Browsing by Author "Ribeiro, H.M."
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- Avaliação do estado nutricional azotado de pés-mãe de Eucalyptus globulus Labill. ssp. globulus com recurso a um medidor portátil de clorofilaPublication . Vasconcelos, E.; Ribeiro, H.M.; Ramos, A.; Coutinho, J.With the aim of evaluating the use of the portable chlorophyll meter “MinoltaSPAD 502” readings (SPAD readings) as an indicator of the nitrogen status of Eucalyptus globulus Labill. ssp. globulus (E. globulus) mother plants, a nitrogen fertilization experiment with this species was performed. Mother plants of two clones (HD 161 and CN5) of E. globulus were grown in an open-air nursery, in 12 L pots. Plants received 5 different nutrient solutions containing 50, 100, 200, 400 e 800 mg N L-1. During 1999, mother plants were subjected to a formative pruning. During 2000 and 2001 the following parameters were evaluated: number of cuttings produced, rooting ability of the cuttings, nitrogen content of the youngest fully expanded leaf, and leaf SPAD readings. Results obtained showed a significant asymptotic relationship between nitrogen availability and SPAD readings and a linear, positive and significant relationship between SPAD readings (y) and nitrogen leaf contents (x, g kg –1): y=23,27+0,75x; r=0.94; n=150. Results also showed a good fitting of quadratic model to the relationship between SPAD readings and the mother plants production (cuttings production and rooting ability of the cuttings). The determination coefficients (78%) were similar to those obtained when the model was adjusted to the relationship between leaf nitrogen and mother plants production (80%). Results indicate that, in this experiment, SPAD readings can be used to evaluate nitrogen status of E. globulus mother plants with a diagnostic “quality” similar to leaf nitrogen contents
- Caracterização de compostos e de materiais orgânicos para a formulação de substratos para viveirosPublication . Cunha-Queda, A.C.; Morais, M.C.; Ribeiro, H.M.; Almeida, M.H.Present work aimed the physic-chemical and biological characterization of products obtained from composting of several organic wastes: sewage sludge produced at wastewater treatment plants (WWTP), organic fraction of municipal solid waste (MSW) and, green waste from parks and gardens. A commercial substrate used at nursery plants was also characterized. The compost that presented minor potentiality to be used on the formulation of substrates was compost produced from organic fraction of MSW due to its high values of pH and electrical conductivity, and low values of germination and growth indexes for Lepidum sativum; composts analysed that presented high potentiality to be used on the formulation of substrates were those that were produced from WWTP sewage sludge and from green wastes
- Carbon and nitrogen mineralization of organic wastes from sugarcane distilleries: vinasse and yeast wastePublication . Vasconcelos, E.; Cabral, F.; Pita, V.; Fangueiro, D.; Ribeiro, H.M.In Madeira Island (Portugal) significant amounts of wastes are generated in sugarcane distilleries, namely vinasse (the remaining fermented must after distillation) and yeast waste (the yeast surplus produced during the alcoholic fermentation). These wastes have high organic loads and low pH, leading to serious environmental problems when released directly into natural watercourses or when poorly managed (Hati et al., 2007). As a solution to avoid expensive treatments, both wastes have been used as soil amendment, since they contain important amounts of plant nutrients and organic matter (Resende et al., 2006; Parnaudeau et al., 2008). Indeed, application to soils of vinasse is a common practice in sugarcane cultivated areas and can fully substitute K and partially P on crops fertilization. Nevertheless, additional mineral nitrogen fertilization is needed when vinasse is spread in the soils (Junior et al., 2007; Oliveira et al., 2009). On the other hand, yeast waste has been considered as an excellent potential source of nitrogen for plant nutrition when applied to soils (Rezende et al., 2004). Thus, combined application of both wastes should ensure a more balanced supply of nutrients to plants. However, scarce information is available on the combine use of both wastes as fertilizer. The main objective of this study is to assess the effect of the combined application to soil of both organic materials (vinasse and yeast waste), and to evaluate its subsequent effects on nitrogen mineralization/immobilization process to supply nitrogen to crops and to preserve/restore soil carbon.
