Peperomia Obtusifolia Research Articles

Leaf Ultrastructure of Peperomia obtusifolia, P. camptotricha, and P. scandens

Three parenchyma tissues are arranged in separate periclinal layers in the leaves of Peperomia obtusifolia, P. camptotricha, and P. scandens. A transparent, multiple epidermis is situated on the adaxial side of the leaf and has large, tightly packed cells containing mostly starch-filled chloroplasts. A median (palisade) mesophyll, situated between the multiple epidermis and an abaxial spongy mesophyll, has small, moderately packed cells. Chloroplasts occupy a large volume of the median mesophyll cells and contain little starch but extensive thylakoid membranes with numerous, highly stacked grana. A spongy mesophyll is situated on the abaxial side of the leaf and has cells much larger than those in the median mesophyll. The spongy mesophyll chloroplasts contain mostly starch, and the thylakoid membranes have fewer, less stacked grana than those in the median mesophyll. The cellular ultrastructure of each tissue type is similar among these species, indicating a specialized function for each tissue. However,...

Nitrogen Source Effects on Growth and Tissue Content of Selected Foliage Plants

Abstract Nine nitrogen fertilizer treatments composed of 25% NH4:75% NO3, 50% NH4:50% NO3, 75% NH4:25% NO3, 25% urea:75% NO3, 50% urea:50% NO3, 75% urea:25% NO3, 100% NH4, 100% urea, and 100% NO3 were applied to Aglaonema Schott, × Silver Queen, Dieffenbachia maculata (Lodd.) G. Don ‘Camille’, Aphelandra squarrosa Nees ‘Dania’, Chamaedorea elegans Mart., Nephrolepis exaltata (L.) Schott. ‘Florida Ruffle’, Peperomia obtusifolia (L.) A. Dietr., and Philodendron scandens oxycardium (Schott) Bunt. Growth and grade of Dieffenbachia and Nephrolepis were not influenced by N source, whereas Aglaonema and Philodendron were improved when they received N sources containing 25% to 100% NH4-N or 100% urea-N. Aphelandra, Chamaedorea, and Peperomia responded to N source, but differences were of no commercial significance.

Dip Treatment of Tropical Ornamental Foliage Cuttings in Fluvalinate to Prevent Spread of Insect and Mite Infestations

Cuttings of tropical ornamental foliage plants were dipped in fluvalinate at rates of 0.84, 1.68, and 3.36 g (AI)/100 liters of water for the control of Tetranychus urticae Koch, Phenacoccus solani Ferris, Myzus persicae (Sulzer), and Trialeurodes vaporariorum (Westwood). When cuttings were dipped for 1 min in the 1.68-g rate of fluvalinate, populations of all pest species were reduced by at least 70%. Phytotoxicity studies were also conducted with the following plant species: Dieffenbachia maculata (Lodd.) G. Don. Dracaena margtnata Lam., Codiaeum variegatum (L.) Blume, Cissus rhombifolia Vahl, Cordyline terminalis (L.) Kunth, Epipremnum aureum (Linden & André) Bunt., Ficus pumila L., Hedera helix L., Hoya carnosa (L.f.) R. Br., Maranta leuconeura E. Morr. kerchoviana, Peperomia obtusifolia (L.) A. Dietr., and Philodendron scandens oxycardium (Schott) Bunt. No noticeable foliar damage was observed for any of the species tested. Significant reductions in number of roots or root weight were obtained for C. rhombifolia and C. terminalis when they were dipped in fluvalinate at the 3.36-g rate for 2 min. All other species had normal to increased root development as a result of dipping. Concentration of fluvalinate in the dip solution had more effect on the expression of phytotoxicity in C. terminalis than did the amount of time cuttings were in the dip solution.

Investigations into the Roles of Fertilizer Level and Irrigation Frequency on Growth, Quality, and Severity of Pythium Root Rot of Peperomia obtusifolia

Abstract Peperomia obtusifolia (L.) A. Dietr. were grown with various fertilizer levels (0.5–3.5 g Osmocote 19-3-10/10-cm pot) and irrigation frequencies (1, 2, or 3 times/week). Plants were inoculated with Pythium splendens Braun 2–6 months after initiation of fertilizer treatments. Top and root quality responses were linear and quadratic with respect to fertilizer level. One month after inoculation, root quality decreased the most for plants with the highest irrigation frequency and the lowest fertilizer level. Plants fertilized at the highest rate did not show a significant decrease in root quality. There was an interaction between fertilizer and irrigation rates as measured by plant height, quality, and disease ratings. Poorest quality plants resulted when watered 3 times/week and fertilized with 0.5 g Osmocote/pot. Highest quality plants resulted when watered 2 or 3 times/week and fertilized with 2.5 g Osmocote/pot.

