In: Phyton 56, Fasc. 2 (2016): S. 225-240 DOI: 10.12905/0380.phyton56(2)2016-0225

The Effect of Prohexadione-Calcium on Enzymatic Antioxidant System in Tomato (Lycopersicon esculentum) and on the Efficiency of Photosynthetic Apparatus

By

Anastasia E. Giannakoula, Ilias F. Ilias, Martha G. Lazaridou and Maria K. Konstantinou

Received September 1, 2015

Accepted March 21, 2016

Key words: Growth-retardant, antioxidants, chlorophyll fluorescence, photosystem II, photosynthetic activity. – Lycopersicon esculentum, Solanum lycopersicum.

Summary
Giannakoula A. E., Ilias I. F., Lazaridou M. G. & Konstantinou M. K. 2016. The effect of prohexadione-calcium on enzymatic antioxidant system in tomato (Lycopersicon esculentum) and on the efficiency of photosynthetic apparatus. – Phyton (Horn, Austria) 56 (2): 225–240, with 4 figures.

The objective of this research was to investigate the effect of the growth-retardant Prohexadione-Calcium (Prohex-Ca) on the growth and physiological Parameters of tomatoes (Lycopersicon esculentum Mill. cvs ‘Karla’ and ‘Hari Moran’) grown under a glass greenhouse environment. Tomatoes have been identified as one of the main dietary sources of antioxidants, due to lycopene and other phytochemicals of great nutritional and medicinal value to humans. Enzymatic activity carbohydrates content, accumulation of H2O2 and malondialdehyde (MDA) were varied depending in the tomato variety. Photosynthetic activity was measured by Chlorophyll a fluorescence and gas exchange (photosynthetic rate-A, stomatal conductance-gs, transpiration rate-E, and intercellular concentration of CO2-Ci). The Efficiency of photosynthetic apparatus measured by the ratio Fv/Fm, ETR (electron transport rate), Yield (real photochemical efficiency of PSII, FPSII), qP (photochemical quenching) and qN (non-photochemical quenching). Prohexadione-Ca in excessive concentration seems to disturb photosynthetic electron transport as well as real photochemical efficiency of PSII and photochemical quenching. The application of 300 mgl–1 of Prohex-Ca resulted in diminution of the leaf chlorophyll concentration in both cultivars.