Akademik Veri Yönetim Sistemi
JOURNAL OF PLANT NUTRITION, cilt.28, sa.1, ss.127-139, 2005 (SCI-Expanded)
The distribution of chlorophyll and carotenoid contents and antioxidant enzyme activities such as superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), ascorbate-dependent peroxidase (AsA-dep POD, EC 1.11.1.11), guaiacol-dependent peroxidase (Gua-dep POD, EC 1.11.1.7), and lipid peroxidation levels (LPO) were investigated according to the leaf positions of Mentha pulegium grown in the presence of 4000 muM Ca2+ and in the absence of Ca2+ on the 14th day after the start of treatments. After reaching the highest values at leaf 6, chlorophyll-carotenoid content, SOD, CAT activities decreased as the leaves aged. The variations in chlorophyll-carotenoid contents and antioxidant enzyme activities were investigated with decreasing Ca2+ concentrations ranging from 2000 to 0 muM with respect to time. The chlorophyll-carotenoid values increased in the absence of Ca2+ approximately 4.5-fold compared to the control plant over the 19 days of the stress period. SOD activity also increased approximately 2-fold with decreasing Ca2+ concentrations on the loth day and decreased afterward. Whereas CAT, AsA-dep, and Gua-dep POD activities were observed under the control levels up to 14th day and then increased over them. The LPO levels in the stress conditions increased with decreasing Ca2+ concentrations during the most of the treatment period. The peroxidation of polyunsaturated fatty acids in M. pulegium membranes was highly suppressed by at least 100 muM Ca2+ concentration in the growth medium.