Seleção clonal na variedade de castanha “Longal” visando a sua aptidão agronómica e agroalimentar
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2018-04-27
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A produção de castanha tem um peso significativo no contexto da agricultura Portuguesa, sendo um sector auto-suficiente. Trás-os-Montes é a principal região portuguesa produtora de castanha, com cerca de 80% da produção nacional, constituindo a Longal uma das principais variedades aqui produzidas. A Longal é conhecida como uma das variedades portuguesas mais ancestrais, frequentemente encontrada em árvores centenárias, encontrando-se espalhada por todas as regiões portuguesas produtoras de castanha. Tem a sinonímia de Enxerta, designação originada pelo facto da Longal sofrer enxertias em tempos antigos. É considerada uma das variedades-mãe, originária de diversas variedades existentes atualmente em Portugal, quer por processos de cruzamentos naturais, quer através de mutações espontâneas. É muito apreciada para consumo fresco e para indústria de transformação, devido à sua reconhecida aptidão tecnológica, nomeadamente excelente sabor, fácil descasque, ótima conservação natural e elevados teores de amido e açúcares solúveis. Paradoxalmente, apesar deste reconhecimento subjacente à sua grande procura, o cultivo desta variedade tem vindo a ser abandonado, devido sobretudo à sua menor valorização, mais baixa que outras variedades como a Judia, decorrente do inferior calibre e baixos níveis de produção, fatores que estão muito associados à idade avançada da maioria das árvores existentes. Nesse contexto, e com o propósito de resgatar o seu intrínseco valor e grande potencialidade quer para o consumo em fresco, quer principalmente para transformação, foi iniciado um programa de seleção e melhoramento para a variedade Longal. O programa partiu de uma base de 100 árvores distribuídas em 19 locais. As análises da biometria e composição química das castanhas permitiram efetuar uma primeira seleção de genótipos com as melhores qualidades comerciais, tecnológicas e agroalimentares. Dos resultados obtidos, destacaram-se as árvores ROS05 e VRL01, que apresentaram um bom calibre (66,67 e 76,27 castanhas/kg, respetivamente) e uma taxa de polispermia nula. Em relação à composição química, a árvore ROS05 destacou-se por ter um elevado teor de açúcares solúveis (15,25% MS) e de gordura bruta (2,08% MS), e a árvore VRL01 destacou-se pelo seu teor de amido de 61,70% MS e seu teor de açúcares solúveis de 14,59% MS
Chestnut production has a significant importance in Portuguese’s agriculture context, with positive trade balance. Trás-os-Montes is the main Portuguese region producing chestnut, with about 80% of national production, constituting Longal one of the main varieties produced here. Longal is known as one of the most ancient Portuguese varieties, being most of times found in centenary trees, and it is found throughout Portuguese chestnut producing regions. It has the synonymy of Enxerta, designation originated by the fact that Longal underwent grafts in ancient times. It is considered one of the mother varieties, originating several varieties that currently exist in Portugal, either by natural cross-breeding processes or by spontaneous mutations. It is highly appreciated either for fresh consumption or agroindustry, due to its recognized technological aptitude, outstandingly excellent flavor, easy peeling, excellent natural conservation and high contents of starch and soluble sugars. Paradoxically, in spite of this recognition underlying its great demand, the cultivation of this variety has been abandoned, mainly due to its lower valorization than others varieties like Judia, due to the lower caliber and low production levels, factors which are very associated with the advanced age of most existing trees. In this context, and with the purpose of recovering its intrinsic value and great potentiality both for consumption fresh and mainly for processing, a selection and breeding program for the Longal variety was started. The program was based on 100 trees distributed in 19 sites. The analyses of the biometry and chemical composition of the nuts allowed to make a first selection of genotypes with the best commercial, technological and agrifood qualities. The results show that ROS05 and VRL01 trees showed a good caliber (66.67 and 76.27 nuts/kg, respectively) and a zero polyspermy rate. About the chemical composition, the ROS05 tree stood out for having a high content of soluble sugars (15.25% DM) and crude fat (2.08% DM), and VRL01 tree stood out by its content of starch of 61.70% DM and its soluble sugars content of 14.59% DM.
Chestnut production has a significant importance in Portuguese’s agriculture context, with positive trade balance. Trás-os-Montes is the main Portuguese region producing chestnut, with about 80% of national production, constituting Longal one of the main varieties produced here. Longal is known as one of the most ancient Portuguese varieties, being most of times found in centenary trees, and it is found throughout Portuguese chestnut producing regions. It has the synonymy of Enxerta, designation originated by the fact that Longal underwent grafts in ancient times. It is considered one of the mother varieties, originating several varieties that currently exist in Portugal, either by natural cross-breeding processes or by spontaneous mutations. It is highly appreciated either for fresh consumption or agroindustry, due to its recognized technological aptitude, outstandingly excellent flavor, easy peeling, excellent natural conservation and high contents of starch and soluble sugars. Paradoxically, in spite of this recognition underlying its great demand, the cultivation of this variety has been abandoned, mainly due to its lower valorization than others varieties like Judia, due to the lower caliber and low production levels, factors which are very associated with the advanced age of most existing trees. In this context, and with the purpose of recovering its intrinsic value and great potentiality both for consumption fresh and mainly for processing, a selection and breeding program for the Longal variety was started. The program was based on 100 trees distributed in 19 sites. The analyses of the biometry and chemical composition of the nuts allowed to make a first selection of genotypes with the best commercial, technological and agrifood qualities. The results show that ROS05 and VRL01 trees showed a good caliber (66.67 and 76.27 nuts/kg, respectively) and a zero polyspermy rate. About the chemical composition, the ROS05 tree stood out for having a high content of soluble sugars (15.25% DM) and crude fat (2.08% DM), and VRL01 tree stood out by its content of starch of 61.70% DM and its soluble sugars content of 14.59% DM.
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castanha longal , seleção clonal , biometria , composição química básica