Effects of Indol-3-butyric acid and Agrobacterium rhizogenes on the rooting of hardwood cuttings of EM9 and MM106 apple rootstocks

Nowadays in the modern and industrial pomology, the rootstocks play an important role in the production, garden economy, trimming and the life of tree, harvest and garden management. In fact, rootstock forms half statue of the tree which is located inside the soil and not been replaceable and improved. In this respect, the choice of suitable rootstock for a cultivar and climatic and soil conditions of the region, as well as a selection of cultivars is important. Application and development of this vegetative rootstocks is necessary and depends on the availability of a simple and easy way to reproduce it.
This study was conducted to evaluate the effects of different concentrations (0-1000-2000-3000 ppm) of Indole-3-butyric acid (IBA) and one strain of Agrobacterium rhizogenese (15834) alone or in combination with each other on the rooting capacity of hardwood cuttings of EM9 and MM106 apple clonal rootstocks in split factorial design with three replications at research greenhouse of Ferdowsi University of Mashhad. It was considered Agrobacterium rhizogenese as a main plot and different levels of Indole-3-butyric acid and rootstocks as a factorial on the sub-plots. The medium of this experiment was the mixture of perlite and disinfected sand in 1:1 ratio.
The results indicated that different percentages of rooting were observed in cuttings treated by Agrobacterium rhizogenese alone and combination of Indole-3-butyric acid and Agrobacterium rhizogenese in both rootstocks while no rooting was observed with Indole-3-butyric acid alone. The highest rooting percentage (% 45/06) was obtained in EM9 rootstock cuttings treated by Agrobacterium rhizogenes plus 3000 ppm IBA. The highest mean root length (4/45 cm) was obtained from Agrobacterium rhizogenese plus 3000 ppm Indole-3-butyric acid treatment. Maximum number of the main and secondary roots (3 and 6/5, respectively), were observed in the MM106 rootstock treated by Agrobacterium rhizogenese. Callusing rate of cuttings were reduced with using of Agrobacterium rhizogenese, so the highest percentage of callus induction (% 86/42) was observed at control treatment of EM9 rootstock.
A combination of Agrobacterium rhizogenes and 3000 ppm Indole-3-butyric acid treatment was found as the best treatment for rooting of MM106 and EM9 apple cutting in this experiment.