Valorizing Ibericus traditional melons for organic farming: Crop limitations, use of grafting, and impact on agronomic performance and fruit quality

Abstract

Melon (Cucumis melo L.) is a major crop in Spain, where traditional cultivars of the Ibericus group, selected by local farmers over centuries, are still grown for local markets and self-consumption. These landraces are valuable for organic and sustainable farming, but their productivity is limited by biotic and abiotic stresses. Understanding the limiting factors is essential to guide cultural or genetic strategies that help mitigate their impact. This study evaluated the agronomic performance and fruit quality of 17 Ibericus cultivars, cultivated as non-grafted and grafted onto commercial Cucurbita and experimental Cucumis rootstocks. Trials were conducted over two years in three contrasting organic fields: (i) a non-stressed location without prior melon cultivation, (ii) a pathogen and virus-prone location with a long melon-growing history, and (iii) a site with saline conditions. Viral (WMV, CMV, CABYV, ToLCNDV), powdery mildew, and soilborne pathogens (Macrophomina phaseolina, Neocosmospora spp., Fusarium spp.) severely affected yield. While salinity had minimal impact on yield, it increased SSC in Piel de Sapo, Amarillo, and Rochet cultivars. Under extreme salinity and low rainfall, pathogen dynamics changed, affecting plant development. Grafting reduced plant mortality and increased yield across cultivars, though rootstocks varied in their pathogen resistance profiles. Cucumis rootstocks, especially F1Pat81, maintained fruit quality better than Cucurbita. Varieties 03PS (’Piel de Sapo’), 22AM-GO (’Amarillo’), and 32BL (’Blanco’) demonstrated favourable performance under saline conditions, particularly when grafted onto F1Pat81 or Cucurbita rootstocks, and are recommended for organic farming. Overall, traditional Ibericus melons demonstrate strong potential for organic systems; however, breeding for improved pathogen resistance and rootstock optimization remains essential to promote their cultivation.