Impatiens Walleriana Hook Research Articles

Effects of Growth Substrate on Greenhouse Gas Emissions from Three Annual Species

AbstractPrevious work by these authors have quantified cumulative greenhouse gas (GHG) emissions for several woody and herbaceous perennial species, in interaction with several standard best management practices (container size, fertilizer application and irrigation delivery methods, and light level). In this study, the greenhouse production of three annual species [coleus (Solenostemon scutellarioides Thonn. ‘Redhead'), vinca (Catharanthus roseus L. ‘Cooler Grape'), and impatiens (Impatiens walleriana Hook. f. ‘Super Elfin XP White')] was evaluated in three substrates [80:20 peat:perlite, 80:20 peat:WholeTree (a whole pine tree-based substrate), 60:40 peat:WholeTree]. Emissions of CO2, N2O and CH4 were collected over a period of 52 days. Without regard to media, coleus had the highest cumulative CO2 efflux (statistically similar to vinca), due to its increased size in comparison with both vinca and impatiens. Without regard to species, plant-pot systems using the highest proportion of WholeTree (40%) had numerically the most cumulative CO2 efflux (statistically similar to those containing only 20% WholeTree). No differences were observed for the main effect of species or media for N2O or CH4. Results suggest that using a more sustainable high wood fiber substrate in similar proportions to that of perlite in an industry standard mix (20%) could yield similarly sized plants with no negative impact on GHG emissions.Index words: alternative substrate, WholeTree, carbon sequestration, carbon dioxide, nitrous oxide, methane, global climate change.Species used in this study: ‘Redhead' coleus, Solenostemon scutellarioides Thonn. ‘Redhead'; ‘Cooler Grape' vinca, Catharanthus roseus L. ‘Cooler Grape'; ‘Super Elfin XP White' impatiens, Impatiens walleriana Hook. f. ‘Super Elfin XP White'.

Comparison of Frankliniella fusca and Frankliniella occidentalis (Thysanoptera: Thripidae) as Vectors for a Peanut Strain of Tomato Spotted Wilt Orthotospovirus.

Tomato spotted wilt orthotospovirus (TSWV) is a major disease in peanut, Arachis hypogaea L., across peanut producing regions of the United States and elsewhere. Two thrips, Frankliniella fusca Hinds and Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), are considered important vectors of TSWV in peanut in the Southeast. We compared the efficiency of acquisition (by larvae) and transmission (adults) of both thrips species for TSWV (Texas peanut-strain) to leaf disks of peanut (Florunner), as well as to Impatiens walleriana Hook. f. (Dwarf White Baby) and Petunia hybrida Juss. 'Fire Chief' using double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). Both species were competent TSWV vectors in peanut and Impatiens, although F. fusca was the more efficient vector overall, i.e., virus acquisition and transmission rates for F. fusca averaged over several bioassays were 51.7 and 26.6%, respectively, compared with 20.0 and 15.3% for F. occidentalis. Neither species effectively transmitted this TSWV strain to Petunia (i.e., ≤3.6% transmission). We found statistically similar virus acquisition and transmission rates between both sexes for each species. We also detected no differences in TSWV-acquisition and transmission frequency between macropterous and brachypterous (short-wing) forms of F. fusca collected from a field population in south Texas. DAS-ELISA failed to detect low levels of TSWV in a few thrips that subsequently proved to be competent vectors.

Evaluation of Indaziflam for Greenhouse Use

Due to the relatively small market, volatility concerns, and high crop-value-per-acre associated with ornamental crops, no preemergence (PRE) herbicides are currently labeled for use in greenhouses containing plants. The objective of this study was to evaluate indaziflam SC for potential use as a PRE herbicide on gravel in greenhouses containing sensitive crops grown in extreme environmental conditions. Mini-greenhouses (MG) were designed and constructed to fit within gravel ground beds as an initial component to this study in order to evaluate herbicide volatility. Species evaluated included ‘Better Boy’ tomato (Lycopersicon esculentum Mill.), ‘Extreme Orange’ impatiens (Impatiens walleriana Hook. f.) and two species of petunia (Petunia × hybrida Juss. ‘Dreams White’ and ‘Dreams Neon Rose’). Indaziflam SC was applied at the manufacturer's labeled rate [40 g ai·ha−1 (0.04 lbs ai·A−1)] (1×) and at twice the labeled rate [80 g ai·ha−1 (0.07 lbs ai·A−1)] (2×). Each rate was applied using one of three different methods: 1) applied to only the gravel in ground beds with plants placed on gravel and covered with MG immediately following application; 2) applied over the top of plants on gravel inside the ground beds and covered with MG immediately application; and 3) applied over the top of plants outside the ground beds on adjacent gravel and left outside of MG. Two nontreated control treatments were maintained for each species and were placed either on nontreated gravel inside ground beds and covered with MG or placed outside ground beds on adjacent nontreated gravel and not covered with MG. Little to no injury was observed on any of the species after being placed on treated gravel and covered with a MG regardless of indaziflam rate. However when indaziflam was applied over-the-top, impatiens and tomatoes exhibited severe injury and death by 30 days after treatment (DAT). Additionally, fresh weights showed that all species receiving either over-the-top treatment were severely injured, while the plants placed on treated gravel inside the MG and both nontreated control treatments (both inside and outside of MG) exhibited no signs of injury or stunted growth. Results from this study indicate that while indaziflam may cause crop injury to ornamental species when applied over-the-top, it is likely that little to no injury will be observed as a result of volatility due to a gravel application in an enclosed structure.

