Reação de genótipos de tomateiro às raças 2 e 3 de Fusarium oxysporum f. sp. lycopersici

Abstract

The Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici, is an important disease of tomato (Solanum lycopersicon L.) in Northeastern Brazil. Order to select genotypes with potential for use in the disease management, 60 strains were evaluated (F7 generation) from the crossing of access BHRS-2, 3 and Viradoro cultivar in relation to isolates from the physiologic races 2 and 3 of F. oxysporum f. sp. lycopersici. Seedlings 21 days old were inoculated using the method of cutting the roots and soak in the suspension of conidia of the pathogen. The evaluation was performed after 21 days, with the scale of grades ranging from 1 to 5. The genotypes were grouped into five classes of reaction. Most genotypes (73.3%) behaved as highly resistant to the race 2 isolate, while 45.0% were classified as susceptible and 28.3% as highly susceptible to the race 3 isolate. Only the L-1 strain showed high resistance reaction to both isolates. The stability of this line of resistance was evaluated on five isolates ofeach race (2 and 3). The line L-1 showed high levels of resistance to all race 2 isolates, therefore indicating high stability of resistance. However, for race 3 isolates, this strain showed three distinct classes of reaction, ranging from highly resistant to susceptible, indicating instability of resistance to this race.