The germination problem of oat seed lots affected by Fusarium head blight

Mycotoxin contamination and reduced germination capacity (GC) of oats affected by Fusarium head blight (FHB) have become serious concerns in Norway. Spawn- and spray-inoculated field trials were conducted from 2007 to 2010 to screen for resistant genotypes and to study the relationship between GC and deoxynivalenol (DON) contamination. Correlation coefficients between GC and DON level varied from −0.412 to −0.711 ( P < 0.001). The strongest and the weakest correlations were recorded for the spray- and spawn-inoculated experiments of 2009, respectively. High DON levels were associated with low GCs but low DON levels did not guarantee higher GCs. DON did not inhibit initiation of germination, but did retard seedling growth in a germination assay conducted on DON-amended water agar. Most of the seedlings grown on the modified WA containing even as little as 2 ppm DON had abnormal morphology and would not be considered as ‘germinated’ in official tests. A greenhouse experiment studying the effect of time of inoculation on GC, DON level, and seed infection (SI) showed a rapid reduction in DON levels resulting from later inoculations. Increments in GC were observed although they were not as strong as the decrements in DON level. Seed infection remained consistently high (> 60 %) for all inoculations. Seed dressing and dehulling individually were not effective in improving GC, but when combined increased GC to the percentage of kernels having viable germ. We hypothesize that in addition to the level of DON, SI influences the GC of Fusarium -damaged oats, especially in wet years that may facilitate late-initiated infections.