ABSTRACT
This study aimed to obtain morphogenetic characterization of ten isolates of Alternaria alternata f. sp. citri collected in the state of Paraíba and to evaluate the reaction of five mandarin orange genotypes inoculated with A. alternata f. sp. citri. The experiment was carried out at Federal University of Paraíba. Ten isolates of A. alternata were evaluated for conidial production, mycelial growth rate and final mycelial growth. A. alternata inoculations were done in detached leaves and seedlings of five mandarin orange genotypes, ‘Tangelo Robinson’, ‘Clementina’ Tangerine, ‘Nova’ Tangerine, ‘Lee’ Tangerine and ‘Swatow’ Tangerine, as well as in fruits of tangerine tree cv. ‘Dancy’. In the inoculation of seedlings, isolate 7 was used, which was from Lagoa Seca-PB and presented the best morphological characteristics. Evaluations were performed at 48h after the pathogen inoculation and used a scale of grades. Isolates 2 and 7 presented higher mycelial growth rate and isolates 6 and 7 caused greater disease severity in fruits of cv. ‘Dancy’. Seven divergent groups of A. alternaria f. sp. citri were obtained by the ISSR marker. Genotypes ‘Tangelo Robinson’, ‘Swatow’ Tangerine and ‘Nova’ Tangerine presented greater resistance to Alternaria brown spot under the conditions of the present study.
Keywords
Alternaria brown spot; severity; aggressiveness; tangerine
