Consumo de energia e custo energético em aquecimento na produção de rosas em estufa

Neste trabalho apresentam-se os resultados de um estudo sobre os locais mais adequados, o consumo de energia e respectivo custo energético em aquecimento durante a estação fria, em estufas de roseiras, localizadas em diferentes zonas do país, perto do mar

Ventilação nocturna de estufas não aquecidas

As estufas utilizadas nas zonas de clima Mediterrâneo são normalmente estruturas simples com cobertura de material plástico e cuja principal técnica de condicionamento ambiental é a ventilação natural. A Botrytis cinerea é o agente responsável pela podridão cinzenta, doença que origina elevados prejuízos nalgumas culturas em estufas não aquecidas. Na cultura do tomate, esta doença pode ser responsável por perdas de produção da ordem de 20% e os tratamentos com fungicidas chegam a representar 60% do consumo total destes pesticidas ao longo de uma época de produção (Prieto et al., 2003). Esta doença contínua a ser de difícil controlo em estufas durante grande parte do ano, sendo as condições ambientais prevalecentes, a elevada densidade de plantas e o seu frequente manuseamento factores que favorecem o seu desenvolvimento. Os produtores, de modo a controlar a podridão cinzenta, recorrem frequentemente a aplicações de fungicidas quer directamente sobre a parte da planta infectada quer de forma generalizada sobre toda a cultura. A utilização frequente de fungicidas apresenta várias desvantagens, entre as quais se destacam: o aumento do risco de aparecimento de resistências, a existência de resíduos nos frutos que impedem a sua comercialização, o aumento dos custos de produção e os efeitos adversos no ambiente em geral. A ventilação nocturna é uma técnica de controlo ambiental que permite a redução da humidade no interior das estufas e que pode ser um meio adequado para minimizar a utilização de fungicidas em estufas não aquecidas. O objectivo principal desta investigação foi estudar o efeito da ventilação nocturna na ocorrência de B. cinerea na cultura de tomate em estufas não aquecidas com vista a encontrar uma solução sustentável que permita controlar a doença, reduzir a aplicação de fungicidas, diminuir os custos de produção e reduzir os efeitos negativos da utilização de pesticidas no ambiente

Sustainable energy in sustainable agriculture

The presented integrated production-energy system for rural areas integrates biorefinery processes within agro-energy complexes for production of biological raw material for numerous bio-products and energy generation from local renewable sources assuming restitution of the natural environment resources, low emissions and minimizing other environment pollutions. The presented scenarios are encompassed within the frameworks of the future market bioeconomy in which the share of services and products resulting from use of innovative biotechnological processes and energy generation will be significant. Areas with large resources of agricultural, forest and water management raw materials as well as those focused on environment-supportive activities, including bioconversion to biofuels and bioenergy, are particularly predisposed for actions in the area of rational use of natural resources and bioeconomy in the circular system. Mutually linked, sustainable development of local energy generation and agriculture will be the determinant of bioeconomy development

Software for the calculation and modeling of effective diffusivity during osmotic dehydration.

This paper concerns a comprehensive and graphic computer program for the calculation of effective diffusivities and Fick’s Law model adjustment. The program was designed to be applicable to situations in which solid materials, with a specific geometry (cubes, infinite planes, spheres, infinite cylinders) and a given initial concentration are immersed in a solution with high and constant concentration. Shrinkage can be taken into account. Detailed statistics about calculated average diffusivity and model adjustments to observed data can also be calculated. Some experimental results were used to show the software’s applicability. The agreement between the outputs from the software and data from the literature were excellent and consistent. The software can be used for simulations and in the analysis of the effect of the number of terms in a series and a model’s agreement with experimental data. The program also has a potential of being exploited for educational purposes

Climate characterization and modeling of pineapple greenhouses in the Azores archipelago

In the Azores Archipelago, Portugal, pineapples are cultivated on the Island of São Miguel, existing around 60 ha of glasshouses dedicated to this crop, being a very important sector for the local economy. The main goal of this work is to characterise the Azores pineapple glasshouse climate and to develop a model that allows predicting its internal air temperature. Climate data were recorded in two meteorological stations, one located inside the greenhouse and the other outside. Greenhouse climate data showed a more favourable inside air temperature after middle of March, but reaching frequently very high values during the day in all the months analysed, which is a result of traditional greenhouse management and deficient ventilation. In these greenhouses external conditions such as external air temperature, global radiation and day length greatly influenced the climate inside the greenhouses and as a consequence the duration of the different crop phases and fruit quality. A climate model to simulate inside air temperature was developed based on glasshouse characteristics and external climate conditions such as air temperature, solar radiation, ventilation openings and wind velocity. Since most of the time ventilation apertures were closed it was considered an infiltration rate (varying between 1 and 3 air renovation) per hour, as a function of the wind velocity. Validation of the model was performed after calibration and showed good agreement

CONSUMO DE ENERGIA E CUSTOS DE AQUECIMENTO NA PRODUÇÃO DE FLORES E LEGUMES EM ESTUFA

Pretende-se determinar os consumos de energia e os custos em aquecimento, na produção de flores e de vegetais, ao longo do ano, em estufas de plástico aquecidas, localizadas em diversas zonas de produção de culturas forçadas. No primeiro ano considerou-se Portugal e a produção de rosa. Foram calculados os consumos energéticos e os custos de aquecimento com gasóleo ou gás natural, para duas combinações de temperaturas mínimas do ar noite/dia, em estufas modernas de plástico. O estudo está a ser alargado para a produção de tomate, englobando Portugal e Espanha

Reducing Botrytis cinerea incidence in unheated tomato greenhouses in real time using a wireless sensors network.

