Hibiscus Moscheutos Research Articles

Soil Organic Matter and Bulk Density: Driving Factors in the Vegetation-Mediated Restoration of Coastal Saline Lands in North China

Coastal saline soils are an important soil resource that, when restored, can enhance arable land and preserve the natural ecology. With the aim of improving the use of coastal saline soils, we conducted a spot survey at Bohai coastal saline land to investigate the differences in soil properties between different vegetation types. The soil physical and chemical properties of various vegetation types, including Aeluropus sinensis, Imperata cylindrica, Tamarix chinensis, Lycium chinense, Hibiscus moscheutos, Helianthus annuus, Gossypium hirsutum, and Zea mays, were examined at two depth layers: 0–20 cm and 20–40 cm, and in two seasons, spring and autumn. The soil properties were compared with bare land as a control. The results indicated that the electrical conductivity, total soil salt content, sodium adsorption ratio, and bulk density of soils with vegetation cover were lower than those with bare land. On the other hand, soil pH, organic matter content, mean weight diameter, and saturated hydraulic conductivity were higher. The redundancy analysis results revealed a substantial positive correlation between soil pH, saturated hydraulic conductivity, water content, mean weight diameter, and organic matter content, as well as a significant positive correlation between soil electrical conductivity, total soil salt content, sodium adsorption ratio, and bulk density. Soil pH, saturated hydraulic conductivity, water content, mean weight diameter, organic matter content, and soil electrical conductivity, total soil salt content, sodium adsorption ratio, and bulk density were negatively correlated. The results of the structural equation model and variance decomposition showed that soil organic matter and bulk density were the key factors affecting the degree of soil salinization, and compared with their independent effects, their combined effect on soil salinization was greater. This study’s conclusions can provide a point of reference for further research on the mechanisms of soil improvement and desalinization in coastal saline land.

НЕКОТОРЫЕ АСПЕКТЫ ВЕГЕТАТИВНОГО РАЗМНОЖЕНИЯ ПЕРСПЕКТИВНЫХ СОРТОВ HIBISCUS X MOSCHEUTOS L.

Hibiscus x moscheutos L. is a promising decorative perennial for inclusion in green plantings in the southern regions of Russia. Currently, there is no data available on the most effective methods of propagating hibiscus in the conditions of southern gardening in Russia. Since 2014, FSBSI «North Caucasian Federal Scientific Center of Horticulture, Viticulture, Wine-making» (Krasnodar) has been carrying out work on introduction and variety study of H. x moscheutos. The collection includes 47 varieties. The purpose of this research is to evaluate the potential of vegetative propagation of promising varieties using the herbaceous cuttings method. The study included 18 varieties and hybrids. In the experiment 2 cutting periods were studied: 1st period – spring (II-III decade of May), 2nd period – summer (III decade of June – 1st decade of July (control). It was established that herbaceous cuttings can be carried out in 2 periods – in the II decade of May, with the placement of mother bushes in protected ground, and in the III decade of June, with the preparation of cuttings from mother plants growing in open ground. For most varieties, spring cuttings are preferable. In this case, young plants overwinter better, and the yield of marketable seedlings after 1 year of growing in pots is higher. During wintering of plants of summer cuttings, a high percentage of death was observed, which is associated with the low winter hardiness of young plants. A significant decrease in the yield of marketable seedlings after 1 year of growing in plants of summer cuttings was detected in the following varieties: Berry Awersome, Midnithe Marvell, Plam Flambe, Perfect Storm – a decrease in the yield of seedlings of I grade was observed by almost 2 times in comparison with plants rooted in spring. The best performance in herbaceous cuttings was found in the following varieties: Cherry Cheescake, Cranberry Crush, Peppermint Schnapps, Jazzberry Jam, Summer in Paradise, Krasny Rusanova, Hybrid № 5. These cultivars combine in their genotype adaptability to abiotic stress factors and increased productivity of uterine bushes during cuttings and provide a high yield of marketable seedlings when grown in pots. Key words: ROSEMALLOW (HIBISCUS MOSCHEUTOS), VEGETATIVE REPRODUCTION, HERBACEOUS CUTTINGS, POT CULTURE

