Evaluation of Iranian Dragon’s Head landraces for resistance to prevalent diseases in the field and glasshouse conditions

Dragon’s head (Lallemantia iberica) as an oilseed crop has been recently introduced to Iranian farmers and due to its tolerance to abiotic stresses grown in drylands and rain-fed areas of the country in rotation with cereals and pulses. In this study, fifty Iranian L. iberica landraces were evaluated for the prevalent diseases under field conditions during 2019–2021 in Gonbad-Kavous, North of Iran. A spot lesion/blight symptom was observed in the field and the subsequent classical and molecular mycological studies identified Alternaria tenuissima and A.atra as the causal agents. Subsequently, a complimentary experiment was conducted to screen genotypes for these disease agents under controlled conditions using the proposed scoring system invented in this study. Results showed a significant negative correlation of Sclerotinia stem rot with yield and plant height, while no relationship was observed between Alternaria spot/blight and agronomic traits. Two and twenty-one genotypes were identified as highly resistant and resistant to Sclerotinia stem rot in the field, respectively; where six of them showed additional resistance to Altarnaria spp. in the glasshouse. The resistant/high-yield genotypes identified through this research can be considered valuable sources to be released as new cultivars or exploited in breeding programs.