Peperomia Obtusifolia Research Articles

Photosynthetic Daily Light Integral Effects on Rooting and Vegetative Growth of Cuttings of Six Foliage Plants

Recently, millennials, social media, and the COVID-19 pandemic have spurred the demand for indoor foliage plants. Between 2019 and 2022, the wholesale value of foliage plants in the United States increased by 45% to $1 billion. However, few propagation protocols are available for greenhouse growers in temperate climates. Additionally, the mechanisms by which shade and succulent crops photosynthesize, root, and accumulate biomass in response to environmental parameters are largely unknown. Therefore, the objective of this study was to determine the photosynthetic daily light integral (DLI) that leads to uniform, high-quality, and rapid rooting of foliage crop cuttings. Vegetative shoot tip cuttings of Curio peregrinus ‘String of Thai Dolphins’ (dolphin plant), Curio rowleyanus ‘String of Pearls’ (string-of-pearls), Curio herreianus ‘String of Pearls Big Bead’ (string-of-pearls big bead), Peperomia obtusifolia ‘Emerald Isle’ (baby rubber plant), Peperomia ferreyrae ‘Happy Bean’ (pincushion peperomia), and Sedum makinoi ‘Tornado’ (stonecrop) were excised from stock plants. Then, the cuttings were inserted in plug trays filled with a propagation medium consisting of a 1:1 (v/v) of half 70% peatmoss, 21% perlite, and 9% vermiculite and half medium perlite. Then, the cuttings were placed under a DLI of approximately 5 mol·m−2·d−1 for 7 days of callus induction, and subsequently under shading of 70% (2.9–3.4 mol·m−2·d−1), 50% (4.5–6.5 mol·m−2·d−1), 30% (7.8–11.2 mol·m−2·d−1), or 0% (10.2–16.4 mol·m−2·d−1), resulting in DLIs ranging from 2.9 to 16.4 mol·m−2·d−1. After 21 days, the stem length of stonecrop and pincushion peperomia rooted cuttings decreased as the DLI increased from 2.9 to 16.4 mol·m−2·d−1. However, the stem length of string-of-pearls and string-of-pearls big beads rooted cuttings increased after 28 days as the DLI increased from 2.9 to 16.4 mol·m−2·d−1. As the DLI increased from 2.9 to 16.4 mol·m−2·d−1, the shoot dry mass of dolphin plant and baby rubber plant significantly increased by 168% and 189%, respectively. Additionally, the root dry mass of dolphin plant and baby rubber plant significantly increased by 376% and 50%, respectively. The quality index of all five cultivars was greatest under DLIs of 10.2 to 16.4 mol·m−2·d−1, with the exception of pincushion peperomia, which had the highest quality index under DLIs of 2.9 to 4.6 mol·m−2·d−1. Our findings indicate that higher DLIs benefit shoot growth during rooting, but not necessarily root biomass accumulation of all genera investigated.

Portable botanical biofilters to address internal combustion engine exhaust exposure

Previous research has identified the capacity of active botanical biofiltration to provide significant benefits for indoor air quality, however existing systems are large and require integration into the building. Thus, a “Portable Botanical Biofilter” (PBB) has been developed, however, its pollutant filtration capacity is unknown and may be constrained due to the limited dimensions of practical portable systems. This study thus aimed to quantify a PBB's removal efficiency under controlled conditions for CO2, PM (Total Suspended Particles (TSP) along with particle size distribution) and total volatile organic compounds (TVOCs). Testing was conducted in a purpose-built 15.6 m3 chamber at two light intensities, regular lighting (79.4 μmol∙m−2 s−1) as commercially supplied to the system and with elevated supplementary lighting (167 μmol∙m−2 s−1). CO2 removal testing was conducted with the plant species Peperomia obtusifolia, Gibasis pellucida, and a no plant control. TVOC and PM removal testing was conducted with systems containing the known pollutant removing plants: Gibasis pellucida, Spathiphyllum wallisii and mixed modules containing Peperomia obtusifolia and Nematanthus glabra at the two lighting levels. All treatments removed CO2 significantly faster than the control, with supplementary lighting allowing CO2 removal at a significantly faster rate than regular lighting (0.232–0.673 g h−1). However, CO2 net removal rates were likely to be insufficient to have valuable effects in a realistically sized room. TSP removal differed significantly between treatments for plant species, but not between light levels. The system removed particles of all sizes, with promising results for the smallest particle size (PM0.3), with highly effective reduction in comparison to the control (up to ∼72%). We conclude that in its delivered, prototype state, the PBB was unlikely to be an effective air purifying device for the removal of indoor CO2, however promising results for the removal of TVOCs and PM were recorded. To improve both CO2 and other pollutant removal, further improvements to lighting, system sealing, and module design are required, along with further testing to allow comparison with other systems.