Establishment of an In Vitro Micropropagation Protocol for Hibiscus moscheutos L. ‘Berry Awesome’

Hibiscus moscheutos L. ‘Berry Awesome’ is a complex hybrid of the new Proven Winners Summerific series of varieties with highly ornamental characteristics. Micropropagation of highly ornamental varieties is important for mass production of planting material for commercial purposes. The traditional methods for propagating Hibiscus varieties, such as cuttings or seed propagation, however, do not guarantee high rates of production of high-quality seedlings. To solve this problem, an attempt was made to develop protocols for micropropagation of Hibiscus moscheutos L. ‘Berry Awesome’ in vitro on agar and liquid medium using a bioreactor system, followed by ex vitro adaptation of the regenerants. The optimal method for sterilization of nodal explants as well as the optimal composition of the initiation medium for shoot proliferation and rooting were determined. For micropropagation on a liquid medium, a rocker-type bioreactor was used, and its advantages over micropropagation on an agar medium were demonstrated. The results showed that the best sterilization method for nodal segment explants was as follows: pretreatment by rinsing with running tap water, sterile water, and distilled water for 70 min and soaking for 5 min in a mixture of solutions of ethyl alcohol (96%), hydrogen peroxide (38%), and water in a ratio of 1:1:2. In this case, live and sterile explants accounted for 62.6%. The optimal initiation medium for axillary buds in nodal segments was the Murashige and Skoog (MS) medium supplemented with 0.1 mg L−1 N-(2-chloro-4-pyridinyl)-N’-phenylurea (CPPU), which resulted in 73.3% of axillary buds being induced. The optimal solid proliferation medium was MS medium supplemented with 0.1 mg L−1 CPPU with a proliferation coefficient of 5.8. In a liquid medium, the optimal concentration of CPPU was 0.05 mg L−1 with a proliferation coefficient of 9.2. The best medium for rooting/shoots with agar and in bioreactors was MS medium with the addition of 0.1 mg L−1 indole-3-butyric acid (IBA). The highest rooting rate was 99.0% in both types of media, and the survival rate of plantlets was 88.7% in solid media and 98.7% in the bioreactor.

Fusarium abutilonis and F. guadeloupense, two novel species in the Fusarium buharicum clade supported by multilocus molecular phylogenetic analyses

ABSTRACT This study was conducted to elucidate evolutionary relationships and species diversity within the Fusarium buharicum species complex (FBSC). We also evaluate the potential of these species to produce mycotoxins and other bioactive secondary metabolites. Maximum likelihood and maximum parsimony analyses of sequences from portions of four marker loci (ITS rDNA, TEF1, RPB1, and RPB2) and the combined 4495 bp data set support recognition of seven genealogically exclusive species within the FBSC. Two of the three newly discovered species are formally described as F. abutilonis and F. guadeloupense based on concordance of gene genealogies and morphological data. Fusarium abutilonis induces leaf, stem, and root lesions on several weedy Malvaceae (Abution theophrasti, Anoda cristata, Sida spinosa) and a fabaceous host (Senna obtusifolia) in North America and also was recovered from soil in New Caledonia. Fusarium abutilonis, together with its unnamed sister, Fusarium sp. ex common marsh mallow (Hibiscus moscheutos) from Washington state, and F. buharicum pathogenic to cotton and kenaf in Russia and Iran, respectively, were strongly supported as a clade of malvaceous pathogens. The four other species of the FBSC are not known to be phytopathogenic; however, F. guadeloupense was isolated from human blood in Texas and soil in Guadeloupe. The former isolate is unique because it represents the only known case of a fusarial infection disseminated hematogenously by a species lacking microconidia and the only documented fusariosis caused by a member of the FBSC. Whole genome sequence data and extracts of cracked maize kernel cultures were analyzed to assess the potential of FBSC isolates to produce mycotoxins, pigments, and phytohormones.

