HOLCMAN E; SENTELHAS PC. 2013. Bromeliads production in greenhouses associated to different shading screens. Horticultura Brasileira 31: 386-391. Bromeliads production in greenhouses associated to different shading screens Ester Holcman; Paulo Cesar Sentelhas ESALQ, Depto. de Eng. de Biossistemas, C. Postal 9, 13418-900 Piracicaba-SP; [email protected]; [email protected] ABSTRACT RESUMO Bromeliads production in greenhouses is highly influenced by Produção de bromélias sob malhas de sombreamento em microclimate, which affects plants growth and development. Based casa de vegetação on that, this study aimed to evaluate the influence of shading screens A produção de bromélias em ambiente protegido é altamente of different colors on microclimatic variables and Aechmea fasciata influenciada pelo microclima, o qual afeta tanto o desenvolvimento bromeliad growth in a greenhouse covered by transparent low-density como o crescimento das plantas. O objetivo do presente trabalho polyethylene. The experiment had five treatments, with screens of foi avaliar a influência de malhas de sombreamento de diferentes different colors, inside a plastic greenhouse: thermo-reflective (T1); cores nas variáveis microclimáticas e no crescimento da bromélia control without screen (T2); red (T3); blue (T4); and black (T5) Aechmea fasciata em ambiente protegido coberto com polietileno screens, all of them with 70% of shading. From the 60 plants arranged de baixa densidade transparente. Os tratamentos foram compostos in each one of the treatments 24 were evaluated, which were obtained por diferentes malhas de sombreamento: termo-refletora (T1), teste- randomly. The statistical design was completely randomized for the munha sem malha (T2), vermelha (T3), azul (T4) e preta (T5), todas biometric variables. An automatic micrometeorological station was com 70% de sombreamento. Das 60 plantas dispostas em cada um installed in each treatment, recording temperature, relative humidity dos tratamentos, foram avaliadas 24 delas obtidas aleatoriamente. O and solar radiation. The plant parameters evaluated weekly were plant delineamento estatístico foi inteiramente casualizado para as variáveis diameter and height, leaf width and length, and number of leaves biométricas. Um sistema automático de aquisição de dados micro- per plant. The rosette diameter and leaf length were the parameters meteorológicos foi instalado em cada tratamento, obtendo registros that presented the highest differences among treatments, which de temperatura do ar, umidade relativa do ar e radiação solar. As was basically a function of changes in solar radiation caused by the variáveis das plantas avaliadas foram altura e diâmetro da planta, shading screens. The red screen provided the best conditions for A. largura e comprimento das folhas e número de folhas por planta. O fasciata bromeliad production. diâmetro da roseta e o comprimento das folhas foram as variáveis que apresentaram as maiores diferenças entre os tratamentos, em função das alterações na radiação solar causadas pelas malhas de sombreamento. A malha vermelha promoveu as melhores condições para a produção da bromélia A. fasciata. Keywords: Aechmea fasciata, plant growth, solar radiation, air Palavras-chave: Aechmea fasciata, crescimento, radiação solar, temperature. temperatura do ar. (Recebido para publicação em 5 de setembro de 2012; aceito em 8 de julho de 2013) (Received on September 5, 2012; accepted on July 8, 2013) romeliads are distributed across degree of shading for them (Carvalho a better production in greenhouses. BTropical and Subtropical areas of et al., 1998; Carvalho & Rocha, 1999). This is possible only by applying the Americas. South America is considered Therefore, for growing bromeliads in a results from the field experiments the center of great diversity. Nowadays, commercial scale is important that the which indicate how good shading can more than 3.200 bromeliads species environment could be adapted according be for producing a given plant or crop. are known, with 70% of the genus and to their climatic requirements. For Cermeño (1994), the sunshine more than 40% of the species occurring The bromeliads are one of the is important for all plants’ metabolic in Brazil (Grant & Zijlstra, 1998), main ornamental plants cultivated processes. Specific advantages can inhabiting all parts of the country, but in greenhouses. Considering that be obtained with the use of different having the Atlantic coast as the largest microclimate inside greenhouses can shading screens, with special optical diversity center (Paula, 2001). be modified and controlled (Medeiros, properties, which can modify the The different bromeliads genera 2002), suitable conditions for bromeliads composition of the light spectrum that