The extraction and determination of the enzymatic activity of peroxidase were conducted through the method recommended by MATSUNO and URITANI (1972), where we took a sample of the leaves from each experimental unit, placed it in a refrigerated porcelain pot, because this analysis must be conducted at temperatures under 4ºC.The samples were macerated with 3.0 mL of buffer phosphate 0.05 M (pH 7) with more 0.005g of polyvinylpyrrolidone. The extract was conditioned in eppendorf tubes properly identified, which were taken to the centrifuge for 20 minutes at 4ºC and 5000
rpm. After the centrifugation, we removed 2.0 mL of the supernatant and placed it in identified test tubes, where there was a solution of 3.0 mL of buffer citrate (pH 5.0) plus 0.5 mL of hydrogen peroxide at 3%and more 0.5 mL of guaiacol 0.5%. The solution was stirred and placed for 15 minutes under Bain Marie at 30ºC and, after, 10 minutes in ice in order to stop the reactions. Finally, we added 0.5 mL of sodium bisulfite, stirred and made the reading at 450 nm through the spectrophotometer,obtaining thus the values of absorbance.