Evaluation of two potential Cucumis spp.resources for grafting melon

[EN] Cultivation of Cucumis melo is hampered by soil stresses. Grafting is used to overcome these limitations. Different cucurbits belonging to several genera have been used as rootstocks for melons: Cucurbita, Lagenaria, Luffa, etc. However, negative effects on fruit quality appear in some rootstock-scion combinations. The selection of new resistant rootstocks that do not cause this negative impact in quality is necessary to improve melon cultivation. In this work, we evaluated two rootstocks, closer genetically to melon scions than those usually employed: a) an F1 hybrid between a commercial melon (C. melo subspecies melo var inodorus market class Piel de Sapo) and one exotic accession (C. melo subspecies agrestis var. chinensis) with resistance to Monosporacus cannonballus, the causal agent of melon vine decline, and with a certain level of tolerance to Fusarium oxysporum f sp. melonis race 1.2, that causes Fusarium wilt, and b) an accession of Cucumis metuliferus, highly resistant to M. cannonballus, F. oxysporum 1.2 and evaluated and classified as highly resistant to Meloidogyne spp. in this work. Grafting compatibility of these two selected genotypes with commercial melons was good. All grafted plants displayed higher vigour and earlier flowering than ungrafted plants. Fruits from plants grafted onto C. metuliferus showed similar quality than those from ungrafted/selfgrafted plants. However, fruits from plants grafted onto the F1 (inodorus x chinensis) had in this experiment lower brix degree than the ungrafted controls. The resistance to soil borne pathogens found in C. metuliferus and the good performance regarding plant development and fruit quality of the scions indicate that this species is a promising rootstock for melons.C. Gisbert and B. Pico thanks the Programa Hispano-Brasileno de Cooperacion Universitaria PHBP14/00021. Authors also thank the MINECO projects AGL2013-49040-C2-1-R, and AGL2014-53398-C2-2-R, cofunded with FEDER funds.Gisbert Domenech, MC.; Gammoudi, N.; Munera, M.; Giné, A.; Pocurull, M.; Sorribas, F.; Picó Sirvent, MB. (2017). Evaluation of two potential Cucumis spp.resources for grafting melon. Acta Horticulturae. 1151:157-161. https://doi.org/10.17660/ActaHortic.2017.1151.25S157161115

Principal Component and Cluster Analysis as a Tool in the Assessment of Tomato Hybrids and Cultivars

Determination of germplasm diversity and genetic relationships among breeding materials is an invaluable aid in crop improvement strategies. This study assessed the breeding value of tomato source material. Two commercial hybrids along with an experimental hybrid and four cultivars were assessed with cluster and principal component analyses based on morphophysiological data, yield and quality, stability of performance, heterosis, and combining abilities. The assessment of commercial hybrids revealed a related origin and subsequently does not support the identification of promising offspring in their crossing. The assessment of the cultivars discriminated them according to origin and evolutionary and selection effects. On the Principal Component 1, the largest group with positive loading included, yield components, heterosis, general and specific combining ability, whereas the largest negative loading was obtained by qualitative and descriptive traits. The Principal Component 2 revealed two smaller groups, a positive one with phenotypic traits and a negative one with tolerance to inbreeding. Stability of performance was loaded positively and/or negatively. In conclusion, combing ability, yield components, and heterosis provided a mechanism for ensuring continued improvement in plant selection programs