Micropropagation of Hibiscus moscheutos L. \u2018Luna White\u2019: effect of growth regulators and explants on nuclear DNA content and ploidy stability of regenerants

Hibiscus moscheutos L., also known as hardy hibiscus, is valued for its medicinal and ornamental attributes. It is usually propagated via seeds or cuttings. The purpose of this investigation was to develop a dependable micropropagation for H. moscheutos ‘Luna White’. To that end, the effect of four explant types (leaf, root, node, shoot tip) and two growth regulators 6-benzylaminopurine (BA) and meta-Topolin (mT) (6-(3-hydroxybenzylamino) purine) on in vitro growth of H. moscheutos was investigated. Genetic stability of the in vitro grown plants was assessed using flow cytometry, and chromosome count was investigated. No shoots were obtained from leaf or root explants. An efficient protocol for micropropagation of H. moscheutos using two explant types, 2-node and shoot tip explants, and two cytokinins (BA and mT) capable of producing true-to-type regenerants was established. Both BA and mT can be used at 2 μM or 4 μM using either 2-node or shoot tip explants. No significant difference was found between the nuclear DNA contents of seed-derived and in vitro grown plants (P < 0.05). The mean 2C DNA and monoploid 1Cx-values of seed-derived plants were 3.25 ± 0.08 pg and 1.62 ± 0.04 pg, respectively, compared with 3.26 ± 0.06 pg and 1.63 ± 0.02 pg, respectively, for in vitro grown plants. The chromosome number of both seed-derived plants and regenerants was determined to be 2n = 2x = 38. The mature regenerants obtained were fertile and phenotypically similar to seed-derived plants.

Physiological, morphological and anatomical responses of Hibiscus moscheutos to non-uniform salinity stress

Plant growth in the heterogeneous salinity soil is better than that of in the uniform salinity soil, thus, planting salt tolerant plants in the partial zone desalinated soil of the saline land may reduce the revegetation costs. The swamp rose mallow (Hibiscus moscheutos, SRM), which is an important landscape plant that grows in coastal saline lands, may be an optional plant that can adapt to the non-uniform salinity soil. In this study, SRM seedlings grown in split-root pots irrigated with different concentration of NaCl solutions were studied. There were four treatments, a control (0 mM NaCl), uniform salinity (200 mM NaCl), and two non-uniform salinities (0/200 mM and 0/400 mM NaCl). We determined the growth, gas exchange properties of the leaves, morphological parameters of the leaves and roots, water potential and consumption, and ion accumulation of the seedlings. The aim was to reveal the physiological and anatomical responses of SRM to non-uniform salinity. Under non-uniform salinity, the total biomass, shoot height, and leaf area of SRM seedlings were significantly higher and the leaf Na+ and Cl− contents were significantly lower than under uniform salinity. The total biomass was negatively corelated with the mean root zone salinity. Once the parts of the roots were in the salt-free zone, the leaf water potential and the daily water consumption of the seedlings under non-uniform salinity were much higher than the uniform salinity treatment. The leaf gas exchange of SRM under non-uniform salinity was not significantly inhibited compared to the control, but was significantly higher than under uniform salinity. The leaf electron transport rate (ETR) and maximum quantum yield (Fv/Fm) of the PSII, leaf SOD activity, and the MDA content of the seedlings subjected to non-uniform salinity treatments were at unstressed level. In terms of leaf anatomical traits, that the palisade and spongy parenchyma was significantly thicker than the uniform salinity. Early senescence of the leaves was observed under both uniform and non-uniform salinity conditions. More roots, especially fine roots, were distributed in the non-saline zone. These results indicate that under non-uniform salinity, SRM seedling growth was significantly inhibited, however, the salt stress was alleviated by the partial salt-free root zone compared to uniform the salinity. Non-uniform salinity led to moderate Na+ accumulation in the leaves, which in turn caused slight oxidative and osmotic stress, but had little influence on the morphological or anatomical traits of the leaves. SRM could adapt to the saline soil where partial zone desalinated or partial zone replaced by the non-saline soil.

