Rhizobacteria strains as promoters of rooting in hybrids of Eucalyptus nitens x Eucalyptus globulus

Paulina González1, Katherine Sossa1, Francisco Rodríguez2, and Eugenio Sanfuentes1*
In Chile, the Eucalyptus nitens (H. Deane & Maiden) Maiden x E. globulus Labill. hybrid presents the highest production potential due to its desirable characteristics for the production of cellulose. Nevertheless, its low ability to rooting complicates the clonal propagation in nurseries, with the need for new alternatives to increase rooting. The objective of this research was to evaluate the effect of rhizobacteria in the adventitious rooting of mini-cuttings of two hybrid E. nitens x E. globulus clones, wherein 106 rhizospheric bacterial isolates from five species and hybrids of Eucalyptus spp. were used. The mini-cuttings were treated at the base with a 20 mL liquid suspension of rhizobacterial strains. In addition, cultured bacteria were applied by manual sprinklers in the rooting substrate. In the first trial, 38% of rhizobacteria increased significantly rooting of X-64 clone mini-cuttings. Of these, in a second trial, 50% of rhizobacteria maintained their effect in promoting the rooting in two clones, and in the third trial among the 20 strains evaluated, 10 strains increased rooting in both clones. The rhizobacteria that had the most consistent effect in the rooting increase of the mini-cuttings were species of Bacillus and Pseudomonas sp., as well as the genera Chryseobacterium, Mucilaginibacter and Rhodococcus sp., with these results, it is concluded that 10 rhizobacterial isolates have increased the adventitious rooting of minicuttings of two hybrid clones of E. nitens x E. globulus, and these inoculants could be used in periods of underperformance of minicuttings, in order to optimize their performance.
Keywords: Eucalyptus, forestry nurseries, rhizobacteria, roots, hybrids.
1Universidad de Concepción, Facultad de Ciencias Forestales, 4070386, Concepción, Chile.
*Corresponding author (esanfuen@udec.cl).
2Forestal Mininco S.A., Vivero Carlos Douglas, 4580000, Yumbel, Chile.