Özet:

The present study was designed to evaluate the effect of lead (Pb) and combine effect of Pb with brassinolide (BL) on the growth, metabolite contents and enzyme activities in radish plants. Pb suppressed the growth of the radish plants, reduced net photosynthesis rate and soluble sugar levels. Activities of nitrate reductase in radish plants were also reduced under Pb stress. However seed treatment with BL mitigated the adverse effects of Pb and stimulated the growth of radish plants. The growth promotion was associated with enhanced rate of photosynthesis and elevated levels of reducing and total sugars and nitrate reductase activities in radish plants under Pb stress. Under Pb stress, reactive oxygen species (ROS) levels and lipid peroxidation were increased in radish plants, which were significantly inhibited by BL application. The activities of antioxidant enzymes such as peroxidase, ascorbate peroxidase and superoxide dismutase were increased during metal stress. Treatment with BL further increased the activity of ascorbate peroxidase, catalase and superoxide dismutase. The BL treatment also enhanced glutathione reductase activity under stress. From the results it can be concluded that BL could play a positive role in the alleviation of oxidative stress caused by ROS by enhancing antioxidant defense system, thus improving the tolerance of radish plants to Pb stress

Anahtar Kelimeler: