Responses of the photosynthetic system and peroxidase activity to the rooting conditions of oak micropropagation

The effects of indole butyric acid (IBA) concentration and the duration of the plant growth regulator (PGR) treatment on the rooting ability, peroxidase level and photosynthetic activity of young Quercus robur L. plants were studied. Four-week-old oak shoots were transplanted to rooting media supplemented with 10 or 20 μM IBA. After 2, 3, 4, 5 or 7 days the shoots were transplanted again to a fresh, PGR-free medium. On the tenth day after transfer to rooting medium, the CO2 fixation capacity, pigment content and peroxidase activity were measured. The photosynthetic parameters varied as a function of the time spent on medium containing PGR, showing maximum values in plants transplanted on the third to fourth day to PGR-free medium. The rooting percentage of these plants reached its maximum within two weeks. However, peroxidase activity was the highest in plants transferred later to PGR-free medium. The most pronounced stimulating effect on rooting was achieved with the higher initial IBA concentration followed by a transfer to PGR-free medium on the third to fourth day. These plants showed the highest vitality and the best rooting ability.