Microclimate and gerbera growth under different greenhouse covers. / Microclima e produção de gérbera em ambientes protegidos com diferentes tipos de cobertura.

AUTOR(ES)

Cristiane Guiselini

DATA DE PUBLICAÇÃO

2003

RESUMO

The objective of this work was to evaluate the influence of white polyethylene as a greenhouse cover and its association with different shading screens (thermal screen and black screen) on the following environmental elements: incoming solar radiation (Qg), photosynthetically active radiation (PAR), temperature (T), relative humidity (RH) and evapotranspiration (ET) and also to evaluate the effects of the different microclimatic conditions on the growth, development and quality of Gerbera Jamesonii. The experiment was carried out between late Autumn and Winter of 2002 at the experimental area of the Exact Sciences Departament, Agricultural College "Luiz de Queiroz", at the University of São Paulo, in Piracicaba, State of São Paulo, Brazil. A greenhouse was installed, sub-divided into three parts. One of them was covered just with white polyethylene (T1), while the others had, yet, shading screens, that were installed within the greenhouse, being one covered with a thermal screen (Alumitela) (T2) and the other one with a black screen (T3), both with 50% of shading, manufactured by Solpack Ltda. The meteorological sensors were installed in the center of each sub-division of the greenhouse and an automatic weather station was located at 100m from the experimental area, to collect external meteorological data. The covers in the greenhouse affected the microclimate, decreasing Qg, PAR, RH and ET and increasing T. The average transmission of solar radiation by the covers (white polyethylene, white polyethylene + thermal screen and white polyethylene + black screen) were, respectively, 23, 11 and 7%. The mean daily air temperatures within the greenhouse were about 6 o C higher in the white polyethylene and 3 o C higher in the environments covered by white polyethylene associated with the shading screens in comparison to the external temperatures. The types of covers, forming different microclimates, affected the growth and development of Gerbera plants. The growth was faster under the white polyethylene and slower under the white polyethylene associated with black screen. The plants cultivated under the greenhouse covered with white polyethylene and with white polyethylene associated with thermal screen filled the requirements in relation to the number of flower buttons. However, the same was not observed in the environment covered with white polyethylene associated with black screen. About the stem size, all the cultivated plants under all environmental conditions not presented the minimum required value (10 cm). In general, the microclimate influenced by the different covers offered adequated conditions for the cultivation of Gerbera, during autumn and winter periods. However, it is not possible to be sure that these conditions are representative for the whole year stations, being recommended forward studies comparing different cover materials on different periods of the year, searching for a better comprehension of the microclimate influence on the commercial production of Gerbera.

ASSUNTO(S)

estufa plasticultura sombreamento microclimate shading gérbera microclima polyethylene greenhouse

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