applied irrigation volume) of Gaura lindheimeri and Phlox paniculata decreased with increasing volumetric water content (WUE a = 3.65 to 8.2 Θ set point + 4.4 Θ set point 2 ). Data points were the mean of two replications with bars representing se s
Stephanie E. Burnett and Marc W. van Iersel
Grace M. Pietsch and Neil O. Anderson
Gaura lindheimeri is a diploid herbaceous perennial species native to Texas and Louisiana and winter hardy only to USDA hardiness zone 5. A potential source of winter hardiness is G. coccinea Pursh., a polyploid widely distributed in North America; of particular interest are autotetraploid populations of G. coccinea from Minnesota. To facilitate interspecific hybridization, a tetraploid G. lindheimeri would be advantageous. Two G. lindheimeri genotypes, MN selections 443-1 and 01G-02, were treated with two different antimitotic agents at two concentrations, trifluralin—15 and 30 μm and colchicine—0.25 and 1.25 mm, along with appropriate controls, to determine the frequency of chromosome doubling. Two-node stem sections were treated for 12, 24, or 48 h and then rooted and grown to flowering. Pollen diameter was measured as an indicator of chromosome doubling in cell layer LII, and morphologic characteristics (days to flower, flower size, plant height, inflorescence height, and plant width) were recorded for all plants. Chromosome doubling was not observed in any plant treated with trifluralin. Based on pollen diameter, genotype 443–1 only had chromosome doubling in the colchicine 1.25 mm concentration when treated for 12 h. All durations of colchicine at 1.25 mm were successful for genotype 01G-02 as well as a small percent treated with colchicine at 0.25 mm treated for 48 h. Autotetraploid plants (2n = 4x = 28) had larger flowers in both genotypes, and autotetraploid derivatives of genotype 01G-02 flowered earlier and were taller than diploid plants. Conformation changes from three-lobed to four-lobed pollen grains were observed when pollen diameter approached that expected of 2n pollen. Visual screening of pollen for conformation changes can quickly determine if chromosome doubling in cell layer LII has occurred. With the autotetraploid G. lindheimeri derived from colchicine application, crosses can be performed with autotetraploid G. coccinea to introgress cold tolerance. Additional breeding can also be done at the tetraploid level to develop new autotetraploid cultivars of G. lindheimeri.
Neil Anderson, Lee Klossner, Neal Eash, Vincent Fritz, Minnie Wang, Stephen Poppe, Judith Reith-Rozelle, David Wildung, Shengrui Yao, Patricia Johnson and Barbara E. Liedl
throughout North America—particularly polyploids—additional adaptive traits such as tolerance of heat and cold tolerance, extremes in soil pH ranges, and drought are also prevalent in the gaura genome ( Anderson et al., 2003 ). Gaura lindheimeri Engelm
Mara Grossman, John Freeborn, Holly Scoggins and Joyce Latimer
branching of the finished liners (Stage 4). Materials and Methods Five plant species were studied: Agastache ‘Purple Haze’, Gaura lindheimeri ‘Siskiyou Pink’, Lavandula × intermedia ‘Provence’, Leucanthemum × superbum ‘Snowcap’, and Salvia
Yan Chen, Regina P. Bracy, Allen D. Owings and Joey P. Quebedeaux
Use of controlled-release fertilizers (CRF) has been recommended to the landscape service industry as a best management practice for establishing landscape plants. However, application practices vary considerably among professionals and recommendations are lacking for the appropriate type (tablet vs. granular), application rate, and timing of CRF to establish herbaceous perennials. In this study, cigar plant (Cuphea ignea), daylily (Hemerocallis ‘Stella de Oro’), gaura (Gaura lindheimeri ‘Siskiyou Pink’), lantana (Lantana camara ‘New Gold’), mexican heather (Cuphea hyssopifolia), purple coneflower (Echinacea purpurea), and rudbeckia (Rudbeckia fulgida ‘Goldsturm’) were fertilized with granular CRF (GF) 15N–3.9P–10K (8 to 9 month) at 0, 1, 2, or 4 lb/1000 ft2 nitrogen (N) at transplant (no fertilization, GF1, GF2, and GF4, respectively), a split application of GF with 1 lb/1000 ft2 N applied at transplant and 1 lb/1000 ft2 N applied 5-months later (GF2-split), or tablet CRF 16N–3.5P–10K (8 to 9 months) at two tablets per plant (7.5 g) at transplant (TF2). Plant size and visual quality (VQ) at 5 months after transplant (MAT) were improved by fertilization for all perennials except ‘Stella de Oro’ daylily. Compared to GF2, GF4 improved the growth of perennials of larger size and greater biomass production (i.e., cigar plant), but did not further improve their VQ. All perennials grown with TF2 had similar size and quality as those grown with GF2 at 5 MAT. At 15 MAT, no difference was found among fertilizer treatments for surviving perennials except cigar plant. Split application (GF2-split) did not improve overwinter survival or second-year plant growth and quality for most species when compared with GF2. On the basis of these results, we recommend applying two tablets (7.5 g) of 16N–3.5P–10K per plant at transplant to establish the perennials tested in this study.
