Tropical Ornamental Plants Research Articles

Accumulation and biomass partition and nutrients per tropical ornamental plants grown in Ribeira Valley region

For many ornamental plants there are no fertilization tables in Brazil and growers use, inappropriately, the same fertilizing for different species of ornamental plants. A first step is to know the nutrient uptake by these plants. The objective of this study was to determine the concentration and to characterize the accumulation of nutrients of the main tropical ornamental plants grown in the Ribeira Valley region, São Paulo state, Brazil: Clusia fluminensis, Dracaena marginata, Dypsis lutescens, Gardenia jasminoides, Ixora coccinea, Ligustrum sinense, Murraya paniculata, Podocarpus macrophyllus, Rhapis excelsa e Viburnum prunifolium. The plants were donated by local farmers and after sorting, these were divided into roots, stems and leaves, and, subsequently, washed, dried and was determined their concentration of nutrients. The experimental design was randomized using four repetitions and the species of ornamental plants were considered as treatments. The results were submitted to analysis of variance and compared by Scott-Knott test (5%). For the macronutrient, the greater accumulation of N was in Podocarpus macrophyllus. The Clusia fluminensis tree had the highest calcium and magnesium accumulations. The largest amounts of P and S were accumulated in Rhapis excelsa and Podocarpus macrophyllus. The greatest accumulation of K was in Rhapis excelsa, Dracaena marginata, Podocarpus macrophyllus, Murraya paniculata and Ixora coccinea. Smaller amounts of macronutrients were accumulated in Dypsis lutescens and Viburnum prunifolium. As for the macronutrients, the largest accumulation of Cu was observed in broad leaf Rhapis excelsa. Clusia fluminensis tree and Dracaena marginata accumulated the largest amounts of Mn. Regarding the Zn, Rhapis excelsa, Dracaena marginata and Ligustrum sinense were plants with higher accumulation. Smaller amounts of B were accumulated in Viburnum prunifolium, Dracaena marginata and Dypsis lutescens. Ligustrum sinense, Dypsis lutescens and Ixora coccinea accumulated lower amounts of Fe in relation to others. The accumulation of nutrients by ornamental plants is very different between species and this information should be used to adjust fertilizer recommendations. Ornamental plants were grouped as demand and NPK ratio, to assist in the management of fertilizer.

Comparative transcriptome analysis of Anthurium "Albama" and its anthocyanin-loss mutant.

Anthurium is one of the most important tropical ornamental plants in the world. The traded value of anthurium is second only to that of tropical orchids among the tropical flowers. The spathe is the main ornamental organ and its color variation mainly arises from anthocyanin contents. Understanding the molecular regulation of spathe color will accelerate new variety creation of anthurium. To announce gene expression differences between Anthurium andraeanum ‘Albama’ and its one unique anthocyanin-loss mutant, we collected spathes of the wild-type and the mutant from two stages in spathe development (the flower separates protrude from the sheath and the spathe is fully expanded) and extracted total RNAs for transcriptome profiling. Using short read sequencing technology (Illumina), 51,955,564, 53,822,224, 54,221,990 and 52,276,418 sequencing raw reads, respectively, for wild-type and mutant in the two stages were assembled de novo into 111,268 unique sequences (unigenes) with a mean length of 652 bp. 47,563 unigenes had significant hits to the sequences in the Nr database, and 32,768 unigenes showed significant similarity to known proteins in the Swiss-Prot database. 28,350 and 19,293 unigenes had significant similarity to existing sequences in the KEGG and COG databases, respectively. Further, analysis of differentially expressed genes in the comparison between wild-type and mutant and between the two different developmental stages was carried out, indicating that the expression of an extensive set of genes changed as the result of mutation. Taken together, these data demonstrated that the Illumina sequencing allowed de novo transcriptome assembly and could obtain differentially expressed genes between A. andraeanum wild-type and the anthocyanin-loss mutant. The expression differences of AN2 and UFGT might cause the anthocyanin-loss mutation.

