Pelargonium X Hortorum Research Articles

Biosynthesis of sterols and triterpenes in Pelargonium hortorum

Although all parts of the geranium plant (Pelargonium hortorum) are capable of synthesizing sterols and triterpenes and their esters in vitro from mevalonic acid-[2-14C], the aerial portions are more active than other tissues. All plant parts were shown to incorporate mevalonic acid-[2-14C] into isoprenoids for at least 3 days. The leaves and petioles had the greatest incorporation on a wet weight basis. Chopped preparations showed comparable incorporations of mevalonate whereby rootlets incorporated about one half as much as most parts; the flower petals incorporated five times the average amount. In leaves the principal sterol synthesized was sitosterol. Metabolic studies with isolated leaves indicated a fairly rapid conversion of free tetracyclic triterpenes to 4-desmethyl-sterols, while β-amyrin was synthesized at a different rate than α-amyrin. Esterified tetracyclic triterpenes exhibited only a slight amount of conversion to 4-desmethylsterols.

Presumptive Cross-affinity Relationship among Pelargonium Species through the Observation of Pollen Tube Behavior by Means of the Fluorescence Microscope

Most of the cultivated forms of geranium (Pelar-gowiwa) may be grouped into four horticultural classes, i.e., (1) zonal geranium, (2) show pelar-gonium, (3) ivy-1eaved geranium, and (4) scented-leaved geranium; the former three are used as ornamertals and the last one as aromatics. In general, geraniums are highly sterile and many of them set few or no seeds. Interspecific hybridization is alm-ost unsuccessful. The present study was underta-kento elucidate the behavior of pollen tubes in inter-and intrapollinations and to presume cross-affinity relationship among several species. After reciprocal crosses were made among different species, the behavior of pollen tubes in the style was observed with the aid of a fiuorescence microscope and fruit-and seed-set was examined.

Epidemiology and Control of Bacterial Leaf Spot and Stem Rot of Pelargonium hortorum

Epidemiology and Control of Bacterial Leaf Spot and Stem Rot of Pelargonium hortorum

Origin of androgenetic callus and haploid geranium plants

Geranium (Pelargonium hortorum Bailey) anthers, containing uninucleate immature pollen at the tetrad stage, were incubated on a modified White's medium at 28 ± 2 °C with 16 h light alternating with 8 h darkness at 23 ± 2 °C. The daughter cells derived from pollen were observed as a colony of four cells after 9 days, and 20 cells after 18 days. Nuclei of cells of the colonies formed were large and diffuse similar to the vegetative nuclei. Examination of dissected anthers after an incubation period of 1 month showed that the induced calli were in the pollen grain sac and not attached to the anther connective tissues. Established calli were subcultured on Murashige and Skoog medium for organoid differentiation. Plants differentiated from the anther callus of varieties Sincerity, Pink Camelia, and Salmon Irene were haploid (2n = 18), had single florets with five petals, and set viable seed.

‘Waltztime’ Geranium1

Abstract The garden or zonal geranium (Pelargonium × hortorum Bailey) has long enjoyed popularity as a garden and greenhouse plant because of its brilliantly colored flowers and tolerance to various degrees of culture. Despite their popularity, most cultivars of P. × hortorum are not well adapted to areas with high summer night temperatures and high relative humidities. The two putative parental species, P. inquinans (L.) L'Her. ex Ait. and P. zonale (L.) L'Her. ex Ait., are native to the subdesert areas of South Africa, which, in common with similar areas around the world, have low humidity and a high day, low night temperature cycle. Further, the early development of the garden geranium occurred in Europe and the northeastern United States where tolerance to high night temperatures was not required.

Improved Geranium Branching with Growth Regulator Sprays

Abstract Foliar sprays of (2-chloroethyl)phosphonic acid (ethephon), 6-benzylamino purine (BA), and 6-(benzylamino)-9-(2-tetrahydropyran-yl)-9H-purine (PBA) significantly increased me branching of pinched ‘Dark Red Irene’ geranium (Pelargonium hortorum Bailey). Spraying pinched plants with 2,3,5-triiodobenzoic acid (TIBA) and indoleacetic acid (IAA) frequently increased the branch no. over pinched but untreated plants. Maximum stimulation of branching of pinched plants occurred from growth regulator sprays at the time of pinching. Ethephon and BA sprays significantly delayed flowering.

Development of the Inflorescence in Petunia, Geranium, and Poinsettia under Ozone Stress1

Abstract Increasing concn of ozone up to 10 to 12 μl/liter decreased anthocyanin content and increased fresh wt but not size in flowers of petunia (Petunia hybrida Vilmorin, cv. Blue Lagoon) and geranium (Pelargonium hortorum Bailey, cv. Red Perfection). Bract anthocyanin increased and bract size decreased in poinsettia (Euphorbia pulcherrima Wildenow, cv. Paul Mikkelson) under the same ozone treatments. Responses were not associated with visible oxidant injury to plant leaves.

