Reaction of melon genotypes to Rhizoctonia solani

Abstract

The intensive exploration of melon (Cucumis melo L.) crops in the Brazilian Northeast favors the occurrence of root diseases such as the Rhizoctonia canker, caused by Rhizoctonia solani. Twenty melon genotypes were challenged against the pathogen isolates RS-9 and RS-10 aiming at selecting those potentially useful for breeding programs and/or integrated disease management. Seeds were planted in infested soil (50 mg of colonized rice grains kg-1 of soil). Disease severity was assessed 15 days after inoculation, by means of a disease scale from 0 to 4, used later to cluster genotypes in five classes. None of the genotypes presented immune-like reaction to R. solani, independent of the pathogen isolate. Disease severity ranged from 6.2 to 85.4% and from 7.8 to 85.2%, for isolates RS-9 and RS-10, respectively. When both isolates were considered simultaneously, genotypes Sancho, AF-1805, Athenas, AF-682, Torreon, and Galileo were highly resistant. Genotypes Sancho and AF-1805 had the lowest disease severity levels in relation to isolate RS-9, and genotype Gold Pride, in relation to RS-10. These genotypes differed significantly from the others, within isolates. Therefore, they are potential sources of resistance to R. solani and should be considered as a priority planting choice in infested areas.

Screening of Cucumis melo L. Cultivars from Iran for Resistance against Soil-Borne Fungal Pathogens

“…Sources of resistance to some of these soil-borne plant pathogenic fungi, namely M. cannonballus [6][7][8]14,20,21] and R. solani [13], have already been identified. However, no attempt has been made to develop a melon cultivar resistant to multiple soil-borne plant pathogenic fungi.…”

“…R. solani was grown on sterilized rice grains (50 g) in Erlenmeyer flasks that were then kept for ten days in an incubator at 25°C with constant luminosity [13]. The colonized substrate was placed in paper bags and dried for 48 h at 30°C with constant luminosity.…”

“…In this context, the use of resistant cultivars is a strategic measure that forms part of the integrated management of Rhizoctonia canker. Michereff et al [13] tested twenty melon genotypes with R. solani and reported that the genotypes Sancho, AF-1805, Athenas, AF-682, Torreon and Galileo were highly resistant to two R. solani isolates.…”

Reaction of melon genotypes to Didymella bryoniae (Fuckel) Rehm

“…However, there are no reports of studies using a full-scale reaction. Therefore, the present study suggested a modified scale, which has been used in studies with other soil-borne pathogens, such as Myrothecium roridum (Noronha et al, 2006), Rhizoctonia solani (Michereff et al, 2008) and Macrophomina phaseolina (Ambrósio et al, 2015).…”

Métodos de inoculação de Rhizoctonia solani e Macrophomina phaseolina em meloeiro (Cucumis melo)

“…A utilização de cultivares resistentes constitui uma medida estratégica no manejo integrado de doenças, porém, apesar de sua relevância, existem poucos estudos sobre a avaliação da resistência de meloeiro aos fitopatógenos em questão. Algumas pesquisas buscaram a obtenção de fontes de resistência a Rhizoctonia solani em acessos e cultivares comerciais de melão (6,19,21) e, segundo os autores, fontes em épocas e locais diferentes na horta didática da UFERSA. Estes apresentam micélios com colorações distintas.…”