Sterility and lack of pollinator services explain reproductive failure in non‐invasive ornamental plants

AbstractAimMutualisms, including pollination, have been hypothesized to influence establishment and success of introduced species. However, lack of pollinators has rarely been demonstrated as a barrier to plant invasion. We examined barriers to seed set in nine introduced non‐invasive tropical ornamental plants which do not regularly produce seeds in Hawai'i.LocationHawai'i.MethodsWe tested for pollen viability using 1% thiazolyl blue tetrazolium bromide (MTT) stain. We also supplementally hand‐pollinated flowers and examined subsequent fruit set.ResultsWe found that four species had non‐viable pollen, as measured by pollen staining, and failed to produce seeds. By contrast, the milkweedCalotropis gigantea, though invasive elsewhere, produced seeds only when hand‐pollinated, indicating that natural seed set is prevented by lack of legitimate pollen deposition. The remaining four species apparently had viable pollen, but did not set seed when hand‐pollinated. Seed set in these species may be limited by lack of compatible mates in Hawai'i.Main conclusionsLack of seed production due to pollen sterility or lack of compatible pollen can function as an early barrier to invasion success in ornamental plants, helping to explain why some ornamental species fail to invade. Additionally, we document one of the first concrete examples of a lack of pollinator services inhibiting invasion success in a species outside of the genusFicus. Understanding the nature of early barriers to invasion can help us evaluate the future invasion risks posed by these species in Hawai'i and elsewhere.

Fertilização de plantas ornamentais pelo método requerimento-suprimento: proposição de técnica experimental

A dose de fertilizantes a ser recomendada para uma cultura depende do balanço de perdas e dos ganhos dos nutrientes no sistema agrícola (Lei da Restituição). Na UFV, o balanço foi modelado para recomendação de corretivos e fertilizantes para eucalipto (NUTRICALC), abacaxizeiro, algodoeiro, arroz, bananeira, cafeeiro, cana de açúcar, coqueiro, laranjeira, meloeiro, milho, pastagens, soja e tomate (FERTICALC) e teca (FERTI-UFV). A fertilização e a nutrição de plantas ornamentais tropicais baseam-se apenas na experiência de produtores e fabricantes de fertilizantes. Os objetivos deste trabalho foram desenvolver e apresentar técnica experimental que permita determinar: as taxas de recuperação de macro e micronutrientes por extratores de formas disponíveis, a demanda e as taxas de recuperação de nutrientes por plantas ornamentais e determinar a dose e os teores de nutrientes em fertilizante que suplementem os requerimentos das plantas. Para a modelagem, consideraram-se dois módulos: o módulo planta, que obtém a demanda e o requerimento dos nutrientes para definida produtividade; e o módulo substrato, que permite calcular o suprimento de nutrientes do vaso ou do canteiro a ser utilizado para o cultivo. A modelagem vislumbrou um novo método de pesquisa para recomendação de corretivos e fertilizantes para culturas com carência de informação, como para cultivo de plantas ornamentais, especialmente as tropicais. Esse Método Requerimento-Suprimento determina a dose e os teores de nutrientes no fertilizante-suprimento (FS), que suplementam os requerimentos das plantas. O método é iterativo e foi desenvolvido por meio de três tentativas. Na primeira tentativa, considerou-se a produção de plântulas de orquídea; e, na segunda e terceira tentativas, determinaram-se as curvas de crescimento com FS no cultivo de violetas, em vasos com substrato, e definiram-se os critérios para determinar as taxas de recuperação de nutrientes pelos extratores em análises químicas do substrato e pelas plantas. Por último, apresentou-se a técnica experimental projetada.

Molecular and physiological role of Epipremnum aureum

Epipremnum aureum (Golden pothos) is a naturally variegated climbing vine that produces abundant yellow‑marbled foliage. It is among the most popular tropical ornamental plant used as hanging basket crop. An insight has been provided about the different varieties of Golden pothos including Neon, Marble Queen, Jade Pothos and N Joy. This paper presents a critical review on botanical study and important characteristics of Golden pothos and special emphasis has been provided on variegated leaves and chloroplast biogenesis explaining the important genes involved during the process and various proteins associated with it. Studies have been included comprising the special features of Epipremnum aureum in phytoremediation for the removal of Cobalt and Cesium and in the purification of air against formaldehyde. The antimicrobial activity of roots and leaf extracts of Epipremnum aureum against many bacterial strains have been included. It also presents the antitermite activity of Golden pothos that can be harnessed for pest control. Key words: Antimicrobial, antitermite, calcium oxalate, Epipremnum aureum, formaldehyde