Composition of Macro and Micro Fertilizers in Zeoponics for Growing Variegated Ornamental Plants

A suitable plant growth medium (PGM) is essential in cultivating ornamental plants, which are raised mainly for their high aesthetic value. For instance, variegated plants are hugely popular among ornamental plant lovers because they exhibit an array of leaf pattern, forms, and colors. The problem, however, is that their unique colors and patterns likely change over time. In this regard, zeoponic PGM, made from zeolite mixed with other materials such as compost and cocopeat, and macro- and micronutrients offers a viable solution. Thus, this study aimed to find the appropriate kind and dosage of fertilizers making up the proper formulation of the PGM to support the desired growth and lasting appearance of variegated plants. Pot trials in the research greenhouse were conducted in a two factor, completely randomized design (CRD). The first factor was plant type - Epipremnum aureum variegata and Peperomia obtusifolia variegata. The second factor was a combination of kind and dosage of macro- and micronutrients those were added to the zeoponics. Plant growth and aestetic parameters were observed, and the chemical properties of the PGM were analyzed. The results showed that the best micro fertilizer and dosage for Epipremnum aureum variegata was Fe-EDTA 0.00096 g/l + Cu-EDTA 0.00067 g/l + Mn-EDTA 0.00269 g/l + Zn-EDTA 0.00167 g/l, while for Peperomia obtusifolia variegata, the best fertilizer dosage was Fe-EDTA 0.00038 g/l + Cu-EDTA 0.00027 g/l + Mn-EDTA 0.00108 g/l + Zn-EDTA 0.00067 g/l.

Cooling, CO2 reduction, and energy-saving benefits of a green-living wall in an actual workplace

Vertical green-living walls (VGWs) are a promising solution for sustainable building design. However, their effectiveness in improving indoor air quality and reducing energy consumption in real-world settings still needs to be studied. Here we aim to contribute to this understanding by examining six indoor plant species (Peperomia obtusifolia, Tradescantia spathacea, Chlorophytum comosum, Spathiphyllum wallisii, Aeschynanthus radicans, and Philodendron hederaceum) in a 15 m2 Patrick Blanc's VGW system established in a shared office space (∼140 m3 volume). Carbon dioxide (CO2) assimilation, transpiration, and stomatal conductance were measured under varying light conditions and CO2 levels. In addition, numerous sensors were placed in the room to assess impacts on the indoor environment. Results indicate that all species but one (Philodendron) were equally effective in reducing CO2. Tradescantia had the highest cooling effect via transpiration. All species except Tradescantia had a very low light compensation point (<5 μmol m−2 s−1 PPFD), indicating their efficiency at reducing CO2 levels even under low light conditions. The net cooling effect of the VGW was 2.5°C–4.5 °C when the ventilation system was on and 1.2°C–3.6 °C when it was off. There was also a positive effect on indoor air quality, with an average CO2 reduction of 5% and sometimes up to 50%. By conducting controlled CO2 enrichment experiments, we estimated a 20% energy consumption savings from reduced air ventilation, equivalent to 1400 kWh/year. These results suggest that VGWs can improve indoor environments and thermal comfort in workplace settings and highlight the importance of choosing appropriate plant species.

