Gaura Lindheimeri Research Articles

Gaura lindheimeri

This datasheet on Gaura lindheimeri covers Identity, Distribution.

Methodology of Ornamental Value Evaluation for Landscape Perennial Planting on the Lack of Sunlight Space

With the aim of evaluating the ornamental quality of herbaceous flowering plants planted to improve the landscape in urban areas, this study established evaluation standards based on their growth and ornamental characteristics, measured differences in their growth under different environmental conditions and calculated their score based on the standards. Herbaceous flowering plants were divided, based on their growth characteristics, into four types - vertical, fan-shaped, semi-spherical and covering types. Measurement items that can express the ornamental characteristics of each plant such as shape, density and color were selected and an equation for calculation was obtained. Three species of each type were selected and changes in their ornamental characteristics under different shading conditions were measured for 7 months. The growth status of plants before and after treating shading was measured and their ornamental value was evaluated using the obtained equation. When the score of the ornamental value of Gaura lindheimeri in its natural habitat is 5points, its ornamental value in the 50% shading environment increased by 2.53 points, and that of Physostegia virginiana in the 80% shading environment decreased by 2.46 points. As such, the evaluation of the quality of green spaces based on the quantified ornamental value of plants is expected to be utilized in differentiating the value of green spaces in different urban spaces.

Comparison of Sole-source and Supplemental Lighting on Callus Formation and Initial Rhizogenesis of Gaura and Salvia Cuttings

Variability in outdoor daily temperatures and photosynthetic daily light integrals (DLIs) from early spring to late fall limits the ability of propagators to accurately control propagation environments to consistently callus, root, and yield compact herbaceous perennial rooted liners. We evaluated and compared the effects of sole-source lighting (SSL) delivered from red (R) and blue (B) light-emitting diodes (LEDs) to supplemental lighting (SL) provided by high-pressure sodium (HPS) lamps on herbaceous perennial cutting morphology, physiology, and growth during callusing and initial rhizogenesis. Cuttings of perennial sage (Salvia nemorosa L. ‘Lyrical Blues’) and wand flower (Gaura lindheimeri Engelm. and A. Gray ‘Siskiyou Pink’) were propagated in a walk-in growth chamber under multilayer SSL provided by LEDs with [R (660 nm)]:[B (460 nm)] light ratios (%) of 100:0 (R100:B0), 75:25 (R75:B25), 50:50 (R50:B50), or 0:100 (R0:B100) delivering 60 µmol·m−2·s–1 for 16 hours (total DLI of 3.4 mol·m−2·d−1). In a glass-glazed greenhouse (GH control), cuttings were propagated under ambient solar light and day-extension SL provided by HPS lamps delivering 40 µmol·m−2·s–1 to provide a 16-hour photoperiod (total DLI of 3.3 mol·m−2·d−1). At 10 days after sticking cuttings, callus diameter and rooting percentage were similar among all light-quality treatments. For instance, callus diameter, a measure of growth, of wand flower cuttings increased from an average 1.7 mm at stick (0 day) to a range of 2.7 to 2.9 mm at 10 days after sticking, regardless of lighting treatment. Relative leaf chlorophyll content was generally greater under SSL R75:B25 or R50:B50 than all other light-quality treatments. However, stem length of perennial sage and wand flower cuttings propagated under SSL R50:B50 at 10 days were 21% and 30% shorter and resulted in 50% and 8% greater root biomass, respectively, compared with those under SL. The herbaceous perennial cuttings propagated in this study under SSL R50:B50 were of similar quality or more compact compared with those under SL, indicating that callus induction and initial rooting can occur under LEDs in a multilayer SSL propagation system.