Carbon Balance of Peperomia obtusifolia Plants during Acclimatization to Low PPFD

Abstract The CO2 exchange rates of Peperomia obtusifolia A. Dietr. plants (tops and roots) were measured for 12-hour light and 12-hour dark cycles during 5 weeks of acclimatization at 30 µEs-1m-2. A carbon balance analysis of the data indicated that the growth conversion efficiency (Yg) remained constant (0.73 ± 0.1 and 0.77 ± 0.04 before and after acclimatization, respectively). The daily rate of substrate production from photosynthesis (ΔS/Δt) remained constant at 18 ± 2 mg C plant-1 24 hr-1, at the acclimatization photosynthetic photon flux density (PPFD), but the daily rate of synthesis of carbon into new material (ΔW/Δt) increased by 55% within the first week. The maintenance coefficient (m) decreased from 13.0 ± 0.9 to 7.4 ± 0.4 mg g-1 24 hr-1, and change in m may be a criterion for selection of plants that can be adapted for use at low PPFD. The light compensation point (LCP) was reduced during acclimatization, but its use underestimated the PPFD required for 24-hour plant maintenance because of failure to account for night-time respiratory losses. It is suggested that the PPFD at which ΔW/Δt is zero or slightly above is more reliable than the light compensation point for determining PPFD required for plant maintenance.

The Effect of Shading and Nutrient Supply on Variegation and Nutrient Content of Variegated Cultivars of Peperomia obtusifolia

Abstract A reduction in light intensity by 27%, 47%, or 73% shading significantly increased percent variegation (relative amount of nongreen area per leaf) and significantly decreased fresh and dry weight, but did not appreciably affect leaf nutrient content of Peperomia obtusifolia L. Nutrient treatments had no consistent effect on variegation or fresh and dry weight.

Neutron scattering method for studying bound water in live tissue application to plant leaves

Illustrative neutron scattering studies are presented of rotational modes of bound H 2O in live leaves of Ficus elastica decora, Philodendron cordatum and Peperomia obtusifolia. Interpretation of data is based on the hypothesis that hindrance of rotational motion should result in shifts to higher frequency. Such shifts are verified by comparing scattering from water with that from ice and cytosine monohydrate. Statistical analysis of the scattering from plant leaves is based on the assumption that least-squares fitting can be carried out using variable percentages of ice and water spectra to describe hydrate and free water fractions. It is found that the amount of water present as a 4-fold bonded hydrate is very small, being of the order of a few percent or less.

Influence of N-P-K Factorial Fertilization on Growth Characteristics and Foliar Content of 4 Foliage Plants1

Abstract Data indicated the N-P2O5-K2O ratio of 1-1-1 is unnecessarily high in P2O5 and K2O for Dieffenbachia maculata (Lodd.) G. Don ‘Exotica’, Dracaena sanderana Hort. Sander ex M. T. Mast, Maranta leuconeura var. kerchoviana E. Morr., and Peperomia obtusifolia (L.) A. Dietr. Plant growth and tissue nutrient levels were more sensitive to changes in N fertilization level than P and K. Tissue N was a more sensitive indicator of optimum growth and fertility practices than P or K.

Influence of Production Light and Ancymidol on Foliage Plants1

Abstract Ficus elastica ‘Decora’ Roxb. ex Hornern, Peperomia obtusifolia (L.) A. Deitr, and Hedera helix ‘Hahn’s Self-branching’ L. were produced under 15 and 30 klx light levels and treated with 4 concentrations of ancymidol (alpha-cyclopropyl-alpha-(p-methoxyphenyl)-5-pyrimi-dinemethanol) and several weeks later were placed in an interior holding environment for 6 weeks. Ficus was taller and heavier when produced under 15 klx light; different ancymidol concentrations caused no significant growth effects. Peperomia was taller with increasing light and decreased in growth with ancymidol treatments. After 6 weeks in the interior holding environment, plant grade increased with increasing production light for Peperomia and remained the same for Ficus. Both Ficus and Peperomia maintained similar responses to production treatment after 6 weeks indoors. Hedera was not influenced by production light or ancymidol treatments.