Greenhouse Evaluation of Neonate and Adult Applications ofColeomegilla maculata(Coleoptera: Coccinellidae) to Control Twospotted Spider Mite Infestations

The lady beetle Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae) is a euryphagous predator that is known to consume the twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Spider mites are frequently problematic in greenhouse operations and often cause damage to the ornamental and bedding plant Impatiens walleriana Hook f. (Ericales: Balsaminaceae). Increasing demand for alternatives to pesticides combined with resistance to registered pest control products necessitates the evaluation of viable alternatives. In this study, naïve impatiens were intentionally infested with twospotted spider mites. When damage was visible on experimental plants, they were treated with lady beetles in containment cages. One treatment was adult C. maculata and another treatment was neonate C. maculata using recently developed methods for rearing and harvesting eggs. Levels of spider mite infestation were assessed after treatments, and images of the treated and untreated plants were collected to assess the effectiveness of C. maculata in a greenhouse environment. Plants with C. maculata treatments were essentially free of spider mites. There is potential to use mass-reared C. maculata eggs as treatment for spider mites in contained crops or indoor decorative plants.

Evaluation of a Commercial Extract of Giant Knotweed on Drought Tolerance of Impatiens

Regalia®, a commercial extract of giant knotweed [Fallopia sachalinensis F. Schmidt (synonyms: Reynoutria sachalinensis (F. Schmidt) Nakai, Polygonum sachalinense F. Schmidt, Tiniaria sachalinesis (F. Schmidt) Janch.)], was evaluated for its potential to enhance drought tolerance of container-grown impatiens (Impatiens walleriana Hook. f. ‘Super Elfin XP White’). In two separate experiments, Regalia® was foliar-applied once a week for 4 weeks at four different rates (0, 5, 10, or 15 mL·L−1). In Expt. 1, Regalia® was applied to impatiens grown under three target substrate volumetric water contents (TVWCs): 85%, 55%, or 25%. In Expt. 2, Regalia® was applied to impatiens watered with 1, 3, or 6 days between waterings (DBW). In Expt. 1, root dry weight (RDW) of impatiens receiving applications of Regalia® at the 0.5× rate was greater compared with the 0.0× rate across all TVWCs. Additionally, soluble protein content was greater after Regalia® application at the 0.5×, 1.0×, or 1.5× rates compared with the 0.0× rate for plants grown at 55% TVWC. In Expt. 2, leaf greenness (SPAD) and leaf net photosynthetic rate (Pn) were greater with Regalia® applied at the 0.5× and 1.0× rates compared with the 0.0× rate, respectively. Soluble protein content was greater in impatiens treated with Regalia® at the 1.5× rate and 1 DBW and the 0.5× rate with 3 DBW compared with the 0.0× rate with 1 or 3 DBW. However, there was no indication that impatiens grown under different moisture levels had increased drought tolerance after application of Regalia®.

The effect of substrates containing municipal sewage sludge compost on the accumulation of macrocomponents in Impatiens walleriana Hook.

