• Energy Research
• Open Access close
• Open Source close
• Embargo close
• 2. Zero hunger close
• Portuguese close

Neste trabalho avaliou-se o efeito da data de sementeira nas características de produção e composição em açúcares do sorgo sacarino, em função das quais se estimou o potencial de produção de bioetanol a partir desta cultura. O estudo foi conduzido durante dois anos (2005 e 2006), com a variedade de sorgo sacarino Madhura. A sementeira foi efectuada nas datas de 17 de maio, 31 de maio, 14 de junho e 28 de junho. Na sementeira efectuada a 17 de maio a produção de caules verdes e secos atingiu os valores de 66 e 13,8 t ha-1, respectivamente, as quais foram significativamente superiores às obtidas nas sementeiras de junho. A produção máxima de açúcar naquele mês foi de 4,6 t ha-1, o que corresponde à produção estimada de 2300 L ha-1 de bioetanol. Os resultados alcançados permitem concluir que as datas de sementeira de maio foram as que melhor potenciaram a aptidão do sorgo sacarino como cultura energética, para a produção de bioetanol. Revista de Ciências Agrárias, vol. 36 n.º 3 (2013)

With the advances of climate change, it is expected harmful consequences to olive tree (Olea europaea L.). Therefore, it is necessary to develop cost-effective practices to reduce the vulnerability of olive crops to the adverse impacts of environmental stresses. Rainfed olive trees were sprayed with zeolites, natural crystalline aluminosilicates, and its effects on photosynthetic activity, phenolic composition, antioxidant activity, leaf minerais concentrations, plant growth, yield, and olive oil quality were assessed. Zeolites application enhanced photosynthetic activity, as well the concentrations of N, Mg, Cu, Zn and Mn in leaves, and changed the secondary metabolism, with decrease oftotal phenols, ortho-diphenols and total antioxidant activity, signs of lower oxidative stress. As consequence, zeolites boosted plant growth, crop yield, and size and weight of fruits. The foliar spray did not significantly affect the oil quality indices free acidity, peroxide value and Km and K270 coefficients. This study strongly suggests that folial' zeolites might be an effective strategy to mitigate the adverse environmental conditions. This research was funded by the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financiai support to ClTAB (UIDB/04033/2020), and the Operational Group "Novas práticas em olivais de sequeiro: estratégias de mitigação e adaptação às alterações climáticas" I funded by PT2020 and EAFRD (European Agricultural Fund for Rural Development). Sandra Martins acknowledges the financiai support provided by the FCT-Portuguese Foundation for Science and Technology (PD/BD/135327/2017), under the Doctoral programme "Agricultural Production Chains-from fork to farm". info:eu-repo/semantics/publishedVersion

Objetivou-se analisar os efeitos das externalidades negativas no meio ambiente, abordar o Teorema de Coase no que se refere ao problema de definição dos direitos de propriedade. Adicionalmente, o trabalho explica a teoria econômica da externalidade e ilustra com exemplos. Descreve o comportamento econômico da externalidade na produção agropecuária e mostra de que modo ela cria ineficiência de mercado. Posteriormente, são avaliadas algumas medidas compensatórias para corrigir essas ineficiências. Nesse sentido, argumenta-se em favor da preservação ambiental como requisito básico da manutenção do desenvolvimento agrícola sustentado. Infere-se que modernização da agricultura brasileira teve importância fundamental para o crescimento econômico do País, apesar de que a prioridade dada ao aumento de produtividade pode ter motivado desequilíbrios no meio ambiente.----------------------The objective was to examine the effects of negative externalities in the environment, address the Coase theorem, as regards the problem of definition of property rights. Additionally, the work explains the economic theory of externalities and illustrated with examples. It describes the behavior of economic externalities in production agriculture and shows in what way it creates inefficiency of the market. Subsequently, are evaluated some compensatory measures to correct these inefficiencies. Therefore, it is argued in favor of environmental preservation as a basic requirement of maintaining the sustained agricultural development. It follows that modernization of Brazilian agriculture has fundamental importance for the economic growth of the country, despite the fact that the priority given to increasing productivity may have motivated imbalances in the environment.

This paper analyzes the production diversity among Brazilian agricultural family farms, using the DAP (declaration of Pronaf entitlement). The diversity is measured with a Simpson index, that goes from zero, for monocultures, to one. Production is considerably diversified in these types of farms. 57% of them have a diversification index above 0,35, although it has been noticed an increase in specialization in recent years. The share of monoculture farms rose from 25% in 2012 to 33% in 2014. The diversification index is set as the dependent variable on a Tobit regression with variables that are commonly used to explain the decision to diversify, such as regional dummies, farm size, number of farms, farmer's age, income from social benefits, education, gross production, or a dummy for access to technical assistance. All of these variables have significant effects on production diversity. The results suggest a strong regional bias in terms of diversification, as well as the importance of technical assistance and the availability of technologies in order to spur diversification among family farmers.

