CONFIGURATION AND DEVELOPMENT OF ROOT SYSTEMS OF CUTTINGS AND SEEDLINGS OF EUCALYPTUS-GLOBULUS

Cuttings are only a viable alternative to seedlings as planting stock if the method of propagation does not affect their growth and developm ent adversely. Full-sibling cuttings and seedlings of Eucalyptus globu lus were compared under controlled environmental conditions to minimis e extraneous sources of variation, and to establish whether changes in growth or development were induced by propagation. On three occasions over a period of eight weeks root-collar diameter, shoot height, leaf and stem weight, shoot/root ratios and root system morphology were me asured on cuttings and seedlings. Seedlings were taller than cuttings throughout the experiment, but both plant types had similar height gro wth rates. Diameter growth rates were lower in cuttings than seedlings , and there were differences in both height and diameter growth rates between families. Root system configuration differed between the plant types. Seedlings had strongly gravitropic tap-roots, with two types o f primary roots from which secondary roots emerged. Cuttings had no ta p roots, and the main structural components of their root systems were adventitious roots formed during propagation. Cuttings did not develo p further structural roots during the experiment, whereas seedlings co ntinued to develop primary roots. Individual primary roots of cuttings were longer and had larger mid-point diameters than those of seedling s, but the total length of primary roots was greater in seedlings. See dlings also had a greater number and total length of secondary roots. Shoot/root ratios, calculated from a range of functional measures, wer e higher in cuttings than seedlings.