Municipal sewage sludge is often used in compost production for agriculture. Composting sediments, which include structure-forming materials, results in the formation of matter rich in organic substances and nutrients that can be used as a component of horticultural substrates, as an alternative to peat. The aim of this research paper is to assess the impact of substrates containing municipal sewage sludge compost on N tot. , P, K, Ca, Mg and S levels in the leaves and roots of Impatiens walleriana Hook. The two-year experiment used four types of compost; in the first year the tests were conducted after a 7-month period of decay and the second year after an 18-month period. The composition of compost material was as follows: compost I – 70% municipal sewage sludge, 30% rye straw; compost II – 70% municipal sewage sludge, 30% coniferous tree sawdust; compost III – 35% municipal sewage sludge, 35% potato pulp, 30% rye straw; compost IV – 35% municipal sewage sludge, 35% potato pulp, 30% coniferous tree sawdust. During the first and second year, five experimental sites were used: four substrate with 50% of the tested compost and 50% sphagnum peat and one sphagnum peat reference substrate with a 2.5 g dm -3 dose of Azofoska multipurpose fertiliser. After 12 weeks of Impatiens walleriana cultivation the recorded level of total nitrogen, calcium, magnesium and sulphur in the leaves was lower than the optimal range of the macrocomponent content recommended for this species. The levels of phosphorus and potassium were the exception. Impatiens cultivated in substrates with compost after a 7-month decay period contained 1.7 times more nitrogen and 1.8 times more potassium in the leaves; they had similar phosphorus and sulphur content and lower calcium and magnesium content than the plants cultivated in the compost substrates after an 18-month decay period. The roots of impatiens contained more calcium than the leaves in both years of the study. The nutrients supplied in the substrates and through top dressing fertilisation were not sufficient to achieve the best cultivation results for Impatiens walleriana.

First Report of Downy Mildew Caused by Plasmopara obducens on Impatiens in Taiwan.

In February 2013, single and double flowered impatiens (Impatiens walleriana Hook. f.) affected by downy mildew were observed in nurseries (cv. Accent) and in the wild in central Taiwan. More than 90% of the plants were infected in areas where the disease broke out. Symptomatic leaves showed yellowing, with white, fungal-like structure covering the lower leaf surfaces, causing the plants to become wilted and defoliated. Under microscopic observation, hyaline, thin-walled sporangiophores branched monopodially and had slightly swollen bases. Three apical branchlets were at right angles to the main axis, measuring 4.3-15.0 μm (average 8.5 μm). Sporangia were hyaline, ovoid, with an average length and width of 14.2 (10.0 to 18.0) × 12.1 (9.3 to 15.0) μm. For molecular categorization, PCR amplification of the 5' end of the large ribosomal subunit gene was performed with primers NL1 and NL4 (2). The amplicons were cloned, sequenced, and deposited in GenBank (Accession Nos. KC905620 and KC905621). The sequence similarities were 99% compared with that of Plasmopara obducens (J. Schröt.) J. Schröt from Florida (JX217746) (3). Based on morphological and molecular characters, the pathogen was identified as P. obducens. Three voucher specimens (TNM Nos. F0026644, F0026645, and F0026646) were deposited in the herbarium of the National Museum of Natural Science, Taichung, Taiwan. Pathogenicity was confirmed by inoculation of five young, potted impatiens plants with a suspension containing 1 × 105 sporangia/ml in 0.05% Tween 20 (approximately 8 ml/plant). An additional five plants sprayed with 0.05% Tween 20 served as negative controls. The plants were maintained in an outdoor ambient environment. After 2 weeks incubation at an average temperature of 20°C and approximately 80% relative humidity, the inoculated plants exhibited typical downy mildew symptoms, while the control plants remained healthy. The pathogenicity test was repeated in a dew chamber under 20°C with similar results. In the Asia-Pacific region, impatiens downy mildew was recently confirmed in Korea and Japan (1,4). To our knowledge, this is the first report of downy mildew on impatiens in Taiwan. Our further surveys indicated the disease has spread to other parts of the island and will become a potential problem requiring prevention.

Plasmopara obducensoccurring onImpatiens wallerianahybrids and species in Hungary: Morphological and molecular characterization of the pathogen

In May 2011, young Impatiens walleriana Hook. f. plants showing downy mildew symptoms were collected from a greenhouse (Kecskemet, Hungary). The upper surface of affected leaves turned yellow and white fungal-like growth was observed on the underside. Diseased plants wilted and rapidly collapsed, resulting in losses of nearly 100%. Downy mildew of impatiens can be caused by two pathogens, Plasmopara obducens or Plasmopara constantinescui (syn: Bremiella sphaerosperma), which can be distinguished by the symptoms and by morphology of sporangiophores and sporangia. For molecular identification the 5′-end of the large subunit of ribosomal RNA gene was amplified by PCR using NL1 and NL4 primers and cloned and sequenced. The nucleotide sequence of the Hungarian isolate showed highest identity (99.72%) with two isolates of Plasmopara obducens from the United Kingdom and Serbia. On the basis of the symptoms, molecular and morphological characters, the pathogen was identified as P. obducens. The appearance of the pathogen in Hungary seriously endangers the production of I. walleriana, which is a popular ornamental in gardens and city parks. The chemical plant protection is not effective against the pathogen, by the occurrence of the first symptoms the diseased plants should be removed from the plantlet and must be destroyed.

