SciELO - Scientific Electronic Library Online

vol.57 número2Quality of carrot roots under different population densitiesBreaking the dormancy of niagara rosada seeds without stratification índice de autoresíndice de materiabúsqueda de artículos
Home Pagelista alfabética de revistas  

Servicios Personalizados




Links relacionados


Revista Ceres

versión impresa ISSN 0034-737X


MOURA, Carlos Roberto Weide; ZOLNIER, Sérgio; RIBEIRO, Aristides  y  OLIVEIRA, Rubens Alves de. Degree-day-based crop coefficient for hydroponic lettuce. Rev. Ceres [online]. 2010, vol.57, n.2, pp.224-233. ISSN 0034-737X.

The main objective in this work was to propose the adoption of a thermal crop coefficient by using accumulated degree-days after transplanting to estimate lettuce daily evapotranspiration (ETc) for the cultivars Grand Rapids, Regina and Great Lakes in a NFT hydroponic system under protected environment. Subsequently, the adjusted model to the observed values of Kc was used for estimating ETc during the growing period after transplanting with the following methods: Penman-Monteith parameterized by FÃO in 1998 (PMF); Penman-Monteith modified for aerodynamic characteristics in protected environment (PMAP); simplified Penman-Monteith (PMAPS); Priestley-Taylor (PT); solar radiation (RS); and simplified solar radiation (RSS). It was verified that the sigmoid model with four parameters fitted well to observed values of Kc,giving adjusted coefficients of determination of 0,9874, 0,9784 and 0,9767 for cultivars Grand Rapids, Regina and Great Lakes, respectively. As far as daily ETc estimates are concerned, the methods PMF, PMAP and RS presented better statistical performance as compared to the methods PMAPS, PT and RSS, regardless of the evaluated cultivar. However, the method PMF systematically underestimated ETc in the lettuce initial growth period.

Palabras clave : Protected cultivation; thermal time; nutrient film technique.

        · resumen en Portugués     · texto en Portugués     · Portugués ( pdf epdf )


Creative Commons License Todo el contenido de esta revista, excepto dónde está identificado, está bajo una Licencia Creative Commons