Determination of Anthocyanins and Antioxidants in 'Titanbicus' Edible Flowers In Vitro and In Vivo.

Titanbicus (TB), a hybrid of Hibiscus moscheutos × H. coccineus (Medic.) Walt., has potential to be used as an edible flower. In this study, proximate nutritional content, anthocyanin content, total polyphenol content (TPC), and antioxidant activities in vitro and in vivo were investigated. Three cultivars of TB, namely Artemis (AR), Rhea (R), and Adonis (AD), were used as materials. Protein and carbohydrates were the primary macronutrients, while crude fat and ash were detected in trace amounts. Cyanidin 3-glucoside (Cy3-G) and cyanidin 3-sambubioside (Cy3-Sam), were identified in all TBs. The highest anthocyanin content was observed in AD (47.09 ± 1.45mg/g extract), followed by R and AR (6.04 ± 0.20 and 2.72 ± 0.11mg/g extract, respectively). The TPC of AD (225.01 ± 1.97mg/g extract) was greater than that of AR and R (185.41 ± 3.24 and 144.10 ± 1.71mg/g extract, respectively). AD exhibited the strongest in vitro antioxidant activity in hydrophilic oxygen radical absorbance capacity, compared to the other two TBs. In addition, AD extract suppressed the generation of reactive oxygen species in caudal fin of wounded zebrafish. Antioxidant activities of AD appeared to be related to its total anthocyanin content, Cy3-G, Cy3-Sam, and TPC. Our findings indicate that TB, particularly the AD cultivar, would be an attractive source of bioactive compounds with antioxidant activities, and can improve both nutritional value and appearance of food.

Micropropagation of Hardy Hibiscus (Hibiscus Moscheutos L.)

Hardy hibiscus (Hibiscus x moscheutos L.) is gaining popularity as a landscape plant and the accelerated increase in the volume of planting material is of particular relevance. The work investigated the effect of the concentration of 6-BAP (0.5, 1.0, 1.5 mg / L) on the shoot formation of hibiscus of the following varieties: cv. Cranberry Crush, Fantasia, Fireball, Jazzberry Jam. It was revealed that the concentration of 6-BAP 0.5 mg / L is optimal for the proliferation of microshoots of Hibiscus x moscheutos L. With the increase in the concentration of 6-BAP, the number of formed microshoots decreases.

Inheritance of foliage color of common rosemallow (Hibiscus moscheutos (L.)) subspecific hybrids

BackgroundCommon rosemallow (Hibiscus moscheutos (L.)) is a native wetland perennial taxon that has been widely used as an ornamental landscape plant for several decades. Its showy blooms, attractive form and foliage, and hardiness attracted the attention of plant enthusiasts, leading to extensive hybridization and subsequent selection of superior genotypes. Red foliage color is a desirable trait, therefore we investigated the mode of inheritance of this trait in H. moscheutos subsp. lasiocarpos (Cavanilles) O. J. Blanchard with intraspecific hybrids of H. moscheutos subsp. moscheutos (L.).ResultsTwo red-foliaged seed parents of Hibiscus moscheutos subsp. moscheutos (L.) were crossed with green-foliaged paternal parent H. moscheutos subsp. lasiocarpos. Two F2 full-sib families (n = 192 and 238) were each found to fit a 3 red: 1 green segregation ratio for foliage color using a Chi square goodness-of-fit analysis. For further evaluation of this segregation pattern, each parent was selfed, as were two red-foliaged F2 plants. The two red-foliaged parents yielded the expected all-red progeny (n = 53 and 178, 1 red: 0 green) and the green-foliaged parent yielded 244 green and 6 red plants, fitting the expected 0 red: 1 green (P = 0.704) ratio. Additionally, progeny from the two red-foliaged F2 plants fit the expected 1 red: 0 green ratio (n = 135 and 120).ConclusionsResults indicate the appearance of red foliage, in any amount, in the two subspecies utilized and our hybrids of hibiscus to be controlled by a single locus with a dominant allele for red foliage. We propose the gene be called “green foliage” where the dominant allele, G, yields a red foliage phenotype. When the recessive allele, g, is present in the homozygous form, progeny consist of an all-green foliage phenotype for Hibiscus moscheutos (L.). Understanding the mode of inheritance of red-foliage phenotype in hibiscus would prove useful in further ornamental breeding work.