Plant selection for rain gardens: Response to simulated cyclical flooding of 15 perennial species

Plant selection for rain gardens can be complicated, as cyclic flooding and a gradient of moisture level are expected in the depression structure of a rain garden. However, few studies to date have quantified how plant establishment is affected by rain garden moisture dynamics. This study investigated tolerance of 15 candidate perennial species, which experienced flooding cycles consisting of 1-day and 4-day inundation and draining phases. In this study, detection of species suitability using survival and growth measurements coupled with the stress indicator (i.e. chlorophyll fluorescence) provided a valid framework for wider use in plant selection for rain gardens. The methodology is also confident in predicting the possible placing in different plant moisture zones. All species survived the cyclic flooding treatments and grew to their maximum. Photosynthesis and physical growth in only a few candidate species (e.g. Amsonia tabernaemontana var. salicifolia, Gaura lindheimeri, Sanguisorba tenuifolia ‘Purpurea’ and Thalictrum aquilegifolium) tended to be inhibited by treatments adopting 4-day cyclic flooding, whilst tolerance to 1-day cyclic flooding was clearly demonstrated in most species. Analysis suggests that most species assumed to withstand infrequent to periodic inundation, such as Iris sibirica, Filipendula purpurea and Miscanthus sinensis, are resilient species and are sensible for use in a wider range of rain garden moisture conditions from damp depression bottom to dry margin. Species assumed to be intolerant of inundation such as Gaura lindheimeri may be successful in the rain garden environment, but they are recommended for the dryer zones.

Ecophysiological and micromorphological characterization of green roof vegetation for urban mitigation

Urban greening helps to improve environment quality and human health thanks to the ability of plants to absorb greenhouse gases and remove significant amounts of air pollutants. Green roofs, providing vegetated surfaces in dense cities, can help to mitigate the negative effects of urban pollution. The present study aimed to evaluate the potential ability of fifteen green roof species (Lonicera pileata, Satureja repandens, Hypericum moserianum, Erigeron karvinskianus, Solidago praecox, Rudbeckia sullivantii ‘Goldsturm’, Filipendula purpurea, Filipendula vulgaris ‘Kahome’, Gaura lindheimeri, Campanula persicifolia, Veronica longifolia, Sedum spectabile, Origanum vulgare, Salvia nemorosa, and Achillea millefolium) to mitigate carbon dioxide (CO2) and urban pollutant concentration analysing the leaf physiological traits (gas exchange) and morphological structures (stomata, trichomes, epicuticular waxes and cuticular ornamentation) involved in pollutant removal. Furthermore, considering the important role of biogenic volatile organic compounds (BVOC) on the photochemical reactivity of the atmosphere, their species-specific emission was also assessed together with the derived ozone forming potential (OFP). Our results suggested that the potential mitigation capacity based on the investigated traits of the shrubs and herbaceous species was species-specific. The very low potential of all the tested species to form ozone indicated their suitability for urban planning programs.

First Report of the Rust Uromyces plumbarius on Gaura lindheimeri in California

First Report of the Rust <i>Uromyces plumbarius</i> on <i>Gaura lindheimeri</i> in California

Benzyladenine Increases Branching but Reduces Root Growth of Herbaceous Perennial Liners

The objective of this study is to evaluate the branching effect of benzyladenine (BA) on herbaceous perennial plants during the production of rooted cuttings (liners) and to examine and quantify the root growth of these liners using multiple methods of root evaluation. Five crops were studied: Agastache Clayt. Ex Gronov. ‘Purple Haze’, Gaura lindheimeri Engelm. &amp; A. Gray ‘Siskiyou Pink’, Lavandula ×intermedia Emeric ex Loisel. ‘Provence’, Leucanthemum ×superbum (Bergmans ex J.W. Ingram) Bergmans ex Kent. ‘Snowcap’, and Salvia ×sylvestris L. (pro sp.) ‘May Night’. After rooting but before transplant, BA was applied to rooted cuttings as four treatments: controls (0 mg·L−1), one application of 300 mg·L−1, two applications of 300 mg·L−1, or one application of 600 mg·L−1. Results varied by crop; all crops except Salvia had increased branching as measured as either increased lateral or basal branches and/or increased leaders at 3 to 4 weeks after initial treatment. Four crops showed reduced root growth, whereas Gaura was unaffected. Root dry weight was found to be highly correlated with root surface area and root volume. After transplant and growing out, branching of the finished plants was increased in Gaura and Lavandula, unaffected in Salvia and Leucanthemum, and decreased in Agastache. Treating rooted cuttings with BA before transplant increased branching but the effects were not long lasting, which suggests that additional applications at or after transplant may improve finished plant quality. Reductions in root growth noted in rooted cuttings did not affect the growth of finished plants. Chemical names: N-(phenylmethyl)-1H-purine-6-amine (benzyladenine, BA).

