A NEW METHOD FOR THE EVALUATION OF THE RESISTANCE OF MAIZE HYBRIDS TO FUSARIAL EAR ROT - THE TOXIN-MOULD-INDEX (TMI)

Abstract

30 maize hybrids grown in Hungary representing the groups FAO 200 - 299, FAO 300 399, FAO 400 - 499, and FAO 500 - were studied in order to gain information about genotypic resistance to Fusarium moulds. The plants grown on an experimental farm were artificially infected using the tooth pick method with F. graminearum and F. oxysporum resp. In addition maize grain meals were also inoculated with isolates of moulds. The surface area of ears covered by moulds 9 weeks after inoculation and the toxin content (zearalenone and T-2 toxin) of infected maize grain meals were measured. Big differences were observed in the mould-covered area of the ear surface (2.00 to 38.88%) and also in the zearalenone content (2.73 to 80.33 mg per kg) and T-2 toxin content (5.37 to .52.33 mg per kg) between genotypes. Poor correlation was found between the mould-covered area and the toxin content measured in the maize grain meal of the same genotypes. For characterization of resistance resp. susceptibility of different genotypes, a new method was introduced using the toxin-mould-index (TMI) taking in to consideration both the growth rate of moulds and their toxin production. In every FAO group resistant genotypes were found confirming the view that not only the duration of the vegetation period influences the resistance or susceptibility.