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Resumo

FRISINA, V.A., ESCOBEDO, J.F. e GOMES, E.N. Estimativa da radiação fotossinteticamente ativa (PAR) em estufa de polietileno.. In: ENCONTRO DE ENERGIA NO MEIO RURAL, 3., 2000, Campinas. Anais eletrnicos... Disponvel em: <http://www.proceedings.scielo.br/scielo.php?script=sci_arttext&pid=MSC0000000022000000200056&lng=pt&nrm=abn>. Acesso em: 19 Maio. 2024.

This paper presents a simple linear regression to estimate the active photosynthetic radiation inside a poliethylene greenhouse (PARin) as function of the external values (PARex). The radiations have been measured at Solar Radiometric Station, UNESP, Botucatu-SP, Brazil, inside a polyethylene greenhouse (100mm) and in a external area. Photosynthetically active photon flux density was measured by means of two LI-COR model quantum sensors installed out and inside the greenhouse. The database have included instantaneous values of irradiations (W/m²) and daily irradiations (MJ/m²) measured between June 1999 to November 1999. In the data acquisition it was utilized a Datalogger Campbell 21X operating at 1 Hz frequency and storing 5 minute averages. The results showed that PAR can be estimated inside a polyethylene greenhouse (PARin) as function of the external PAR measurements (PARex) with high correlation coefficient of the linear regression. The following equations have been obtained: PAR_in = 4,629 + 0,603 PAR_ex with R = 95,98% to the instantaneous measurements and PAR_in = 0,830 + 0,527 PAR_ex with R = 97,84% to the daily measurements.

Palavras-chave : radiação fotossinteticamente ativa; estimativa; estufa de polietileno.