Quantity and Quality of Cuttings as Influenced by Stock Plant Nutrition of Herbaceous Perennials

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.

The effect of silicon foliar application on the development of Season ornamental plants. Part II: Argyranthemum frutescens 'Blazer Rose', Xerochrysum bracteatum 'Gold', Osteospermum ecklonis 'Grande Pink Blush' and Gaura lindheimeri 'Corinas Choice'

Recent research has proved that supplementary application of silicon, involved in plant tolerance against many stress factors, positively influences plant development improving the quality of ornamental plants. A two-factorial experiment involved four cultivars of ornamental plants: &lt;i&gt;Argyranthemum frutescens&lt;/i&gt; 'Blazer Rose', &lt;i&gt;Xerochrysum bracteatum&lt;/i&gt; 'Gold', &lt;i&gt;Osteospermum ecklonis&lt;/i&gt; 'Grande Pink Blush', and &lt;i&gt;Gaura lindheimeri&lt;/i&gt; 'Corinas Choice' The first experimental factor was the concentration of Actisil preparation being an equivalent of 60, 120, and 180 mg Si×dm&lt;sup&gt;-3&lt;/sup&gt;, applied three times by spraying, while the second one was the type of medium: peat substrate and peat substrate with sand. Actisil had a beneficial effect on the number of lateral shoots in all plants. The highest number of buds and inflorescences was determined in &lt;i&gt;Xerochrysum&lt;/i&gt; and &lt;i&gt;Osteospermum&lt;/i&gt; plants sprayed with 0.3% Actisil, and 0.2% Actisil in case of Argyranthemum and Gaura. The effect of medium type on plant growth depended on plant species. &lt;i&gt;Argyranthemum&lt;/i&gt; and &lt;i&gt;Osteospermum&lt;/i&gt; plants cultivated in the medium with sand showed inhibited growth, although medium type did not affect the growth of &lt;i&gt;Xerochrysum&lt;/i&gt;.

Effect of seawater aerosol on leaves of six plant species potentially useful for ornamental purposes in coastal areas

Aerosol marine strongly affects the growth and development of urban, garden and landscape plants. Few studies have focused on the effects of sodium chloride on plant growth, which is usually applied through irrigation water or substrate media. Even less information is available on the eco-physiological responses of plants to marine aerosol. The aim of this work was to evaluate the physiological responses of different plant species to seawater nebulisation treatments. Plant species that are commonly used along sea fronts were selected as being potentially useful for the study. Plants were bought from a local nursery and included: Acacia cultriformis, Callistemon citrinus, Carissa edulis microphylla, Gaura lindheimeri, Jasminum sambac, Westringia fruticosa. Plants were placed in a randomised block design in a greenhouse and treated for 5 s with seawater or irrigation water (control) using a nebulisation system once every day for 77 days. In the seawater aerosol-treated plants, the following parameters were monitored: leaf area damage using an image analysis tool, chlorophyll a fluorescence, hormonal changes and cation concentrations. We found that seawater aerosol treatment leads to: (i) leaf necrosis; (ii) chlorophyll loss; and (iii) a decrease in chlorophyll a fluorescence. The ion exclusion mechanism might have played a key role in the tolerance mechanism. Ethylene production increased in all species as a good biomarker and the strong increase in ABA content in the sensitive species may play a role in the plant's adaptation to stress. The chlorophyll a fluorescence parameters such as Fv/Fm and the performance index were the most affected by treatment and led to a screening sensitive ( A. cultriformis and G. lindheimeri) and tolerant ( W. fruticosa) species.

EFFECT OF SALT SPRAY ON SIX ORNAMENTAL SPECIES

Marine aerosol strongly affects the growth and development of urban, garden and landscape plants. The few studies available are focused on the sodium chloride effect on plant growth, usually applied in the irrigation water or substrate media. No information is available on responses of plants to marine aerosol. Therefore, the aim of this work was to evaluate the physiological responses of some species to sea water nebulisation treatment. Species were selected among those that are commonly used along the seaside and among those that might be potentially used. Plants were bought from local nursery and species used were: Acacia cultriformis, Callistemon citrinus, Carissa edulis microphylla, Gaura lindheimeri, Jasminum sambac, Westringia fruticosa. Plants were placed in randomised block in greenhouse and treated once a day for 5-10 seconds with sea water or irrigation water (control) using a nebulisation system. The effect of marine aerosol was studied by monitoring leaf chlorophyll a fluorescence, chlorophyll content, and leaf area damage by image analysis. Results were different among species. The effect of treatment was represented by leaf necrosis, reduction of chlorophyll and chlorophyll a fluorescence. The resistant species was Westringia fruticosa, while the intolerant species were A. cultriformis and G. lindheimeri. Intermediate behaviour was observed in the other species.

