Peroxidase, Guaiacol Peroxidase and Ascorbate Peroxidase Activity Accumulation in Leaves and Roots of Walnut Trees in Response to Drought Stress

Peroxidase isozymes (POX, POD and APX) activity were determined in 1-year-old walnut plants grown in environmental conditions characterized by high temperatures and high photosynthetic photon flux density levels and subjected to withholding irrigation for a 20-day period. These mechanisms have been investigated over both irrigated and drought-stressed plants in order to investigate the plant response under stressed conditions and its ability to recover. Before and during the experimental period, leaf and root samples were collected and their POD was analyzed. Significant increases of POD especially APX isozyme activity were also observed during the progressive increment of drought stress in both leaf and root tissues of tolerant genotypes at the seventh day after the beginning of the drought period. The differences in drought tolerance may be closely related with efficient photo protective systems as well as the increased capacity of the anti oxidative system to scavenge reactive oxygen species.