Combining Ability for Resistance to White Mold in a Diallel Cross of Soybean

Abstract

The white mold, caused by Sclerotinia sclerotiorum (Lib.) de Bary, is one of the most important diseases of soybean. The objective of the present work was to evaluate the soybean reaction to the fungus S. sclerotiorum, which causes white mold, in a partial diallel with 50 crosses. The Group I of parents was composed of ten experimental lines with high grain yield and the group II consisted in five genotypes with possible resistance to white mold. Ten plants of each cross in the F 4 generation and the parents were evaluated for reaction to fungus infection using the method of inoculation in detached leaves in order to assess the severity of the disease and to later estimate the combining abilities. Estimates of the specific combining ability (SCA) was a significant reaction to S. sclerotiorum, indicating that there is variability for fungus resistance due to non-additive genes action.

Research Article Diallel analysis for soybean resistance to the fungal pathogen <i>Sclerotinia</i> <i>sclerotiorum</i>

“…Therefore, the use of resistant cultivars is the best alternative for controlling stem rot. However, genetic resistance to S. sclerotiorum is complex and has low heritability, with only a few cultivars showing some degree of resistance (Kim et al, 2000;Juliatti et al, 2014;Zhao et al, 2015;Pereira et al, 2019). In addition, plants have escape mechanisms that make it difficult to evaluate the disease in the field, such as flowering date, height, and architecture (Cunha et al, 2010).…”