IDENTIFYING THE STORAGE POTENTIAL OF UNROOTED SHOOT-TIP CUTTINGS OF EIGHT ORNAMENTAL SPECIES

Unrooted cuttings are typically produced in tropical climates and shipped via air freight to North American and European markets. Shipments usually occur during 3 to 4 days per week, since customers do not desire to receive cuttings on Friday, Saturday or Sunday. Thus, the number of days per week to actually harvest cuttings is limited unless those cuttings can be held in storage prior to shipment. The objective of this project was to identify the storage potential of the following eight ornamental species: Artemisia × hybrida, Angelonia angustifolia, Diascia × hybrida, Gaura lindheimeri, Ipomea batatas, Nemesia × hybrida, Solenostemon scutellarioides and Verbena × hybrida. Cuttings were harvested from stock plants and placed at 0, 5, 10, 15 or 20°C for 2, 4, 6 or 8 days and then placed into a simulated shipping environment for two days. A control group of cuttings was not stored and only received the simulated shipping treatment. Roots and shoots were visually rated after three weeks in propagation. Angelonia and Solenstemon were the least cold tolerant species, e.g., they had damaged tissue after 2 days storage at 0°C. Angelonia, Diascia, Gaura and Nemesia were the least heat tolerant species, e.g., they did not perform well in propagation following for more than 2 days of storage at 20°C. While the optimal temperature varied from 5 to 15°C for each species, all species performed well at this temperature range following 2 to 4 days of storage. This work suggests that cutting suppliers can harvest cuttings every day of the week and ship the cuttings only 1 to 2 days per week. This creates the opportunity for companies to minimize the number of trained cutters that need to be employed and to minimize transportation costs by consolidating orders harvested throughout the week into a minimum number of shipments.

First Report of Botrytis Blight Caused by Botrytis cinerea on Gaura lindheimeri in Italy

Gaura lindheimeri (wand flower) is a perennial plant belonging to the Onagraceae family that is used for perennial borders in xeric and mesic landscapes. It produces flowers floating above the plant like small, dancing butterflies. This plant is becoming popular in the Albenga Region (northern Italy) where white and rose varieties are grown as potted plants. In January of 2008, 5-month-old 'Whirling Butterflies' plants grown in plastic pots (14 cm in diameter) in the open field started showing symptoms of a previously unknown blight. When the disease developed, temperatures ranged between 3 and 17°C (average 9°C) and average relative humidity was 64%. Small, brown spots appeared on the basal portion of leaves first, eventually spreading to cover entire leaves. Subsequently, the pathogen developed abundant, soft gray mycelium on affected leaf tissue. Severely infected leaves eventually became completely rotten and desiccated. Sixty percent of plants were affected by the disease. Tissues were excised from diseased leaves, immersed in a solution containing 1% sodium hypochlorite for 10 s, and then cultured on potato dextrose agar (PDA) medium. The fungus produced abundant mycelium on PDA medium when incubated under constant fluorescent light at 22 ± 1°C. The conidia were smooth, hyaline, globoid, measuring 11.8 to 9.4 × 8.3 to 6.6 (average 10.7 × 7.4) μm, and are similar to those described for Botrytis cinerea. The identity of the pathogen was also confirmed by the production of numerous sclerotia on PDA plates incubated for 20 days at 8 ± 1°C. Sclerotia were dark, irregular, and measured 3 to 4 × 2 to 3 mm. The fungus was identified as B. cinerea on the basis of these characters (1). Pathogenicity tests were performed by spraying leaves of healthy, potted 8-month-old G. lindheimeri 'Whirling Butterflies' plants with a 105 conidia/ml suspension. Plants sprayed with water only served as controls. Five plants per treatment were used. Plants were covered with plastic bags for 6 days after inoculation and maintained in a growth chamber at 20 ± 1°C. The first foliar lesions developed on leaves 5 days after inoculation, whereas control plants remained healthy. B. cinerea was consistently reisolated from these lesions. The pathogenicity test was completed twice. To our knowledge, this is the first report of the presence of B. cinerea on G. lindheimeri in Italy. The economic importance of this disease will increase with the increased cultivation of this species. Reference: (1) H. L. Barnett and B. B. Hunter. Illustrated Genera of Imperfect Fungi. Burgess Publishing Company, Minneapolis, MN, 1972.

