The Effect of Different Concentrations of Putrescine and Indole Butyric Acid (IBA) on Rooting of Semi-Hardwood Cuttings of GN15 Hybrid Rootstocks

In order to investigate the effect of putrescine and auxin (IBA) on rooting of semi-hardwood cuttings of the GN15 hybrid rootstocks, an experiment was conducted at the Flower Biology Laboratory of Faculty of Agriculture, Tabriz University in 1994. Cuttings were obtained from Sahand Gardening Research Station. This experiment was conducted in a completely randomized design with four replications and five treatments including IBA at 4000 mg/L for 5 seconds, Putrescine at three levels of 1000, 2000 and 3000 mg/L for 1 minute as well as control treatment. The results showed that all traits such as rooting percentage, root volume, mean length of rooted portion, root number and root length were affected by the treatments. The highest percentage of rooting (62.27%) was observed in Putrescine treatment with a concentration of 3000 mg/L, so that it was significantly greater than the other treatments. IBA at 4000 mg/L had the highest root portion and root volume so that it was significantly greater than the other treatments. Putrescine at 3000 mg/L and IBA at 4000 mg/L led to the greatest root length, root number and fresh and dry weight so that they were significantly greater than the other treatments. Also, the control treatment showed the highest percentage of callus. Overall, putrescine at 3000 mg/L and then IBA 4000 at mg/L had the greatest positive effects on these traits, and could be considered as good practices for rooting GN15 cuttings.