PRODUCTION OF EUCALYPTUS CLOEZIANA CUTTINGS IN RESPONSE TO STOCK PLANT TEMPERATURE

Propagation of tropical and subtropical eucalypts is often limited by reduced production of rooted cuttings in winter. We assessed whether changing the temperature of stock plants of Eucalyptus cloeziana from 28/23 (day/night) to 18/13, 23/18 or 33/28 °C affected the production, nutrient concentrations and percentages of cuttings that subsequently formed roots. Lowering the temperature to 18/13 or 23/18 °C greatly reduced the number of cuttings harvested from stock plants but did not affect the percentage of cuttings that formed roots. However, raising the temperature to 33/28 °C greatly increased the number of cuttings produced by stock plants and the ensuing percentage of cuttings that formed adventitious roots, thereby increasing the final number of rooted cuttings produced from each stock plant. The effects of stock plant temperatures on rooting were not the result of altered nutrient concentrations. However, consistent relationships were found between adventitious root formation and boron concentration. Rooting percentages were very low (1–14%) but rooted cutting production per stock plant (e.g. 12 rooted cuttings over a 14-week period at 33/28 °C) was sufficient to establish field tests for clonal plantation forestry.