Bioavailability Assessment and Accumulation by Five Garden Flower Species Grown in Artificially Cadmium-Contaminated Soils

Many studies have been conducted on phytoextraction; however, non-native hyperaccumulator species are not suitable for the natural environment of Taiwan in many cases. Drawing upon previous results, the growth and heavy metal accumulation in artificially cadmium-contaminated soils were compared for five local garden flower species. The treatments included a control (CK), 9.73 ± 0.05 mg kg−1 (Cd-10), and 17.6 ± 0.8 mg kg−1 (Cd-20). All plants were harvested at 35 days after transplanting and analyzed for Cd content. Cd accumulation in the shoot of French marigold (Tagetes patula L.) and Impatiens (Impatiens walleriana Hook. f.) grown in Cd-20 treatment were 66.3 ± 6.5 and 100 ± 11 mg kg−l, which equated to a removal of 0.80 ± 0.11 and 0.60 ± 0.37 mg Cd plant−1, respectively. The maximum Cd accumulation of Impatiens reached the threshold value (100 mg kg−l) characteristic of a Cd hyperaccumulator and its bioconcentration factor (BCF) and translocation factor (TF) were greater than one. Impatiens therefore has the potential to hyperaccumulate Cd from Cd-contaminated soils. With the exception of Garden verbena, significant relationships were found between Cd concentrations in soil extracted by 0.05 M EDTA, 0.005 M DTPA, and 0.01 M CaCl2 and the concentration of Cd in the shoots of the tested garden flowers.

In vitro and in vivo assessment of the potential of compost and its humic acid fraction to protect ornamental plants from soil-borne pathogenic fungi

Five humic acid fractions (HAs) were isolated from various organic substrates used for plant growth in containers, including both conventional ones, i.e. peat (P) and coconut fiber (CF), and newly introduced ones, i.e. compost (Co) and mixtures at 20% and 60% (v/v) of Co with P (Co20 + P and Co60 + P) and Co with CF (Co20 + CF and Co60 + CF). The effects of these HAs at 50 and 300 mg L −1 were evaluated on the mycelial growth of two soil-borne phytopathogens, Pythium ultimum ( PYT) and Fusarium oxysporum f. sp. callistephi ( FOC), in a series of in vitro experiments. Furthermore, in experiments performed in a climatic chamber, the bulk substrates were tested on the growth and health of two ornamental plant species: impatiens ( Impatiens walleriana Hook) and China aster ( Callistephus chinensis L. Nees), repeatedly infected respectively with PYT and FOC. In general, any HA at either dose reduced significantly the radial growth of PYT mycelium after 42 h, whereas Co-HA and P-HA at the higher concentration showed a high inhibition on PYT during the whole experiment. A significant inhibition of FOC growth was exerted by all HAs, especially at the higher dose, during the 192-h experimental time. No significant correlation exists between the extent of the inhibitory action on the two fungi and the chemical and functional properties of HA. The only exception is the existence of a negative correlation between the inhibition of PYT and the HA oxygen content. The various substrates used in trials conducted in vivo caused different plant growth response. The treatments with Co alone or its mixtures at 60% with P or CF were lethal for both plants, even before the first fungal inoculation. The substrates Co20 + P and Co20 + CF were very effective in controlling the fungal attack and increasing the growth of impatiens and China aster.

Physiological Responses to Different Substrate Water Contents: Screening for High Water-use Efficiency in Bedding Plants