Effect of glutamine and arginine on growth of Hibiscus moscheutos “in vitro”

Nitrogen is the most essential element for plant growth and development. Amino acids, serving as the main organic nitrogen source in tissue culture media, provide for shoot and root elongation. Glutamine has been widely used in tissue culture for dedifferentiation and re-differentiation processes. Experiments were conducted to assess the effects of glutamine in comparison to some commonly used plant growth regulators (PGRs) on the growth of Hibiscus moscheutos propagated via tissue culture. An initial study suggested that 10 mg L-1 glutamine in MS basal medium was optimal for shoot elongation. At this optimal rate, glutamine showed superiority over other PGRs. No difference was found between glutamine treatments and the control in a later study. When comparing glutamine with arginine, shoots cultured on media with arginine displayed slightly greater growth. With arginine containing two extra nitrogen groups in its molecular structure, the higher percentage of nitrogen may have resulted in improved growth.

Plant response to biowaste soluble hydrolysates in hibiscus grown under limiting nutrient availability

ABSTRACTBiostimulants are substances promoting plant growth, quality and stress resistance. The present work aimed to investigate whether soluble hydrolysates from biowaste performed as biostimulants. Hibiscus (Hibiscus moscheutos L. subsp. palustris) plants were subjected to four treatments: standard fertilization, low fertilization (LF), and LF with added soluble digestate or soluble compost. Plant performance indicators were biomass accumulation, biometric parameters, leaf gaseous exchanges and elemental composition, and nitrogen (N)-use efficiency. LF negatively affected most of the investigated parameters. However, plants treated with biowaste-derived products performed better than untreated low-fertilized plants (+21 to 145% for biomass accumulation and biometric parameters, and carbon assimilation rate) and for many parameters reached values comparable to those showed by standard-fertilized plants or even higher, as in the case of Potassium (K), Silicon (Si), and Molybdenum (Mo) leaf content, and N use efficiency. Therefore, the tested soluble hydrolysates demonstrated to have biostimulant properties in hibiscus grown under nutritional stress.

First Report of the Genus Telamoptilia from the Western Hemisphere with Descriptions of Two New Species (Gracillariidae)

ABSTRACT. The genus Telamoptilia (Acrocercopinae) is reported from the Western Hemisphere for the first time. Two new species, Telamoptilia hibiscivora, from the eastern United States, and T. pavoniae , from western Cuba, are described and illustrated. The larvae initially begin as serpentine leafminers and eventually form mostly full depth blotch leafmines on Malvaceae. Telamoptilia hibiscivora mines the leaves of Hibiscus moscheutos L. and the lavae of T. pavoniae mine Pavonia fructicosa (Mill.), Malvaceae.

