154 J.E. FAUST, J.M. DOLE, AND R.G. LOPEZ
2001), hibiscus (Kachecheba 1976), petunia (Cabaleiro and Economou
1992; Lopez and Runkle 2008a), impatiens (Lopez and Runkle 2008a),
Phlox (Enfield 2002), Angelonia, argyranthemum,Diascia,lantana,
nemesia, osteospermum (Osteospermum fruticosum),Scaevola,and
verbena (Currey et al. 2012). For example, Islam and Willumsen (2001)
determined that baby’s breath cuttings rooted under high light lev-
els (natural light+ 146 μmol⋅m−^2 ⋅s−^1 supplemental light from high-
pressure sodium (HPS) lamps for 20 h) produced higher amounts of
carbohydrates; consequently, root initiation, formation, and overall
biomass was improved during propagation when compared to plants
grown under lower light intensities (natural light+ 146 μmol⋅m−^2 ⋅s−^1
supplemental light by HPS lamps for 10 h). Lopez and Runkle (2008a)
reported that after 16 d in propagation, root mass of petunia and New
Guinea impatiens increased linearly as DLI increased from approxi-
mately 1.2–8.4 mol⋅m−^2 ⋅d−^1 and 1.3–10.7 mol⋅m−^2 ⋅d−^1 , respectively. As
DLI increases, photosynthetic rates generally contribute to faster rooting
and subsequent shoot growth. For example, Lopez and Runkle (2008a)
reported that root and shoot dry matter accumulation and root number
of New Guinea impatiens increased by 737% and 106%, respectively,
as mean propagation DLI increased from 1.2 to 7.5 mol⋅m−^2 ⋅d−^1. Lopez
and Runkle (2006) also reported that petunia root number, root length,
and root and shoot dry mass increased from 17 to 36, 9.4 to 12.9 cm, and
452% and 47%, respectively, while height decreased from 6.3 to 4.1 cm,
as propagation DLI increased from 1.2 to 3.9 mol⋅m−^2 ⋅d−^1.
Increasing DLI during propagation has been reported to enhance sub-
sequent growth and development of cuttings (Lopez and Runkle 2008a;
Hutchinson et al. 2012). Lopez and Runkle (2008a) reported that time
to flower of petunia and New Guinea impatiens decreased from 50 to
29 d and from 85 to 70 d, respectively, as the DLI during cutting prop-
agation increased from 1.4 to 10.7 mol⋅m−^2 ⋅d−^1. In a separate study,
time to flower of angelonia and osteospermum was hastened by 23
and 19 d, respectively, as DLI during propagation increased from 1.2
to 12.3 mol⋅m−^2 ⋅d−^1 (Hutchinson et al. 2012). In summary, the general
recommendation is to provide a PPF between 200 and 400μmol⋅m−^2 ⋅s−^1
resulting in a DLI of 8–12 mol⋅m−^2 ⋅d−^1 (Currey et al. 2012) during Stage
3 of cutting propagation.
E. Toning (Stage 4)
The final stage of propagation (Stage 4) is commercially referred to
as “toning.” During this stage, the rooted cuttings are acclimated to
environmental and cultural conditions similar to those after transplant