Improving the Rooting Capacity of Stem Cuttings of Virginia Pine by Severe Stumping of Parent Trees

Two experiments were conducted to develop a protocol for rooting stem cuttings from 5-year-old Virginia pine (Pinus virginiana Mill.). The first experiment tested the effects of stumping treatment (none and ¼, ½, and ¾ original height remaining), auxin type[indole-3-butyric acid or 1-napthalene acetic acid (NAA)], and auxin concentration (0, 2, 4, 6, 8, or 12 mM) on adventitious root formation. Stumping refers to the process of cutting back the stem combined with partial crown removal. The second experiment quantified the effects of crown position on the rooting of stem cuttings from stumped and nonstumped trees. Rooting percentage increased and percentage of mortality decreased as the severity of the stumping treatment increased. Auxin concentration significantly affected every rooting trait except root angle. Overall,cuttings from trees stumped to ¼ original height and treated with 4 mM NAA rooted in higher percentages (74%) and produced more primary roots (5.5) with greater total root lengths (601 mm) than the other treatments. The original crown position, particularly height, significantly affected rooting percentage. Primary needle length significantly increased as the severity of the stumping treatment increased and was positively correlated with rooting capacity. South. J. Appl. For. 30(4):182–187.