Epigenetic variation in tissue cultured Gaura lindheimeri

High levels of variability were observed in tissue cultured Gaura lindheimeri genotypes when flowered in situ. Tissue culture treatments for chromosome doubling (colchicine: 0, 0.25, 1.25 mM; trifluralin: 0, 15, 30 μM) were all highly variable for morphological traits. Experiment No. 1 tested the tissue culture protocols used. In the first control (C1), plantlets were subcultured continuously. Nodes were excised and placed on solid medium for the second control (C2). In the third control (C3), nodes were excised and put in liquid medium for 24 h at room temperature. The fourth control (C4) was the same as the third control except liquid cultures were moved to 4°C for 48 h after treatment at room temperature. Experiment No. 2 examined the stability of the variation. Representative plants with different traits were selected for clonal propagation and grown in a replicated trial in the greenhouse. Several morphological traits (flower size, leaf length:width ratios, petal length:width ratios, and flower color) were measured. All of the controls had as much variability as the treated plants. Flower size of the first flower for plant number 01G-02 was significantly different in C1 compared with C3, but not with C2 and C4. Plant number 443-1 (white) was more stable in the replicated trial for the flower size than plant number 01G-02 (pink). All traits measured for plant number 01G-02 were unstable; most flower colors and patterns reverted back to the original color of the non-tissue cultured plants. The somaclonal variation observed was epigenetic in nature, indicating changes in DNA methylation.

Effect of Temperature and Host Plant on Survival and Development of Altica litigata Fall

Altica litigata Fall (Coleoptera: Chrysomelidae) is oligophagus, feeding on numerous plants in the Lythraceae and Onagraceae families which include weeds and cultivated plants, such as primroses (Oenothera spp.) often found in commercial nurseries. Adult A. litigata are important pests of crapemyrtles (Lagerstroemia spp.; Lythraceae) grown in container nurseries in the southern United States. The severity of the pest problem attributed to feeding by these beetles has increased substantially during the past decade. Whereas commonly recommended pesticides easily control these beetles, knowing when to time applications to avoid large defoliation events could focus scouting efforts and prevent economic loss. The objective of our research was to define more closely the relationship between temperature, host plant and development of A. litigata to permit prediction of damaging stages of the beetle on landscape and nursery plants. A. litigata completed development between 15 and 30°C on six weedy or cultivated hosts: Gaura lindheimeri Engelman &amp; A. Gray ‘Siskyou pink’, G. lindheimeri ‘Corries gold’, G. lindheimeri ‘Whirling butterflies’, Oenothera speciosa Nutt., Oenothera laciniata J. Hill and Oenothera missourensis_Simms. Development was optimal on Oenothera spp. Duration of development from eclosion to adult emergence ranged from 13.3 d at 30°C on O. speciosa to 64.0 d at 15°C on G. lindeimeri ‘Whirling butterflies.’ Duration of egg development ranged from 4.5 d at 30°C to 15.8 d at 15°C. The relationship between temperature and rate of development was expressed as a linear thermal unit model for each stage and for combined larval/pupal development. Development parameters varied with host plant. Averaged among the six hosts, larval and pupal development required 237.3 degree-days (DD) above a threshold of 9.2°C. Eggs required 87.5 DD above a 9.8°C threshold. Observation of beetles or feeding injury on indicator plants such as weedy or cultivated Oenothera spp. in late winter or early spring can alert nursery or landscape managers to anticipate a new generation within 300–400 DD above the approximate 10°C developmental threshold used for many DD calculator models for landscape and nursery pests.

