AbstractA method was developed to assess sunflower resistance to sclerotinia root infections in greenhouses. Some of the genotypes were also tested in the field to validate the greenhouse testing method. Efficiency of this method was also tested in a diallel cross. The susceptibility could be assessed by the final percentage of dead plants or by the time required to reach a given threshold of attack (threshold latency parameter). The correlation coefficients between susceptibility assessed in the field and with the greenhouse method were significant. The diallel cross analysis indicated that only additive effects are important. Correlation for susceptibility to sclerotinia wilt, between parental lines and the mean of their hybrids, was significant. It is concluded that breeding programmes for increase of resistance to sclerotinia root and basal stem attacks, using the described testing method, should be effective.
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