EFFECTS OF UV-B ON PHOTOSYNTHETIC PARAMETERS, LIPID PEROXIDATION, FLAVONOIDS AND GROWTH TRAITS OF CONOCARPUS LANCIFOLIUS (ENGL.)
Patrice Suleman, Amina Redha, Mohamad Afzal and Redha Al-Hasan
DOI : 10.3844/ajabssp.2014.55.63
American Journal of Agricultural and Biological Sciences
Volume 9, Issue 1
Conocarpus lancifolius is a perennial ornamental plant adapted to the semi-arid conditions of Kuwait. It accumulates most of its biomass during the stressful summer conditions which includes UV-B irradiation. The study evaluated equivalent UV-B irradiation intensities that plants would normally experience sometime during the course of a year in Kuwait. Leaf area, plant height, photosynthetic parameters, Lipid Peroxidation (LP) and Phenyl Alanine Lyase (PAL) were measured in C. lancifolius plants exposed to different UV-B treatments. UV-B treatments decreased leaf area and plant height but induced the formation of lateral branches. Chlorophyll content, photosynthesis, chlorophyll fluorescence measured as maximum quantum efficiency of photosystem II (Fv/Fm) and Electron Transport Rate (ETR) decreased in the short term or the first 10-20 days after treatment. Lipid Peroxidation (LP) measured in terms of Malondiadehyde (MDA) content decreased in the long term after a short term increase but Phenyl Alanine Lyase (PAL) activity increased linearly by 41.2, 66.8 and 78.6% after 30 days. There was also Positive Linear Correlation between UV-B dosage and total flavonoid accumulation which was localized in epidermal cell walls, trichomes and cuticular layer. The response of C. lancifolius to ameliorate and/or tolerate UV-B stress involved multiple mechanisms that included increased concentrations of PAL activity, increased flavonoids production; and reduced lipid peroxidation. The net effect of flavonoid accumulation and PAL enzyme activity probably contributed significantly to the protection or tolerance of the species to the effects of UV-B.
© 2014 Patrice Suleman, Amina Redha, Mohamad Afzal and Redha Al-Hasan. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.