CORRELATIONS AMONG FUSARIUM-CULMORUM HEAD BLIGHT RESISTANCE, FUNGAL COLONIZATION AND MYCOTOXIN CONTENTS IN WINTER RYE

Fusarium culmorum head blight infections may lead to accumulation of t oxic metabolites in winter rye grain. To estimate the correlation betw een resistance traits, fungal colonization and accumulation of deoxyni valenol (DON), 3-acetyldeoxynivalenol (3-AcDON) and zearalenone (ZEA), 27 winter rye single-cross hybrids were artificially inoculated in 19 92 and 1993. Resistance traits were head blight rating and grain weigh t of the inoculated relative to the non-inoculated plots. Fungal colon ization was determined by the analysis of ergosterol (ERG) content in the grain. Head blight rating and relative grain yield showed a medium to high disease severity and ERG indicated a considerable fungal colo nization of the kernels with a mean of 85 mg/kg in 1992 and 66 mg/kg i n 1993. DON content among genotypes ranged from 0.7-28 mg/kg in 1992 a nd from 11 to 35 mg/kg in 1993. 3-AcDON and ZEA contents were low in b oth years with overall means of 1.1 and 0.09 mg/kg, respectively. Acro ss both years, considerable genotypic variation was found for head bli ght rating, relative grain weight, and ERG content with medium to high heritabilities (0.6-0.7). For the mycotoxin contents, however, genoty pe-year interaction variance was the most important source of variatio n. The correlations between relative grain weight and DON, 3-AcDON, or ZEA were low in 1992 (r approximate to 0.3), but considerably higher in 1993 (r approximate to 0.7, P = 0.01). In contrast, correlation bet ween relative grain weight and ERG was significant in both years (r ap proximate to 0.5, P = 0.01). In F. culmorum head blight infections, DO N, 3-AcDON and ZEA contents appear to be affected, at least partially, by different environmental factors than resistance traits and fungal colonization.