Response of Container-grown Plants to Six Consumer Growing Media1

Abstract Bulk density, moisture holding capacity, pH, initial nutrient level, aeration or soluble salt characteristics were not consistently related to growth response in 6 commercial growing media. Growth of Tradescantia albiflora Kunth ‘Albovittata’, Hemigraphis alternata (Burm,f.) T. Anderson, Wedelia trilobata(L.) A. S. Hitchc, Peperomia obtusifolia (L.) Dietr., Lycopersicon esculentum Mill. ‘Better Boy’, and Hypoestes phyllostachya Bak. were highly variable among media.

Influence of Photoperiod and Light Quality on Lateral Branching and Flowering of Selected Vegetatively-propagated Plants1

Abstract Alternanthra amoena Voss, Coleus × hybridus Voss., Hedra helix L., Pelargonium × hortorum Bailey, Peperomia obtusifolia L.,Pilea cadierei Gagnep. & Guillaum, Pilea ‘Moon Valley’ and Pilea involucrata ‘Panamegia’ Sims were grown under normal photoperiods (ND), short photoperiods (SD) and several night lighting regimes using red, incandescent, or far red light. Lateral branching and cutting production was promoted on P. ‘Moon Valley’ under SD while flowering was inhibited. P. ‘Moon Valley’ and P. involucrata flowered under long days. The remaining plant species produced more cuttings under ND or the night lighting treatments when compared to SD. Cycling P. ‘Moon Valley’ and P. involucrata between SD and day continuation red lighting treatments every 20 days significantly increased cutting production on plants compared to plants grown continuously under SD or ND.

Foliage Plant Responses to Translucence of the Growing Container1

Abstract Aglaonema commutatum Schott. ‘Silver Queen’, Ficus benjamina L., Peperomia obtusifolia (L.) A. Dietr. ‘Marble’ and Chamaedorea elegans Mart, were grown in a glass greenhouse under 15 klx of light maximum in black, white or clear 15 cm diameter containers that transmitted 0, 5 or 14 klx maximum respectively at perimeter of root ball. Visual root grades of Ficus and Peperomia were not influenced by treatment, but those of Aglaonema and Chamaedorea were lower at 5 or 14 klx light. Fresh weight of tops and roots of the 4 foliage plant species were not affected by treatments.

Responses of Succulents to Plant Water Stress

Experiments were performed to test the hypothesis that succulents "shift" their method of photosynthetic metabolism in response to environmental change. Our data showed that there were at least three different responses of succulents to plant water status. When plant water status of Portulacaria afra (L.) Jacq. was lowered either by withholding water or by irrigating with 2% NaCl, a change from C(3)-photosynthesis to Crassulacean acid metabolism (CAM) occurred. Fluctuation of titratable acidity and nocturnal CO(2) uptake was induced in the stressed plants. Stressed Peperomia obtusifolia A. Dietr. plants showed a change from C(3)-photosynthesis to internal cycling of CO(2). Acid fluctuation commenced in response to stress but exogenous CO(2) uptake did not occur. Zygocactus truncatus Haworth plants showed a pattern of acid fluctuation and nocturnal CO(2) uptake typical of CAM even when well irrigated. The cacti converted from CAM to an internal CO(2) cycle similar to Peperomia when plants were water-stressed. Reverse phase gas exchange in succulents results in low water loss to carbon gain. Water is conserved and low levels of metabolic activity are maintained during drought periods by complete stomatal closure and continual fluctuation of organic acids.

