Protocolos de avaliação da resistência do trigo (Triticum aestivum L.) à brusone e caracterização de genótipos em diferentes ambientes

Abstract

Wheat (Triticum aestivum L.) shows high importance worldwide, due to the demand for its derivatives for both human food and animal feed. Brazil is not self-sufficient in the production of this cereal, producing less than half of what is consumed. Wheat blast, caused by the fungus Pyricularia oryzae Triticum pathotype, is an important shoot disease in the crop. Wheat blast resistant cultivars are scarce, which pose pressure to plant breeding. Resistance evaluation methods are highly useful, but also scarce. The aim of this work was to evaluate wheat blast resistance assessment protocols at field and greenhouse conditions. A pilot experiment allowed for selecting an aggressive isolate for the experiments. In the field study, eight contrasting genotypes were assayed in 2019, in two regions and under three inoculation conditions. There were no visual disease symptoms in any treatment, possibly due to the meteorological conditions experienced. There were sensible differences regarding the agronomic traits, and OR Marfim was confirmed as susceptible to blast. The protocol has to be better validated, but both inoculations tested showed to be potentially efficient. In the greenhouse study, six genotypes were assayed during two years (2019 and 2020) and under six different types of inoculations, i.e., plant stages and types of inoculum application. A varied and massive amount of results was obtained. All methods showed a certain level of efficiency, but spraying the inoculum at the flowering stage harvest the best results, allowing a clear differentiation of the genotypes studied.