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Chestnut cultivation and production in Spain has employed grafted seedlings from selected local cultivars. Previously, we have characterised the Spanish cultivars by morphological and molecular markers. We are presenting in this paper the proximate analysis and mineral content for the main Spanish cultivars. A total of 131 samples were collected from 47 cultivars in six important Spanish chestnut production regions; located in the North such as Asturias, Castilla-Leon (El Bierzo) and Galicia; in the Central such as Extremadura and in the South such as Andalucia; as well as the Canary Islands, the southermost part of Spain near to North Africa. High variability in chemical composition between cultivars and regions corresponded to the high genetic variability between cultivars. Correlations with environmental parameters were low, indicating that differences found between regions were probably reflecting the differences between cultivars. In Central and Southern Spain, some cultivars presented lowest moisture content due to the low summer rainfall in these regions. Differences in starch and total sugar contents were high and were negatively correlated with each other. There was no negative correlation between nut size and total sugar content. Lowest values of fibre content and ease of digestibility were found in cultivars from Galicia and Extremadura. No significant differences in Fe, Zn and Cu were found although Zn content is twice the value reported for European chestnuts. This work would be a valuable reference to chestnut quality for the food processing industry, nutritionists, breeders and growers alike.

European chestnut (Castanea sativa Mill.) covers in total 2.53 million hectares, of which 2.2 million hectares are forests and the remaining parts, are orchards. In Europe it is growing in an area comprised by 27o N and 53o N latitude, from sea level in seaside regions to 2000 m above sea level (a.s.l.) in the south of Europe. According to Fernandez-Lopez et al. (2005), chestnut species is characterized by the existence of some differentiation among extreme populations, which can be supposed due to its long-range distribution across the Mediterranean region, through varying climatic conditions. As reported by Heiniger (1992), chestnut is a good indicator of warm regions with oceanic climate. In spite of C. sativa Mill. be characterized as a mesophilic species, nowadays the chestnut shows many growth limitations, which partially can be ascribed to the climate changes, since they influence abiotic and biotic factors and consequently photosynthetic productivity. From abiotic factors, water and heat stress have been the most important limitations, inducing less growth, less vigor increasing susceptibility to the biotic factors such as ink and blight diseases. When compared with other hardwood species, the trees can absorb the same amount of carbon, but due to the fast-growing chestnut can store more carbon in less time. So, this agro forest system has been identified as an important way to slow climate change. Photosynthesis, according to (Givnish, 1988), provides green plants with almost all of their chemical energy, being central to their activity to compete and reproduce. So understanding

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; This is a large-scale molecular study based on simple sequence repeat (SSR) loci of the diversification process in chestnut cultivars from Portugal and Spain, from the northern Iberian Peninsula to the Canary Islands and the Azores. A total of 593 grafted chestnut trees (Castanea sativa Mill.) were analysed with 10 SSRs: 292 from Portugal and 301 from Spain. Some of the trees studied were more than 300 years old. Accessions were analysed using a model-based Bayesian procedure to assess the geographical structure and to assign individuals to reconstructed populations based on the SSR genotypes. We found 356 different genotypes with a mean value of clonality of 33% owing to grafting. Mutations accounted for 6%, with hybridization being the main diversification process that can explain the great diversity found. Ten main cultivar groups were detected: four in northern Spain, five in the centre of the Iberian Peninsula, and one in southern Spain related to the centre of the Iberian Peninsula. This work demonstrated that cultivar origin and the diversification process was a combination of clonal propagation of selected seedlings, hybridization, and mutations, which allowed high levels of diversity to be maintained with respect to selected clones for fruit production. Furthermore, seedlings and graft sticks facilitated the transport to new destinations in the colonization process, transporting sometimes more than 3000 km if we consider the Azores and the Canary Islands.; Les auteurs ont réalisé, à l’aide de marqueurs SSR, une étude moléculaire à grande échelle sur le processus de diversification des cultivars de châtaignier du Portugal et de l’Espagne, l’étude couvre une zone allant du nord de la Péninsule Ibérique jusqu’aux iles Canaries et aux Açores. Au total, 593 châtaigniers (Castanea sativa Mill.) greffés ont été analysés avec 10 SSR : 292 provenaient du Portugal et 301 de l’Espagne. Certains de ces arbres étaient vieux de plus de 300 ans. Une analyse basée sur un modèle bayésien a été réalisée pour déterminer la structure géographique des accessions et attribuer les individus au sein des différentes populations établies sur la base des génotypes SSR. Les auteurs ont trouvé 356 génotypes distincts dont en moyenne 33 % relèvent d’un état clonal attribuable au greffage. Les mutations permettent d’expliquer 6 % des génotypes observés alors que l’hybridation apparaît comme le principal processus de diversification et permettrait d’expliquer la grande diversité observée. Dix groupes principaux de cultivars ont été détectés, quatre dans le nord de l’Espagne, cinq autres au centre de la Péninsule Ibérique et un dans le sud de l’Espagne proche des groupes du centre. Ce travail montre que l’origine des cultivars et le processus de diversification sont le produit d’une combinaison de propagation clonale de plantules sélectionnées, d’hybridation et de mutations. Ces deux dernières permettent de maintenir une importante diversité au sein de clones sélectionnés pour la production de fruits. En outre, les plantules et les greffons ont facilité le transport vers de nouvelles destinations au cours du processus de colonisation, et ce parfois sur plus de 3000 km si l’on considère les Açores et les Îles Canaries.

Chestnut (Castanea sativa Mill.) is an important crop in Spain. This inventory of chestnut cultivars complements previous studies. We have located 152 chestnut cultivars in 131 municipalities covering 108.6 ha, with 72 new cultivars in addition to the 80 previously found. Fewer than 50% of these cultivars are extensively cultivated. Chestnuts in Spain are grown from sea level to 1100 m, but are more frequent between 200 and 800 m on northern-facing slopes. Most of the chestnuts are harvested from 25 Oct. to 10 Nov.