Efficient use of irrigation water is increasingly important in the production of bedding plants. Two approaches to efficient water use include reducing irrigation water wastage during production by growing plants at the optimal substrate water content (θ) and growing species with high water-use efficiency (WUE). However, there is little information on the effects of different θ levels on leaf physiology of bedding plants and variation in WUE among different species of bedding plants. The objectives of this study were to determine the effects of θ on leaf water relations, gas exchange, chlorophyll fluorescence, and WUE of bedding plants and to identify the physiological basis for differences in WUE between two bedding plant species. We grew salvia ‘Bonfire Red’ (Salvia splendens Sellow ex Roemer & J.A. Schultes), vinca ‘Cooler Peppermint’ [Catharanthus roseus (L.) G. Don.], petunia ‘Lavender White’ (Petunia × hybrida Hort ex. Vilm.), and impatiens ‘Cherry’ (Impatiens walleriana Hook F.) at four constant levels of θ (0.09, 0.15, 0.22, and 0.32 m3·m−3) using an automated irrigation controller. Regardless of species, leaf water potential (Ψw) and leaf photosynthesis (A) of all four species were lower at a θ of 0.09 m3·m−3 and were not different among the other θ levels, but stomatal conductance to H2O (g S) was lower at 0.09 than at 0.15 and 0.22 m3·m−3 and highest at 0.32 m3·m−3. WUE of bedding plants at different θ levels depended on species. The WUE of petunia was unaffected by θ, whereas for the other three species, WUE was higher at a θ of 0.09 m3·m−3 than at 0.32 m3·m−3. Differences in WUE between petunia and salvia were partly from differences in photosynthetic capacity between the two species. Based on the response of A to leaf internal CO2 concentration (Ci), mesophyll conductance to CO2 [gm (a measure of photosynthetic capacity)] was higher in petunia than salvia, whereas gas phase conductance to CO2 (gCO2 ) was similar for these two species, which resulted in higher WUE in petunia than salvia.

PLANTAS INVASORAS ENCONTRADAS NA ÁREA URBANA DE CURITIBA (PR)

A grande maioria das espécies invasoras nas áreas urbanas é introduzida pela população e pelos órgãos públicos. Muitas delas, quando plantadas excessivamente, podem gerar problemas ambientais muito graves, principalmente como ameaça às plantas nativas remanescentes, por ocupar seu espaço. O objetivo deste trabalho foi analisar o potencial invasor da vegetação urbana da cidade de Curitiba, com base numa amostragem aleatória composta de setenta unidades distribuídas em cinco condições espaciais diferentes – ruas, parques, praças, terrenos baldios e jardins – em quarenta e cinco bairros diferentes, e levando-se em consideração o crescimento demográfico e a evolução da ocupação urbana de Curitiba. Das 370 espécies amostradas na área urbana de Curitiba, 155 espécies (42%) são consideradas invasoras por algum país e 21 espécies (5,7%) são consideradas invasoras no Brasil (Centella asiatica (L.) Urban, Chrysanthemum myconis L., Cirsium vulgare (Savi) Tem., Citrus limon (L.) Burm. f., Crocosmia x crocosmaeflora Lem., Cynodon dactylon (L.) Pers., Cyperus rotundus L., Dracaena fragrans Ker-Gawl., Eragrostis curvula (Schrad.) Nees, Eriobotrya japonica Lindl., Impatiens walleriana Hook. f., Ligustrum lucidum Aiton., Melia azedarach Blanco, Morus nigra L., Ophiopogon japonicum Ker-Gawl., Passiflora alata (Dryand.) Ait., Psidium guajava L., Schizolobium parahyba (Vell.) Blake, Sechium edule (Jacq.) Sw., Tradescantia fluminensis Vell. e Tradescantia zebrina Hort. ex Bosse). Destas espécies, 8 são invasoras (2,2%) na região de Curitiba (Cirsium vulgare, Eriobotrya japonica, Melia azedarach, Morus nigra, Ophiopogon japonicum, Psidium guajava e Tradescantia zebrina).

Drought response of two bedding plants

Bedding plants are an important part of the urban public space and private gardens. However, they are not always properly watered and suffer from drought stress, especially when grown in containers. In this trial a response to water stress of two commonly used species, impatiens (Impatiens walleriana Hook) and geranium (Pelargonium hortorum L. H. Bailey) were compared. The former is highly herbaceous and prone to wilting whereas the latter has hairy leaves and is better adapted to drought. Plants were grown at three levels of soil water content (SWC): 80% (control), 60% (mild stress) and 30% (severe stress). Drought was maintained during three 10 day cycles, separated by 10 day periods of normal watering. In both species roots were significantly longer in plants grown at 30% SWC as compared to 80% SWC while plant height and flower number were reduced by drought only in impatiens. The initial relative water content (RWC) was lower in geranium and decreased less in response to drought than in impatiens. Ammonium content in leaves of both species increased significantly under stress but the ranges of increase were different in both species. There was a significant increase in the free amino acids content in leaves of impatiens as compared to geranium but this rise was more time than drought dependent. The reduction in the a + b chlorophyll concentration in leaves of impatiens was significantly time and stress dependent while no reaction in geranium was observed. The above results show that changes in leaf RWC merit further attention as a possible indicator of plant response to drought stress in ornamental plants but additional studies are needed before this or other parameters can be used to evaluate new bedding plants for introduction into urban growing conditions, or as selection criteria in breeding for adaptation to demanding growing conditions.

