Effects of resource plant size on rooting of Dryobalanops lanceolata cuttings

Abstract

Cuttings from older trees of the Dipterocarpaceae generally lose their ability to root. However, branches in a canopy of adult dipterocarps are a possible source of cuttings because they show juvenile characteristics in architecture due to “adaptive reiteration”, suggesting physiological rejuvenation. Effects of resource plant size on the rooting of cuttings and the possibility of using cuttings from reiterated branches of adult trees were studied for Dryobalanops lanceolata, an emergent dipterocarp species. A cutting experiment with non-mist propagators was conducted for cuttings collected from resource plants of four different size classes: <2m, 2–5m, 8–15m, and 70m in height. The smallest size class included two different age classes: <2 and >2 years old. Cuttings from the tallest resource plant were collected from reiterated branches. Rooting percentage was negatively correlated with resource plant size: 77–78% for resource plants <2m, 63% for 2–5m, 36% for 8–15m, and 0% for 70m. Rooting percentages of cuttings collected from different individuals were not different for the 2–5m tall class, while they were significantly different for the 8–15m tall class. Resource plant size was negatively correlated with the number of roots for rooted cuttings. No significant relationship was observed between resource plant size and mean length of each root, total root length or total root dry weight for rooted cuttings. The results suggest the possibility of collecting cuttings from relatively large resource plants up to 15m tall and >20 years old if we chose good individuals for resource plants. The results, however, show the difficulty in using reiterated branches of adult trees as a source of cuttings for D. lanceolata.