Rooting cuttings of Pieris species and hybrids in two propagation systems

S.E. Svenson
The objective of this study was to compare the success of rooting stem tip cuttings of clones of Pieris japonica, P. formosa, and hybrids of P. japonica, P. formosa, and P. floribunda, using mist or no-mist sub-irrigation propagation. Four replications of each clone were placed under intermittent mist, or into sub-irrigation propagation trays without mist, following collection from 5 year-old or older stock plants on June 20 or September 20. Each replication consisted of four cuttings. Before insertion into the rooting medium, all cuttings were treated with 0.1% indolebutyric acid (water soluble solution soak for 10 s). Bottom heat was not used. The rooting substrate was a 1:1 blend of sphagnum peat and perlite. Percentage rooting was evaluated after 60 days. The experiment was a randomized complete block design of cuttings of Pieris cultivars within a split-plot (propagation system). Cuttings collection dates were analyzed separately. The experiment was repeated twice. Within both cutting collection dates, there was a significant interaction between clone and propagation system. Rooting ranged from 0% for 'Brouwer's Beauty' and 'Valley Fire' cuttings collected on June 20 and rooted using mist, to 100% for 'Flaming Silver,' 'Scarlett O'Hara,' and 'Spring Snow' cuttings collected on September 20 and rooted using sub-irrigation. Cuttings from Pieris japonica clones generally rooted better when cuttings were taken on September 20, but Pieris formosa cuttings rooted better when cuttings were taken on June 20. The variation in rooting of Pieris cultivars suggests that using a single propagation procedure to root Pieris cuttings will limit the diversity of Pieris clones that can be successfully propagated.
Svenson, S.E. (2018). Rooting cuttings of Pieris species and hybrids in two propagation systems. Acta Hortic. 1191, 97-104
DOI: 10.17660/ActaHortic.2018.1191.14
Pieris japonica, Pieris floribunda, Pieris formosa, sub-irrigation, mist propagation

Acta Horticulturae