Ultraviolet Radiation Reflectance, Transmittance, and Absorptance by Plant Leaf Epidermises1

AbstractPartial destruction of ozone in the earth's upper atmosphere (stratosphere) will increase levels of ultraviolet (UV) radiation that reach the earth's surface; consequently, plants could be exposed to harmful amounts of UV‐B radiation (280 to 320 nm). The objective of our research was to characterize the reflectance, transmittance, and absorptance of UV‐B radiation by leaf epidermises. Accordingly, measurements were made spectrophotometrically over the 260 to 360‐nm wavelength, to encompass the UV‐B waveband, on epidermises of different thicknesses from six plant genera: Century plant (Agave americana L.), onion bulb (Allium cepa L.), peperomia (Peperomia obtusifolia A. Dietr.), yucca (Yucca treculeana Carr.), kalanchoe (Kalanchoe laciniata DC.), and pricklypear (Opuntia lindheimeri Engelm.).Thick epidermises of pricklypear, peperomia, century plant, and yucca reflected and transmitted less and absorbed more UV radiation over the 260 to 360‐nm waveband than thinner epidermises of onion and kalanchoe. Absorptance of the critical UV‐B radiation ranged from 91 to 96% for the thick epidermises and from O to 66% for the thinner epidermises.It is concluded that leaves of plants with thick epidermises would have less internal damage to inner tissues of their mesophylls by UV‐B radiation than leaves with thinner epidermises; however, UV‐B radiation may damage the epidermis itself.

The thermal conductivity of leaves

Thermal conductivities of fresh leaves, both unmodified and infiltrated with water, were measured. Samples were placed between silver plates of known and differing temperatures, and the time required to boil off a constant volume of liquid was measured. The species used are evergreens: Eucalyptus globulus Labill. (sclerophyllous) with isolateral leaf symmetry; and Peperomia obtusifolia A. Dietr. (succulent), Citrus limon Burm. f. (mesophyllous), Arbutus menziessii Pursh. (sclerophyllous), and Heteromeles arbutifolia M. Roem. (sclerophyllous), all with bilateral leaf symmetry. Mean values found were in the range of 0.268 to 0.573 W/m · °C for fresh leaves, and 0.540 to 0.548 W/m · °C for leaves infiltrated with water. An analysis of errors in the technique indicated that these values may be somewhat low. These results are several times higher than previously reported values. It is concluded that ordinary mesophytic and xerophytic leaves will not develop large gradients in temperature between the surfaces.

Transient Heat and Mass Transfer from a Leaf Undergoing Stomatal Closure in a Low Pressure Environment

Stomatal control of water loss was studied in a low pressure environment by using detached leaves of Crassula argentea Thunb., Peperomia obtusifolia (L.) A. Dietr., and Setcreasea pallida Rose cv. ;Purple Heart.' The transient behavior of temperature and rate of mass loss were determined. A model based on free molecule gas flow was developed and used to predict mass loss to within the same order of magnitude of experimentally obtained results. By utilizing this model, the transient behavior of stomatal aperture was determined. The "nonphysiological" experimental conditions do not inhibit the closing process; therefore, this new experimental technique is a valid method of studying stomatal closure.

Withholding Phosphorus as a Conservation Measure for Vegetable Plants

Abstract Two experiments were conducted to test the hypothesis that plants in the vegetative state would not succumb as rapidly to low light intensities if they had no phosphorous available as the resulting restriction in growth would permit stored photosynthate to be available for plant maintenance. The first used Peperomia obtusifolia ‘Variegata’ as the test plant. The rooted cuttings were received on December 22, 1965, and potted in propagator’s sand. They were grown in sand cultures to the surface of which a mineral nutrient solution was applied daily with the leachate allowed to drain away. The mineral nutrient solution contained in millimoles per liter, 5, 6, 1, and 1 of Ca(NO3)2, KNO3, KH2PO4, and Mg-SO4, respectively. Two ppm of Fe were added as a chelate (Fe 138) and trace elements were added as usual for a solution culture according to the recipe of Hoagland.

Withholding Phosphorus as a Conservation Measure for Vegetable Plants

Abstract Two experiments were conducted to test the hypothesis that plants in the vegetative state would not succumb as rapidly to low light intensities if they had no phosphorous available as the resulting restriction in growth would permit stored photosynthate to be available for plant maintenance. The first used Peperomia obtusifolia ‘Variegata’ as the test plant. The rooted cuttings were received on December 22, 1965, and potted in propagator’s sand. They were grown in sand cultures to the surface of which a mineral nutrient solution was applied daily with the leachate allowed to drain away. The mineral nutrient solution contained in millimoles per liter, 5, 6, 1, and 1 of Ca(NO3)2, KNO3, KH2PO4, and Mg-SO4, respectively. Two ppm of Fe were added as a chelate (Fe 138) and trace elements were added as usual for a solution culture according to the recipe of Hoagland.