Flowering, morphological observations and FT expression of Curcuma kwangsiensis var nanlingensis bud in development process

Curcuma kwangsiensis var nanlingensis is an attractive tropical ornamental plant in China with high ornamental and commercial value. The effects of temperature on the flowering percentage of its rhizomes were studied. High temperature induced bud differentiation in Curcuma kwangsiensis var nanlingensis. The flowering percentage of rhizomes cultured at 30°C was 100%, which was significantly higher than those of rhizomes cultured at 25°C or 20°C. Rhizomes that underwent a low temperature treatment after being hydroponically cultured at 30°C until stage IV also achieved a flowering percentage of 100% and good ornamental quality. Observations of the appearance and anatomic morphology during the stages of flower bud differentiation were made using paraffin sections and a scanning electron microscope (SEM). The results showed that the rhizomes of different developmental stages cultured at 30°C could be divided into five phases: initial differentiation phase, inflorescence and bract primordium differentiation phase, flower primordium differentiation phase, small floral primordium differentiation phase and flower organ differentiation phase. The differential expression of the FT gene was examined in the bud during the different developmental stages and organs under different temperature conditions using the real-time PCR technique. FT expression in the Curcuma kwangsiensis var nanlingensis bract and inflorescence axis was higher than that in the petiole and leaf. Under a high temperature treatment, FT expression reached a sharp peak at the beginning of bud differentiation and declined slightly between differentiation and maturation of the bud. FT expression at 30°C was clearly higher than expression at 25°C or 20°C. The results of the FT expression and anatomic morphology observations suggest that FT expression is associated with flowering differentiation. High temperature treatment in the initial differentiation phase led to the highest expression of the FT and is a key procedure to ensure a high flowering percentage in Curcuma kwangsiensis var nanlingensis.

Essential oils from Alpinia purpurata (Zingiberaceae): Chemical composition, oviposition deterrence, larvicidal and antibacterial activity

Essential oils and aqueous extracts were obtained by hydrodistillation of flowers of red and pink variants of Alpinia purpurata (Zingiberaceae), a widely cultivated tropical ornamental plant. GC/MS analyses revealed the presence of 42 essential oil components with α-pinene, β-pinene and β-caryophyllene being the major constituents. Oils from the red and pink variants presented potent larvicidal activities against 4th instar Aedes aegypti with LC50 values of 80.7 and 71.5ppm, respectively. Aqueous extracts of the two variants were also active against the dengue mosquito larvae (LC50 values of 18.3 and 12.6%, respectively). Oils and aqueous extracts of both variants showed significant oviposition deterrent effects at concentrations of 100ppm and 20%, respectively. Oil from the red cultivar inhibited significantly the growth of gram-positive and gram-negative bacteria. The study demonstrates that products with valuable biological activities can be produced from flowers of A. purpurata that are not of commercial quality.

Direct and callus-mediated regeneration of Curcuma soloensis Valeton (Zingiberaceae) and ex vitro performance of regenerated plants

Protocols are outlined for the regeneration of Curcuma soloensis, an attractive tropical ornamental plant, from young vegetative bud explants. We used both direct and callus-mediated regeneration techniques to produce material suitable for mass propagation and the development of transgenic plants. During direct plantlet propagation, the presence of thidiazuron (TDZ) in the growing medium induced more than three times as many shoots as 6-benzylaminopurine (BA), with a mean of 18.7 shoots per explant on MS medium containing 2.5 μM TDZ compared to 5.0 shoots with 40 μM BA. Subsequently, the shoots rooted readily on MS basal medium that was free of plant growth regulators. During indirect plantlet regeneration, TDZ combined with BA and 2,4-dichlorophenoxyacetic acid (2,4-D) had significant effects on embryogenic callus induction and multiplication. The frequency of callus formation was 91.1% for explants cultured on MS basal medium supplemented with 2.5 μM TDZ, 2.0 μM BA and 1.2 μM 2,4-D. On average 7.1 shoots were produced per callus mass cultured on MS medium supplemented with 2.5 μM TDZ, 9.0 μM BA and 1.2 μM naphthaleneacetic acid (NAA). Regenerated shoots were transferred to MS medium supplemented with 2.5 μM TDZ, to produce multiple shoots. In vitro cultured plantlets readily acclimatized to greenhouse conditions, showing 100% survival rates in a sphagnum, perlite and sand (1:1:1) medium. These plants were transplanted into pots or planted in the field. The ex vitro acclimated plants grew vigorously and produced showy inflorescences 5–6 months after planting. The high-frequency of shoot multiplication and rapid flowering of tissue-cultured plants indicate that C. soloensis has great potential in the floricultural market.

