative humidity and age of plant tissue) to the pathogen development, reported by other studies before, In comparision with other investigations, varieties which were reported to be resistant or susceptible had confirmed their reactions in our study, it will be interesting to include them into a primary range of varieties for use to study the fungus Septoria tritici.