Correlations between R, G, and B Values, Pigment Concentration, and Nitrogen Status in Three Ornamental Potted Plants

Image technologies have been used for real-time estimation of nitrogen (N) and leaf chlorophyll (Chl) concentrations as well as for photosynthetic properties. The aim of this work was to establish correlations between RGB values and chlorophyll and nitrogen concentrations in three ornamental potted plants. We evaluated the RGB values, nitrogen status, and chlorophyll concentrations in the leaves of Peperomia obtusifolia, Maytenus senegalensis, and Rosmarinus officinalis. The correlation between the RGB values and the chlorophyll and nitrogen concentrations in the leaves was different for each species, since baby rubber correlated with the R and G values, the confetti tree correlated with the G and B values, and rosemary correlated with the R, G, and B values. The correlation between the normalized RGB (rgb) values and the color parameters and the chlorophyll and nitrogen concentrations showed R2 values lower than 0.70 in all species. Moreover, the estimation of vegetation indices was not effective due to the lack of correlations between these indices and the chlorophyll and nitrogen concentrations in the leaves of each species. According to the findings, rosemary exhibited the best association between the RGB values and chlorophyll and nitrogen concentrations in the leaves.

Bioactive Phenolic Compounds from Peperomia obtusifolia.

Peperomia obtusifolia (L.) A. Dietr., native to Middle America, is an ornamental plant also traditionally used for its mild antimicrobial properties. Chemical investigation on the leaves of P. obtusifolia resulted in the isolation of two previously undescribed compounds, named peperomic ester (1) and peperoside (2), together with five known compounds, viz. N-[2-(3,4-dihydroxyphenyl)ethyl]-3,4-dihydroxybenzamide (3), becatamide (4), peperobtusin A (5), peperomin B (6), and arabinothalictoside (7). The structures of these compounds were elucidated by 1D and 2D NMR techniques and HREIMS analyses. Compounds 1–7 were evaluated for their anthelmintic (against Caenorhabditis elegans), antifungal (against Botrytis cinerea, Septoria tritici and Phytophthora infestans), antibacterial (against Bacillus subtilis and Aliivibrio fischeri), and antiproliferative (against PC-3 and HT-29 human cancer cell lines) activities. The known peperobtusin A (5) was the most active compound against the PC-3 cancer cell line with IC50 values of 25.6 µM and 36.0 µM in MTT and CV assays, respectively. This compound also induced 90% inhibition of bacterial growth of the Gram-positive B. subtilis at a concentration of 100 µM. In addition, compound 3 showed anti-oomycotic activity against P. infestans with an inhibition value of 56% by using a concentration of 125 µM. However, no anthelmintic activity was observed.

State of knowledge: Histolocalisation in phytochemical study of medicinal plants

Background and aimThe renewed interest in medicinal plants has led us to examine more closely the usefulness of metabolite histolocalisation in screening work before any in-depth phytochemical studies. Indeed, this method is a histochemical technique allowing characterizing plant tissues constituents; and in particular metabolites of therapeutic interest, without destroying or altering as much as possible the studied plant material. This work aims at allowing us carring out a wide screening to highlight bioactive metabolites in plants studied from our rich university heritage collection. Material and methodsThe histochemical characterisation used in our work is a chemical, morphological and topographical (localisation) technique that uses precipitation reactions using dyes, among others. To do this we made thin cross-sections using razor blades on fresh plant material. The sections were then coloured using conventional chemical stains and observations were made using a MOTIC BA210 microscope equipped with a MOTICAM camera. Results and conclusionIn view of obtained results, this technique, therefore, proves to be a useful screening and analysis method when applied in phytochemical studies on plants such as Datura stramonium, Peperomia obtusifolia, Cecropia obtusa, Orthosiphon aristatus and Vitex agnus castus. The obtained results confirm presence of sought metabolites, and allow their precise histological localisation. This will make extraction process more profiTable, simpler or even more ecological by avoiding waste.

A New Type of Ecological Floating Bed Based on Ornamental Plants Experimented in an Artificially Made Eutrophic Water Body in the Laboratory for Nutrient Removal.

In this study, a new type of ecological floating bed (NT-EFB) employing ornamental plants (either Spathiphyllum floribundum, Hydrocotyle sibthorpioids, Chlorophytum comosum or Peperomia obtusifolia) was designed to purify confected eutrophic water for 39days. The growth characteristics of the plants and the effect of water treatment were analyzed and compared. The results showed that: (1) all the four ornamental plants examined survived well in the eutrophic water and an increase of plant biomass was observed; (2) the degradation efficiency of TOC by adding plants was about 85.0%; (3) the removal rate of NH4+-N was about 97.0%; (4) all the four plants can be used as floating bed plants to treat eutrophic water and Hydrocotyle sibthorpioids had the best growth characteristics and treatment efficiency. The study provides an adequate reference for the treatment of eutrophication using ecological floating beds.

