Chemical composition of eight sweet chestnut cultivars from the three protected designation of origin (PDO) areas in the Trás-osMontes region were studied: Aveleira, Rebordã, Trigueira and Zeive from PDO 'Terra Fria', Demanda, Longal and Martaínha from PDO 'Soutos da Lapa' and Judia from PDO 'Padrela'. Chestnuts were characterised by high moisture content ($50%), high levels of starch (43 g 100 g À1 dry matter -d.m.) and low fat content (3 g 100 g À1 d.m.). Nuts contained significant amounts of fibre (3% d.m.), were rich in K ($750 mg 100 g À1 d.m.), P ($120 mg 100 g À1 d.m.) and Mg ($75 mg 100 g À1 d.m.). Moreover, chestnuts are a good source of total amino acids (6-9 g 100 g À1 d.m.). Amino acid profiles were dominated by L-aspartic acid, followed by L-glutamic acid, leucine, L-alanine and arginine. These results provide additional information about the nutritional value of each cultivar and confirm that chestnuts are an interesting healthy food.

In recent years, chestnuts have increasingly become important in human nutrition because of their nutrient contents and potential beneficial health effects. In Portugal, Tra´s-os-Montes e Alto Douro is the most important region for chestnut production, generating 85% of the total national output. In 1994, three chestnut protected designation of origin (PDO) areas were created: Terra Fria, Soutos da Lapa, and Padrela within the jurisdiction area of the Regional Agricultural Services of Tra´s-os-Montes Region. Seventeen cultivars were selected from these PDO to evaluate crude fat content and fatty acid (FA) composition over a period of 2 years. Total fat extraction was performed according to AOAC methodology, using a Soxhlet apparatus for 16 h. Petroleum ether was used for extraction and FAs were identified and quantified by gas chromatography. The cultivars studied confirm that chestnuts have low crude fat content, low saturated fatty acids (SFA) (17%) and high unsaturated fatty acids (USFA) (83%). The major FAs are linoleic, oleic and palmitic; these accounted for more than 85% of the total FA content. From the results two potentially health-beneficial cultivars were identified: cv. Lada, with high linoleic acid content, and cv. Aveleira, with higher USFA content. With respect to FA profiles of chestnuts from the three PDO regions, Padrela chestnuts consistently contained the highest level of linoleic acid. The variation detected among cultivars and PDO areas may reflect differences in genotype and are influenced by environmental and growing conditions. The Longal chestnuts, the only traditional cv. growing on two different PDO areas, had better nutritional qualities in PDO Terra Fria, which confirm that the ecological conditions where chestnut orchards are established influences nut quality. r

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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.

Chestnut plantations for fruit production in Northern Portugal have been subjected to intensive management system, including soil tillage, mineral fertilization and pruning. Some of these practices have no positive effect on productivity and soilplant-water relations. Other systems (e.g., no tillage with maintenance of grass cover) have been adopted, aiming a multifunctional land use, exploiting nuts, pasture and edible mushrooms. Thus, an experimental trial was installed to assess the effects of such systems on productivity, sustainability and annual net income, as compared with the conventional system, over a six-year period. The treatments were: conventional soil tillage (CT); no tillage with permanent spontaneous herbaceous vegetation cover (NV); no tillage with permanent rainfed seeded pasture cover (NP); and as NP but with irrigation (NIP). Production of nuts, forage and edible mushrooms were measured and sustainability was assessed by production and diversity of fungal sporocarps. Annual net income was estimated by the difference between the annual gross outputs (market values for nuts, forage and edible commercial mushrooms) and the annual input costs. The greatest nut and edible mushroom production and sporocarp biodiversity were achieved in the NIP and NV and the smallest in the CT treatment. The highest annual gross output was estimated for the NV and NIP treatments, whereas the highest annual net income was obtained for the NV. No tillage with maintenance of spontaneous grass cover showed to be the most favourable management system, as it has increased productivity and biodiversity.