Effects of Intercellular Resistances on Estimates of the Intracellular Resistance to Co2 Uptake by Plant Leaves

A model is presented for net CO2 uptake by plant leaves, which is particularly relevant to those leaves having different upper and lower stomatal resistances. The model includes intercellular space resistances to CO2 uptake via both the upper and lower surfaces. Experimental data obtained with Pelargonium hortorum Bailey show that the ratio of the rates of C02 exchange through the lower and upper surfaces respectively is in all cases greater than the ratio of the corresponding rates of water vapour exchange. This provides evidence for a substantial vapour phase resistance to C02 uptake via the upper epidermis, which is not accounted for by the usual water vapour analogue. The data also suggest that calculations of intracellular resistance r'i, using conventional resistance models, may be subject to error. How-ever, the magnitude of the error in estimates of the intracellular resistance is seldom likely to exceed 10%, so that for most purposes changes in the conventional models do not appear to be warranted.

The Role of Cell Interaction in the Growth and Differentiation of Pelargonium hortorum Cells In vitro. I. Cell Interaction and Growth

Pelargonium cells of known number were cultured in conical nylon containers Growth of cells reaggregated in direct physical contact with one another in this manner was compared with growth of cells in suspension. There was a lag phase in both systems at low cell densities However, the exponential growth phase for cells in suspension was at the same rate, regardless of cell number, while the exponential growth rate for cells in the reaggregates varied with the number of cells present

The Role of Cell Interaction in the Growth and Differentiation of Pelargonium hortorum Cells In vitro. II. Cell Interaction and Differentiation

A quantitative analysis was made on the extent to which cell interaction influences the differentiation of sclereids from Pelargonium cells cultured in nylon cones Data collected after 2, 4, and 7 weeks of growth revealed that the frequency of sclereid differentiation was dependent upon cell number; that the sclereids were always associated with groups of small, densely cytoplasmic cells; and that their distribution within the reaggregate was nonrandom Massive starch accumulation followed periods of rapid cell division and differentiation The starch grains were almost exclusively found in the small cells comprising the groups where sclereids had also differentiated

Growth and tissue formation from single geranium cells from virus-infected geraniums.

Single geranium (Pelargonium hortorum, Bailey) cells from callus isolated originally from stem tips of virus-infected plants were grown in microculture chambers in liquid Murashige and Skoog medium supplemented with 0.1 mg per liter of α-naphthalane acetic acid and 10.0 mg per liter of kinetin. Four of 1,000 of these single cells divided in the microculture chamber and produced colonies of 15 to 20 cells in 9 to 16 days. In all of the cases the plane of the first few cell division was at right angles to the long axis of the cells. Subsequently, one of the masses of cells obtained from a single cell, when transferred to solid Murashige and Skoog medium, established itself as a clone of callus tissue. Although the yield was low, the results were encouraging for the ultimate production of plants. These results suggested that, just as virus-free tobacco plants have been induced from single cell clones from certain tobacco species, virus-free single geranium cells may be useful to establish single cell clones from which pathogen-free geranium plants may be induced to differentiate.

Earlier Flowering of Geranium cv. Carefree Scarlet by High Intensity Supplemental Light Treatment1

Abstract Geraniums (Pelargonium hortorum Bailey) grown under constant supplemental lighting using 105 watt Wide Spectrum Gro-Lux fluorescent lamps at 14 lamp watts/ft2 for periods of 0 to 4 weeks flowered in approximately the same no. of days from seeding and the terminal stems had similar no. of nodes. Plants lighted 6 to 10 weeks also flowered uniformly but 24-55 days (21-33%) earlier and with 2-6 fewer nodes than those receiving no supplement light or lighted for less time.

Density and Behavior of Stomata of Pelargonium hortorum Ait. Grown Under Three Soil Moisture Regimes.1,2

Abstract Two cultivars of Pelargonium hortorum Ait. were exposed to 3 soil moisture regimes for 10 weeks at which time rubber silicone impressions were made of the abaxial leaf surface of young and old leaves. ‘Dark Red Irene’ leaves had fewer stomata per unit area and greater diffusion resistance than did ‘Princess Irene’ exposed to the same regime. Increase in soil water content promoted the differentiation of stomata in early stages of leaf development. As the leaves increased in size and matured the number of stomata per unit area became inversely related to soil moisture content as a result of increased leaf area with high soil moisture. The stomatal resistance, determined by diffusion porometer, in young leaves of both cultivars was highest for plants grown in soils with high moisture and lowest with medium moisture.

