Do Flowering Habits Influence Fusarium Head Blight Susceptibility in Wheat Cultivars under Heat Stress

Abstract

Fusarium head blight (FHB) is a major threat to wheat production worldwide, affecting grain yield, quality, and food safety through contamination with mycotoxins such as deoxynivalenol (DON). Despite its importance, limited information is available on how infection timing interacts with heat stress under climate change scenarios. An experiment was conducted using elite lines of wheat in a controlled environment to evaluate the effect of inoculation at different flowering stages and subsequent increase in temperature during grain-filling on Fusarium head blight FHB, DON and grain yield. The experiment was completely randomised, consisting of eight cultivars with three replicates. Flowers were scored for the progress of anthers when the lower glume could be opened with a thumbnail (glume loose; GL). Fusarium graminearum was used to spray-inoculate wheat spikes at GL+0, GL+4 and GL+8. Pots were transferred to controlled environment cabinets set at 23/15oC or 28/20°C (day/night, 16 h day). DON concentration was quantified using a standard curve-based assay, and data were analysed using ANOVA. Results showed that there was variation in anther maturity among elite cultivars, and this influenced the FHB severity and grain yield. High temperature increased FHB severity in five of the eight cultivars. Cv Soissons had the lowest mean severity (39%), while Oakley and Solstice had the highest mean severity (61%). Time of inoculation had a significant effect on FHB severity, and inoculation at GL+4 resulted in the highest mean FHB severity. The effect of high temperature on DON concentration and grain yield also depended on the time of inoculation. At GL+4, high temperature increased DON concentration only in Gallant, Solstice and Xi19. Soissons linked with Ppd-D1a increased grains per spike and showed no temperature or time of inoculation effect. The effect of FHB severity was reflected in the grain yield, and inoculation at GL+4 produced the lowest yield in most cultivars, except in Alchemy and Solstice, which yielded lower at GL+0 and GL+8, respectively, under high temperature. These findings highlight the importance of flowering dynamics and their interaction with heat stress in determining FHB risk and its impact on wheat productivity.