The major objective of this chapter is to analyse and briefly describe the evolution of Portuguese agriculture in the context of the European Agriculture. It is not a comprehensive analysis. It is a sketch of its major changes due to major aspects that had influenced in particular the Common Agricultural Policy, and how has evolved with respect to changes in CAP orientation and reforms. This analysis provides an example that might be useful to understand what can be done in the future both in Portugal as in other countries In some aspects figures about these countries including Poland will be presented to benchmark the analysis. Besides this introduction, the chapter has five additional sections. In the next section, background on the Portuguese agriculture and policy before accession is provided. Then, in the third, socio-economic structural characteristics of Portuguese agriculture and their evolution for the last four decades are briefly presented. In the fourth section analysis turns read and understand the evolution as major implications of changes in agricultural policy from CAP reforms. In the fifth section we turn to aspects that are the focus of post-2013 CAP reform and 14 relate them to Portuguese status. Finally, as a conclusion, we look for CAP and the sustainable orientations for Portuguese farmers.

This document aims to provide information about the actions planned with the students within the SAL - Environmental Seed project, as well as to support its preparation. SAL - Seed Environment is a pilot project to raise environmental awareness and promote changes in food consumption among the population. These objectives will be achieved by sharing knowledge about the importance of more sustainable production and consumption practices in the school community. Through information, awareness, training and active participation, from the place of production to the place of consumption, the aim is to encourage more informed choices and, consequently, promote changes in consumption habits and more sustainable behaviour.

Abstract Objectives: During summer in Mediterranean regions, well adapted native cattle breeds present differences in environmental tolerance. The objective of this study was to compare heat tolerance of Alentejana and Mertolenga heifers under direct solar radiation, by quantifying the pathways of evaporative thermolysis and thermostability. Materials and Methods: The experiment was carried out in 5 days. 6 Alentejana and 6 Mertolenga heifers were kept under direct solar radiation, in individual stalls (3.0 —1.1 m) and restrained by head halted. Food, water and mineral mixture were available ad libitum. Respiratory frequencies (RF) were measured by observing costal movements, rectal temperatures (RT ) were measured using a digital thermometer (Digitron, with an 8-cm flexible probe) and thermal balance was calculated according to procedures described by Silva et al., (2010). These measurements were carried out every day at 06:00, 10:00, 13:00 16:00 and 20:00h. Heat storage (HS) was calculated as described by McGovern and Bruce (2000). Sweat rate was measured at 15:00 hours using methodology described by Pereira et. al. (2010). Variables were analyzed according to a general linear model procedure with 2 fixed factors (breed and hour) and 1 nested factor (animal within breed). Results: Except for the cases of RT and HS, in the other variables no significant differences between the breeds were found. Despite the absence of significant differences in the thermal balance between breeds, there was a slightly tendency for a bigger acquisition of heat in Alentejana and a faster recovery in the Mertolenga after 16:00h. The sweating rates were not significantly different, with mean values of 271.5 and 286.3 (g.m-2.h-1) respectively for the Alentejana and Mertolenga. Respiratory frequencies were virtually equal between breeds. In RT there were significant differences between breeds. The Mertolenga has shown significantly lower RT at 16:00h and 20:00h, with 38,9ºC and 38,7ºC compared to 39,3ºC and 39,1ºC in Alentejana. The same trend was found in the HS at 16:00h and 20:00h with 0,018 and 0,016 W.m2 in Alentejana compared to 0,014 and 0,009 W.m2 in Mertolenga. Conclusions: The results show that both breeds present good heat tolerance. The sweating rate values of both breeds are very high and are quite similar to those found in tropical cattle breeds. However, Mertolenga shows slightly better thermal balance and evaporative heat loss (SR ans RF), which eventually may have contributed to the enhanced thermostability comparatively to Alentejana. The superior stability of the RT and particularly the lower HS suggest a higher heat tolerance of Mertolenga breed.

