Influence of spectral quality on the rooting of Corymbia and Eucalyptus spp. minicuttings

The pursuit of better adaptation in clonal plants seedling production processes based on the minicutting technique has expanded the use of species and hybrid combinations of genera Corymbia and Eucalyptus in the composition of commercial crops. The aim of the work was to evaluate the effect of spectral quality on the rooting of Eucalyptus andrewsii, E. saligna, E. microcorys, E. cloeziana, E. pilularis, E. grandis, E. grandis × E. urophylla and Corymbia torelliana minicuttings to help better understanding the production of clonal plants. E. grandis × E. urophylla and C. torelliana root anatomy was analyzed. The effects of spectral quality on the rooting of minicuttings were evaluated based on three sources (fluorescent, red and blue). Survival (SUR), callogenesis (CAL), oxidation (OXI) and rooting (RO) percentage; length (RL) and diameter of the largest root (ROD); mean number of roots per minicutting (NRM), root epidermis thickness (RET), root cortex diameter (RCD), diameter of the root vascular cylinder (DRVC) and root diameter (RD) were evaluated at 30 days. Based on the results, wavelength specificity was a useful technology to optimize the large-scale production of clonal plants of Eucalyptus. Fluorescent spectral quality was the most appropriate source in the rooting of E. saligna (68.7%), E. microcorys (43.7%), E. pilularis (75.0%) and C. torelliana (75.0%) minicuttings; blue spectral quality was the most appropriate for E. andrewsii (55.5%), E. grandis (75.0%) and E. grandis × E. urophylla (81.3%); and red spectral quality was the most appropriate for E. cloeziana (56.2%).