Influence of abiotic stresses on the antioxidant enzyme activity of cereals

The unfavourable effects of climate change were studied in terms of changes in the stress tolerance of cereals. Changes in the antioxidant enzyme activities were analysed as a function of the weather in a 2-year field experiment in order to determine the effect of extreme temperatures and rainfall conditions on the enzyme activity. The enzyme responses of two winter wheat genotypes to drought stress, simulated by withholding water completely for 7 days, were analysed under phytotronic conditions in three phenophases. The plants were raised either at ambient CO₂ concentration or at a doubled level. The quantities of glutathione reductase (GR), glutathione-S-transferase (GST), catalase (CAT), guaiacol peroxidase (POD) and ascorbate peroxidase (APX) were determined from leaf samples. The peroxidases had the most intense activity during the winter and early spring periods, with guaiacol peroxidase being dominant until the end of the winter. CAT generally became more active in late spring and summer, the activity being correlated with the development of water deficiency. The activity of GR, GST, POD and CAT was found to increase during the dry period, while the role of GR and POD was extremely important for resistance to low temperature.