Purple Pride Research Articles

Influence of type and concentration of sugars, supplemented with 8-hydroxyquinoline sulphate, on the vase life of waxflower

AbstractA study was conducted to test the effect of 58.5 mM maltose, glucose, fructose, galactose and sucrose, and sucrose concentrations of 14.6, 29.2, 58.5 and 117.0 mM supplemented with 200 mg L-18-hydroxyquinoline sulphate (HQS) on the vase life and stem fresh weight changes in waxflower (Chamelaucium Desf.). The effect of the interaction between sucrose and HQS concentrations on the vase life of the cultivar ‘Alba’ was also investigated. All the types of exogenous sugar significantly increased the vase life of flowers, but decreased the vase life of leaves of waxflower cultivars compared with the deionized water controls, except the leaves of ‘Lady Stephanie’, ‘Purple Pride’ and ‘Mullering Brook’. The flower vase life of almost all the cultivars treated with sucrose was not significantly different from the life of the cultivars kept in fructose and glucose, except ‘Laura Mae Pearl’, whose flower vase life in sucrose was significantly lower (9.7%) than in fructose. By contrast, the vase life of flowers of the cultivars treated with sucrose was longer than of those in maltose and galactose. At sucrose concentrations of up to 117.0 mM coupled with 200 mg L-1HQS, the flower vase life of six out of eight cultivars significantly increased, except in ‘Laura Mae Pearl’ and ‘Mullering Brook’, whose flower vase life was maximized at the concentrations of 29.2 and 58.5 mM respectively, while the vase life of their leaves decreased. Sucrose concentrations from 14.6 to 29.2 mM coupled with 50 mg L-1HQS maximized vase life for both the flowers and leaves of ‘Alba’. Cultivars with a longer vase life of flowers maintained stem fresh weight above the initial stem fresh weight longer.

Effects of postharvest methyl jasmonate treatments against Botrytis cinerea on Geraldton waxflower (Chamelaucium uncinatum)

Cut Geraldton waxflower (Chamelaucium uncinatum Schauer) flowers are often infected with Botrytis cinerea. Release of infection from quiescence can cause ethylene production by invaded host tissues and result in flower abscission. Postharvest floral organ abscission is a major problem for the commercial waxflower industry. Methyl jasmonate (MeJA) occurs naturally in plant tissue and has a signalling role in eliciting induced systemic resistance against disease. MeJA treatments have been shown to suppress B. cinerea infecting cut rose flowers. The present experiments investigated the potential of exogenous MeJA treatments for B. cinerea management on harvested waxflower. MeJA treatments of 10 and 100 µL liquid MeJA/L of air applied to cv. Purple Pride and 1 µL MeJA/L to cv. Mullering Brook gave reductions in disease severity for uninoculated stems. However, concentrations of 100 µL MeJA/L applied to Purple Pride in addition to 1 and 10 µL MeJA/L applied to Mullering Brook increased the incidence of floral organ fall. Flower abscission upon treatment with MeJA may be due to induced systemic resistance-associated upregulation of ethylene biosynthesis. MeJA treatments had no direct effect on B. cinerea hyphal elongation in vitro. Collectively, these results show that while MeJA treatment may elicit defence in waxflower against Botrytis, the chemical also causes floral organ fall. Thus, exogenous MeJA treatments do not have potential for B. cinerea management on harvested waxflower.

Variation in ethylene-induced postharvest flower abscission responses among Chamelaucium Desf. (Myrtaceae) genotypes

Postharvest flower abscission is an ethylene-mediated process that can reduce the marketability of cut Chamelaucium Desf. (Myrtaceae) flowers. The sensitivity of 51 Chamelaucium cut flower genotypes to ethylene was evaluated. Sensitivity varied among genotypes both between and within different species and crosses. Chamelaucium uncinatum × Chamelaucium micranthum cv. ‘Sweet Georgia’ and C. uncinatum cvv. ‘Early Nir’, ‘Paddy’s Late’, ‘Purple Pride’, ‘CWA Pink’ and ‘Early Hard’ flowers were highly sensitive to ethylene. These genotypes shed 10% of their flowers in response to a 12 h treatment with <0.01 μl l −1 ethylene at 20 °C. In contrast, C. megalopetalum ‘Winter White’ and ‘Iceberg’ flowers were insensitive to ethylene even at 100 μl l −1 for 12 h at 20 °C. Sensitivity to ethylene varied between harvests during the flowering season and for the same genotypes harvested from different farms. Sensitivity of C. uncinatum cv. ‘Purple Pride’ flowers to treatment with 1 μl l −1 ethylene also decreased towards the end of vase life in association with slight dehydration. Variation in ethylene-induced abscission responses highlights the need to screen flowers from multiple harvests and varying growing conditions when assessing ethylene sensitivity. Screening genotypes for ethylene sensitivity should facilitate selection of Chamelaucium species with greater durability for export handling.