Palm Nutrition and Fertilization

Palms (Arecaceae) growing in containers have similar nutritional requirements as other tropical ornamental plants and grow well with fertilizers having an elemental ratio of 3N:0.4P:1.7K. However, palms growing in the landscape or field nurseries have very different nutritional requirements from dicotyledonous plants. Whereas nitrogen (N) is the primary limiting nutrient element in container production, potassium (K), manganese (Mn), magnesium (Mg), boron (B), and iron (Fe) deficiencies are more widespread than N deficiency in most landscape soils. Because palms have a single apical meristem, deficiencies of K, Mn, or B can be fatal. In addition to insufficient nutrients in the soil, palm nutrient deficiencies can be caused by high soil pH, certain types of organic matter, deep planting, poor soil aeration, cold soil temperatures, and nutrient imbalances. Correction of nutritional deficiencies in palms can take up to 2 years or longer and therefore prevention of deficiencies by proper fertilization is important. Research has shown that high N:K ratio fertilizers applied directly, or indirectly via application to adjacent turfgrass in a landscape, can exacerbate K and Mg deficiencies in palms, sometimes fatally. For sandy Atlantic coastal plain soils in the southeastern United States, an analysis of 8N–0.9P–10K–4Mg plus micronutrients has been recommended.

Palm Nutrition and Fertilization

Palms (Arecaceae) growing in containers have similar nutritional requirements as other tropical ornamental plants and grow well with fertilizers having an elemental ratio of 3N:0.4P:1.7K. However, palms growing in the landscape or field nurseries have very different nutritional requirements from dicotyledonous plants. Whereas nitrogen (N) is the primary limiting nutrient element in container production, potassium (K), manganese (Mn), magnesium (Mg), boron (B), and iron (Fe) deficiencies are more widespread than N deficiency in most landscape soils. Because palms have a single apical meristem, deficiencies of K, Mn, or B can be fatal. In addition to insufficient nutrients in the soil, palm nutrient deficiencies can be caused by high soil pH, certain types of organic matter, deep planting, poor soil aeration, cold soil temperatures, and nutrient imbalances. Correction of nutritional deficiencies in palms can take up to 2 years or longer and therefore prevention of deficiencies by proper fertilization is important. Research has shown that high N:K ratio fertilizers applied directly, or indirectly via application to adjacent turfgrass in a landscape, can exacerbate K and Mg deficiencies in palms, sometimes fatally. For sandy Atlantic coastal plain soils in the southeastern United States, an analysis of 8N–0.9P–10K–4Mg plus micronutrients has been recommended.

Performance of Laboratory-Scale Wetlands Planted with Tropical Ornamental Plants to Treat Domestic Wastewater

Abstract This work proposes an innovative wastewater treatment system that consists of a constructed subsurface flow wetland planted with ornamental flowers of high market value. In addition to the benefit of the water treatment, this cash crop provides a profitable business by producing commercial flowers that can meet all biological and safety requirements in order to be commercialized. This characteristic of the treatment system makes it very valuable for application in developing countries. Five different species of ornamental plants were studied from September 2004 to January 2005. Several water quality parameters were evaluated at the inlet and outlet of a laboratory-scale system. COD was reduced by more than 75% in all cases; BOD and nitrogen were removed by more than 70%, except in one cell; phosphorus was reduced by more than 66% and the dissolved oxygen increased from 0.175 to 5.8 mg L-1. Total and fecal coliforms were removed in the wetland by more than 99.3%. According to these results, it is feasible to couple ornamental flower production with wastewater treatment. A pilot-scale study is recommended in order to validate the preliminary results under more realistic conditions.

