Journal of Plant Nutrition, 32: 1486–1497, 2009 Copyright © Taylor & Francis Group, LLC ISSN: 0190-4167 print / 1532-4087 online DOI: 10.1080/01904160903092689 Pre-Harvest Rind-Spotting in ‘Clementine’ Mandarin Anna Assimakopoulou, 1 Charikleia Tsougrianis, 1 Kalomira Elena, 2 Constantinos Fasseas, 3 and George Karabourniotis 4 1 Ministry of Agriculture, District Laboratory of Agricultural Advisory Service and Fertilizer Analysis, Xylokastro, Greece 2 Laboratory of Mycology, Benaki Phytopathological Institute, Kifissia, Greece 3 Laboratory of Electron Microscopy, Agricultural University of Athens, Athens, Greece 4 Laboratory of Plant Physiology, Agricultural University of Athens, Athens, Greece ABSTRACT A severe physiological disorder of ‘Clementine’ mandarins in the Assini area of Argolis, Southestern Greece, was investigated for two successive years. Irregular-shaped necrotic spots were observed on the rinds of mandarins, mainly at the fruit stylar-ends, from the color break till harvest time. In order to investigate the possible correlation between the disorder and the inorganic nutrition of the fruit, spotted and symptomless mandarin rinds, in four commercial orchards were chemically analyzed. The relationship between fruit inorganic nutrition and the disorder symptoms were not consistent. Using Electron Scanning Microscopy, invisible cracks were observed at the cuticle and the external strata of the spotted rind whereas oil glands remained intact. Considering the results of chemical analyses, microscopic observations, as well as, the information given by the growers, this physiological disorder should be attributed to sudden changes of climatic conditions and not to nutritional imbalance. Keywords: peel blemish; nutritional disorder; citrus ultrastructure INTRODUCTION ‘Clementine’ mandarin [Citrus reticulate Blanco x Citrus aurantifolia (Christm.) Swingle] (variety Poros) was introduced in Argolis area in Greece Received 16 February 2008; accepted 11 May 2008. Address correspondence to A. Assimakopoulou, Technological Educational Insti- tute of Kalamata, School of Agriculture, Department of Crop Production, GR-24100 Antikalamos, Kalamata, Greece. E-mail: dalakl@otenet.gr 1486