Fungal endophytes in Peperomia obtusifolia and their potential as inhibitors of chickpea fungal pathogens.

Chickpea (Cicer arietinum L., Fabaceae) is the second most important legume after common bean (Phaseolus vulgaris L., Fabaceae) and third in production among the legumes grains worldwide. Ascochyta blight and Fusarium wilt are among the main fungal infections which cause the major losses of chickpea crop. In this work we report the phyto-pathogen controlling properties of 24 endophyte Phomopsis/Diaporthe isolates on the chickpea fungal pathogens Ascochyta rabiei, Fusarium oxysporum and Fusarium solani. The Phomopsis/Diaporthe strains were isolated amongst a total of 62 endophytic fungi from the aerial parts of the herbaceous perennial American plant Peperomia obtusifolia (Piperaceae) along with Fusarium, Septoria, Colletotrichum, Alternaria and Roussoella genera among others. Phomopsis/Diaporthe isolates were identified as Diaporthe infecunda (12 isolates), Diaporthe sackstoni (1 isolate), Diaporthe cf. brasiliensis (4 isolates) and Phomopsis cf. tuberivora (7 isolates). All the Phomopsis/Diaporthe strains antagonized A. rabiei strain AR2 with a mean of inhibition (% I) of 86.59 ± 1.49% in dual cultures. The metabolic characterization of the Phomopsis/Diaporthe strains showed groups in three clusters which were in agreement with the taxonomic identification. Bioautographic evaluation of organic extracts showed that those of D. cf. brasiliensis and D. infecunda were better as inhibitors. Strain Po 45 was one of the most active (cluster 1, 96.87% I), and its ethyl acetate extract inhibited A. rabiei growth in a bioautographic assay until at least 10 μg/mm applied showing a specific chromatographic band as the responsible of the A. rabiei inhibition.

Study on the fire growth in underground green corridors

Underground green corridors are getting popular worldwide intending to integrate greenery into built environments. Green corridors provide greenery benefits and aesthetic pleasing view. Proper irrigation is necessary to maintain live plants in green walls. Automated irrigation with adequate amounts and proper drainage is vital to avoid overflows and drowning of plants. Due to improper irrigation plants in green walls can die quickly, creating a potential fire risk in underground green corridors. This paper aims at investigating the ignition, fire propagation and smoke propagation in underground green corridors. Numerical simulations with computational fluid dynamics (CFD) and physical scale modeling experiments were performed. The simulation has been completed based on heat release rate (HRR, kW/m2) data obtained from the cone calorimeter experiments for three plant species, namely; Hedera helix, Peperomia obtusifolia and Aglaonema commutatum. CFD simulations were conducted for an underground passage with a green wall. Results showed that a fire does not occur in underground corridors with fresh and live plants. However, fire risk increases gradually with drying out of plants. For dry plants, the surface temperature may reach above 850 °C. The fire spreads rapidly in about 20 s. An experimental study was carried out on a reduced-scale underground green corridor to investigate the fire and smoke propagation. It is observed that in the vertical direction fire spreads up to the ceiling rapidly. However, fire spreads slowly in the horizontal direction along the green wall. The experiments show that when the green wall is ignited, it may tremendously affect the evacuation due to smoke spread along the corridor and fire propagation in the vertical direction. It is recommended to decrease the fire risk in underground corridors with properly maintained green walls, especially in evacuation paths. This work is an initial study towards the analysis of fire and smoke propagation in underground green corridors.

