Evaluation of local watermelon and melon rootstocks resistance to six soilborne plant pathogenic fungi in Tunisia. Boughalleb-M’Hamdi, N., Ben Salem, I., Bnejdi, F., and M’Hamdi, M. (Tunisia)

Abstract

Five melon (M16, M17, M12, M9.1, and V4R3) and two watermelon (P7 and P6.1) accessions were evaluated under greenhouse conditions for their resistance to Fusarium oxysporum f. sp. melonis (FOM), F. solani f. sp. cucurbitae (FSC), F. oxysporum f. sp. niveum (FON) Monosporascus cannonballus, M. eutypoides, and Macrophomina phaseolina based on disease severity index, leaf alteration index and shoot and root dry biomass. Student-Fisher test revealed significant difference in the susceptibility among the tested local germplasms. Separate statistical analyses of variance confirmed the Duncan test and revealed a significant effect of genotype × isolate interaction. For the four assessed traits, mean scores indicated that the resistance to the six soilborne pathogens varied from moderate to high. The local melon germplasm M9.1 was found to be the best accession showing the highest resistance. M9.1 and M17 accessions have showed important shoot and dry biomasses. For watermelon accessions, the lowest disease severity index and leaf alteration index were recorded for the combination germplasm, P6.1 and M. eutypoides. In the other hand, the presence of plant-pathogen interaction indicated that the mechanism controlling the resistance for each pathogen varied from one accession to another. The presence of several genetic sources of resistance to the six soilborne pathogens in the accessions assessed had two advantages, firstly the exploitation of the pool genes for further breeding program and secondly the limitation of emergence of new fungal adapted species.

Keywords

• Local germplasms
• melon
• rootstock resistance
• soilborne pathogens
• watermelon