Sensitivity of Geraldton waxflower to ethylene-induced flower abscission is reduced at low temperature

SummaryExposure to ethylene gas elicits flower abscission from cut stems of Geraldton waxflower (Chamelaucium uncinatum Schauer). Ethylene response rates in plants are mediated by temperature. At 20°C, flower abscission from waxflower ‘Purple Pride’ occurred upon 12 h exposure to 1 µ11–1 ethylene. This ethylene treatment did not cause flower abscission at either 10 or 2°C. Moreover, flowers held at 2°C were insensitive to 48 h exposure to 1, 10 and 100 µ11–1 ethylene. However, increasing the duration of treatment with 1 µ11–1 ethylene at 10 and 2°C to 48 and 144 h, respectively, induced flower abscission. When flowers were held at 20°C in air without exogenous ethylene following continuous exposure to 1 µ11–1 ethylene at 2°C, the duration required to elicit flower abscission was reduced from 144 to 72 h. Collectively, these responses show that maintaining harvested waxflower at low temperature (e.g. 2°C) is an effective means to minimise ethylene-mediated flower abscission.

Geraldton wax (Chamelaucium uncinatum) flowers—looking beneath the epidermis

Chamelaucium uncinatum Schauer. (Geraldton wax) is well known as a garden and cut-flower species in Western Australia. The location of pigmented cells and the shape of the epidermal cells that interact with incident light can affect flower colour. This study examined the location of pigments within petals of three C. uncinatum cultivars, 'Purple Pride', 'CWA Pink' and 'Alba', which represent the range of colours found in this species. The white cultivar ('Alba') lacked coloured pigments in the petals while the pink ('CWA Pink') and purple ('Purple Pride') cultivars had pigmented vacuoles in petal epidermal and mesophyll cells. A waxy coating was present on petal epidermal cells of all cultivars and cells of the adaxial epidermis were found to be conical. Patterns in petals of 'CWA Pink' and 'Purple Pride' were due to cultivar-specific location of pigments.

Seasonal Variation in Nutrient Status of Australian Waxflowers

Seasonal fluctuations in the concentrations of 12 nutrients were assessed over 3 years for Chamelaucium uncinatum cultivars Alba and Purple Pride and for Chamelaucium hybrid (C. floriferum × C. uncinatum) known locally as Walpole wax. The plantings were located in the Mount Lofty Ranges, Lower South East and Lower Murray regions of South Australia. Tips of stems, 25–40 mm long, were collected on a monthly basis. The nutrient data were used to identify the most suitable time for tissue analysis; to determine the magnitude of the differences in nutrient composition between cultivars; and to determine the correlations between nutrients. The effect of the sampling error was also determined. The seasonal decrease in concentrations of nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), and sulfur (S) corresponded with vegetative flushing (growth dilution effect). Concentrations of the variably mobile nutrients copper (Cu) and zinc (Zn) were unstable, particularly during autumn–winter. Concentrations of phloem immobile nutrients calcium (Ca), boron (B), and manganese (Mn) decreased early in the season, were lowest when vegetative flushing peaked (summer), and tended to increase in autumn and winter. For preferred sampling times, seasonal trends showed that concentrations of N, P, Ca, Mg, sodium (Na), chloride (Cl), B, Zn, and Mn were fairly stable over the period January–March. Similarly, concentrations of K, S, and Cu were relatively stable during the period July–September when vegetative growth was minimal. The error associated with our sampling procedure was within acceptable limits (coefficients of variation <10%) for N, P, K, Ca, Mg, Na, Cl, S, B, and Mn. For the cultivar Alba, the seasonal trends for all nutrients were similar even though they were grown at different sites. Nitrogen and Mg concentrations in stem tips of the cultivar Alba were consistently higher than those in stem tips of the cultivar Purple Pride. In contrast, concentrations of K, Na, Cl, and Mn were lower. For these nutrients, different interpretation standards may be required for these cultivars. Significant (P < 0.05) correlations were found between many nutrients. For example, K concentrations were positively correlated with Cl, S, Cu, and Zn and negatively correlated with Ca and Mg concentrations. These significant relationships may indicate synergistic and antagonistic interactions between nutrients, which need to be considered when interpreting plant test data.