Genetic Relationships of Spathiphyllum Cultivars Analyzed by AFLP Markers

Peace lily (Spathiphyllum Schott) is one of the most popular tropical ornamental foliage plants and is used worldwide for interiorscaping. However, little information is available on the genetic relationships of cultivars. Using amplified fragment length polymorphism (AFLP) markers with near-infrared fluorescence-labeled primers, this study analyzed genetic relatedness of 63 commercial cultivars and breeding lines. Forty-eight EcoRI + 2/MseI + 3 primer set combinations were initially screened, from which six primer sets were selected and used in this investigation. All cultivars were clearly differentiated by their AFLP fingerprints, and the relationships were analyzed using the unweighted pair-group method of arithmetic average cluster analysis (UPGMA). The 63 cultivars were divided into four clusters. All commercial cultivars or breeding lines resulted from crosses of some of the cultivars, a total of 45, were positioned in cluster I with Jaccard's similarity coefficients between 0.61 and 0.88. There was only one cultivar in cluster II. Cluster III contained 16 cultivars; they are either species or breeding lines generated from interspecific hybridization. Cluster IV had one unknown species. This study provides genetic evidence as to why cultivars from cluster I and III are not readily crossable because the Jaccard's similarity coefficient between the two clusters was only 0.35. Results also indicate that commercial cultivars are genetically close. Strategies for increasing genetic diversity of cultivated peace lily should be sought for future breeding efforts.

Effects of Phosphorous and Phosphoric Acids on Growth and Phosphorus Concentrations in Container-grown Tropical Ornamental Plants

Chinese hibiscus (Hibiscus rosa-chinensis), shooting star (Pseuderanthemum laxiflorum), downy jasmine (Jasminum multiflorum), areca palm (Dypsis lutescens), and `Jetty' spathiphyllum (Spathiphyllum) were grown in containers using Osmocote Plus 15-9-12 (15N-3.9P-10K), which provided phosphorus (two experiments), or resin-coated urea plus sulfur-coated potassium sulfate, which provided no phosphorus (one experiment). Plants were treated with water drenches (controls), drenches with metalaxyl fungicide only, drenches with phosphoric acid (PO4-P), drenches with metalaxyl plus phosphorus from phosphoric acid, drenches with PhytoFos 4-28-10 [4N-12.2P-8.3K, a fertilizer containing phosphorous acid (PO3-P), a known fungicidal compound], or a foliar spray with PhytoFos 4-28-10. Plants receiving soil drenches with equivalent amounts of P from PhytoFos 4-28-10, PO4-P, or PO4-P+metalaxyl generally had the greatest shoot and root dry weights and foliar PO4-P concentrations. There were no differences between the control and metalaxyl-treated plants, indicating that root rot diseases were not a factor. Therefore, responses from PhytoFos 4-28-10 were believed to be due to its nutrient content, rather than its fungicidal properties. Foliar-applied PhytoFos 4-29-10 produced plants that were generally similar in size to control plants or those receiving metalaxyl only drenches. Fertilizers containing PO3-P appear to be about as effective as PO4-P sources when applied to the soil, but are relatively ineffective as a P source when applied as a foliar spray. A distinct positive synergistic response for shoot and root dry weights and foliar PO4-P concentrations was observed for the PO4-P+metalaxyl treatment when no P was applied except as a treatment.

Growth of Some Tropical Ornamental Plants on Artificial Topsoils Derived from Mixtures of Flyash, Sludge, Biochips, and Rengam Series Subsoil

Four mixtures of artificial topsoils produced from mixing incinerator flyash, sewage sludge, biochips (from plant parts), and subsoil (from granite origin) in various proportions were used to grow some popular ornamental plants. The plants used were Bougainvillea spectabilis Ixora coccineaand three Heliconiataxa, H. psithacorum × H. spathocircinatacv. “Golden Torch,” H. rostrataand H. psithacorumcv. “Tay.” Their physiological responses to the heavy metals present in the different artificial topsoil mixtures were monitored using chlorophyll fluorescence F v /F m ratio, maximum photosynthetic rates and quantum yield. The overall results indicated that B. spectabiliswas the most tolerant and could grow well in all the four artificial topsoils. Ixora coccineawas the least tolerant and could only grow well in the mixtures with lesser heavy metals. The three Heliconiashad intermediate tolerance level compared with B. spectabilisand I. coccinea. Leaching test was then conducted using one of the artificial topsoils with higher flyash content to quantify the heavy metals such as cadmium (Cd), copper (Cu), chromium (Cr), iron (Fe), lead (Pb), and zinc (Zn) in the leachate under simulated heavy rainfall condition. The overall leaching test revealed that plants significantly reduced the amount of heavy metals present in the leachate. However, the amounts of Cd, Cr, Fe, and Pb present in the leachate were still higher than the control treatment, even in the presence of plants. However, the leachate Cu and Zn contents in the presence of plants were either similar to or lower than the control and, therefore, pose less environmental hazard.

