Host Specificity and Damage Assessment of Broomrape (Orobanche cumana) Races on Sunflower Genotypes

Abstract

Host specificity and damage assessment of broomrape (Orobanche cumana) races were evaluated on different sunflower genotypes to determine variability in host–parasite interactions and associated yield impacts. Field and pot experiments were conducted using genetically distinct sunflower lines exposed to multiple O. cumana races under controlled infestation conditions. Parasite emergence, attachment success, biomass accumulation, and host damage parameters were recorded to quantify race-specific virulence. Results indicated pronounced differences in host susceptibility, with certain sunflower genotypes exhibiting strong resistance characterized by reduced tubercle formation and limited parasite emergence, while susceptible genotypes supported extensive broomrape development and severe growth suppression. Distinct O. cumana races demonstrated varying levels of aggressiveness, indicating host-specific adaptation and differential virulence profiles. Damage assessment revealed significant reductions in plant height, head diameter, and seed yield in highly susceptible genotype–race combinations. Early parasite attachment was identified as a critical stage influencing overall infection success and subsequent host damage. The interaction between sunflower genotypes and broomrape races highlighted a dynamic co-evolutionary pattern driven by selection pressure on resistance genes. These findings emphasize the importance of race-specific screening in sunflower breeding programs to develop durable resistance. The study provides essential insights into broomrape management and supports the deployment of resistant genotypes as a key strategy for minimizing yield losses in sunflower production systems.