Relationships between Floral Morphology, Breeding Behavior, and Flower Longevity in Easter Cactus

The effects of floral morphology and breeding behavior on flower longevity were investigated in Easter cactus [Hatiora ×graeseri (Werderm.) Barthlott)]. Four clones were studied: two diploid (n = 11) clones (`Evita' and `Purple Pride') that were highly self-incompatible (SI), and two cytochimeras (diploid epidermis and tetraploid subepidermis) that were recovered from the diploid cultivars, both of which were self-compatible (SC). The clones exhibited differences in the stage of floral development in which autogamy commenced. Autogamy commenced on the day of anthesis in the two `Evita' clones and occurred ≈5 days after anthesis in the `Purple Pride' cytochimera. In the `Purple Pride' diploid clone, anthers and stigmatic lobes remained spatially separated during the period from anthesis to senescence. Examination of styles collected from senesced, undisturbed flowers showed that few pollen tubes traversed to the base of the styles for the two SI diploid clones, whereas large numbers of pollen tubes were present at the base of the styles for the two SC cytochimeras. Flower longevity for the `Evita' cytochimera was significantly less than for `Evita' diploid, but the diploid and cytochimeral clones of `Purple Pride' exhibited similar flower longevities. Application of 2 mm silver thiosulfate, an inhibitor of ethylene (C2H4) action, did not affect flower longevity of `Evita' cytochimera. Our results show that flower longevity in Easter cactus is influenced by breeding behavior and the stage of floral development at which autogamy commences.

Relationships between Floral Morphology, Breeding Behavior, and Flower Longevity in Easter Cactus (Hatiora ×graeseri)

Experiments were performed to determine the influence of floral morphology and breeding behavior on flower longevity in Easter cactus. Four clones were used for this study: two clones (`Evita' and `Purple Pride') were highly self-incompatible (SI) and diploid (n = 11) and two other clones were self-compatible (SC) cytochimeras (diploid epidermis and tetraploid subepidermis) that were recovered from the diploid clones. There were clonal differences in the degree of herkogamy (spatial separation between anthers and stigma) and the stage of floral development in which autogamy commenced. Autogamy commenced on the day of anthesis in the `Evita' clones, but commenced ≈5 days after anthesis in the `Purple Pride' clones. Styles from undisturbed flowers were collected at senescence, fixed, and examined with epifluorescence microscopy. The SI diploid clones contained few pollen tubes at the base of the style, whereas the SC cytochimeras contained numerous pollen tubes at the base of the style. Among the `Evita' clones, flowers of the SC cytochimera senesced ≈3 days earlier the SI diploid. However, diploid and cytochimeral clones of `Purple Pride' were similar in flower longevity. Differences in flower longevity were attributed to clonal variation in breeding behavior and floral morphology. These data suggest that herkogamy should be used as a selection criterion when breeding for increased flower longevity in tetraploid (SC) Easter cactus.

Vase Life of Some Cut Flowers Following Fumigation with Phosphine

Phosphine (PH3) is a potential alternative fumigant to methyl bromide for insect disinfestation of cut flowers. King protea (Protea cynaroides L.), tulip (Tulipa gesneriana `Apeldoorn'), kangaroo paw (Anigozanthos manglesii Hook.), and geraldton wax (Chamelaucium uncinatum `Purple Pride') were fumigated with PH3 at varying concentrations (100 to 8000 μL·L-1) for 2, 4, or 6 hours. Vase life was evaluated at 20 °C, 65% relative humidity, and constant illumination with a photosynthetically active radiation of 15 μmol·m-2·S-1. No significant change in vase life was observed for kangaroo paws after any of the PH3 fumigations. A 6-hour fumigation at 8000 μL·L-1 significantly reduced vase life in king protea, tulip, and geraldton wax flower. Geraldton wax flower and tulip were relatively sensitive to PH3, as they were damaged by 4000 μL·L-1 for 6 hours and 8000 μL·L-1 for 4 hours, respectively. Phosphine has potential as an insect disinfestation fumigant for king protea, tulip, and kangaroo paw at 4000 (μL·L-1 for 6 hours without affecting vase life or causing damage.

