The effects of zinc oxide nanoparticles loaded with IAA and IBA on in vitro rooting of apple microcuttings

In the micropropagation of difficult-to-root plants, the low rates of rooting cause high economic losses. The local apple (Malus domestica Borkh.) cultivar #67, which is highly resistant to fire blight disease, has been shown to have low rooting success. Nanoparticles loaded with auxins could increase the rooting success with their physicochemical properties. To increase rooting percentage, the effects of zinc oxide nanoparticles (nZnO), nZnO loaded with indole-3-acetic acid (IAA-nZnO) and indole-3-butyric acid (IBA-nZnO) at different concentrations (1.0, 2.0, 3.0, 4.0, 5.0, and 6.0 mg L-1) on in vitro rooting of microcuttings were investigated. The concentrations of auxin carried by the nanoparticles were 2.8, 5.7, 8.0, 10.8, 13.7, 16.0 mu M IAA or 2.5, 4.4, 6.9, 9.3, 11.3, 13.8 mu M IBA. The various concentrations of IAA (0.0, 2.8, 5.7, 11.4, 17.1 mu M) and IBA (0.0, 2.5, 4.9, 9.8, 14.8 mu M) were also examined. All substances as described previously were incorporated to half-strength Murashige and Skoog (1/2 MS) medium containing 2% sucrose at pH 5.8, and solidified with 0.7% agar. The microcuttings were cultured on these media for 5 days in the dark before being transferred to a 16 h photoperiod conditions at 25 +/- 1 degrees C for 6 weeks.