In Mediterranean-type climates crop yield depends strongly on the early development of individual plants. Extreme variations of soil temperature close to the surface of bare soils and fast changes of soil water content due to irregular rainfall and high evaporative demand reduce the success of germination, emergence and early leaf production, reducing crop productivity. According to IPCC Fourth Assesment report, climate change in Southern Europe “is projected to worsen hygrometric and thermal conditions (high temperature and drought) and to reduce water availability” and, consequently, to decrease general crop productivity. The aim of this study was to evaluate the thermal conditions in the top soil layer under different climate change scenarios, and their effects on the early development of some representative crops of Mediterranean agriculture (pea, broad bean, maize and sunflower). For this purpose, soil temperatures near the surface of a Luvisol and a Vertisol during the usual sowing season of winter (October) and summer crops (April) were compared to those recorded in the air above ground, to forecast future values. The impact of simulations on the speed, size and dispersion of germination, emergence and early leaf production was estimated using values of bioclimatic parameters of the crops (cardinal temperatures and thermal times for different phases of establishment) found in the literature. In both seasons, monthly mean temperatures at soil top layer were significantly greater (*P<0.05) than those found in the air above ground. However, the relationships between air and top soil temperatures were different in both soils and in both seasons. Summer crops seem to be less affected by an increase in temperature than winter crops. Otherwise, the former seem to be more affected by a decrease in soil water availability than the later. In addition, final emergence, speed of emergence and leaf production of the different species will be more affected by global warming than the dispersion around the most likely thermal times. The magnitude of these effects depends also on the magnitude of warming.

Resumo: A busca por uma maior sustentabilidade tem levado a uma mudança em direção à utilização de fontes renováveis para geração de energia em detrimento do uso de combustíveis fósseis, visando a uma modificação na matriz energética global. A utilização da biomassa de microalgas para produção de biocombustíveis vem sendo vista como uma alternativa promissora, uma vez que o seu cultivo proporciona produtividades em carboidratos e lipídios superiores às matérias-primas vegetais convencionalmente utilizadas na obtenção de etanol e biodiesel. Neste contexto, o objetivo da presente dissertação de mestrado foi avaliar a produção de biomassa da microalga clorofícea Chlorella vulgaris em fotobiorreator de placa plana em diferentes condições de fluxo luminoso, concentração de CO2 na alimentação gasosa e concentração de NaNO3 no meio de cultivo, visando o acúmulo de carboidratos para obtenção de bioetanol de terceira geração. As influências das variáveis nutricionais e de processo sobre a eficiência fotossintética das microalgas também foram estimadas para determinação do estado fisiológico das culturas. A produtividade média de biomassa e a concentração máxima final das microalgas foram significativamente afetadas pela incidência de radiação luminosa e pela suplementação de CO2 gasoso, obtendo-se maiores produtividades de carboidratos em cultivos com alto fluxo luminoso e concentrações de CO2 intermediárias (7,5%). Também foi observado o efeito positivo do aumento do fotoperíodo sobre o crescimento das microalgas. Através de hidrólise ácida foi possível atingir concentrações de até 2 g L-1 de açúcares fermentescíveis no hidrolisado a partir de biomassa de microalgas cultivadas em meio com baixo teor de nitrogênio. A fermentação etanólica foi então conduzida com a levedura Dekkerabruxellensis capaz de converter diferentes hexoses e pentoses em bioetanol, dada a presença de ambos os tipos de açúcares no hidrolisado Abstract: The search for industrial processes with higher sustainability has led to a change towards the utilization of renewable sources for energy generation in substitution of fossil fuels, aiming the modification of the global energy matrix. The utilization of microalgal biomass for the production of biofuels is viewed as a promising alternative, since its cultivation yields carbohydrate and lipid productivities superior to those of conventional sources used in the obtention of bioethanol and biodiesel. In this context, the goal of this master thesis was to evaluate the biomass production of the chlorophycean microalga Chlorella vulgaris in a flat plate photobioreactor under different conditions of light flux, CO2 concentration in the gas feed and NaNO3 concentration in the culture medium, aiming carbohydrate accumulation for the production of third generation bioethanol. The influences of both process and nutritional variables on the photosynthetic efficiency of microalgae were estimated for the determination of the physiological condition of the cultures. The mean biomass productivity and the maximum final microalgae concentration were significantly affected by the incidence of light radiation and by the supplementation of gaseous CO2, the highest carbohydrate productivities being obtained in cultivations with high light flux and intermediate CO2 concentrations (7,5%). It was also observed the positive effect of increasing the photoperiod over microalgae growth. Through acid hydrolysis, it was possible to attain fermentable sugar concentration of up to 2 g L-1 from biomass of microalgae cultivated in low-nitrogen medium. The ethanolic fermentation was then carried out with the Dekkerabruxellensis yeast, capable of converting different hexoses and pentoses into ethanol, due to the presence of both sugar types in the hydrolysate Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química Orientadores: Maria Regina Wolf Maciel, Reinaldo Gaspar Bastos Desenvolvimento de Processos Químicos Mestre em Engenharia Química Mestrado