Nitrogen and potassium nutrition of Australian waxflowers grown in siliceous sands. 1. Stem growth and yield responses

The effects of nitrogen (N) and potassium (K) on stem growth and yield responses of Australian waxflowers were investigated. Experiments were conducted in commercial plantings at 3 sites in South Australia. Plantings of Chamelaucium uncinatum cvv. Alba (2 sites) and Purple Pride (1 site) and a Chamelaucium hybrid (C. floriferum x C. uncinatum), known locally as Walpole wax (1 site), were 3-5 years old when the study began in 1990. Nitrogen and K were applied at rates up to 160 g N and 80 g K/plant.year. Application of N significantly (P&lt;0.05) increased stem growth, with the magnitude varying considerably between sites and years. Increasing the rate of applied N from 0 to 80 or 160 g/plant.year increased mean tip-growth of flowering stems of cv. Alba by 47.7% at site 1 and 137.1% at site 3, and of Walpole wax by 144.2% at site 2. In contrast, the effect on cv. Purple Pride was minimal. Tip-growth also varied significantly (P&lt;0.05) between sites. Applied K did not significantly affect stem growth at any site. Application of N significantly (P&lt;0.05) increased the yield of 41-70 and &gt;70 cm stems, and total stem yield at all sites with variation between years and cultivars. For example at site 2 increasing the applied N rate from 0 to 80 or 160 g/plant .year increased total stem yield by 13.9, 176.2 and 77.6% in 1991, 1992 and 1993, respectively. In contrast, the effect of applying K was inconsistent. Application of N significantly increased the weight of prunings at all sites and yield of prunings also varied between years. Applied K significantly affected the yield of prunings at site 3, where application of 80 compared with 0 g1plant.year decreased the yield by 17.9%. For all sites, the mean ratios between total stem weight and total biomass harvested were in the range 0.68-0.82. The effect of applied N was only significant at site 3, where the ratio decreased from 0.76 to 0.57 when the rate of applied N increased from 0 to 160 g/plant.year. The effect of K was not significant at any site. At sites 1 and 2, and for cv. Alba at site 3, application of 80 or 160 g N1plant.year decreased mean stem dry matter by 8.0, 9.3 and 11.0%, respectively. Stem dry matter content also varied significantly between years at all sites. The effect of applied K was only significant at site 3, where application of 80 g1plant.year reduced dry matter content by 5.3% compared with 34.2% for the nil rate. Based on data for all sites, stem fractionation showed that dry matter yields (as a percentage of total stem dry weight), were in the order, woody tissue (3 15-49.9%) &gt; leaves (22.1-29.2%) &gt; flowers (15.9-25.8%) &gt; tip-growth (5.0-21.9%). The effect of applied K on the yield of the different stem parts was only significant (P&lt;0.05) at site 1, where in 1991 yield of the tip-growth fraction decreased. We conclude that to develop effective N fertiliser strategies for waxflowers requires knowledge of (i) soil type, in particular residual N fertility; (ii) annual vegetative growth cycle (i.e. periods of growth flushing); (iii) harvest period; and (iv) flowering time. For cultivars or hybrids harvested when vegetative growth is negligible (e.g. winter) N nutrition can be optimised, while for those harvested during periods of vegetative flushing (e.g. September-November) lower rates of N should be applied to ensure tip-growth is not excessive. Although yield responses to applied K were inconsistent, we recommend 20 g K/plant.year to ensure that productivity is maintained over the 5-10 years flowering stems can be harvested from commercial plantings.

