Resistance To Powdery Mildew (Erysiphe Cichoracearum Dc.) In Oriental And Semi-Oriental Tobacco Germplasm Under Field Conditions

Powdery mildew (Erysiphe cichoracearum DC.) is an important disease of tobacco (Nicotiana tabacum L.) in many countries. Losses in yield and quality have been reported to be around 30% to 80% in severe cases. Northwestern Iran is a hotspot for tobacco powdery mildew. To identify resistant genotypes, tobacco germplasm, including recombinant inbred lines (RILs) derived from the cross Basma S.31 x Dubec566, some Iranian landraces, and cultivars from different countries were evaluated under field conditions using a simple lattice design (10x10) with two replications. Each plot comprised 3 rows, 5 meters long. Spacing between rows was 65 cm and between plants within rows 20 cm. Susceptible line (Basma S.31) was planted throughout the experiment to guarantee homogeneous inoculation. The most resistant genotypes were 12 RILs (PD205, PD209, PD379, PD324, PD328, PD329, PD336, PD345, PD364, PD365, PD371, and PD381), three Iranian landraces (SPT413, Jahrom15, and Jahrom12), and cultivars (Basma104-1 and Pobeda1). Three cultivars (Kuklen6, Nevrokop261, and L17), two mutants (Mutant 2 and Mutant 3), and Matianus were included in the resistant group. The more resistant RILs (PD205 and PD209) were evaluated across three years and showed consistent behavior across years. Most genotypes studied were susceptible or highly susceptible to the disease. This information should be helpful in tobacco breeding programs.