M. Ziganira, I. Bertling
Studies on Eucalyptus grandis × E. nitens (GN) coppice yields of mini-hedges and rooting frequency in nurseries have shown that stockplant planting density, size and position of cuttings may affect yield and the subsequent rooting of cuttings. The aim of this study was to investigate the impact of endogenous sugars and hormone concentrations of stockplants on coppice yields and rooting rates of GN cuttings. The soluble sugar concentration of GN tissue samples in relation to size of stockplant, position of cuttings, planting density and season were determined by HPLC, and the rooting rates of GN 018B (difficult-to-root clone) and PP 2107 (easy-to-root clone) were evaluated using the mung bean bioassay. Experiments were carried out in September 2010 and in December 2010. Clone PP 2107 had greater sugar concentration, particularly sucrose, than GN 018B at low planting density (29.1 and 24.3) mg (g DW)-1, respectively. Although apical cutting tissues had relatively high sugar concentration, basal cutting tissue had lower sugar concentrations but higher hormone activity, at either high or low planting density. Maintaining PP 2107 cuttings at high planting density resulted in higher hormone activities in September (corresponding to spring) but lower ones in December (summer). However, opposite effects were observed with GN 018B cuttings which showed higher hormone activity in December and lower activity in September, in particular at low planting density. Position, size and genotype had a significant impact on type and concentration of sugar (i.e., sucrose, glucose and fructose), particularly in clone PP 2107. The possibility of manipulating planting density in the early developmental stage of E. grandis × E. nitens stockplants may provide a valuable management tool. Rooting of mini-cuttings seems not related to endogenous rooting co-factors.
Ziganira, M. and Bertling, I. (2013). ANALYSES OF ENDOGENOUS SOLUBLE SUGARS AND ROOTING STIMULANTS. Acta Hortic. 1007, 787-794
DOI: 10.17660/ActaHortic.2013.1007.93
eucalypt clones, mung bean bioassay, soluble sugars, rooting co-factors, planting density, position of cuttings, size of stockplants

Acta Horticulturae