Environment-specific selection to identify high yielding wheat genotypes and response to fungicide application

ABSTRACT Selection of disease resistant genotypes is the main goal of wheat (Triticum aestivum L.) breeding programs. However, because of the lack of genotypes resistant to all diseases and the strong influence of the environment on the level of resistance of the genotypes, the use of fungicides is necessary in the cultivation of wheat. The objective of this study was to compare the gain in yield and the selection efficiency of wheat genotypes due to the fungicide application in trials carried out in different sites and years. This study used grain yield data from 816 wheat genotypes evaluated in 248 advanced trials at eight sites during the years from 2004 to 2012. The gain resulting from fungicide application for a given genotype was estimated by the difference between yield of plots on which fungicide was applied and control treatment. The greatest gains with fungicide application were observed in sites with lower average temperatures and higher rainfall indices, such as Campo Mourão, Castro, Não-Me-Toque and Guarapuava. On the other hand, the lowest gains with fungicide application occurred in Dourados and Palotina, environments where crops in general suffer water stress and present higher average temperatures. The year effect resulted in yield increases due to fungicide application ranging from 16.9 to 60.7%. The selection and evaluation of the response to the application of fungicide in wheat should be environment-specific to maximize the use of genotype x environment interaction.