Irrigation Affects Landscape Establishment of Burford Holly, Pittosporum, and Sweet Viburnum

Abstract

<jats:p> <jats:italic>Ilex cornuta</jats:italic> Lindl. &amp; Paxt. ‘Burfordii Nana’ (dwarf burford holly), <jats:italic>Pittosporum tobira</jats:italic> [Dryand]. ‘Variegata’ (pittosporum), and <jats:italic>Viburnum odorotissimum</jats:italic> Ker Gawl. (sweet viburnum) were transplanted into field plots in an open-sided, clear polyethylene-covered shelter to evaluate growth, aesthetic quality, and establishment rates in response to 2-, 4-, or 7-d irrigation frequencies. Establishment was delayed 1 to 2 months for <jats:italic>I. cornuta</jats:italic> ‘Burrford Nana’ irrigated every 7 d compared with 2- and 4-d frequencies; however, growth and aesthetic quality were similar among treatments. Plants irrigated every 7 d also had higher cumulative water stress levels. Leaf area, shoot dry weight, and total biomass increased among <jats:italic>P. tobira</jats:italic> ‘Variegata’ and <jats:italic>V. odorotissimum</jats:italic> irrigated every 2 d. <jats:italic>Pittosporum tobira</jats:italic> ‘Variegata’ and <jats:italic>V. odorotissimum</jats:italic> irrigated every 2 d also had greater canopy size and root dry weight, respectively. Neither cumulative water stress nor establishment was affected by irrigation frequency for either species.</jats:p>

Posttransplant Irrigation Frequency Affects Growth of Container-grown Sweet Viburnum in Three Hardiness Zones

“…Similarly, differences in GI for shrubs irrigated using the 2-and 4-d frequencies in Zone 10 b were not significant at 28, 52, or 104 WAP (Table 1). These results were different from those reported by Scheiber et al (2007), probably as a result of the influence of rainfall events in our study (Fig. 1) or climatic differences.…”

“…Twenty-five percent of sweet viburnum planted in Zone 10a between Sept. 2004 and June 2005 that were irrigated every 8 d were dead by 52 WAP compared with 0% and 8.3% of the plants irrigated every 2 and 4 d, respectively. These results were similar to those reported by Scheiber et al (2007), in which more than half the sweet viburnum irrigated every 7 d under a rainout shelter died by 16 WAP. Therefore, 8-d irrigation treatment was removed from the study in Zone 10b because it resulted in too many dead plants for most landscape applications.…”

“…Paine et al (1992) (Table 1). These results are supported by the findings of Scheiber et al (2007), which reported that sweet viburnum plants grown in a rainout shelter in Apopka, FL (Zone 9b) and irrigated every 2 d were larger than plants irrigated every 4 or 7 d with 9 L of water per irrigation event. Shrubs irrigated every 2 d were larger than those irrigated every 8 d when planted in Zone 9a; however, there was no difference in GI for plants irrigated every 2 and 4 d (Table 1).…”

“…Irrigation frequency also had no significant effect on sweet viburnum quality at any location at 28, 52, or 104 WAP (data not shown) despite a large variation in the total volume of irrigation applied (mean volume of 197, 98, and 49 L for shrubs watered every 2, 4, and 8 d, respectively). These results differ from those of Scheiber et al (2007), who reported that the aesthetic quality of sweet viburnum was reduced when irrigated every 7 d when compared with plants watered every 2 or 4 d. However, the study by Scheiber et al (2007) was conducted under a rainout shelter, thereby eliminating the effect of rainfall events. In our study, plants received irrigation as a supplement to natural rainfall events (Fig.…”

“…& Paxt. 'Burfordii Nana', and Pittosporum tobira [Dryand] 'Variegata' grown in a rainout shelter required irrigation for a period of 16 to 20 weeks after planting (WAP) to ensure successful establishment in the landscape (Scheiber et al, 2007).…”