- A fertilização azotada de pés-mãe de Eucalyptus globulus Labill.: efeito no crescimentoPublication . Vasconcelos, E.; Ribeiro, H.M.; Ramos, A.; Coutinho, J.To asses the effect of N fertilization on the growth of E. globulus stock plants, a nitrogen fertilization experiment was performed. During 3 years, stock plants of 2 clones (HD161 and CN5) were fertilized with complete nutrient solutions containing 5 different levels of N (50, 100, 200, 400 and 800 mg N L-1). Total biomass, leafbiomass, leaf area and number of shoots produced during the 3 years period were measured. Increasing levels of applied nitrogen till 400 mg N L-1 led to a significant increase of both biomass and shoot production. However, these productions were not significantly affected when N fertilization increased from 400 to 800 mg N L-1. Increasing levels of applied nitrogen also led to an increase of: i) total leaf area ii) specific leaf area (29% increase) and iii) leaf area ratio (13% increase), showing that with a higher N availability stock plants tend to improve their photosynthetic apparatus. Results show that nitrogen is a fundamental nutrient for the growth of E globulus stock plants and, as a consequence, nitrogen fertilization must be optimized. The maximum growth of E. globulus mother plants was achieved with 400 mg N L-1.
- O comportamento de pés-mãe de Eucalyptus globulus Labill. sujeitos a diferentes níveis de azoto e potássioPublication . Vasconcelos, Ernesto; Ribeiro, H.M.; Ramos, A.; Coutinho, J.In Portugal the traditional propagation of Eucalyptus globulus Labill (E. globulus) by seed is being replaced by vegetative propagation by stem cuttings. However, for E. globulus, there is no sufficient information related to the management of mother plant fertilization. So, it is important to study the relationship between the fertilization of the mother plant and the rooting ability of the cuttings. With the aim of evaluating the effect of nitrogen and potassium on E. globulus mother plants, a fertilization experiment was performed during 2 years. 2 clones of E. globulus (clone HD161 and clone CN5) were fertilized, periodically, with 6 different nutrient solutions corresponding to 3 levels of nitrogen (50, 100 and 200 mg N L-1) and 2 levels of potassium (50 and 100 mg K L-1). In 1998, stock plants were subjected to formative pruning. In 1999, biomass, number of cuttings produced by the mother plants and rooting ability of the cuttings were evaluated. With the two levels of potassium applied no significant effects were found. On the contrary, increasing levels of nitrogen applied to the mother plants led to: i) an increase of total biomass, ii) a higherproduction of stem cuttings, iii) an improvement of the rooting ability of the cuttings. Results showed that nitrogen fertilization and, as consequence, nitrogen reserves, constitute a limiting factor for rooting in E. globulus cuttings. Thus, research on the optimization of nitrogen fertilization of E. globulus mother plants should be performed.
- Use of pulp mill inorganic wastes as alternative liming materialsPublication . Cabral, F.; Ribeiro, H.M.; Hilário, L.; Machado, L.; Vasconcelos, E.A laboratory aerobic incubation study was performed during 18 weeks under controlled conditions to assess the effects of applying different doses of pulp mill inorganic wastes on the physical–chemical properties of an acid Dystric Cambissol. Three different inorganic wastes were tested – wood ash, dregs and grits, and an agriculture limestone was used as reference. Results showed that increasing the dose applied of the different inorganic wastes tested always led to significant raises of soil pH at different incubation times demonstrating that its use as alternative-liming materials could be a valid and less expensive option to the use of commercial agricultural limestone. Moreover, no immediate concerns seem to be expected related to soil exchangeable sodium (Na) content, at least for the doses needed to increase soil pH until the targeted value 6.5. Particularly for wood ash a pronounced increase on soil extractable potassium and phosphorous was observed, indicating that besides the liming effect this waste can contribute to improve soil fertility by supplying significant available amounts of these nutrients. Finally, metals do not seem to be a limiting factor for the application to land of these byproducts