require different light intensities to growth can be generated and the shading reaches the plants, improving the yield their full development. The optimal screens have been used for this purpose. and quality of them (Oren-Shamir et al., climatic conditions for each species of Thus, the knowledge of the actual solar 2001). Shading can result in a positive bromeliad are those predominant in the radiation transmissivity of the cover effect on the quality and homogeneity center of origin, which determine the materials is of crucial importance for of production (Briassoulis et al., 2007), 386 Hortic. bras., v. 31, n. 3, jul. - set. 2013 Bromeliads production in greenhouses associated to different shading screens mainly in sunny and hot regions (Al- Based on that, the objective of this the screens, which represent the most Helal & Abdel-Ghany, 2010). Because study was to evaluate the influence used by growers, had 70% of shading of their physical structure, shading of shading screens of different colors and were installed at 1.0 m above of the screens promote a mixture of direct and on microclimatic parameters and on plants. Each treatment was composed by diffuse radiation, which is issued by the A. fasciata bromeliad growth in a 60 vases cultivated with one bromeliad photo-selective threads (Shahak, 2008). greenhouse covered by transparent low- plant per vase, organized in 6 lines However, not all microclimatic changes density polyethylene. and 10 columns, with dimensions are beneficial for plants (Sentelhas & of 3.0 x 1.2 m and height of 1 m. Santos, 1995). The plants cultivated MATERIAL AND METHODS Measurements related to the A. fasciata in greenhouses normally suffer with bromeliads growth were made weekly heat excess along the summer season on 24 samples per treatment, starting on in tropical and sub-tropical regions, The experiment was conducted 23/12/2005. The experimental design when the solar irradiance is very intense from 11/04/2005 to 30/06/2006 in the for biometric characteristics (rosette (Mashonjowa et al., 2010). experimental area of the Agricultural diameter, plant height, leaf number per College “Luiz de Queiroz”, University According to Oliveira (1995), the plant, leaf width and leaf length) was of São Paulo, in Piracicaba, São Paulo main problems associated to the use the samples completely randomized. state, Brazil (22º42’40”S, 47º37’30”W, of greenhouses in tropical regions are The results were submitted to the altitude of 546 m). In accordance with caused by high air temperatures and analysis of variance and the averages the Köppen classification, the climate of relative humidity observed within were compared by the Tukey test, at the region is Cwa, which means tropical these structures, causing physiological 5% of probability, using the Software humid with dry winter. The experiment disturbs and favoring occurrence of ASSISTAT (7.6 beta version). was installed in a greenhouse with 17.5 diseases. Also, the lack of information m of length; 6.4 m of width; 3.5 m of The environmental physics analysis about how to manage the greenhouse height, being covered with a transparent was done by micrometeorological appropriately in relation to the macro low density polyethylene plastic film, measurements with automatic sensors. and microclima is the cause of low crop 0.15-mm thick. As the micrometeorological sensors yield and quality. A. fasciata micropropagated plants were not available for the five treatments The bromeliads are one of the used in the experiment were provided simultaneously, they were installed for major ornamental plants cultivated in by “Bromélias Rio” company, with the period of one week in each treatment, greenhouses, since they require very 33 weeks of age. In 11/04/2005, the in a system of rotation. With such system, specific conditions to grow properly, bromeliads were transplanted to vases the micrometeorological measurements combining temperature, relative (n° 14), filled with commercial substrate, were done for five weeks in each humidity, light, nutrients and soil with the following composition: pine treatment. The sensors were connected water availability, which vary among bark, peat, coal, fosmag (magnesium to a datalogger CR10x model (Campbell the different species (Went, 1940; multiphosphate), FTE and limestone, Sci.), which continuously recorded air Pittendrigh, 1948; Johansson, 1974; manufactured by Terra do Paraíso®. temperature (T) and relative humidity Grant & Zijlstra, 1998). The fertilization was done with two (RH), with a thermocouple psicrometer In order to circumvent the difficulties different nutritive solutions (A and of forced ventilation. Moreover, a faced by greenhouse growers in tropical B). The fertirrigation was performed 3 sensor was used for the measurement