Efficacy of Colchicine and Trifluralin in Creating In Vitro Autotetraploid Gaura lindheimeri Engelm. and Gray

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.

Statistical discrimination between pollen tube growth and seed set in establishing self incompatibility in Gaura lindheimeri 1

The University of Minnesota Gaura breeding program is developing USDA Z3-4 winter-hardy genotypes via interspecific hybridization of G. lindheimeri (Z5-6) and G. coccinea (Z2-4). Prior to commencing interspecific hybridization, the reproductive barriers operating in both parental species need to be characterized. The objective of this research was to determine the type and stability of reproductive barriers operating in G. lindheimeri by statistical comparisons between pollen tube growth and seed set in a full-sib diallel. Slowed or aborted pollen tube growth in the style indicated the presence of a gametophytic self incompatibility (SI) system. A statistical method, female (FCC) and male (MCC) coefficients of crossability, was used to verify that a stable SI system was operating and that other reproductive barriers were present. Several genotypes also expressed stage-specific inbreeding depression and incongruity. The simple linear regression equation for FCC/MCC, using pollen tube growth, was Y = 0.0124 + 0.974X, which was much closer to the expected Y = 0.0 + 1.0X (indicating a stable SI system) than the equation for seed set, Y = 0.012 + 0.910X. Using pollen tube length, both general combining ability (GCA) and specific combining ability (SCA) values were highly significant for G. lindheimeri (P ≤ 0.001). Histograms were used to delineate cut-offs to identify intra-incompatible/inter-compatible classes and S allele groups. Four possible classes were identified, but further research is needed to verify S allele genotypes.

Determination of Optimum Fertilizer Concentration and Corresponding Substrate Electrical Conductivity for Ten Taxa of Herbaceous Perennials

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. &amp; Savat.`Purpurkerze', Campanula carpatica Jacq. `Deep Blue Clips', Coreopsis verticillata L.`Golden Gain', Gaura lindheimeri Engelm. &amp; 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.

Daily Light Integral Affects Flowering and Quality of Greenhouse-grown Achillea, Gaura, and Lavandula

The growth and development of Achillea ×millefolium L. `Red Velvet', Gaura lindheimeri Engelm. &amp; 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 &lt;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.

Plant Growth Retardant Application to Achillea x ‘Coronation Gold’ and Gaura lindheimeri ‘Corrie's Gold’

Abstract In two experiments conducted under nursery conditions in 1998 and 1999, the herbaceous perennials, Achillea x ‘Coronation Gold’ and Gaura lindheimeri ‘Corrie's Gold’ were treated with one of four plant growth retardants (PGRs): B-Nine at 2,500, 5,000, or 7,500 ppm; Bonzi at 33, 66, or 99 ppm; Cutless at 50, 100, or 150 ppm; Pistill at 500 or 1,000 ppm; or left untreated. Only Pistill delayed flowering of achillea while Bonzi and Cutless accelerated flowering of achillea. In 1998, B-Nine provided little growth suppression of achillea; however in 1999, when plants were pruned just prior to treatment and thus less reproductively developed, height at the most effective concentration of 7,500 ppm was reduced 33% compared to untreated plants over the duration of the experiment. At the most effective concentration of 99 ppm, Bonzi retarded growth 15% and 31%, over the duration of the experiment, while Cutless at 150 ppm suppressed growth 21% and 46% in 1998 and 1999, respectively, compared to an untreated control. Plants treated with the most effective concentration of Pistill were 13% and 21% shorter than non-treated plants over the duration of the experiment in 1998 and 1999, respectively. However, in 1998 quality ratings of Pistill-treated plants were lower than for control plants, and the duration of control was shorter than with B-Nine, Bonzi, or Cutless in 1999. Only Cutless provided consistent growth suppression of gaura; plants treated with the most effective concentration of 150 ppm were an average of 19% smaller at 60 days after treatment (DAT) in 1998 and 13% smaller than control plants from 28 to 70 DAT in 1999. B-Nine and Pistill provided more transitory control. In 1999, the most effective concentration of B-Nine suppressed growth 9% from 28 to 56 DAT. Plants treated with the most effective concentration of Pistill of 500 ppm averaged 23% smaller at 14 and 28 DAT than control plants. Application of Pistill delayed flowering 11 to 13 days in 1998.