Transpiration Capacity in Poinsettia Cuttings at Different Rooting Stages and the Development of a Cutting Coefficient for Scheduling Mist

Abstract

<jats:p>Rooting stage, transpiration capacity, and relative water content were measured in cuttings every 5 days for 25 days. Cell divisions in phloem parenchyma were evident between 5 and 10 days after sticking, organized subcuticular root primordia were present between 10 and 12 days, and roots emerged between 12 and 15 days. Transpiration was measured in poinsettia (<jats:italic>Euphorbia pulcherrima</jats:italic> Willd. ex Klotzsch `Freedom Dark Red') cuttings under light or dark conditions at increasing vapor pressure deficit (VPDair) levels during different stages of rooting. Transpiration capacity did not increase until roots emerged on the cuttings. Light had a significant impact on transpiration rates only after roots emerged. Light was more significant than VPDair for determining actual transpiration. Between visible rooting (15 days) and 25 days, increase in total root length was linear (<jats:italic>r</jats:italic><jats:sup>2</jats:sup> = 0.92) and significantly correlated with transpiration (<jats:italic>r</jats:italic><jats:sup>2</jats:sup> = 0.98). Transpiration capacity increased after visible rooting, but did not significantly increase under non-misted conditions until cuttings were well-rooted and had a total root length &gt;50 cm (18 days after sticking). Relative water content measured before and after entering the transpiration chamber confirmed that cuttings were only able to take enough water from the medium to continue sustained transpiration after 18 days. A cutting coefficient was developed from transpiration data to modify the misting interval for dynamic controlled misting. Greenhouse studies showed a 55% or greater reduction in water use with dynamic control compared to constant static or stepped down static control. Rooting performance was unaffected by misting interval. Foliar nutrition was significantly reduced in all cuttings after 7 days in the mist bench, but changes in foliar elemental content were not correlated with misting interval.</jats:p>

Effect of coconut (Cocos nucifera L.) water extracts on adventitious root development in vegetative propagation of Dracaena purplecompacta L.

“…may be slow to form adventitious roots and the cuttings disintegrate prior to the formation of functional roots (Rose and Pellett 1994;Stankova and Panetsos 1997;Voyiatzi et al 2002). Species where roots emerge rapidly are often categorized as 'easy to root' (Wilkerson et al 2005) in contrast to those more 'difficult to root' ones that require longer periods before emergence of roots (Tarrago et al 2005).…”

Timing of Macronutrient Supply during Cutting Propagation of Petunia

“…A decline in tissue nutrient concentration was also observed in poinsettia (Euphorbia pulcherrima Willd. ex Klotsch) after 7 d under mist, and this decline was not correlated with three different rates of water volume applied (Wilkerson and Gates, 2005). A decline in tissue nutrient concentration also occurred in poinsettias that did not have any water applied to foliage 13 d after sticking (Svenson and Davies, 1995).…”

“…Therefore, commercial fertilizer application early in propagation before root formation may be required to recharge leached nutrients from the substrate. Water-soluble fertilizer applications before root emergence may also facilitate foliar uptake of nutrients (Tukey et al, 1958) and reduce observed tissue nutrient declines during preliminary phases of propagation (Svenson and Davies, 1995;Wilkerson and Gates, 2005).…”

Surveying Changes in Sectional Tissue Nutrient Concentrations of Hibiscus acetosella ‘Panama Red’ during Adventitious Root Formation

“…Zinc and Mg were also lost from the upper stems (Table 1). Nutrient leaching typically occurs in cuttings under intermittent mist (Tukey, 1978;Wilkerson et al, 2005;Wott and Tukey, 1967). Although decreases in tissue nutrient concentration can also be due to dilution, this would require growth and expansion of the cutting (Blazich, 1988;Blazich et al, 1983;Svenson and Davies, 1995).…”