The objective was to investigate the influence of ventilation on the humidity conditions in unheated tomato greenhouses and the consequences for Botrytis cinerea control and generate the necessary knowledge to build a warning system for this problem. Two different natural ventilation treatments were randomly assigned to the greenhouses. One treatment was permanent ventilation (PV), with the vents open during the day and night, while the other was classical ventilation (CV), in which the vents were open during the day and closed during the night. On a second stage and supported by a wireless network of air relative humidity and temperature sensors a rules based engine with defined setpoints will be developed to make available a early warning system via SMS, e- mail and Web. This will allow the growers to act only when needed, making possible to reduce chemical use, lowering both production costs and environmental impacts

Nocturnal Ventilation For Controling Greenhouse Humidity and Botrytis Cinerea Severity In Unheated Tomato Greenhouses

Grey mould disease is one of the most important diseases affecting crops grown in unheated greenhouses, where ventilation is the main technique used to control inside environmental conditions. The main goal of this investigation was to study the influence of nocturnal ventilation on the humidity conditions in unheated tomato greenhouses and the consequences for Botrytis cinerea control. Experimental work was realised at the High Institute of Agronomy in Lisbon in two identical adjacent double-span greenhouses covered with three layer co-extruded plastic film. Two different natural ventilation treatments were randomly assigned to the greenhouses, being one treatment nocturnal or permanent ventilation (PV), with the vents open during the day and night and the other classical ventilation (CV), in which the vents were open during the day and closed during the night. Inside the nocturnally ventilated greenhouse air humidity was significantly reduced comparing with the classical ventilated greenhouse. Also, it was observed a great contribution to reducing disease severity on tomato leaves caused by B. cinerea

Modelação do clima em estufa climatizada com sistema de controlo proporcional – Modelo de aquecimento

O controlo ambiental em culturas protegidas assume uma grande importância e, a par da rega e da nutrição, é um dos factores limitantes do crescimento e desenvolvimento das plantas. A eficácia deste controlo pode ser avaliada pela utilização de modelos matemáticos para a previsão das condições climáticas interiores, que após a sua validação, permite a simulação para diferentes condições climáticas exteriores e/ou diferentes estratégias de funcionamento dos equipamentos de condicionamento ambiental. Neste trabalho é apresentado um modelo de simulação de temperatura e de humidade, baseado em balanços de energia e de massa para uma situação de Inverno – modelo de aquecimento. O modelo foi desenvolvido para uma estufa do tipo “Venlo” em vidro, equipada para a propagação clonal de Eucalyptus globulus Labill. pela técnica de miniestacaria. O modelo proposto foi validado estatisticamente comparando os valores medidos e simulados. As diferenças absolutas entre os valores de temperatura e humidade relativa medidos e simulados foram, respectivamente, de 1,31ºC e 7,46% e o erro padrão da estimativa de 0,91ºC e 7,65%

Comparion of humidity conditions in unheated tomato greenhouses with different natural ventilation management and implications for climate and Botrytis cinerea control

The objective of the research was to investigate the influence of nocturnal ventilation on the humidity conditions in unheated tomato greenhouses and the consequences for Botrytis cinerea control. Experiments were carried out at the Instituto Superior de Agronomia in Lisbon in two identical adjacent double-span greenhouses covered with three layer co-extruded film. The climate was controlled by natural ventilation, using continuous apertures located on the roof and side walls over the entire length of the greenhouses. Two different natural ventilation treatments were randomly assigned to the greenhouses. One treatment was permanent ventilation (PV), with the vents open during the day and night, while the other was classical ventilation (CV), in which the vents were open during the day and closed during the night. A spring tomato crop (Lycopersicon esculentum Miller), cultivar Zapata was grown directly in the soil between the end of February and the end of July. The growing technique was the usual for greenhouse tomatoes in Portugal. Trickle ferti-irrigation tubes were located between each two rows of plants. Climatic data were measured with three meteorological stations, one located in the centre of each greenhouse and one outside. All data were averaged and recorded on an hourly basis using two data logger systems. The number of leaflets with lesions caused by B. cinerea were counted and removed from the greenhouse from the randomly selected groups of plants. A significant reduction of air humidity occurred in the nocturnally ventilated greenhouse. Nocturnal or permanent ventilation was shown to give a great contribution to reducing disease severity on tomato leaves caused by B. cinerea. Nocturnal ventilation management is an environmental control technique which can be used as a prophylactic control measure, since it reduces the severity of B. cinerea on tomato crops grown in unheated greenhouses, enabling a reduction in chemical use and lowering both production costs and environmental impacts