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 x 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 & DEG;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 & DEG;C.