Avaliação de genótipos de batata (Solanum tuberosum L.) quanto à resistência a Phytophthora infestans (Mont.) de Bary

Abstract

Potato (Solanum tuberosum L.) is extremely important for the food security of mankind. Its production is limited to many factors, especially diseases that affect the crop, among them the late blight, caused by the oomycete Phytophthora infestans (Mont.) De Bary, which is considered one of the most destructive and with great economic impact. The use of resistant cultivars is the most economical way to control this disease, however in Brazil the cultivars widely used are susceptible to the pathogen. For the development of highly resistant genotypes, it is necessary that potato breeding programs to know the inheritance of resistance of the genitors. Faced with this situation, two studies were carried out. The objective of the first study was to characterize potato genotypes for resistance to isolates of P. infestans of different complexities, using different methods. Nineteen potato genotypes were evaluated in field and in vitro experiments for the severity of different isolates. The 19 potato genotypes presented different levels of resistance to P. infestans in the field and in vitro experiments, with genotypes having qualitative and quantitative types of resistance. The genotypes were classified as: 'EPAGRI Catucha', resistant to P. infestans; 'IAC Ibituaçu' and clone F50-08-01, moderately resistant; 'BRS F63' (Camila), F63-10-07, 'BRS Pérola', F63-10-13, F183-08-01 and F37-08-01, moderately susceptible; F131-08-01, F21-07-09, 'BRS Clara', 'Innovator', 'BRS Ana', 'Asterix', 'Ludmilla' and CL 308, highly susceptible. Of the two in vitro methods tested, the detached leaflet offered better results. The second study had as objective to compare two potato resistance genitors, ‘BRS Eliza’ and ‘BRS Clara’, regarding the capacity of generating a hybrid population. Two hybrid populations of 120 individuals (genotypes) each were obtained from crossing 'BRS Eliza' and 'BRS Clara' with C1883-22-97 (susceptible). Heritability estimates of the area under disease progress curve (AUDPC) of the two populations were of moderate magnitude, and expected selection response did not differ from each other. However, the mean AUDPC of individuals from the 'BRS Eliza' x C1883-22-97 cross was lower (i.e., more resistant), indicating the superiority of 'BRS Eliza' compared to ‘BRS Clara’.