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URI permanente desta comunidadehttps://thoth.dti.ufv.br/handle/123456789/3352
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Item Stomatal behavior and components of the antioxidative system in coffee plants under water stress(Escola Superior de Agricultura "Luiz de Queiroz", 2011-01) Deuner, Sidnei; Alves, José Donizeti; Zanandrea, Ilisandra; Goulart, Patrícia de Fátima Pereira; Silveira, Neidiquele Maria; Henrique, Paôla de Castro; Mesquita, Alessandro CarlosCoffee (Coffea arabica) plants show a positive relationship between stomatal closure and formation and accumulation of H2O2. However, for coffee plants under water restriction such relationship has never been studied. The objective of the present study was evaluate the stomatal movement and the antioxidant capacity of coffee seedlings under different water regimes. Eight months old coffee seedlings of cv. Catuaí IAC 99 were submitted to field capacity, gradual and total suspension of irrigation during a period of 21 days. Evaluations of leaf water potential (Ψ w) were performed in the beginning of the morning, and stomatal resistance, transpiration rate and vapor pressure deficit were determined at 10 am and 5 pm. All biochemical and enzymatic determinations were performed in leaves collected at 5 pm. Evaluations and samplings were performed at three days intervals. There was no variation in Ψ w during the evaluated period for plants in field capacity. However, an expressive decrease of Ψ w following day 12, reaching values near -2.5 MPa at the end of the experiment was observed for plants submitted to gradual suspension of irrigation. For plants submitted to total suspension of irrigation, Ψ w decreases after the sixth day, reaching -2.5 MPa at day 15. The decay of Ψ w in plants submitted to gradual and total suspension of irrigation reflected in increased stomatal resistance and in a decreased transpiration rate leading to an increase in hydrogen peroxide formation and, on final stages, increase in lipid peroxidation. As a conclusion, an increase in the activity of antioxidant enzymes as well as in the levels of ascorbate and dehydroascorbate was observed, which act in the detoxification of free radicals formed as result of the water stress.Item Alterações morfofisiológicas em folhas de cafeeiro (Coffea arabica L.) consorciado com seringueira (Hevea brasiliensis Muell. Arg.)(Universidade Federal de Santa Maria, 2006-05) Nascimento, Erivaldo Alves do; Oliveira, Luiz Edson Mota de; Castro, Evaristo Mauro de; Delú Filho, Nelson; Mesquita, Alessandro Carlos; Vieira, Carlos VinicioO cultivo da seringueira em monocultivo ou consorciada com cafeeiro surge como alternativa promissora e uma opção para os cafeeicultores frente às constantes oscilações da produção e do mercado. Porém, a produtividade de ambas as culturas é fortemente afetada pelas variações climáticas e pelo sistema de cultivo adotado. O objetivo deste trabalho foi avaliar os efeitos da variação dos fatores do clima e dos sistemas de cultivo sobre as trocas gasosas, eficiência fotoquímica do fotossistema II (FV/FM) e anatomia foliar do cafeeiro. Foram estudados quatro sistemas de cultivo: café em monocultivo (C), três fileiras de cafeeiros a cada fileira dupla de seringueira (SSCCCSS), uma fileira de cafeeiros a cada fileira de seringueira (SCS) e três plantas de café a cada planta de seringueira na mesma fileira (SCSCS). As plantas dos sistemas (SSCCCSS), (SCS) e (SCSCS) apresentaram os menores valores de taxas fotossintéticas (A), condutância estomática (gs), transpiração (E) e maiores valores para a razão Fv/Fm. As plantas de café em (C) apresentaram médias superiores de espessura dos parênquimas paliçádico e lacunoso, do limbo foliar, além de maior índice estomático em relação aos demais sistemas de cultivo, apresentando, dessa forma, plasticidade anatômica para a espécie, quando comparada às plantas de sol e sombreadas pela seringueira.Item Source-sink manipulations in Coffea arabica L. and its effect on growth of shoots and root system(Editora UFLA, 2011-09) Alves, José Donizeti; Paglis, Carlos Maurício; Livramento, Darlan Einstein do; Linhares, Suellen Sarah Drumond; Becker, Frederico Biagi; Mesquita, Alessandro CarlosThis paper investigated changes in growth and carbohydrate content of shoots and root systems in response to source-sink manipulation in field-grown coffee trees. The source-sink manipulations were carried out using manual de-fruiting. Two plots of trees were established: in one group, the fruit was left on the tree, while in the second group all fruits were removed manually. Similar results were obtained for coffee trees with and without fruit in terms of height, stem and skirt diameter and branch lengths. A biochemical evaluation of the roots showed that no differences were found between the levels of carbohydrates. In the leaves, levels of soluble sugars and reducing sugars were higher in plants with fruit. The starch concentration in leaves and roots did not vary between the plots. Root length density did not vary between plants with and without fruit in the 0 - 0.4 m soil layer. However, plants without fruit had a higher root length density than plants with a full fruit load. These results contrast with results published by others on source-sink relationships of coffee plants. The joint data analysis shows that young trees, with a moderate fruit load, and with good nutritional and health status, produce carbohydrates in sufficient quantities to maintain vegetative and reproductive growth, without harming root system growth.