Performance of Selected Herbaceous Annual Ornamentals Grown at Decreasing Levels of Irrigation

This study was conducted to evaluate the growth, visual quality, and stress response of 17 species of bedding plants and Kentucky bluegrass (Poa pratensis L.) grown outdoors for 10 weeks during the summer of 2003 at three locations in Colorado. Plants were irrigated at 100% of the reference evapotranspiration (ET0) (amount required to maintain Kentucky bluegrass in an optimum condition) for 2 weeks followed by 8 weeks at five irrigation levels: 0%, 25%, 50%, 75%, and 100% ET0. Begonia carrieri Hort. `Vodka', Lobelia erinus L. `Cobalt Blue', and Viola ×wittrockiana Gams. `Crown Gold' grew well with a minimum of 50% or more ET0 based on Kentucky bluegrass. Impatiens walleriana Hook. fil. `Tempo White' grew well only with 100% ET0. Antirrhinum majus L. `Sonnet Yellow', Dianthus L. `First Love', Lobularia maritima (L.) Desv. `Carpet White', and Pelargonium ×hortorum L.H. Bailey performed well with 25% to 50% ET0. The species Catharanthus roseus (L.) G. Don `Peppermint Cooler', Rudbeckia hirta L. `Indian Summer', Senecio cineraria D.C. `Silver Dust', Tagetes erecta L. `Inca Yellow' and T. patula L. `Bonanza Gold', Zinnia angustifolia Kunth., and Salvia farinacea Benth. `Rhea Blue', which are adapted to midsummer heat and low water, performed well with 0% to 25% ET0. Species considered to be heat or drought tolerant—Petunia ×hybrida hort. ex. E. Vilm. `Merlin White' and Glandularia J.F. Gmel. `Imagination'—required little or no irrigation. The bedding plant species evaluated in this study that required 25% or less ET0 are well adapted for low-water landscape installations.

PEG-8000 Alters Morphology and Nutrient Concentration of Hydroponic Impatiens

Osmotic compounds, such as polyethylene glycol 8000 (PEG-8000), reduce plant elongation by imposing controlled drought. However, the effects of PEG-8000 on nutrient uptake are unknown. Impatiens `Dazzler Pink' (Impatiens walleriana Hook. F.) were grown hydroponically in modified Hoagland solutions containing 0, 10, 17.5, 25, 32.5, 40, 47.5, 55, or 62.5 g·L–1 PEG-8000. Impatiens were up to 68% shorter than control plants when grown with PEG-8000 in the nutrient solution. Plants treated with PEG-8000 rates above 25 g·L–1 were either damaged or similar in size to seedlings treated with 25 g·L–1 of PEG-8000. Impatiens leaf water potentials (Ψw) were positively correlated with plant height. PEG-8000 reduced the electrical conductivity of Hoagland solutions as much as 40% compared to nontreated Hoagland solutions, suggesting that PEG-8000 may bind some of the nutrient ions in solution. Foliar tissue of PEG-treated impatiens contained significantly less nitrogen, calcium, zinc, and copper, but significantly more phosphorus and nickel than tissue from nontreated impatiens. However, no nutrient deficiency symptoms were induced.

Properties of Plastic, Peat, and Processed Poultry Feather Fiber Growing Containers

When the substrate surface and drainage holes of feather fiber, peat, and plastic containers were sealed with wax, hyperbolic growth curves were good fits to cumulative water loss on a per container and per cm2 basis, with R2 values ranging from 0.88 to 0.96. The effect of container type was significant as the differences in asymptotic maximum water loss (max) values for all container pairs were significant at P < 0.05 for both water loss per container and water loss per cm2. The predicted total water loss for peat containers was ≈2.5 times greater than feather containers, and the predicted water loss per cm2 for the peat container was ≈3 times greater than feather containers. Vinca [Catharanthus roseus (L.) G. Don.] `Cooler Blush' and impatiens (Impatiens walleriana Hook f.) `Dazzler Rose Star' plants grown in feather and peat containers required more water and more frequent irrigations than those grown in plastic containers. However, plants grown in feather containers required less water and fewer irrigations than plants grown in peat containers. The surface area of containers covered by algal or fungal growth was significantly higher on peat containers than on feather containers. No fungal or algal growth was observed on plastic containers. Additionally, primarily algae were observed on peat containers whereas most discoloration observed on feather containers was due to fungal growth. Dry feather containers had a higher longitudinal strength than dry plastic containers but a lower longitudinal strength than dry peat containers. Wet feather containers had higher longitudinal strength than wet peat containers but a similar longitudinal strength as wet plastic containers. Dry feather and plastic containers had similar lateral strengths and both had significantly higher lateral strength than dry peat containers. Wet feather containers had significantly lower lateral strength than wet plastic containers but had higher lateral strength than wet peat containers. Dry and wet plastic containers had higher punch strength than wet or dry peat and feather containers. Dry peat containers had significantly higher punch strength than dry feather containers. However, wet feather containers had significantly higher punch strength than wet peat containers. Decomposition of peat and feather containers was significantly affected by container type and the species grown in the container. When planted with tomato (Lycopersicum esculentum L.) `Better Boy', decomposition was not significantly different between the peat and feather containers. However, when vinca and marigold (Tagetes patula L.) `Janie Bright Yellow' were grown in the containers, decomposition was significantly higher for feather containers than for peat containers. Therefore, containers made from processed feather fiber provided a new type of biodegradable container with significantly improved characteristics as compared to peat containers.