Assessment of Genetic Relationships among Philodendron Cultivars Using AFLP Markers

Philodendrons (Philodendron Schott) are among the most popular tropical ornamental foliage plants used for interior decoration. However, limited information is available on the genetic relationships among popular Philodendron species and cultivars. This study analyzed genetic similarity of 43 cultivars across 15 species using amplified fragment length polymorphism (AFLP) markers with near infrared fluorescence labeled primers. Forty-eight EcoR I + 2/Mse I + 3 primer set combinations were screened, from which six primer sets were selected and used in this investigation. Each selected primer set generated 96 to 130 scorable fragments. A total of 664 AFLP fragments were detected, of which 424 (64%) were polymorphic. All cultivars were clearly differentiated by their AFLP fingerprints, and the relationships were analyzed using the unweighted pair-group method of arithmetic average cluster analysis (UPGMA) and principal coordinated analysis (PCA). The 43 cultivars were divided into five clusters. Cluster I comprises eight cultivars with arborescent growth style. Cluster II has only one cultivar, `Goeldii'. There are 16 cultivars in cluster III, and most of them are self-heading interspecific hybrids originated from R.H. McColley's breeding program in Apopka, Fla. Cluster IV contains 13 cultivars that exhibit semi-vining growth style. Cluster V has five cultivars that are true vining in morphology, and they have lowest genetic similarity with philodendrons in other clusters. Cultivated philodendrons are generally genetically diverse except the self-heading hybrids in cluster III that were mainly developed using self-heading and semi-vining species as parents. Seven hybrid cultivars have Jaccard's similarity coefficients of 0.88 or higher, suggesting that future hybrid development needs to select parents with diverse genetic backgrounds.

Influence of Fertilizer Placement on Plant Quality, Root Distribution, and Weed Growth in Container-grown Tropical Ornamental Plants

In two experiments, chinese hibiscus (Hibiscus rosa-sinensis), bamboo palm (Chamaedorea seifrizii), areca palm (Dypsis lutescens), fishtail palm (Caryota mitis), macarthur palm (Ptychosperma macarthurii), shooting star (Pseuderanthemum laxiflorum), downy jasmine (Jasminum multiflorum), plumbago (Plumbago auriculata), alexandra palm (Archontophoenix alexandrae), and foxtail palm (Wodyetia bifurcata) were transplanted into 6.2-L (2-gal) containers. They were fertilized with Osmocote Plus 15N-3.9P-10K (12-to14-month formulation) (Expt. 1) or Nutricote Total 18N-2.6P-6.7K (type 360) (Expt. 2) applied by either top dressing, substrate incorporation, or layering the fertilizer just below the transplanted root ball. Shoot dry weight, plant color, root dry weights in the upper and lower halves of the root ball, and weed shoot dry weight were determined when each species reached marketable size. Optimal fertilizer placement method varied among the species tested. With the exception of areca palm, none of the species tested grew best with incorporated fertilizer. Root dry weights in the lower half of the root ball for chinese hibiscus, bamboo palm, and downy jasmine were greatest when the fertilizer was layered and root dry weights in the upper half of the root ball were greatest for top-dressed chinese hibiscus. Weed growth was lower in pots receiving layered fertilizer for four of the six palm species tested.

