Interspecific hybrids of wild Cucumis species ('Fian' and 'Fimy'): new rootstocks for melon highly resistant to biotic soil stress

Abstract

[EN] Two hybrids, "UPV-FA" and "UPV-FMy", hereinafter "Fian" and "Fimy", were obtained by crossing the wild Cucumis species C. ficifolius with C. anguria and C. myriocarpus, respectively. These species are known to be resistant to nematodes. The hybrids have been tested against the main melon soil borne and aerial fungal pathogens. Both were highly resistant to Macrophomina phaseolina and to Fusarium oxysporum f. sp. melonis (Fom) race 1.2 (wilting isolate), and moderately resistant to Fom 1.2 (yellowing isolate) and to Monosporascus cannonballus. "Fimy" was highly resistant to powdery mildew races 2 and 5, and "Fian" was highly and moderately resistant to these races, respectively. These hybrids were previously evaluated as rootstocks for melon in greenhouses and experimental fields with good results (adequate compatibility, growth development and production, and no negative impact on fruit quality). This behavior was now confirmed in commercial fields. The same grafting combinations were used: as scion the muskmelon cultivar "Vendrantais", a Charentais type, and the cultivar "Finura", a Piel de Sapo type, and as rootstocks "Fian", "Fimy" and two commercial rootstocks "Cobalt" (Cucumis maxima × Cucumis moschata) and "64-376" (Cucumis melo). As in previous assays, fruit from plants grafted onto "Cobalt" yielded larger fruits, with wider seminal cavities. In fruit harvested from plants grafted onto "Fian", "Fimy" or onto the other Cucumis rootstock some mild differences that do not affect the market quality of fruit were found. All these results confirm the suitability of both hybrids as rootstocks for melon: they show good grafting performance, with reduced impact on fruit quality compared to Cucurbita rootstocks, and better resistance to the fungal pathogens that limit melon production worldwide.