Journal of Agricultural Science; Vol. 11, No. 7; 2019 ISSN 1916-9752 E-ISSN 1916-9760 Published by Canadian Center of Science and Education 14 Non-destructive Method for Estimating the Leaf Area of Pear cv. ‘Triunfo’ Vinicius de Souza Oliveira 1 , Karina Tiemi Hassuda dos Santos 2 , Andréia Lopes de Morais 1 , Gleyce Pereira Santos 2 , Jéssica Sayuri Hassuda Santos 2 , Omar Schmildt 1 , Marcio Paulo Czepak 2 , Ivoney Gontijo 2 , Rodrigo Sobreira Alexandre 3 & Edilson Romais Schmildt 2 1 Postgraduate Program in Tropical Agriculture, Federal University of Espírito Santo, São Mateus, ES, Brazil 2 Departament of Agrarian and Biological Sciences, Federal University of Espírito Santo, São Mateus, ES, Brazil 3 Federal University of Espírito Santo, Alegre, ES, Brazil Correspondence: Vinicius de Souza Oliveira, Postgraduate Program in Tropical Agriculture, Federal University of Espírito Santo, São Mateus, ES, Brazil. E-mail: souzaoliveiravini@gmail.com Received: February 12, 2019 Accepted: March 15, 2019 Online Published: May 31, 2019 doi:10.5539/jas.v11n7p14 URL: https://doi.org/10.5539/jas.v11n7p14 Abstract The present study had as objective to determine mathematical equations to estimate the leaf area of pear cv. ‘Triunfo’ using linear dimensions of the leaves. For that, 300 healthy leaves of different sizes from each quadrant of plants from the small farm of Boa Vista located in the city of Montanha, at the northern side of the State of Espírito Santo, Brazil were used. The length (L) along the main vein was measured, along with the maximum width (W) of the leaf blade and observed leaf area (OLA), in addition to the product of the length and width (LW) of each leaf. From these measurements models of linear equations of first degree, quadratic and power were adjusted and their respective R 2, using OLA as dependent variable and L, W and LW as independent variable. Based on the proposed equations, the data were validated obtaining the estimated leaf area (ELA). The mean of the ELA and OLA were compared by Student t test 5% probability. The mean error (E), the mean absolute error (MAE) and the root mean squared error (RMSE) was also used as validation criterion. The best equation model was defined based on the non-significant values from the comparison of means of ELA and OLA, E, MAE and RMSE values closer to zero and highest R 2 . The leaf area of pear cv. ‘Triunfo’ can be estimated by the equation ELA = -0.432338 + 0.712862(LW) non-destructively and with a high degree of precision. Keywords: Pyrus communis L., linear dimensions, mathematical equations 1. Introduction The pear tree (Pyrus communis L.) belongs to the faimily of the Rosaceae, being the cv. ‘Triunfo’ a hybrid with characteristics of fast growth, high productivity, vigorous plants, large fruits of green color, oblong shape and punctuation in the shell, firm flesh and with sweet acidulated taste (Nakasu et al., 2007). The determination of leaf area is a fundamental characteristic in studies involving plant development, light interception, photosynthesis efficiency, evapotranspiration, fertilizer and irrigation related responses, being directly related to the yield and quality of the plant (Blanco & Folegatti, 2005). The measurement of the leaf area can be done directly or indirectly. Although the direct methods are more efficient, it needs a lot of time, require complex and expensive equipment and are in most cases destructive, preventing successive measurements which often makes their use impracticable (Jonckheere et al., 2004; Pompelli et al., 2012). Indirect methods are based on easy methods to obtain measurements allowing constant measurements of the leaf area, for example during the entire plant development period (Tsialtas & Maslaris, 2005). One of the most commonly used indirect techniques is based on linear measures of the leaves and the correlation with the leaf area of the plants, generating mathematical models that allow the estimation of the leaf area in a fast and non-destructive way. However this method requires adequate calibration and parameterization to be used. (Peksen, 2007; Costa, Pôças, & Cunha, 2016).