Field Based Variability in Oat Crown Rust (Puccinia coronata f. sp.Avenae) Resistance in Exotic Oat Germplasm

Rust pathogens represent a major threat to cereal crops, though little is known about the status of oat crown rust in Pakistan. This study was designed to assess crown rust status and field based partial resistance of 16 exotic oat lines introduced from Europe along with local check, under natural field conditions at District Mansehra, Pakistan. Data on crown rust severity and host reaction was taken at three scoring dates to assess partial resistance using area under rust progress curve, infection rate, co-efficient of infection and final rust severity. A moderate crown rust pressure was observed during oat season 2015-16, with relatively late crown rust onset after mid of April. Based on the crown rust resistance response, the tested germplasm was clustered into four groups i.e., G1 contained eight, G2 contained three, G3 contained two and G4 contained three genotypes. Group 1 could be regarded as the most resistant genotypes group, and contained genotypes O-SA-1, O-SA-5, O-SA- 15, O-SA-10, O-SA-14, O-SA-4, O-SA-6 and O-SA-11. Genotype O-SA-9, O-SA-7 and O-SA-12 had relatively high crown rust susceptibility. Further studies on across location and over-years crown rust resistance response of these genotypes must enable their exploitation in oat genetic improvement and crown rust control.