Encontro de Energia no Meio Rural
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Abstract

FRISINA, V.A., ESCOBEDO, J.F. and GOMES, E.N. Estimativa da radiação fotossinteticamente ativa (PAR) em estufa de polietileno. In Proceedings of the 3. Encontro de Energia no Meio Rural, 2000, Campinas (SP, Brazil) [online]. 2003 [cited 24 April 2024]. Available from: <http://www.proceedings.scielo.br/scielo.php?script=sci_arttext&pid=MSC0000000022000000200056&lng=en&nrm=iso> .

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.

Keywords : radiação fotossinteticamente ativa; estimativa; estufa de polietileno.