Growth, proline accumulation and peroxidase activity in maize seedlings under osmotic stress

The influence of osmotic stress induced by polyethylene glycol (PEG) on plant growth, proline content and activities of soluble peroxidases was studied on 12 maize inbred lines at seedling stage. Reduction of plant growth, fresh weight and length of roots and shoots occurred in all of the studied genotypes and was followed by increase in free proline content of shoots and especially in roots of the majority of genotypes. Correlation analysis of changes in root proline content with growth parameters revealed direct positive correlation. Changes in root peroxidase activities ranged from approximately 40 % reduction to 20 % stimulation, depending on the genotype. It was shown that genotypes with higher proline changes under drought treatment exhibited lower peroxidase activities. In addition, genotypes with less pronounced root growth reduction under stress conditions exhibited increased peroxidase activities, as well as lower proline content. In the field experiments, grain yield was positively correlated with root proline content and negatively with root length changes in drought-treated seedlings grown in laboratory conditions.