Data/hora: 09/06/2024 14:32:55

Provedor de dados: | 86
País: | Brazil
Título: | Radiation and energy balance of lettuce culture inside a polyethylene greenhouse
Autores: | Frisina,Valéria de Almeida; Escobedo,João Francisco.
Data: | 1999-10-01
Ano: | 1999
Palavras-chave: | Global radiation; Reflected radiation; Net radiation; Heat fluxes.
Resumo: | The objective of this paper was to describe the radiation and energy balance, during the lettuce (Lactuca sativa, L. cv. Verônica) crop cycle inside a polyethylene greenhouse. The radiation and energy balance was made inside a tunnel greenhouse with polyethylene cover (100 mum) and in an external area, both areas with 35 m². Global, reflected and net radiation, soil heat flux and air temperature (dry and humid) were measured during the crop cycle. A Datalogger, which operated at 1 Hz frequency, storing 5 minutes averages was utilized. The global (K&lt;FONT FACE=Symbol&gt;¯&lt;/FONT&gt;) and reflected (K&lt;FONT FACE=Symbol&gt;­&lt;/FONT&gt;) radiations showed that the average transmission of global radiation (K&lt;FONT FACE=Symbol&gt;¯&lt;/FONT&gt;in / K&lt;FONT FACE=Symbol&gt;¯&lt;/FONT&gt;ex) was almost constant, near to 79.59%, while the average ratio of reflected radiation (K&lt;FONT FACE=Symbol&gt;­&lt;/FONT&gt;in / K&lt;FONT FACE=Symbol&gt;­&lt;/FONT&gt;ex) was 69.21% with 8.47% standard-deviation. The normalized curves of short-wave net radiation, in relation to the global radiation (K*/ K&lt;FONT FACE=Symbol&gt;¯&lt;/FONT&gt;), found for both environments, were almost constant at the beginning of cycle; this relation decreased in the final stage of culture. The normalized relation (Rn/ K&lt;FONT FACE=Symbol&gt;¯&lt;/FONT&gt;) was bigger in the external area, about 12%, when the green culture covered the soil surface. The long-wave radiation balance average (L*) was bigger outside, about 50%. The energy balance, estimated in terms of vertical fluxes, showed that, for the external area, in average, 83.07% of total net radiation was converted in latent heat evaporation (LE), and 18% in soil heat flux (G), and 9.96% in sensible heat (H), while inside of the greenhouse, 58.71% of total net radiation was converted in LE, 42.68% in H, and 28.79% in G.
Tipo: | Info:eu-repo/semantics/article
Idioma: | Inglês
Identificador: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X1999001000003

Editor:

Embrapa Secretaria de Pesquisa e Desenvolvimento

Pesquisa Agropecuária Brasileira

Relação: | 10.1590/S0100-204X1999001000003
Formato: | text/html
Fonte: | Pesquisa Agropecuária Brasileira  v.34 n.10 1999
Fonte: | info:eu-repo/semantics/openAccess