Development and Evaluation of Diploid and Polyploid Hibiscus moscheutos

Hibiscus moscheutos L. is an herbaceous hibiscus native to eastern North America that has been a popular landscape and container plant exhibiting large and colorful flowers in the summer. However, unsightly fruit develop and remain on the stalks at the end of the blooming season, which greatly decreases the ornamental value. Thus, breeding for sterility was attempted through ploidy level manipulation to reduce formation and growth of seed stalks, and to improve blooming vigor and longevity. Colchicine and oryzalin were used as mitotic inhibitors to induce tetraploid breeding lines that could be used to develop sterile triploids. Germinated seedlings of ‘Luna Red’ were soaked in three concentrations of each doubling agent for three different durations. Exposure to a low concentration of colchicine solution for a long time or to a low concentration of oryzalin for a short period was found to be effective in yielding a high number of tetraploids with a low rate of mortality. Triploids were obtained from the traditional method of crossing tetraploids with diploids. Triploid and tetraploid plants showed a decrease in height with a more compact form. Leaves of tetraploid plants were more ruffled, with an increase in overall leaf thickness, but were not different from leaves of diploids and triploids in regard to leaf mass per area (LMA). Triploid plants bloomed longer but had smaller flowers than diploid plants. Although the whole planting was infected by aerial phytophthora, diploid, tetraploid, and triploid plants were significantly different in their tolerances: all diploid branches were infected, but only a minor infection occurred on one triploid branch, and the transmission remained slow. Flowers of tetraploid plants failed to produce pollen, whereas flowers of triploid plants produced only nonviable pollen grains and fruits aborted after pollination, which led to infertility of induced triploids.

Wilt, Crown, and Root Rot of Common Rose Mallow (Hibiscus moscheutos) Caused by a Novel Fusarium sp.

A new crown and root rot disease of landscape plantings of the malvaceous ornamental common rose mallow (Hibiscus moscheutos) was first detected in Washington State in 2012. The main objectives of this study were to complete Koch's postulates, document the disease symptoms photographically, and identify the causal agent using multilocus molecular phylogenetics. Results of the pathogenicity experiments demonstrated that the Fusarium sp. could induce vascular wilt and root and crown rot symptoms on H. moscheutos 'Luna Rose'. Maximum-likelihood and maximum-parsimony phylogenetic analyses of portions of translation elongation factor 1-α and DNA-directed RNA polymerase II largest and second-largest subunit indicated that the Hibiscus pathogen represents a novel, undescribed Fusarium sp. nested within the Fusarium buharicum species complex.

Measuring Root Hydraulic Parameters of Container-grown Herbaceous and Woody Plants Using the Hydraulic Conductance Flow Meter

Root hydraulic conductance and conductivity are physiological traits describing the ease with which water can move through the belowground vascular system of a plant, and are used as indicators of plant performance and adaptability to a given environment. The ability to measure hydraulic conductance of container-grown herbaceous and semiwoody plants with soft conductive tissue was tested using a hydraulic conductance flow meter (HCFM). Although the HCFM is a hydraulic apparatus that has been used on woody plants to measure hydraulic conductance of intact roots, it has never been reportedly used on container-grown horticultural plants. Two herbaceous species, Chrysanthemum L. and Solenstemon scutellarioides Thonn., were grown in containers and hydraulic parameters were measured, including root conductance and root conductivity, as well as physical traits such as stem diameter and dry root mass. The HCFM was easily connected to intact roots even on herbaceous stems and was used to determine hydraulic conductance and conductivity directly on container-grown plants with minimal disturbance on the root system. Chrysanthemums, Buddleja davidii Franch., and Hibiscus moscheutos L. were grown in three different substrates, and both root mass and root hydraulic parameters were determined. Chrysanthemums showed a positive response with increasing root hydraulic conductance with increasing root mass. The substrates used in these studies only had an effect on root biomass of chrysanthemums, but substrates had no differential effect on root hydraulic conductivity.

Determining Sensor Orientation and Depth within an 11.4 L Container to Estimate Whole Container Volumetric Water Content