Antibacterial activity of prenylated benzopyrans from Peperomia obtusifolia (Piperaceae)

Peperomia obtusifolia is a herbaceous perennial plant native to the Americas reported as a traditional medicine to treat snake bites and as a skin cleanser. The bioassay-guided fractionation of crude extracts from aerial parts of P. obtusifolia against a panel of clinically important fungi and bacteria, showed that hexane and dichloromethane extracts demonstrated selective bacterial inhibition, allowing the isolation of the known compounds peperobtusin A (1), and 3,4-dihydro-5-hydroxy-2,7-dimethyl-8-(3”-methyl-2”-butenyl)-2-(4’-methyl-1’,3’-pentadienyl)-2H-1-benzopyran-6-carboxylic acid (2) from dichloromethane extract. Compound 2 was active against Gram-positive bacteria including community acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) isolates and an Enterococcus faecalis vancomycin-resistant strain, with minimal inhibitory concentration (MIC) values of 4 μg/mL (10.8 μM) and 8 μg/mL (21.6 μM) respectively. The interaction of compound 2 with the bacterial membrane was demonstrated by means of Zeta potential experiments on S. aureus, then confirming the membrane damage by fluorescent microscopy experiments.

First Report of Tomato spotted wilt virus Infecting Peperomia obtusifolia in South Korea

First Report of <i>Tomato spotted wilt virus</i> Infecting <i>Peperomia obtusifolia</i> in South Korea

Moisture Content, Ignitability, and Fire Risk of Vegetation in Vertical Greenery Systems

Vertical greenery systems (VGS) are getting popular as a green cladding material. However, they have not been adequately assessed in terms of fire safety. Lack of maintenance and improper irrigation systems will cause drying of plants in VGS, creating substantial fire risk. Dry plants may be easily ignited and intensify the vertical spread of fire. However, potential fire hazards of VGS are barely discussed in the existing literature. The moisture content (MC) of a plant is one of the most critical factors affecting its ignitability. This study explores ignitability and fire risk of plants under radiative heat flux at different MCs. Three commonly used plant species for VGS—namely, Hedera helix Lowe, Peperomia obtusifolia (L.) A.Dietr., and Aglaonema commutatum Schott (the cultivar Lady Valentine)—were selected for study. These plants were subjected to natural drying under ambient conditions without water supply to simulate the plants in VGS without proper irrigation. The MC of the plants was measured and cone calorimeter testing was performed at different time intervals during their drying process. Ignition, heat release, and gaseous emissions were studied under radiative heat flux. When the plants were fresh and green, no ignition was observed for all three species. Hedera helix started to ignite once MC was lower than 243 %, at a heat flux of 50 kW m−2. Peperomia obtusifolia began to ignite once MC dropped below 200%, at a heat flux of 20 kW m−2. Aglaonema commutatum ignition occurred once MC was lower than 316 %, at a heat flux of 50 kW m−2. Cone calorimeter test data were used for analyzing the three key parameters: flashover propensity, total heat release per unit area, and smoke toxicity hazard. Analysis showed that low MC creates a high risk of flash-over. Thermal risk and smoke toxicity hazard also increased at lower MC, but the risk was low for the three plants tested. These findings demonstrate the importance of maintaining healthy live plants to ensure that fire risk of VGS is minimal. This study provides good direction for assessing and understanding the fire behavior of vegetation in VGS.

Non-Clinical Studies for Evaluation of 8-C-Rhamnosyl Apigenin Purified from Peperomia obtusifolia against Acute Edema.

Compound 8-C-rhamnosyl apigenin (8CR) induced a moderate reduction in the enzymatic activity of secretory phospholipase A2 (sPLA2) from Crotalus durissus terrificus and cytosolic phospholipase A2 (cPLA2), but the compound also significantly inhibited the enzymatic activity of the enzyme cyclooxygenase. In vitro assays showed that the compound induced a slight change in the secondary structure of sPLA2 from Crotalus durissus terrificus snake venom. In vivo assays were divided into two steps. In the first step, the 8CR compound was administered by intraperitoneal injections 30 min prior to administration of sPLA2. In this condition, 8CR inhibited edema and myonecrosis induced by the sPLA2 activity of Crotalus durissus terrificus in a dose-dependent manner by decreasing interleukin-1β (IL-1β), tumor necrosis factor α (TNF-α), prostaglandin E2 (PGE2), and lipid peroxidation. This has been demonstrated by monitoring the levels of malondialdehyde (MDA) in rat paws after the course of edema induced by sPLA2. These results, for the first time, show that sPLA2 of Crotalus durissus terrificus venom induces massive muscle damage, as well as significant edema by mobilization of cyclooxygenase enzymes. Additionally, its pharmacological activity involves increased lipid peroxidation as well as TNF-α and IL-1β production. Previous administration by the peritoneal route has shown that dose-dependent 8CR significantly decreases the enzymatic activity of cyclooxygenase enzymes. This resulted in a decrease of the amount of bioactive lipids involved in inflammation; it also promoted a significant cellular protection against lipid peroxidation. In vivo experiments performed with 8CR at a concentration adjusted to 200 μg (8 mg/kg) of intraperitoneal injection 15 min after sPLA2 injection significantly reduced sPLA2 edema and the myotoxic effect induced by sPLA2 through the decrease in the enzymatic activity of cPLA2, cyclooxygenase, and a massive reduction of lipid peroxidation. These results clearly show that 8CR is a potent anti-inflammatory that inhibits cyclooxygenase-2 (COX-2), and it may modulate the enzymatic activity of sPLA2 and cPLA2. In addition, it was shown that Crotalus durissus terrificus sPLA2 increases cell oxidative stress during edema and myonecrosis, and the antioxidant properties of the polyphenolic compound may be significant in mitigating the pharmacological effect induced by sPLA2 and other snake venom toxins.

