Plant management and IBA application in rooting of Pinus patula cuttings

Rooted cuttings are an alternative for the massive cloning of selected trees, with desirable and superior traits for commercial plantations. However, rooting capacity diminishes rapidly at 2 or 3 years of age in conifer species. The aim of this work was to evaluate the rooting capacity of Pinus patula cuttings obtained from 15- and 18-months-old mother plants grown with different fertilization doses and growth conditions (management), with the application of 5000 x 10(-6) (5000 ppm) of indole-3-butyric acid (IBA) in liquid solution or with the Radix((R)) commercial product as paste. Fourteen weeks after establishing the rooting trial, survival, rooting, and callus formation were evaluated in cuttings, as well as the number and length of primary roots, and presence of secondary roots. Significant effects (p <= 0.05) were found on the evaluated factors and in their interaction. Application of IBA in solution for 10 s or 20 s caused the highest rooting percentage (> 25%), 2-3 times more than the control (8.5%). Fertilization of mother plants with 7 g L-1 Osmocote (R) under shade mesh caused high cutting mortality (30%). No differences were found in length of the longest root, nor in average length of primary roots. The combination of an 18-month-old mother plant fertilized with 5 g L-1 Osmocote (R) in the greenhouse, and the application of IBA in liquid solution for 20 s produced 73.8% rooted cuttings, an acceptable value in a Pinus patula cloning operational program.