Fresh Parboiled Rice Hulls Serve as an Alternative to Perlite in Greenhouse Crop Substrates

Ten substrates were formulated by blending perlite or parboiled fresh rice hulls (PFH) at 20%, 30%, 40%, 50%, or 60% (v/v) with sphagnum peat. After 6 weeks, NH4+ concentrations were not significantly different among substrates containing perlite and those containing equivalent amounts of PFH. Nitrate concentrations were significantly higher in the 40% perlite substrate than in the 40% PFH substrate, but there were no significant differences in NO3- concentrations among the remaining substrates containing equivalent amounts of PFH or perlite. When tomato (Lycopersicon esculentum Mill.) was grown in the substrates for 5 weeks, tissue N concentrations were not significantly different between equivalent perlite and PFH-containing substrates. Non-parboiled fresh rice hulls produced organically contained a higher number of viable weed seeds than non-parboiled fresh rice hulls produced conventionally. No weed seeds germinated in the PFH. `Better Boy' tomato, `Bonanza Yellow' marigold (Tagetes patula L. French M.), `Orbit Cardinal' geranium (Pelargonium ×hortorum L.H. Bailey), `Cooler Blush' vinca (Catharanthus roseus L.G. Don), `Dazzler Rose Star' impatiens (Impatiens walleriana Hook. f.), and `Bingo Azure' pansy (Viola ×wittrockiana Gams) were grown in sphagnum peat-based substrates containing perlite or PFH at 10%, 15%, 20%, 25%, 30%, 35%, or 40% (v/v). Dry root weights of vinca and geranium were not significantly different among plants grown in the substrates. Tomato plants grown in 10%, 15%, 25%, 30%, and 35% PFH had significantly higher dry root weights than those grown in equivalent perlite-containing substrates. Impatiens grown in 35% PFH had higher dry root weights than those grown in 35% perlite. Marigold grown in 20% perlite had higher dry root weights than those grown in 20% PFH. However, there were no significant differences in impatiens or marigold dry root weights among the remaining substrates containing equivalent amounts of PFH or perlite. Dry root weights of pansy grown in 10%, 20% 25%, 35%, and 40% perlite were not significantly different from those grown in equivalent PFH-containing substrates. Across substrates, root dry weights of impatiens, marigold, and pansy grown in perlite-containing substrates were not significantly different from those grown in PFH-containing substrates. No significant difference in dry shoot weights of vinca, geranium, impatiens, and marigold occurred between equivalent perlite and PFH-containing substrates. Tomato plants grown in 20% to 40% perlite had significantly higher dry shoot weights than those grown in equivalent PFH-containing substrates. However, dry shoot weights of tomato grown in 10% to 15% perlite were not significantly different from those grown in equivalent PFH-containing substrates. Dry shoot weights of pansy grown in 10%, 25%, 30%, 35%, and 40% perlite were not significantly different from those grown in equivalent PFH substrates.

Stem extension and subsequent flowering of seedlings grown under a film creating a far-red deficient environment