The Combined Use of Proteomics and Transcriptomics Reveals a Complex Secondary Metabolite Network in Peperomia obtusifolia.

Peperomia obtusifolia, an ornamental plant from the Piperaceae family, accumulates a series of secondary metabolites with interesting biological properties. From a biosynthesis standpoint, this species produces several benzopyrans derived from orsellinic acid, which is a polyketide typically found in fungi. Additionally, the chiral benzopyrans were reported as racemic and/or as diastereomeric mixtures, which raises questions about the level of enzymatic control in the cyclization step for the formation of the 3,4-dihydro-2H-pyran moiety. Therefore, this article describes the use of shotgun proteomic and transcriptome studies as well as phytochemical profiling for the characterization of the main biosynthesis pathways active in P.obtusifolia. This combined approach resulted in the identification of a series of proteins involved in its secondary metabolism, including tocopherol cyclase and prenyltransferases. The activity of these enzymes was supported by the phytochemical profiling performed in different organs of P.obtusifolia. However, the polyketide synthases possibly involved in the production of orsellinic acid could not be identified, suggesting that orsellinic acid may be produced by endophytes intimately associated with the plant.

Biosynthetic Insights into p-Hydroxybenzoic Acid-Derived Benzopyrans in Piper gaudichaudianum

Piper gaudichaudianum Kunth (Piperaceae) accumulates gaudichaudianic acid, a prenylated benzopyran, as its major component. Interestingly, this trypanocidal compound occurs as a racemic mixture. Herein, transcriptomic investigations of Piper gaudichaudianum using the RNA-seq approach are reported, and from the analysis of the transcripts expressed it was possible to propose a complete biosynthetic pathway for the production of gaudichaudianic acid, including the steps that originate its precursor, p-hydroxybenzoic acid. Peperomia obtusifolia (L.) A. Dietr. (Piperaceae) also accumulates racemic benzopyrans, however, its chromanes originate from the polyketide pathway, while the chromenes from Piper derives from the shikimate pathway. Recent transcriptomic and proteomic studies of the former species did not identify polyketide synthases involved in the production of the benzopyran moiety, but revealed the expression of tocopherol cyclase, which may be responsible for the cyclization of the 3,4-dihydro-2H-pyran ring. The analysis of the enzymes involved in the secondary metabolism of Piper gaudichaudianum and the comparison with the data previously obtained from Peperomia obtusifolia can provide valuable information on how these compounds are biosynthesized.

