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PLANT GROWTH REGULATORS TREATMENTS MODULATE GROWTH, PHYSIOLOGY AND QUALITY CHARACTERISTICS OF CUCUMIS MELO L. PLANTS

GEORGIA OUZOUNIDOU¹*, PARTHENA PAPADOPOULOU¹, ANASTASIA GIANNAKOULA² AND ILIAS ILIAS²

Abstract: Our objective was to identify the effects of Gibberellic acid (GA3), Prohexadione-Calcium (Prohex-Ca), Cycocel and Ethephon applied as foliar sprays, on pre- and post-harvest physiology and quality characteristics of melon (Cucumis melo L.). GA3 promoted melon growth, while a significant inhibition with Cycocel and Ethephon was observed. The chlorophyll a+b concentration as well as the chlorophyll fluorescence characteristics were negatively affected by Prohex-Ca, Cycocel and Ethephon application. The maximum quantum yield of PSII (Fv/Fm) was declined showing an impairment of the primary photochemical efficiency of the photosynthetic apparatus during the time course of the experiment. The significant decrease of Fv/Fo is an indicator of structural damage, which occur in the thylakoids and affects the photosynthetic electron transport. With GA3 application, fructose, glucose and soluble solids remained unchanged, whereas ascorbic acid content increased significantly. With the retardants a significant decrease in sugars, soluble solids and ascorbic acid content and an increase in respiration rate and in titratable acidity of fruits, was induced. Less soluble solids accumulation in melon from plants treated with growth retardants could be a consequence of delayed maturity, a fact that it can be proved by the lower maturity index.

¹Institute of Food Technology, National Agricultural Research Foundation, Lycovrissi 141 23 Greece;

²Department of Crop Production, Technological Educational Institute of Thessaloniki, PO Box 141, Thessaloniki 541 00 Greece;

*Correspondence E-mail: geouz@nagref.gr; phone: +30 210 2845940; fax: +30 210 2840740)