Photoselective plastic filters that reduce the transmission of far-red light (FR, 700–800 nm) have been developed to potentially reduce stem extension and thus plant height. However, an FR-deficient (FR d) environment can also delay flowering, particularly in long-day plants (LDP). Our objective was to determine if seedlings could be grown under an FR d environment to reduce extension growth without subsequently delaying flowering upon removal from filter treatments. Pansy ( Viola × wittrockiana Gams.), petunia ( Petunia × hybrida Vilm.-Andr.), impatiens ( Impatiens walleriana Hook.), snapdragon ( Antirrhinum majus L.), and tomato [ Solanum lycopersicon L. (syn.: Lycopersicon esculentum)] were placed under the FR-intercepting (FR-i) filter or a neutral density (N) filter that transmitted a similar photosynthetic daily light integral. A third treatment consisted of transferring plants from the N to the FR-i filter when leaves of each species began to touch (after 18 or 24 days under the N filter). After 25–35 treatment days with a 16-hour photoperiod at 20 °C, seedlings were measured and then grown under natural photoperiods (≥14.5 h) at 20 °C in a glass greenhouse with no filter treatments until flowering. Compared with that of seedlings continually under the N filter, stem or petiole length in the FR d environment was significantly reduced in impatiens (by 10%), pansy (by 18%), petunia (by 34%), snapdragon (by 5%), and tomato (by 24%). Extension growth in plants held continually under the FR-i filter was similar to that of plants transferred from the N to the FR-i filter when leaves first touched. Flowering of plants from plugs in the FR d environment was delayed by 2–3 days in snapdragon, petunia, and pansy. At flowering, flower number and plant height of all species were similar among treatments. Therefore, the FR-i filter presents an attractive method of controlling seedling height with minimal impact on flowering when plants are subsequently removed from filter treatments.

Efficacy of the Press Extraction Method for Bedding Plant Plug Nutrient Monitoring

There is a need for a substrate testing method suited for plug plant production. Methods currently used by most growers and analytical labs include the saturated media extract (SME) and the 2 water: 1 substrate (v/v) suspension. These methods are not particularly well-adapted to plug production. The press extraction (PE) method has been developed as a simple and quick alternative to these methods. However, interpretive standards for chemical analysis of plug substrates do not exist for PE. This study was designed to provide the necessary correlations between these methods to allow for development of pH, electrical conductivity (EC), and nutrient interpretive ranges for plugs. Plugs of begonia (Begonia ×semperflorens-hybrida Hort.), impatiens (Impatiens walleriana Hook. f.), marigold (Tagetes erecta L.), petunia (Petunia ×hybrida Hort. Vilm.-Andr.), salvia (Salvia splendens F. Sellow ex Roem. & Schult.), and vinca (Catharanthus roseus L.) were collected from commercial greenhouses and the substrate solution extracted with the PE, SME, and 1:2 methods. Plugs of begonia, celosia (Celosia argentea L. var. cristata (L.) Kuntze Plumosa Group), marigold, petunia, and vinca were grown with three fertilizer rates of 50, 150, and 250 mg·L-1 N. Shoots were harvested 30 days after planting and the solution was extracted from each flat using the three methods. For both experiments, PE EC was equal to or higher than the SME EC, and the pH was equal to or lower than the SME pH. The pH from the 1:2 was also similar to the PE. However, 1:2 EC results were consistently the lowest because of the dilution inherent in the 1:2 method. Interpretation ranges for pH and EC relationships were calculated to compare results from the PE with published sufficiency ranges for the SME and 1:2.

Evaluation of Seedling Size Following Germination Using Computer-aided Analysis of Digital Images from a Flat-bed Scanner

Early seedling growth rate can be used to estimate seed vigor for small-seeded vegetable and flower seeds. However, hand measurement of small seedlings is tedious and difficult to reproduce among analysts. Computer-aided analysis digital images of seedlings should improve accuracy and reproducibility. A flat-bed scanner fitted with base and top lighting provided high resolution images of even small-seeded species like petunia [Petunia ×hybrida `Blue Picotee' (Hort) Vilm.] and lisianthus [Eustoma grandiflorum `Mariachi Pure White' (Raf.) Shinn]. Uniform lighting was provided and images were captured and analyzed in less than 2 minutes. A clear, cellulose film was used as the germination substrate in petri dish germination assays to facilitate capturing images with a flat-bed scanner. The transparent medium permitted seedlings to be imaged without removal from the petri dish and also allowed for repeated measures of the same seedlings in order to calculate growth rate. Six species evaluated in this study included cauliflower (Brassica oleracea L., var. Botrytis), tomato (Lycopersicon esculentum Mill. `New Yorker'), pepper (Capsicum annuum L. `North Star'), impatiens [Impatiens walleriana Hook. f. `Impact Lavender'], vinca [Catharanthus roseus (L.) G. Don. `Little Bright Eye'], and marigold (Tagetes patula L. `Little Devil Flame'). For germination and early seedling growth, the cellulose film compared favorably with other standard germination media (blue blotter and germination paper) for five of the six species tested. Computer analysis of seedling length was possible for all six species and was statistically similar to hand measurements averaged for three analysts.