Computational simulations of mass and energy flow help in implementing alternative cooling systems in protected environments. The aim of this study was to model and simulate the interaction between external and internal environments of a protected environment by means of computational fluid dynamics (CFD) techniques and validate micrometeorological variables for subsequent comparison between natural and indirect ventilation by ground heat exchangers. At the first phase, the micrometeorological variables global solar radiation (Qg), air temperature (Tair), and air relative humidity (RH) were monitored. The second phase consisted of the numerical modeling of finite volumes, with validation through recorded data, as well as simulation and comparison of two ventilation systems. The functional relationship between simulated and recorded meteorological elements presented a good linear association, with coefficients of determination of 0.97, 0.93, and 0.94 for Qg, Tair, and RH, respectively. Simulation of indirect ventilation system by ground heat exchangers presented a reduction of 4 °C in Tair and 15% in RH compared to that recorded inside the environment. The natural ventilation system allowed a reduction of 1 °C in Tair when compared to the protected environment.

Brazil is the world’s largest producer of sugarcane (Saccharum officinarum L.) and research aimed at propagation has promoted higher quality in production. The objective of this study was to investigate the effect of the variation of micrometeorological elements on the survival and quality of pre-sprouted sugarcane plantlets. The study was carried out in a protected environment (UFRPE). Plantlets of the cultivar RB92579 were obtained by the technique of production of pre-sprouted plantlets. The protected environments were divided into four modules covered with low-density polyethylene plastic + photo-selective shade nets and one module without shade net. Micrometeorological data of global and photosynthetically active solar radiation, air temperature, substrate temperature, relative humidity and the solar radiation spectrum were recorded in each module. The experiment was conducted in a completely randomized design and the principal component analysis was used to verify the association between the cultivation modules, micrometeorological variables and crop variables. Anti-UV low-density polyethylene plastic + freshnet led to lower transmittance of global solar radiation, higher percentage of photosynthetically active radiation and lower plantlet mortality. Substrate temperature above 30.2 °C resulted in higher plantlet mortality. Larger spectrum in the red range led to the production of better quality plantlet. The use of freshnet shade net promoted adequate conditions for the cultivation of sugarcane plantlets and allows obtaining better quality plantlets.

Sugarcane has a great economic interest in Brazil, so it needs technologies to increase its yield strength, especially for seedling production. This study aimed to ascertain the influence of shading nets on early growth and development of pre-sprouted sugarcane seedlings. An experiment was conducted in a protected environment, in the Rural Federal University of Pernambuco (UFRPE), in Recife-PE, Brazil. The protected environments were covered with anti-UV low-density polyethylene plastic plus: Solpack ® red ultranet net, Solpack ® white net, Solpack ® freshnet net, and without shade net, and five replications each. The experiment was carried out in a completely randomized design, and multivariate principal component analysis (PCA) was used to verify associations among cultivation modules, micrometeorological factors, and seedling growth parameters. Anti-UV low-density polyethylene + shade net improved seedling growth and development up to 27 days after planting. Higher substrate temperatures benefited early growth of seedlings. After 27 days of planting, sugarcane seedlings required higher air temperatures, as well as increased global and photosynthetically active solar radiation.

Sugarcane is considered one of the main alternatives for biofuel production and an important product of Brazilian agriculture, so it is indispensable to adopt new techniques for its cultivation and management. Thus, the present study aimed to evaluate the effect of the quality of supplemental lighting, based on light-emitting diode (LED), on the acclimation of pre-sprouted sugarcane seedlings in a protected environment. The experimental design was completely randomized, consisting of three supplemental LED lighting systems, with light proportions of 90% red + 10% blue (R:B 90/10), 80% red + 20% blue (R:B 80/20) and 70% red + 30% blue (R:B 70/30), and a control, with natural solar radiation, with 5 replicates. Multivariate principal component analysis was used based on the matrix of correlation between all variables (meteorological, physiological and biometric). It was found that the different LED lighting systems increased the photosynthetically active radiation; however, until 20 days after planting, the seedlings were little influenced by the supplemental lighting systems. At the end of the acclimation period, the R:B 80/20 lighting system was the most associated with the growth and size of sugarcane seedlings.

Sugarcane is a grass species that stands out worldwide in the production of ethanol. Brazil is the world's largest producer and leader in exports, responsible for more than 50% of the products that are marketed worldwide. The objective of this study was to investigate the effect of photo-selective nets on micrometeorological variables and on sprouting of pre-sprouted sugarcane seedlings. The experiment was carried out in a protected environment at Universidade Federal Rural de Pernambuco -UFRPE, in a completely randomized design. Seedlings of cultivar RB92579 were obtained by the technique of production of pre-sprouted seedlings. The protected environment was divided into four modules corresponding to the treatments: covered with anti-UV low-density polyethylene plastic: + Solpack ® red ultranet net, + Solpack ® white net, + Solpack ® freshnet net and without shade net. Micrometeorological data of air temperature and substrate temperature were recorded in each module. The first count of emergence, sprouting speed index and sprouting percentage were calculated. Principal component analysis was used to verify the association between the cultivation modules and the micrometeorological and sprouting variables of the seedlings. Air temperature in the protected environment was 8.7% higher than that in the external environment. The white net led to sprouting of 78.93%. The substrate temperature above 30.4 °C favored seedling sprouting. The modules with white net and red ultranet net favored seedling sprouting.Key words: Saccharum officinarum, protected environment, shade net, propagation of seedlings Brotação de mudas pré-brotadas de cana-de-açúcar e variáveis micrometeriológicas sob malhas fotosseletivas RESUMO: A cana-de-açúcar é uma gramínea que se destaca mundialmente na produção de etanol. O Brasil é o maior produtor mundial e líder na exportação, responsável por mais de 50% dos produtos derivados que são comercializados no mundo. Objetivou-se averiguar a influência de malhas fotosseletivas nas variáveis micrometeorológicas e na brotação de mudas pré-brotadas de cana-de-açúcar. A pesquisa foi realizada em ambiente protegido na Universidade Federal Rural de Pernambuco, em delineamento inteiramente casualizado. As mudas da cultivar RB92579 foram obtidas pela técnica de produção de mudas pré-brotadas. O ambiente protegido foi dividido em quatro módulos, correspondentes aos tratamentos: coberto com plástico polietileno de baixa densidade anti-UV + malha ultranet vermelha Solpack ® , + malha branca Solpack ® , + malha freshnet Solpack ® e sem malha de sombreamento. Foram registrados os dados micrometeorológicos de temperatura do ar e temperatura do substrato em cada módulo. Foram calculadas a primeira contagem de emergência, o índice de velocidade de brotação e a porcentagem de brotação. Foi utilizada a análise multivariada de componentes principais para verificar a associação entre os módulos de cultivo e as variáveis micrometeorológicas e de brotação das mudas. A temperatura do ar no ambiente protegido foi 8.7% maior ...