title: Rapid estimation of nutritional elements on citrus leaves by near infrared reflectance spectroscopy.
abstract: Sufficient nutrient application is one of the most important factors in producing quality citrus fruits. One of the main guides in planning citrus fertilizer programs is by directly monitoring the plant nutrient content. However, this requires analysis of a large number of leaf samples using expensive and time-consuming chemical techniques. Over the last 5 years, it has been demonstrated that it is possible to quantitatively estimate certain nutritional elements in citrus leaves by using the spectral reflectance values, obtained by using near infrared reflectance spectroscopy (NIRS). This technique is rapid, non-destructive, cost-effective and environmentally friendly. Therefore, the estimation of macro and micronutrients in citrus leaves by this method would be beneficial in identifying the mineral status of the trees. However, to be used effectively NIRS must be evaluated against the standard techniques across different cultivars. In this study, NIRS spectral analysis, and subsequent nutrient estimations for N, K, Ca, Mg, B, Fe, Cu, Mn, and Zn concentration, were performed using 217 leaf samples from different citrus trees species. Partial least square regression and different pre-processing signal treatments were used to generate the best estimation against the current best practice techniques. It was verified a high proficiency in the estimation of N (Rv = 0.99) and Ca (Rv = 0.98) as well as achieving acceptable estimation for K, Mg, Fe, and Zn. However, no successful calibrations were obtained for the estimation of B, Cu, and Mn.
authors.affiliation: Departamento de Producción Vegetal y Microbiología, Miguel Hernández University Alicante, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Galvez-Sola
authors.affiliation: Departamento de Nutrición Vegetal, Centro de Edafología y Biología Aplicada del Segura, Consejo Superior de Investigaciones Científicas Murcia, Spain ; Unidad Asociada de Fertirriego y Calidad Hortofrutícola (Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario - Centro de Edafología y Biología Aplicada del Segura), Murcia Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: García-Sánchez
authors.affiliation: Unidad Asociada de Fertirriego y Calidad Hortofrutícola (Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario - Centro de Edafología y Biología Aplicada del Segura), Murcia Spain ; Departamento de Citricultura, Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario Murcia, Spain.
authors.forename: Juan G
authors.initials: JG
authors.lastname: Pérez-Pérez
authors.affiliation: Departamento de Agronomia, Universidad ISA Santiago De Los Caballeros, Republica Dominicana.
authors.forename: Vicente
authors.initials: V
authors.lastname: Gimeno
authors.affiliation: Unidad Asociada de Fertirriego y Calidad Hortofrutícola (Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario - Centro de Edafología y Biología Aplicada del Segura), Murcia Spain ; Departamento de Citricultura, Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario Murcia, Spain.
authors.forename: Josefa M
authors.initials: JM
authors.lastname: Navarro
authors.affiliation: Departamento de Producción Vegetal y Microbiología, Miguel Hernández University Alicante, Spain.
authors.forename: Raul
authors.initials: R
authors.lastname: Moral
authors.affiliation: Departamento de Producción Vegetal y Microbiología, Miguel Hernández University Alicante, Spain.
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Martínez-Nicolás
authors.affiliation: Departamento de Producción Vegetal y Microbiología, Miguel Hernández University Alicante, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Nieves
keywords: NIRS; calibration; macronutrients; micronutrients; nitrogen; nutritional status