Association between yield loss and Fusarium head blight traits in resistant and susceptible winter wheat cultivars

Abstract

The influence of abiotic and biotic factors on yield loss has usually been analysed separately without considering their interactions. Consequently, the main objective of this study was to investigate the relationship between FHB index, Fusarium-damaged kernels (FDK) and yield loss, while considering effect of climatic conditions and cultivar resistance/susceptibility to FHB as a coherent whole. The study was conducted over two growing seasons (2013/2014 and 2014/2015), using 25 commercial winter wheat cultivars. Fungicide-sprayed and non-sprayed treatments were applied, while corn kernels infected with F. graminearum provided an artificial source of FHB inoculum. Average FHB index of 25 cultivars in 2014 (31%) and FDK (15%) differed significantly from FHB index (10%) and FDK (5%) in 2015. Variability in FHB index and FDK was more uniformly related with yield loss of moderately resistant than it was in susceptible/moderately susceptible cultivars. Correlation of FHB index and FDK also differed between susceptible/moderately susceptible (r = 0.362, p = 0.035) and moderately resistant cultivars (r = 0.732, p = 0.001). Yield loss of susceptible/moderately susceptible cultivars caused by FHB differed less uniformly than it did in moderately resistant ones. Different responses of susceptible/moderately susceptible cultivars on FHB pressure in the same environment indicated that there might be a threshold of pathogen pressure below which a cultivar will not response with significant yield loss in cases where other requirements relevant to exhibit the cultivar's yield potential are met.