Production and Interior Performances of Tropical Ornamental Foliage Plants Grown in Container Substrates Amended with Composts

Three representative Florida composts were mixed by volume with sphagnum peat and pine bark to formulate 12 container substrates. After physical and chemical characterization, the substrates, along with a control, were used to grow containerized Cordyline terminalis ‘Baby Doll’, Dieffenbachia maculata ‘Camille’, and Dracaena fragans ‘Massangeana’ cane. All substrates were able to produce marketable plants, but only five or seven, depending on plant genus, of the 12 compost-formulated substrates resulted in plants comparable or superior to those of the control substrate. The five also had substrate shrinkage equal to or less than the control. Plants were then moved to an interior evaluation site to determine the suitability of compost-formulated substrates in sustaining foliage plant growth under an interior environment. During a six-month interior evaluation, the plants maintained their aesthetic appearances. Based on plant growth parameters and quality ratings as well as substrate shrinkage both in production and interior evaluation, five of 12 compost-formulated substrates were identified to be equal or superior to the control. This study showed that the three composts, after being appropriately mixed with sphagnum peat and pine bark, can be used as container substrates in every phase of tropical foliage plant production and utilization.

Influence of Light Intensity on Optimum Fertilization Rate in Five Species of Tropical Ornamental Plants

Five species of tropical ornamental plants—artillery fern (Pilea serpyllacea), pleomele (Dracaena reflexa), fishtail palm (Caryota mitis), areca palm (Dypsis lutescens), and sunshine palm (Veitchia mcdanielsii)—were grown in containers under full sun, 55% shade, or 73% shade. They were fertilized every 6 months with Osmocote Plus 15-9-12 (15N-4P-10K) at rates of 3, 6, 12, 18, 24, 30, and 36 g/pot (0.1, 0.2, 0.4, 0.6, 0.8, 1.1, and 1.3 oz/pot). For pleomele and the three palm species, optimum shoot dry weights and color ratings were similar among the three light intensities tested. However, artillery fern grown in full sun required fertilizer rates at least 50% higher for optimum shoot dry weight and color than under 55% or 73% shade. Light intensit × fertilizer rate interactions were highly significant for pilea and fishtail palm color and dry weight and sunshine palm and pleomele color.

Effects of a Microbial Inoculant on Plant Growth and Rhizosphere Bacterial Populations of Container-grown Plants

A commercially available microbial inoculant (Plant Growth Activator Plus) that contains 50 microorganisms, primarily bacteria, was evaluated in a soilless container substrate to determine its effects on root bacterial populations and growth response of container-grown plants at three fertilizer rates. The tropical ornamental plants included hibiscus (Hibiscus rosa-sinensis `Double Red'), spathiphyllum (Spathiphyllum `Green Velvet') and areca palm (Dypsis lutescens). The bacterial groups enumerated were fluorescent pseudomonads, actinomycetes, heat-tolerant bacteria, and total aerobic bacteria. Analysis of the inoculant before its use determined that fluorescent pseudomonads claimed to be in the inoculant were not viable. The plant variables measured were plant color rating, shoot dry weight and root dry weight. Only hibiscus shoot dry weight and color rating increased in response to the addition of the inoculant to the substrate. Hibiscus roots also had a significant increase in the populations of fluores-cent pseudomonads and heat-tolerant bacteria. From a commercial production point of view, increasing fertilizer rates in the substrate provided a stronger response in hibiscus than did addition of the microbial inoculant. Furthermore, use of the inoculant in this substrate did not compensate for reduced fertilizer inputs.

Aglaonema Cultivars Differ in Resistance to Chilling Temperatures

Abstract Aglaonema is considered one of the most chilling sensitive tropical ornamental foliage plants. However, information on resistance of the ever-increasing number of new cultivars to chilling temperatures is not available. In this study, the chilling response of 12 Aglaonema cultivars was evaluated after exposure to 1.7, 7.2, or 12.8C (35, 45, or 55F) for 24 hours. Results showed that a high degree of genetic variation existed among the cultivars. The cultivar ‘Silver Queen’ demonstrated the greatest sensitivity to chilling with 30% of leaves injured at 12.8C (55F). In contrast, three new cultivars, ‘Emerald Star’, ‘Stars’, and ‘Jewel of India’, were the most resistant, each showing no visible injury at 1.7C (35F). Data also indicated that chilling injury to young leaves was much less pronounced than in either mature or old leaves. Additionally, chilling sensitivity of the cultivars was reduced by pre-exposure to cooler temperatures that were slightly above the chilling range.