An experiment was conducted to determine which of five substrate-moisture sensor placements best estimates volumetric water content (VWC) for 11.4 L containers filled with Hibiscus moscheutos ‘Pink Elephant,’ as well as the effect of low VWC on sensor measurements. Five sensor placements were tested; three sensors were horizontally inserted into the sidewall at 5, 10, and 15 cm from the base of the container and the other two placements were inserted into the substrate surface either vertically or diagonally. All positions showed a strong linear relationship (r2> 0.92) with VWC determined gravimetrically, indicating they all are appropriate models of container substrate moisture. Sensors placed 15 cm above the base had a y-intercept closer to zero than sensors at 5 cm from the base, vertical and diagonal, but the slope was less accurate (farther from 1, P-value 0.0148) than the vertical placement. Vertical placement had a more accurate slope than 15 cm from the base, but the y-intercept was further from zero. The substrate was dried to 0.11 m3·m-3 during the experiments and became hydrophobic. This substantially decreased the amount of water that could be held at effective container capacity and decreased sensor accuracy. For this species and container size, no probe placement proved superior to the other placements, but choosing a horizontal placement was most practical for pesticide applications, pruning and hand weeding while surface installed placements may be most practical for sensor calibration and ease of installation, and removal.

Determination of the extent of hybridization between the threatened Hibiscus dasycalyx, Hibiscus laevis, and Hibiscus moscheutos using ISSR genetic markers

East Texas is home to several native Hibiscus species, including Hibiscus dasycalyx, Hibiscus laevis, and Hibiscus moscheutos. These species are herbaceous perennials that live in wetland conditions. Of the three morphologically distinct species, H. dasycalyx has been listed as threatened by the US Fish and Wildlife Service. Before restoration can occur, the gene flow and level of hybridization with the other two species must be determined in its native habitat. Previous investigations in our laboratory of these species have suggested that the Hibiscus dasycalyx is an individual species with little to no hybridization, however, a more comprehensive analysis is needed using a larger sampling set. The objective of this study is to identify species specific Intersimple Sequence Repeat (ISSR) markers for Hibiscus dasycalyx, H. laevis and H. moscheutos so that these markers could be used for tracking the extent of hybridization that occurs between the three species as well as the gene flow of H. dasycalyx. Genomic DNA was extracted and PCR amplified using ISSR primers (Wolfe,1998). PCR products were separated on an ALF sequencer to detect polymorphisms between the three Hibiscus species. Population analysis software was used to determine the gene flow and extent of hybridization between H. dasycalyx, H. laevis and H. moscheutos.

‘Lufkin Red’ and ‘Lufkin White’ Winter-hardy Hibiscus (Hibiscus ×laevis All.)

Winter-hardy hibiscuses are herbaceous perennials that regenerate from root buds each spring in USDA hardiness zones 5 through 9. Colloquially known as Rose Mallows, the most recent taxonomic revision (Blanchard, 1976) recognizes five species (Hibiscus coccineus Walter, Hibiscus dasycalyx Blake & Shiller, Hibiscus grandiflorus Michaux, Hibiscus laevis Allioni, and Hibiscus moscheutos L.) that comprise the North American taxon Hibiscus L. sect. Muenchhusia (Heister ex Fabricium) O. Blanchard (Malvaceae) (Small, 2004). A number of additional taxa associated with H. moscheutos have been variously recognized historically as varieties, subspecies, or distinct species. Primary among these are Hibiscus moscheutos subsp. palustris L., native to the northeastern United States, and Hibiscus moscheutos subsp. incanus Wendl., indigenous to the southeastern coastal plain (Blanchard, 1976). Native populations prefer wetland habitats such as flood plains but are tolerant to wide fluctuations in soil moisture. Rose mallows are long-day plants (Warner and Erwin, 2001) that flower from late spring through fall. Flowers last for a single day with color varying from scarlet rose in H. coccineus to white, lavender, and pink shades in the other four species. Studies of pollination in H. moscheutos indicate that the species is generally self-compatible but that the trait is variable with some lines rapidly develop inbreeding depression in progeny (Snow and Spira, 1993). The five species have a shared chromosome number of N =19, but artificial hybridization studies resulted in grouping the species into two groups based on seed set (Wise and Menzel, 1971). Hibiscus grandiorus and H. moscheutos (Group I) were entirely interfertile, and H. coccineus and H. laevis (Group II) were also interfertile, but crosses between groups produced few viable seed. Although Wise and Menzel (1971) did not include H. dasycalyx in their studies, subsequent work has shown that H. dasycalyx is closely related to H. laevis (Klips. 1995; Small, 2004) and clearly belongs in Group II. Although breeding of rose mallows has focused on developing new clones with improved horticultural traits (Malinowski et al., 2012) such as branching and flower color, there is a need for clones with improved disease resistance, particularly in the southeastern United States. Both ‘Lufkin Red’ and ‘Lufkin White’ have desirable horticultural traits in combination with demonstrated high levels of field resistance to the leaf spot complex (Pirone, 1970) that is problematic on winter-hardy hibiscus clones in areas with warm nights and high humidity.