Effect of postharvest dipping in insecticides on the vase life of Geraldton waxflower

In postharvest dipping treatment of Geraldton waxflower (Chamelaucium uncinatum), 13 insecticides tested at recommended application rates caused no visual injury, but some reduced vase life. Flowers of cv. Purple Pride were more sensitive to insecticides than leaves. There was no loss of vase life of flowers following dipping in chlorpyrifos, dimethoate or permethrin. Following dipping in deltamethrin, carbaryl, dichlorvos, cypermethrin, endosulfan or fenvalerate there was 31-49% loss of vase life. No loss of vase life was observed for cv. Alba, after dipping in carbaryl, fenvalerate or dimethoate. Insecticide dips containing wetting agent and a fungicide (e.g. a combination of deltamenthrin, Aqua and benomyl) was a suitable dip for Geraldton waxflower. Wetting agents varied in their effect on vase life. Aqua shortened vase life less than Agral, and D-CTrate less than D-C-Tron. Stems rapidly lost weight when held out of water following dipping, and vase life was reduced when ambient temperatures were above 30�C or drying times exceeded 60 min. It was concluded that flowers should be kept cool and well hydrated following dipping treatment.

Nitrogen and potassium nutrition of Australian waxflowers grown in siliceous sands. 2. Effect on leaf colour, vase life, and soil pH and conductance

The effects of nitrogen (N) and potassium (K) on leaf colour, vase life of flowering stems, and soil pH and electrical conductivity (conductance) were investigated for Australian waxflowers. Experiments were conducted on commercial plantings of Chamelaucium uncinatum cvv. Alba and Purple Pride, and a Chamelaucium hybrid (C. floriferum x C. uncinatum) known locally as Walpole wax, at 3 sites in South Australia. Nitrogen (as NH4NO3) and K (as K2SO4) were applied at rates up to 160 g N/plant and 80 g K/plant over several side dressings during the growing season. Application of N significantly (P&lt;0.05) increased leaf colour ratings for the cv. Alba and Walpole wax. At the higher N rates leaves were dark green. Differences between years were small compared with the effect of applied N. The N x year interaction, and the effect of applied K, were not significant (P&gt;0.05) at any site. For cv. Alba, application of N significantly increased vase life by 5 days in 1992 and 3 days in 1993. For Walpole wax, the effect of N was not consistent between years. Each year, the vase life of flowering stems from cv. Alba were consistently greater compared with stems from Walpole wax. Application of K did not significantly (P&gt;0.05) effect vase life at any site. Annual applications of 80 or 160 g N/plant, as ammonium nitrate, significantly decreased soil pH by 0.3-1.4 units after 2-3 years, whereas application of K, as potassium sulfate, did not affect soil pH. The effect of applied N on soil conductance, although significant, was not consistent between sites. For example, at site 1, increasing the rate of applied N from 0 to 80 g N/plant increased conductance from 0.04 to 0.08 mS/cm in 1992. However, in 1993 it decreased from 0.04 to 0.02 mS/cm. The low conductance values (0.02-0.09 mS/cm) in the 0-60 cm soils, show that fertiliser salts did not accumulate over the course of the study to concentrations which adversely affect plant growth and yield. We conclude that N stress was a significant factor in the occurrence of poor leaf colour, and may be a major factor in the occurrence of defoliation during the flowering period. Optimising N nutrition improved leaf colour, vase life and, depending on the rate, did not significantly increase soil acidity or conductance after 2-3 years.

Flowering Responses of Easter Cactus Clones at Optimal and Supraoptimal Temperatures

The effects of temperature and clonal genotype on flowering of Easter cactus (Rhipsalidopsis Britton &amp; Rose) were investigated in two experiments. Plants of `Crimson Giant', `Evita', `Purple Pride', and `Red Pride' were exposed to 6 weeks of either 10C or 18C night temperature (NT) under 9- to 9.5-hour natural daylengths (ND), and afterwards were forced at 18C NT and long days (LD). All clones produced fewer flowers when exposed to 18C and ND as compared with 10C and ND; however, the clones varied significantly in their flowering responses. Relative to 10C NT and ND, exposure to 18C NT and ND resulted in an 84% to 95% decrease in the number of flower buds for `Evita', `Purple Pride', and `Red Pride', but only a 50% decrease in the number of flower buds for `Crimson Giant'. In another experiment, 23 clones were exposed to 18C NT and 8-hour short days for 6 weeks, then forced at 18C NT and LD. The clones exhibited differences in percentage of plants flowering, days to flowering, percentage of apical phylloclades flowering, and number of flower buds. `Crimson Giant' outperformed all other clones. Further breeding and selection may yield genotypes that flower more prolifically at 18C minimum than current cultivars.