RESPONSE OF PEPEROMIA OBTUSIFOLIA (L.) A. DIETR CV. VARIEGATA PLANT TO SOME FERTILIZATION TREATMENTS

An experiment was established under plastic house at the nursery of Hort. Res. Inst., ARC, Giza, Egypt during 2012 and 2013 seasons to find out the effect of foliar spraying with active dry yeast solution at 0, 1, 3 and 5 g/l, soil drenching with NPK mixture (2:2:1) at 2 g/pot and the interaction between each level of yeast and that of NPK mixture on growth and chemical composition of 3- months-old transplants of Peperomia obtusifolia (L.) A. Diter. grown in 14-cm-diameter plastic pots filled with about 1 kg of an equal mixture of washed sand, clay and peatmoss (1:1:1, by volume.) The obtained results indicated that various single and combined treatments improved all vegetative and root growth parameters with various significant differences compared to the control in both seasons. Active dry yeast alone at 3 g/l treatment gave better result than the other individual ones, whereas comparing between any level of dry yeast combined with NPK (2 g/pot) was more effective in improving vegetative and root growth of plants than all the individual treatments, the interaction between 3 g/l active dry yeast and 2 g/pot NPK recorded the best growth at all in both seasons. On the same line were those results of pigments content in the leaves reached maximum by 3 g/l dry yeast, but the opposite was right regarding the percentages of total soluble sugars, N, P and K content those reached the highest values by the level of 5 g/l dry yeast in most cases of both seasons. However, content of those constituents was doubled by connecting between active dry yeast at any level and NPK mixture 2 g/pot, with the prevalence of 3 g/l active dry yeast plus 2 g/pot NPK combination, that gave the highest content in the two seasons. Hence, it can be recommended to fertilize Peperomia obtusifolia cv. Variegata plants cultivated in 14-cm-diameter plastic pots with active dry yeast at 3 g/l (as a foliar spray) plus NPK mixture (2:2:1) at 2 g/pot (as a soil drench), 5 times with one month interval to obtain the best vegetative growth and high pot plant quality

IDENTIFICATION AND GENETIC DIVERSITY OF PECTOLYTIC PHYTOPATHOGENIC BACTERIA OF MONO- AND DICOTYLEDONOUS ORNAMENTAL PLANTS IN IRAN

Bacterial soft rot can be a destructive disease of ornamental plants. To identify the pathogenic soft rot bacteria occurring in ornamental plants in Tehran and Markazi provinces (Iran), 57 isolates were obtained from 12 different mono- and dicotyledonous hosts and investigated with regard to phenotypic, genotypic and pathogenicity features. Based on phenotypic characteristics, the bacterial strains were identified as Pectobacterium carotovorum subsp. carotovorum. This was confirmed by subspecies-specific primers using PCR. Inoculation of all isolates into Aglaonema leaves confirmed the pathogenecity of the isolated strains. To assess the genetic diversity within Pectobacterium carotovorum subsp. carotovorum populations by rep-PCR, 26 isolates were selected according to their host and geographic distribution as well as two strains from Guilan province. Cluster analysis was conducted using the UPGMA method and revealed a possible close relationship between DNA fingerprints and geographical origins of isolates. Our results showed significant genetic variation among the populations of this pathogen. To the best of our knowledge, this is the first report of Pectobacterium carotovorum subsp. carotovorum on Peperomia obtusifolia, P. caperata, Pilea cadierei, Plectranthus australis, Saintpaulia ionantha and Kalanchoe tubiflora in Iran.

New Species of &lt;I&gt;Peperomia&lt;/I&gt; (Piperaceae) from Brazil

Abstract Two new species of Peperomia from Brazil are described and illustrated based on morphological traits: Peperomia diamantinensis from the state of Bahia and Peperomia cruzeirensis from the state of Acre. Peperomia diamantinensis is very similar to Peperomia obtusifolia and Peperomia magnoliifolia, differing from the latter in the acute leaf apex and the short internodes. Peperomia cruzeirensis is similar to Peperomia elongata Kunth, but differs from the latter in the short pedicel of the fruits, and the petiole without two rows of trichomes. Discussions on taxonomy, geographic distribution, conservation status and habitat are provided, as well as identification keys to the Brazilian species of the Oxyrhynchum and Leptorhynchum clades.

First Report of Sclerotium Rot of Foliage Ornamental Plants in Poland

Abstract Stem and leaf rot incited by Sclerotium rolfsii was found on Epipremnum aureum, Hedera helix, and Peperomia obtusifolia rooting cuttings. S. rolfsii was isolated from about 90% of the analysed plant materials. Isolate from E. aureum colonized all the parts of the 3 host plants as well as eustoma and lavender. Necrosis spread significantly faster on peperomia and the nonhost plants. The fungus produced dense, floccose, white mycelium with numerous, small, brown sclerotia. The optimum temperature for development was 30°C.