W. Garrett Owen and Roberto G. Lopez
flower ( Gaura lindheimeri Engelm. and A. Gray ‘Siskiyou Pink’) were received from a commercial cutting supplier (Darwin Perennials, Ball Horticultural Co., West Chicago, IL). Species were selected according to the survey conducted by Owen and Lopez
Christina M. Twardowski, Jaime L. Crocker, John R. Freeborn and Holly L. Scoggins
Some popular garden perennials yield low numbers of viable cuttings per stock plant or produce cuttings that are slow to root, preventing propagators from meeting demand for rooted liners. We quantified the effects of a range of nitrogen (N) rates from 0 to 300 mg·L−1 N applied to stock plants on the number of cuttings (yield), rooting percentage, and subsequent root development of cuttings. Species studied include ‘Siskiyou Pink’ gaura (Gaura lindheimeri), ‘Pixie Star’ dianthus (Dianthus alpinus), perovskia (Perovskia atriplicifolia), and ‘Mainacht’ salvia (Salvia ×sylvestris). We found 100 to 150 mg·L−1 N to be the best rates for producing quality rooted cuttings. Little benefit was obtained from the higher rates, and the 0- and 50-mg·L−1 N treatments produced the lowest number of potential cuttings across all species.
D. Bradley Rowe
Accelerating growth of nursery stock can produce marketable plants in less time, thus potentially increasing profits. The primary objective of this study was to compare adventitious rooting and initial growth of cuttings of three perennials species in response to slow-release fertilizer incorporated into the propagation media. The experiment was a split-plot consisting of four blocks, nine nutrient treatments, three species, and four cuttings per replication within each block-nutrient, species treatment. Treatments consisted of Nutricote 13-13-13 Type 180 and Nutricote 18-6-8 Type 180 incorporated into the rooting media, each at 3, 6, 9, and 12 g·L-1, and a control with no Nutricote. Species studied were Artemisia ludoviciana `Valerie Finnis', Gaura lindheimeri `Whirling Butterflies', and Nepeta ×faassenii `Six Hills Giant'. There were of 144 cuttings per species for a total of 432 cuttings. Fertilizer treatments did not influence rooting percentage, and no significant differences were found between the two formulations of fertilizer for top growth, root growth, rooting percentage, or root number. However, regardless of formulation or rate, the eight fertilizer treatments resulted in greater top and root dry weights when compared to the control. Top and root dry weight increased linearly within both fertilizer formulations.
Holly L. Scoggins
Little taxa-specific information is available regarding the nutrition needs of container-grown herbaceous perennials. The goal was to determine optimum fertilizer concentrations and corresponding substrate testing values for greenhouse production of 10 taxa. Astilbe chinensis (Maxim.) Franch. & Savat.`Purpurkerze', Campanula carpatica Jacq. `Deep Blue Clips', Coreopsis verticillata L.`Golden Gain', Gaura lindheimeri Engelm. & Gray, `Siskiyou Pink', Heucherasanguinea Engelm. `Mt St. Helens', Lamium maculatum L. `White Nancy', Penstemon ×hybridus Hort. `Sour Grapes', Perovskia atriplicifolia Benth. `Longin', Salvia nemerosa L. `Blue Hill', and Veronica × Hort. `Goodness Grows' were grown for 10 weeks with 15N–7P–14K at four rates (50, 150, 250, and 350 mg·L–1 N) of constant liquid feed. Substrate pH and soluble salts levels were measured weekly using the pour-through extraction method. In analysis of all taxa, most effects [quality, shoot dry weight, pH and electrical conductivity (EC)] varied by rate × taxa. Though higher levels of fertilizer produced the largest plants in some cases, satisfactory quality was also attained with a lower rate. Quality and pH were negatively correlated for a few genera but most showed no relationship. Results of this study indicate not all taxa tolerate increased fertilizer levels and that the herbaceous perennials studied could be grouped by nutritional needs. Furthermore, target ranges for EC can be developed based on dry mass and quality ratings.
Beth A. Fausey, Royal D. Heins and Arthur C. Cameron
The growth and development of Achillea ×millefolium L. `Red Velvet', Gaura lindheimeri Engelm. & Gray `Siskiyou Pink' and Lavandula angustifolia Mill. `Hidcote Blue' were evaluated under average daily light integrals (DLIs) of 5 to 20 mol·m-2·d-1. Plants were grown in a 22 ± 2 °C glass greenhouse with a 16-h photoperiod under four light environments: 50% shading of ambient light plus PPF of 100 μmol·m-2·s-1 (L1); ambient light plus PPF of 20 μmol·m-2·s-1 (L2); ambient light plus PPF of 100 μmol·m-2·s-1 (L3); and ambient light plus PPF of 150 μmol·m-2·s-1 (L4). Between 5 to 20 mol·m-2·d-1, DLI did not limit flowering and had little effect on timing in these studies. Hence, the minimum DLI required for flowering of Achillea, Gaura and Lavandula must be <5 mol·m-2·d-1, the lowest light level tested. However, all species exhibited prostrate growth with weakened stems when grown at a DLI of about 10 mol·m-2·d-1. Visual quality and shoot dry mass of Achillea, Gaura and Lavandula linearly increased as DLI increased from 5 to 20 mol·m-2·d-1 and there was no evidence that these responses to light were beginning to decline. While 10 mol·m-2·d-1 has been suggested as an adequate DLI, these results suggest that 15 to 20 mol·m-2·d-1 should be considered a minimum for production of these herbaceous perennials when grown at about 22 °C.