Xylem sap flow, growth and flower production of cultivated Geraldton wax with different vigour under semi-arid conditions

Diurnal and seasonal water use and the effects of different levels of irrigation on growth and flower production were studied using commercially cultivated Geraldton wax (Chamelaucium uncinatum Schauer cv. Purple Pride) under semi-arid conditions. Water use and growth responses to increased irrigation differed widely with vigour. Vigorous plants had extensive root systems and used more water than less vigorous plants whether irrigated or unirrigated and responded to increased irrigation by producing more shoots, secondary stems and flowers. In vigorous plants, marketable stem length and flower number were increased from 63 to 89 cm and 61 to 226 when irrigation was increased from 25 to 75% of pan replacement respectively. Less vigorous plants had distorted root systems (i.e. curling and circling) and showed no significant growth response to increased irrigation. Increase of stem length to a desirable length of 90 cm in less vigorous plants, which are wide-spread in commercial plantings, was unlikely. The results highlight the significance of good propagation and establishment techniques to aid vigorous growth. The sap flow study shows that Geraldton wax is a high water using species. A single plant can use in excess of 20 L per day under high evaporative demand when root growth is not limiting.

Growth and flower production of container-grown Geraldton wax cvv. Alba and Purple Pride at different levels of irrigation

The effects of 3 levels of irrigation (25, 50, 75% pan replacement) on growth and flower production were studied on 2 container-grown Geraldton wax cultivars (Alba and Purple Pride) under field conditions. Water deficit during the vegetative phase reduced all vegetative growth components (shoot number, primary stem length, cumulative stem length, leaf number, crown area) and flower production in both cultivars. Primary stem length was reduced by 47% and shoot or flower number by &gt;50% when irrigation was reduced from 75 to 25% pan replacement. The response to reduced irrigation was more severe in Purple Pride than in Alba. During the vegetative phase, 800-840 mm water or 60-63% pan evaporation is required to maximise marketable stems of 90 cm under the conditions studied.

Morphological Responses of Geraldton Wax to Transient Soil-Water Deficit

Changes in leaf angle and flower diameter of Geraldton wax (Chamelaucium uncinatum) in response to declining shoot water potential (ψshoot)) were assessed as indicators of plant water status. Leaves and petals in Geraldton wax moved vertically as ψshoot decreased. In cv. Purple Pride, the leaf angle of recently-matured, fully-expanded leaves and the diameter of fully developed flowers showed strong linear correlations with declining ψshoot (r2 = 0.90 and 0.94 respectively). The relationships were less strong when applied to almost fully expanded leaves (r2 = 0.51) and young flowers (r2 = 0.64). Older leaves showed no consistent correlation between leaf angle and ψshoot (r2 = 0.01). Similar results were observed in cvv. Alba and Lady Stephanie, but the change in orientation for a given change in ψshoot was smaller in cv. Alba than those observed in cvv. Purple Pride and Lady Stephanie. Vertical orientation of leaves and flower petals in droughted plants could be used as indicators of level of water deficit.

Postharvest disinfestation of arthropods from field‐grown Geraldton wax(Chamelaucium uncinatumSchauer)

Abstract Before dipping started in field‐grown Geraldton wax (Chamelaucium uncinatum Schauer) to remove arthropods, six orders of arthropods were found (Araneida, Coleoptera, Hemiptera, Lepidoptera, Neuroptera, and Thysanoptera). Thrips (family— Thripidae and Aeolothripidae) were the most abundant arthropods present on the cultivars ‘Purple Pride’ and ‘Alba’ with the Scarab beetle (Phyllotocus ustulatus Blanch.) only present on ‘Alba’. Arthropod numbers increased during the flowering season reaching a maximum in October with nine times as many present on the later flowering ‘Alba’ compared with on the earlier flowering ‘Purple Pride’. At this time 10 out of 11 arthropods were thrips on ‘Purple Pride’ compared to 67 out of 99 for ‘Alba’. Postharvest dipping of Geraldton wax flowers in insecticide solution was found to be an effective method of arthropod disinfestation for flowers. Washing flowers for 1 min in water (with the addition of a non‐ionic surfactant or petroleum oil) and shaking excess dipping so...

