Influence of mini-tunnel and different rooting environments on the production of rooted mini-cuttings of subtropical Eucalyptus

Improving mini-cutting techniques and processes for subtropical eucalyptus can yield new superior clones and increase the production rate of high-quality rooted mini-cuttings. In this study, we evaluated the influence of mini-tunnels in a clonal mini-garden, associated with different rooting environments, on the survival, rhizogenesis, and morphology of established mini-cuttings of subtropical eucalyptus during the spring–summer and autumn–winter seasons in southern Brazil. Two clones of Eucalyptus benthamii (B1 and B2) and Eucalyptus dunnii (D1 and D2) and one hybrid of Eucalyptus urophylla × Eucalyptus dunnii (UD) were evaluated. Experiments were conducted in a factorial scheme, testing three rooting environments [greenhouse without mini-tunnel (G0), with polyethylene mini-tunnel (G1), and with red shade net mini-tunnel (G2)] and two mini-cutting production environments [clonal mini-garden without (M0) and with a mini-tunnel (M1)]. Mini-cuttings from M1 presented a higher percentage of rooting. Dry matter production by E. benthamii clones increased when mini-cuttings were obtained from M1 during spring–summer. G1 and G2 conditions in the greenhouse allowed greater rooting for clones D2 and UD. Using a mini-tunnel in the rooting house did not substantially change the morphology of established mini-cuttings. Variations in environmental conditions between the study periods were confirmed to be the predominant factor in adventitious rhizogenesis. Low average temperatures (15–20 °C) were optimal for the rooting of clones B1, B2, and D2; in contrast, UD and D1 showed higher plasticity, with higher percentages under average temperatures between 15 and 25 °C.