Contribution of Primary Spikes Vs Tillers to Total Deoxynivalenol in Harvested Grain of Wheat and Barley

Formation of higher number of tillers is desirable for higher grain yield in both wheat and barley; tillers have delayed physiological development. Studies addressing the contribution of secondary tillers in final DON concentration for wheat and barley are limited. This project aims to improve our understanding of the relationship between FHB symptoms and DON concentration by examining the contribution of primary spikes and secondary tillers as it relates to the final DON concentration. Experiments, established as split-split plot design with five replications, was be conducted in South Dakota with moderately resistant and susceptible cultivars of each spring wheat, winter wheat and barley. Two inoculation time treatments was applied; at the anthesis of primary spikes (Feekes 10.5) and at anthesis of tillers (Feekes 11.2). Primary spikes (inoculated at Feekes 10.5) and tillers (inoculated at Feekes 11.2) were harvested separately, analyzed for visually scabby kernels and deoxynivalenol following standard protocols. Levels of DON were statistically higher in main heads of barley and spring wheat in each cultivar compared to its tillers. In winter wheat, though there was higher DON level in tillers than main heads in each cultivar, it was not statistically different. Based upon our result, it is suggested that cultivars with high tillers number should be selected in breeding programs to develop cultivars with high yield and low DON. Similarly, planting density of wheat and barley can be adjusted such that it will result in higher numbers of tillers, increasing tillers proportion that might lower DON concentration in final harvest.