Investigation and a New Evaluation Method of the Resistance of Maize Hybrids grown in Hungary to Fusarium moulds

Thirty maize hybrids grown in Hungary representing groups FAO 200±299, FAO 400±499 and FAO 500-were studied in order to obtain information about genotypic resistance to Fusarium moulds. The plants were grown on an experimental farm and were inoculated using the toothpick method with Fusarium graminearum and Fusarium culmorum. In addition maize grain meals were also inoculated with isolates of moulds. Measurements were made of the mould-covered surface area of the ears 9 weeks after inoculation and of the zearalenone and T2-toxin content of the inoculated maize meals. Large di€erences among hybrids were observed for the mould- covered area of the ear surface (2.00±38.88%), the zearalenone content (4.20±71.20 mg/kg) and the T2- toxin content (1.60±122.50 mg/kg). Relatively poor correlation (rˆ0.489) was found between the area of mould covering the ear surface and mycotoxin content of maize. Bearing in mind that the user of feed grain is interested in obtaining a feed with the lowest mycotoxin content, a new method of evaluation of hybrids which uses a toxin±mould index (TMI) was introduced. This index is calculated on the basis of both growth rate of moulds and their toxin-producing activity. Although a decreasing tendency in resistance of hybrids with a longer growing vegetation period could be observed, resistant genotypes were found in every FAO group, con®rming the views that in addition to the in¯uence of duration of the vegetation period on the resistance, genetic factors may also play a signi®cant role.