Use of Ground Miscanthus Straw in Container Nursery Substrates

Abstract Pine bark (PB) is the primary component in nursery substrates in the United States. Availability of pine bark is decreasing and price is increasing. The objective of this research was to determine if miscanthus straw (MS) can replace all or part of the pine bark fraction in nursery container substrates. Five substrates were created that contained 15% sphagnum peatmoss, 5% municipal solid waste compost, and the remaining 80% consisted of one of the five following PB:MS ratios: 0:80, 20:60, 40:40, 60:20, and 80:0. Luna Red hibiscus (Hibiscus moscheutos) were grown in each substrate and evaluated for eight weeks in a greenhouse. Ground MS increased air space and decreased container capacity and bulk density as its concentration in the substrate increased. Additions of MS did not affect hibiscus chlorophyll content, and had negligible effects on hibiscus foliar nutrient levels. Increasing levels of MS caused a decrease in plant shoot dry weight, although growth reduction was most pronounced with 80% MS. Ground MS has potential to be a suitable substrate for nursery growers, however, some changes to management practices will be necessary.

Nitrogen:Phosphorus:Potassium Ratios Affect Production of Two Herbaceous Perennials

A series of experiments were undertaken to determine the effects of nitrogen (N), phosphorus (P), and potassium (K) concentrations and N:P:K ratio on flowering and vegetative growth of two herbaceous perennials, Hibiscus moscheutos L. (hibiscus) and Rudbeckia fulgida var. sullivantii Ait. ‘Goldsturm’ (rudbeckia). Plant growth and flowering of both hibiscus and rudbeckia were influenced by concentration and ratio of N, P, and K. When N was held constant at 100 mg·L−1, 4:1 N:K (25 mg·L−1 K) and 16:1 N:P (6.3 mg·L−1 P) were optimal for growing hibiscus, whereas higher K concentration (1:2 N:K, 200 mg·L−1 K) and lower P concentration (32:1 N:P, 3.1 mg·L−1 N) were required for optimal growth of rudbeckia. However, when holding N constant at 100 mg·L−1 and varying both P and K in the fertilizer solutions, higher P and K concentrations and a 2:1:2 (50 mg·L−1 P, 100 mg·L−1 K) N:P:K ratio best supported hibiscus growth, whereas 3:1:2 (33 mg·L−1 P, 66 mg·L−1 K) N:P:K was needed for growth of rudbeckia. Finally, when both N concentration and N:P:K ratio were altered, optimum growth of both hibiscus and rudbeckia was achieved at similar and lower P and K concentrations (25 mg·L−1 P and 50 mg·L−1 K) and 200 mg·L−1 N. An 8:1:2 N:P:K ratio was optimum for production of both hibiscus and rudbeckia, although 12:1:2 N:P:K (200 mg·L−1 N, 17 mg·L−1 P, 33 mg·L−1 K) produced similar growth of rudbeckia. Based on results of these two herbaceous perennials, it appears herbaceous perennials have N requirements similar to annual plants and P and K requirements similar to woody plants. Furthermore, the two herbaceous perennials used in this study required nutrients in the fertilizer solution at a higher N:P:K ratio than either annual or woody plants. Foliar concentrations of 2.2% N, 0.4% P, and 1.9% K were adequate for growth of hibiscus, whereas 2.4% N, 0.2% P, and 2.6% K were required to maximize growth of rudbeckia.