Pre-Harvest Rind-Spotting in ‘Clementine’ Mandarin

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

ACKNOWLEDGMENTS

We would like to thank the Greek Ministry of Rural Development and Food, Directorate of Plant Produce Protection, Department of Plant Protection, for the financial support of the research, as well as, M. Gouma, P. Bastounas and N. Panogopoulou for their technical assistance and I. A. Rodger for correcting the English.

Notes

∗Means within rows followed by the same letter are not significantly different at P ≥ 0.05.

∗Means within rows followed by the same letter are not significantly different at P ≥ 0.05.

∗Means within rows followed by the same letter are not significantly different at P ≥ 0.05.

∗∗Mean FW of the whole rind of the injured or non-injured mandarins.

∗Means within rows followed by the same letter are not significant different at P ≥ 0.05.