Reactions of Short, Intermediate and Long Day Onion Genotypes in Turkish National Onion Breeding Program to Fusarium Basal Rot Disease

Abstract

Onion basal rot (Fusarium oxysporum f. sp. cepae) disease exerts serious threats on global onion (Allium cepa L.) production and trade. Present breeding programs mostly focus on development of cultivars resistant to onion basal rot disease. Characterization of breeding material in breeding gene pool is the first step of breeding. This study was conducted to determine the susceptibility of 4 onion cultivars, 30 long-day, 1 intermediate-day and 21 short-day onion genotypes to onion basal rot disease. Significant differences were seen in disease susceptibility of the genotypes (P<0.01 ) in both onion seedling and bulb tests. Onion seedling and bulb tests revealed that resistance was not detected in short and intermediate-day onion genotypes and cultivars, while two of long-day onion genotypes (ACLD 7 and 8) were found to be tolerant. Based on present finding, 3 cultivars, 28 long-day, 1 intermediate-day and 21 short-day genotypes were identified as sensitive. ACLD 7 and 8 long-day onion genotypes, which were identified as promising in seedling tests, were also identified as tolerant in bulb tests and such findings proved the compliance of seedling and bulb tests. Bulbs were obtained from the long-day onion lines (ACLD 7-8 genotypes) that were found to be promising and survived in seedling tests and seeds were obtained from these genotypes to ensure progress of generation and they were included in breeding gene pool.