Adventitious root initiation, plasticity, and response to plant growth regulator treatments of seedling, juvenile, and adult Elaeocarpus hookerianus plants

Abstract

We characterise the propagation success of cuttings from juvenile and adult plants of the New Zealand endemic tree Elaeocarpus hookerianus, and describe the response of seedling, juvenile, and adult plants to various environmental and plant growth regulator treatments. Unexpectedly, more adult cuttings formed roots than juveniles when cuttings were taken during winter, but this was reversed when cuttings were taken during summer. Juvenile plants displayed more variability in leaf properties in response to shaded or glasshouse environments, and to gibberellic acid, benzyladenine, or paclobutrazol treatments than seedlings or adult plants. Juvenile plants displayed larger episodic changes in internode length along the vertical axis than seedling or adult plants. No substantial maturation of juvenile plants or rejuvenation of adult plants was observed following any of the treatments. Age of the shoot appeared to be more important than the size of the plant for control of the transition between juvenile and adult phases, and for the expression of morphological and physiological properties characteristic of each on‐togenetic phase.