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Physiological and biochemical aspect associated with the rizogenetics of hazelnut (Corylus avellana L.)

Ellena, M., Masia, A., Marino, G.
Acta horticulturae 2014 no.1052 pp. 157-165
Corylus avellana, IAA oxidase, agar, cultivars, enzyme activity, ethylene, ethylene production, explants, hazelnuts, indole acetic acid, indole butyric acid, micropropagation, niacin, pH, peroxidase, photoperiod, process control, pyridoxine, rooting, roots, statistics, trees
The traditional methods of propagation of hazelnut trees used, such as layering, cuttings, rooted suckers of the trees in the orchard, often present a low rate of multiplication and in certain occasions phytopathological problems, depending on the precedence and management of the plant materials. The propagation of hazelnut through micro-propagation method is an alternative technique for this species that presents little rizogenetic capacity, in particular some commercial cultivars with regards to the traditional methods. This study was carried out to determine some protocols for the rooting phase in vitro on hazelnut and the variation of the peroxidase, polifenoloxidase IAA oxidase activity and ethylene production during the rooting phase. In our research, we used explants of 20-25 mm of the cultivar ‘Tonda Romana’ maintained in proliferation media DKW (Driver and Kuniyuki, 1984), supplemented with (mg/L: BA 1, IBA 0.01, pyridoxine 0.5, myoinositol 100, glicine 2, tiamin 1, nicotinic acid 0.5 and g/L: saccharose 30, agar 7), pH 5.5. In the elongation step, explants elongated on the DKW media without IBA. The rooting (Exp. 1) was performed on DKW media supplemented with IBA (0, 0.25, 0.5 and 1 mg/L). During the rooting process the explants were maintained at standard (photoperiod of 16/24 h of light, 30 µE). The best rooting of explants occurred in the treatment with higher level of auxin, IBA (1 mg/L), with 60% of rooting at day 25. Also, the higher IBA concentration significantly influenced the number and length of roots. However, the number of roots is high in treatment with 0.5 mg/L of IBA. Concerning, the ethylene production (Exp. 1), all the treatments of rooting, during the first day show a similar activity and successively the concentration tends to be low until the final of the rooting process in the control, while the curve of ethylene activity was significantly increased by the treatments with 0.5 and 1 mg/L of IBA until day 10. On the other hand, the IAAox activity shows a very complex behavior, with the higher value until day 10 with the dose of 0, 0.25 and 0.5 mg/L of IBA, with statistics of significant differences with regards to the higher dose of auxin (1 mg/L) of IBA. Also, the POD activity presents a complex trend, with a higher enzyme activity at day 21 in treatment with the high concentration of IBA (1 mg/L), while for the control the activity was constant during all the rooting steps. For the PPO activity, the higher values were shown at day 4 in the treatments of 0.5, 0.25 and 0 mg/L of IBA, with significant differences between the treatments, successively the curve declines until day 10 in the samples with 0.25 and 0 mg/L and returns to increase until day 15 with the dose of 0.25 mg/L of IBA and until day 21 with the control (IBA 0 mg/L), while with 0.5 mg/L of IBA, the curve descended from day 10 until the last step of the rooting, while for the higher dose of IBA (1 mg/L) the lowest value was showed, and with a little pick at day 21.