Análise de diferentes métodos para inoculação de Xanthomonas axonopodis pv. phaseoli em feijão

Abstract

The common bean (Phaseolus vulgaris L.) is cultivated in all regions of the world, on different weather conditions, systems of cultivation, and periods, being a great importance crop. The common bean plant can be affected by many diseases, including the common bacterial blight, caused by Xanthomonas axonopodis pv. phaseoli. This disease has as characteristic, necrotic lesions with a yellowish halo on the leaves and pods. The main objective of this work was to identify the best method of Xanthomonas axonopodis pv. phaseoli inoculation on two different genotypes of bean for resistance to common bacterial blight. The experiment was conducted on greenhouse at Federal Technological University of Paraná (UTFPR), Campus Pato Branco - PR, in a random block design, factorial arrangement, being 2 cultivars (IPR Colibri and IAC Milênio) x 7 methods (inoculated seeds by immersion, inoculated seeds by vacuum infiltration, inoculated leaves, lesioned leaves, inoculated stem, lesioned stem, and not inoculated plants (control)) x 4 evaluations with 4 repetitions. On this experiment, the plants were inoculated by the methods of seed immersion, vacuum infiltration, multiple needles and hypodermic syringe. The severity analysis was done at 7, 14, 21 and 28 days of disease colonization. After 28 days, the plants were harvested, and the fresh and dry mass were analyzed from stems and leaves. Both genotypes showed symptoms of severity due to a favorable environmental conditions to the disease development, but on IPR Colibri cultivar (susceptible) the symptoms of the disease were more apparent than the IAC Milênio cultivar (moderately resistant). The IPR Colibri cultivar showed the lower values for the fresh and dry mass. Therefore, all the methods of inoculation were efficient, being able to use any method, but, considering time and easiness for inoculation of the pathogen, it must be seed immersion.