The Role of Water and Cultural Practices on Oedema of Pelargonium hortorum Ait.1,2

Abstract Two cultivars of Pelargonium hortorum Ait. were used to determine the effect of certain environmental conditions and cultural practices on the formation and development of oedema. High light intensity, low nutritional levels and high soil moisture content increased susceptibility of leaves to oedema. Severity increased when plants were subsequently exposed to environmental conditions that favored water absorption rather than transpiration. A study of stomatal behavior of oedematous leaves showed greater vapor diffusion resistance compared with normal leaves. The excess water in leaf tissues caused hypertrophy of some cells in the leaf which resulted in plugging the sub-stomatal chamber. Sometimes there was an increase in the size of epidermal cells adjacent to guard cells forcing them to close. The stoma was sometimes collapsed as a result of hypertrophy of surrounding cells. The differences in the susceptibility of the 2 cultivars to oedema under high soil moisture was due to differences in their internal structure and stomatal behavior.

Measuring Osmotic Pressure of Sap within Live Cells by Means of a Visual Melting Point Apparatus

A freezing slide apparatus is described for visual observation of freezing water and melting ice within plant cells. The slide consists of an ordinary microscope slide glued into a Plexiglass jacket, through which cold 90% ethyl alcohol is pumped at varying rates for temperature control. Temperature is recorded by means of an iron-constantan thermocouple wire (25-micron diameter) connected to a recording potentiometer. Tissue strips were quick frozen (at a cooling rate of 33 C per (1/2) minute) and then warmed very slowly (at a rate of 2 C per minute) for observation of melting points. This apparatus has been used to determine osmotic pressures of cell sap of guard and adjoining epidermal cells of Chrysanthemum morifolium and Pelargonium hortorum. An accuracy of +/- 1.2 atmospheres is possible. Wide variations among osmotic pressures of both guard and epidermal cells were found at any one stomatal aperture in both species.

A Study of Critical Nutrient Levels in Pelargonium hortorum, Cultivar ‘Irene’1

Abstract The mineral nutrient requirements of geranium, Pelargonium hortorum, cv. ‘Irene’, were studied. Plants were grown in solution culture containing varying quantities of N, P, K, Mg, and Ca, or deficient in S, B, Fe, Mn, Cu, or Zn. Deficiency symptoms of the elements listed are described. The mineral levels in leaves which first show deficiency were found to be at approximate incipient deficiency: N, 2.40%; P, 0.28%; K, 0.62%; Ca, 0.77%; Mg, 0.14%; S, 0.12%; B, 18 ppm; Fe, 60 ppm; Cu, 5.5 ppm; Zn, 6 ppm; and Mn, 9 ppm. Additional useful analytical data are presented.

Occurrence, Severity and Nature of Oedema in Pelargonium hortorum Ait.12

Abstract Five cultivars of Pelargonium hortorum Ait. were used to determine the effect of soil and air temperatures, photoperiod, light intensity, soil water content, and cultivar response on the occurrence and severity of oedema. Oedema was most severe on the peripheral portions of the lower epidermis of the lower, older leaves of the plants. As the disorder progressed, the symptoms became prevalent over the entire lower epidermis. Symptom expression was similar in appearance on most of the cultivars, but the cultivars differed in their susceptibility. A continuously warm moist soil with humid cool night temperatures predisposed plants to oedema. Anatomically, hypertrophy of the spongy parenchyma cells into the sub-stomatal cavity resulted in the occlusion of the stomatal pore. In severe stages the spongy parenchyma cells divided periclinally and a periderm was differentiated which resulted in the raised macroscopic intumescences characteristic of oedema.

Trifluralin-Treated Cloth Controls Weeds in Geranium Plantings

Abstract (Cloth and cotton fiber mats impregnated with trifluralin [alpha, alpha, alphatrifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine] at 1/2 lb/A used to treat soil in potted geranium (Pelargonium hortorum) (Ricard cultivar) plantings were herbicidally effective and did not injure the geraniums. Time required for disintegration of the treated cloths and mats ranged from less than 30 days to more than 120 days.)

Trifluralin-Treated Cloth Controls Weeds in Geranium Plantings

Abstract (Cloth and cotton fiber mats impregnated with trifluralin [alpha, alpha, alphatrifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine] at 1/2 lb/A used to treat soil in potted geranium (Pelargonium hortorum) (Ricard cultivar) plantings were herbicidally effective and did not injure the geraniums. Time required for disintegration of the treated cloths and mats ranged from less than 30 days to more than 120 days.)

NATURAL OCCURRENCE OF TOBACCO RINGSPOT VIRUS IN PELARGONIUM IN ONTARIO

Simultaneous-infection and serological tests demonstrate that a ringspot virus associated with a disease of Pelargonium hortorum cv. Mme. Salleron is related to tobacco ringspot virus. This report is believed to constitute the first record of natural infection of Pelargonium by this virus.