Effect of environment and applied chemicals on the flowering and form of Geraldton Wax ( Chamelaucium uncinatum Schauer)

Flowering in a number of cultivars of Geraldton Wax ( Chamelaucium uncinatum Schauer) is promoted by exposure to short days. For the cultivar ‘Purple Pride’ the critical photoperiod above which flowering does not occur was between 13 and 13.5 h for 3–4-month-old plants grown from cuttings. In 14 and 16 h photoperiods no flowering occurred in these young plants, although in plants older than 5 or 7 months there was often a low level of flowering. One cultivar failed to flower in any daylength and in a hybrid line there was a complex response to temperature and photoperiod. Temperatures of 20–25°C and high irradiance favoured flowering of ‘Purple Pride’. At lower temperature (below 16°C) there was poor flowering. The flowers also developed more slowly but were larger when open. Higher temperature (above 25°C) led to rapid flower bud appearance, but flower number was drastically reduced and the flowers were much smaller. Cool (12–15°C) temperatures imposed during 3–6 weeks of short days blocked the induction of flowering. By contrast, these temperatures were favourable for flowering of a hybrid between Chamelaucium floriferum and C. uncinatum, although the effect of daylength was far greater. Flower development proceeded even at these cool temperatures. Both paclobutrazol and chlormequat inhibited shoot growth and generally had little effect on flowering. Benzyladenine caused substantial branching and could either depress or promote flowering. Flower drop was triggered within 3 days with ethephon. The implications of these findings for the regulation of flowering under field and greenhouse conditions are discussed.

Micropropagation of some Myrtaceae species which show potential as 'new' ornamental plants

Eleven species of Australian Myrtaceae were evaluated for their ability to be cultured in vitro. Ten species produced axillary shoots (microcuttings) suitable for inducing roots in vitro. Microcuttings of 9 species successfully developed roots and were transferred to soil culture in a glasshouse, where plants grew normally. Nodal explants were grown on a modified Murashige and Skoog (MS) medium supplemented with varying concentrations of 6-benzylaminopurine (BAP), to study shoot proliferation. Beaufortia heterophylla Turcz. explants did not respond to BAP, and all explants eventually died. The rate of shoot proliferation for the other species varied according to BAP concentration. Microcuttings of 10 species were grown on a modified half-strength MS medium supplemented with varying concentrations of the auxins indole-3-butyric acid (IBA) and naphthaleneacetic acid (NAA), to induce root formation. An increase in root number and an associated decrease in root length was observed as the concentration of IBA and NAA was increased. Verticordia muelleriana E. Pritzel did not develop roots in any treatment. Chamelaucium uncinatum Schauer cv. Purple Pride, Kunzea parvifolia Schauer, K. pulchella (Lindl.) A. S. George, Leptospermum rotundifolium (Maiden &amp; Betche) F. Rodway ex Cheel, Verticordia drunzmondii Schauer, V. graizdis J. L. Drumm., V. hughanii F. Muell., V. nzonaclelpha Turcz., and V. roeii Endl. microcuttings developed roots both with and without added auxins. Roots that formed on microcuttings at higher auxin concentrations were generally thicker and slower in growth.

Cold Storage of Selected Members of the Proteaceae and Australian Native Cut Flowers

Five members of the Proteaceae and 13 Australian native cut flower cultivars were stored for 35 days under standard conditions at 1C to assess their ability to withstand long-term storage and transport. Protea cynaroides L., Leucadendron `Silvan Red', Leucospermum `Firewheel', Thryptomene calycina (Lindl.) Stapf., Telopea speciosissima R. Br., and Verticordia grandtiflora Endl. retained a vase life of at least 7 days after 21 days of storage. Leucospermum cordifolium Salisb. ex Knight, Protea neriifoli R. Br., Chamelaucium uncinatum `Alba', C. uncinatum `Purple Pride', Verticordia monadelpha Turcz., Verticordia plumosa (Desf.) Druce, and Verticordia nitens (Lindl.) Schau. suffered a decline in vase life ranging from 31% to 100% after 14 to 21 days of storage. Species of Verticordia and Chamelaucium were particularly susceptible to fungal infection. Anigozanthos pulcherrimus Hook. and the Anigozanthos cultivars Ruby Delight, Bush Harmony, Bush Haze, and Gold Fever all showed a significant reduction in vase life after 14 days of storage compared with unstored controls.