Spatial variability of soil chemical attributes and productivity and the chemical and physical properties of oranges

Abstract

The purpose of this study was to analyze the spatial variability of soil properties and productivity and the chemical and physical properties of oranges (Monte Parnaso variety) in their geographical quadrants. This experiment was conducted in a commercial orange orchard in the municipality of Nova Laranjeiras in the State of Parana, Brazil. A GPS receiver and a total station were used to measure the spatial location of the fruit and to determine which quadrant they were located in. In this experiment, 13 trees were studied. Twelve fruits were evaluated in each geographical quadrant, and 156 fruits were considered. After harvest, the productivity was expressed as kg per quadrant (kg quadrant -1 ). Next, physical tests (equatorial diameter (EqD), total fruit mass (TFM), juice yield (JY)) and chemical tests (total soluble solids (TSS), total titrable acidity (TTA), the TSS/TTA ratio, and the ascorbic acid (AA) content) were conducted in the laboratory. In addition, the data were subjected to analysis by descriptive statistics and geostatistics to determine the spatial variability of the physical and chemical properties of the oranges, the variations of the soil properties and the correlations between the following parameters: the pH properties of the fruit and Zn; TFM and K; EqD and K, and C and TSS. The orchard varies spatially, especially regarding the EqD, TFM, JcP, TSS and AA for the quadrants with the highest values (the Northwest, Southeast, Northeast, Southwest and Southeast, respectively). The soil potassium and zinc contents were strongly correlated with the physical and chemical properties of the orange fruits. El objetivo de este estudio ha sido analizar la variabilidad espacial de los atributos del suelo, de la productividad y de las propiedades fisicas y quimicas de los frutos de la variedad de naranja Monte Parnaso, en relacion a los cuadrantes geograficos en que se ubican los frutos analizados. El experimento se realizo en un huerto comercial de naranjos en Nova Laranjeiras, Estado de Parana, Brasil. En el procedimiento de georreferenciacion de la area y de cada arbol de la muestra, se utilizo un GPS y una estacion total para medir la localizacion espacial de la fruta y luego la definicion de que cuadrante se ubicaban. En el experimento, se utilizaron 13 arboles en las cuales se analizaron tres frutas por cuadrante geografico de cada arbol, por un total de 156 frutas. Despues de la cosecha se estimo la productividad en kg cuadrante -1 y en el laboratorio fueran realizados analisis fisica (diametro ecuatorial (ED), masa total de la fruta (MT), rendimiento de jugo (RS)) y quimicos (solidos solubles totales (SST), acidez titulable (AT), relacion SST/AT y acido ascorbico (AA)) de la fruta. Los datos fueron sometidos a analisis de la estadistica descriptiva y de la geoestadistica senalando la variabilidad espacial de las propiedades fisico-quimicas de las naranjas y los atributos del suelo y tambien correlacion entre los atributos de la fruta pH y Zn, MT y K, ED y K y finalmente SST y C. El huerto tiene variaciones espaciales principalmente para los atributos diametro ecuatorial, masa total de la fruta, rendimiento del jugo, SST y acido ascorbico, siendo los cuadrantes con mayores valores fueron, respectivamente, noroeste, sureste, noreste, suroeste y sureste. Especialmente potasio y zinc, las propiedades del suelo, fuertemente correlacionados con las propiedades fisicas y quimicas de las frutas de color naranja.