2.5. Biochemical analysesSamples of 0.25 g were collected from green parts of nine-weekold microplants. Triplicate extracts were prepared for each analysisand three measurements were done for each extract. Hydrogen peroxide (H2O2) was measured according to Pick and Keisari (1980), andthe catalase activity according to Goth (1991) . Absorbance was measured with the spectrophotometer UV-1601PC (Schimadzu)