Although consumers appreciate the genetic diversity among tomato landraces, traditional varieties have been displaced from commercial agriculture. Their cultivation through organic farming in natural parks can contribute to their resurgence. With this aim, we developed a participatory plant breeding (PPB) program in Collserola Natural Park (Barcelona, Spain) to promote the conservation of the Mando landrace and to obtain new varieties adapted to local organic farms. Taking advantage of the natural genetic variation from the variety’s high cross-pollination rate, farmers developed five experimental inbreeds that were tested in a multi-locality trial in 2018. As a result of the PPB program, cultivation of the original landrace increased from 80 plants in 2011 to more than 2000 plants in 2018, which protected the variety from genetic erosion. Locality was the factor that contributed mostly to agronomic traits (e.g., yield (66% of the phenotypic variance)), while the genotype contributed more to the quality traits (except for soluble solids (37%) and dry matter (38%)). Farmer evaluations were highly correlated with the phenotypic traits recorded by researchers (Pearson coefficient ranging from 0.63–0.83), and led to the same final varietal selection. The superior inbred selected (3.9) is now being cultivated in the area of study. This paper discusses the efficiency of PPB in guiding the evolution of landraces.

Non-trellised culture of tomato is gaining interest among farmers cultivating long shelf-life (LSL) landraces because of the reduction in production costs. This cropping system can benefit from the selection of determinate growth genotypes, mirroring the advancements achieved in processing tomatoes. With this aim, and profiting from the natural variation found within the Penjar landrace, we selected traditional determinate genotypes and breed novel lines carrying both the self-pruning (sp) and the compound inflorescence (s) mutations. Traditional genotypes and breeding lines were compared to commercial controls in a three multi-locality trial and under two irrigation regimes (normal watered, 100% ET_c; and water deficit, 50% ET_c). Water use efficiency, harvest index, yield and fruit quality traits were studied at harvest. During postharvest, the effects of genotype and management practices on shelf life were assessed under different storage conditions (controlled conditions/cold storage/farmer facilities). All genotypes used water more efficiently under water deficit irrigation than under normal irrigation. Harvest index was improved in the determinate genotypes and was neither affected by locality nor by irrigation factors. Breeding lines showed yields similar to the controls and the traditional ones; however, they displayed a plant architecture that facilitated their management. They also presented higher postharvest shelf life than controls and traditional lines. Shelf life was significantly affected by genotype (G), locality (L, at early stages), and irrigation regime (I, at later stages), with the contribution of the genotype to the phenotypic variance increasing along the postharvest. Low watering increased shelf life in some genotypes while cold storage and high humidity conditions impeded the long shelf-life trait. Overall, sunscald incidence and percentage of unripe fruits when using a single harvest strategy are the major limitations for non-trellised culture of Penjar tomato. In conclusion, this study sheds light on the main aspects of management and on breeding targets to promote a non-trellised culture of Penjar tomato in combination with optimal water use efficiency.