bluuebunny/crossref_metadata_2025 huggingface dataset:
Height Control in Three Pepper Types Treated with Drench-applied Abscisic Acid
Authors: Biai Christopher J. , Garzon José G. , Osborne Jason A. , Schultheis Jonathan R. , Gehl Ronald J. , Gunter Christopher C.
Published: February 2019

Vegetable transplants can have excessive internode elongation before field establishment, producing challenges for the growers using mechanical transplanters to establish their crops. Thus, controlling the height of vegetable transplants before planting could be an advantage for commercial vegetable growers. A greenhouse experiment was conducted in 2008 (Year 1–2008) and 2009 (Year 2–2009) to determine the efficacy of exogenous drench-applied abscisic acid (ABA) applications for height control of transplanted pepper. Three types of pepper (Capsicum annuum L.) were investigated: bell pepper ‘Aristotle’, Jalapeño ‘Grande’, and banana pepper ‘Pageant’. In this greenhouse study, 10 ABA treatments, based on application frequency and timing, and an untreated control were arranged in a randomized complete block design with six (Year 1–2008) or five (Year 2–2009) replications and were evaluated over an 8-week period each year. Treatments included: single application at Week 1 (cotyledon stage), Week 2, Week 3, and Week 4; double applications were made at Weeks 1 + 2, Weeks 2 + 3, and Weeks 3 + 4; and multiple applications of ABA at Weeks 1 + 2 + 3, Weeks 2 + 3 + 4, and Weeks 1 + 2 + 3 + 4. All ABA applications were delivered as a drench applied directly to the planting container at a rate of 250 mg·L−1 ABA. Early, single-dose applications (Week 1) were more effective at controlling height than a single dose applied later; a Week 1 application measured during week 5 was 4.1 cm versus a Week 4 application measured at Week 5, which was 5.7 cm. Multiple ABA applications initiated early (at the cotyledon stage) of ‘Aristotle’ bell peppers were effective in controlling transplant height compared with any single ABA application; measured at Week 5, an application at Week 1 + 2 was 3.1 cm compared with the single application treatments from that same measurement date, which ranged from 4.1 to 5.7 cm. Differences among the response of pepper types to ABA application were observed. ‘Aristotle’ had significant treatment effects even 6 weeks after treatment. ‘Pageant’ (banana pepper) exhibited an intermediate response with effects lasting only 2 weeks. No significant height reductions resulting from ABA treatment were observed for ‘Grande’ (Jalapeño pepper). Multiple ABA dose applications initiated at the cotyledon plant growth stage can be used to effectively control transplant height of ‘Aristotle’ bell pepper seedlings.
Estimating Daily Water Use of Two Petunia Cultivars Based on Plant and Environmental Factors
Authors: Kim Jongyun , van Iersel Marc W. , Burnett Stephanie E.
Published: February 2019

Many ornamental plant growers water excessively to reduce the risk of drought stress. Scheduling irrigation in greenhouses is challenging because there is little quantitative information about ornamental plant water requirements and how water use changes when plants are grown in varying greenhouse environmental conditions. Models to estimate the daily water use (DWU) of greenhouse crops may provide a useful tool to conserve irrigation water. Our objective was to develop a model to predict DWU based on plant age and easily acquirable environmental data. Two petunia (Petunia ×hybrida) cultivars, Single Dreams Pink and Prostrate Easy Wave Pink, were grown in different sized containers (diameter = 10, 12.5, and 15 cm) to quantify their DWU for 6 weeks. The substrate water content (θ, v/v) was maintained at 0.40 m3·m−3 using an automated irrigation system with capacitance soil moisture sensors. Every irrigation event was recorded by a data logger, and this information was used to calculate the DWU of the plants. On overcast days early in the experiment, plants used only 4.8 to 13.8 mL·d−1. The maximum DWU of ‘Single Dreams Pink’ was 63, 96, and 109 mL·d−1 in 10-, 12.5-, and 15-cm containers, respectively. Late in the experiment, ‘Prostrate Easy Wave Pink’ petunia used more water than ‘Single Dreams Pink’ because of their more vigorous growth habit. DWU was modeled as a function of days after planting (DAP), daily light integral (DLI), vapor pressure deficit (VPD), temperature, container size, and interactions between these factors and DAP (R2 = 0.93 and 0.91 for ‘Single Dreams Pink’ and ‘Prostrate Easy Wave Pink’, respectively). Days after planting and container size were the most important factors affecting DWU and are indicative of plant size. Daily light integral was the most important environmental factor affecting DWU. These models, describing the DWU as a function of the DAP and environmental conditions, may be used as guidelines for accurately watering petunias in greenhouses and may improve irrigation scheduling.
Zoysiagrass Genotypes Differ in Susceptibility to the Bluegrass Billbug, Sphenophorus parvulus
Authors: Fry Jack D. , Cloyd Raymond A.
Published: February 2019

Zoysiagrass, in general, has few insect pest problems but may suffer significant damage from infestations of the bluegrass billbug (Sphenophorus parvulus Gyllenhal). This study evaluated ‘Meyer’ and DALZ 0102 zoysiagrass (both Zoysia japonica Steud.) and 31 experimental zoysiagrass progeny, including reciprocal crosses between Z. japonica × Z. matrella (L.) Merr. or crosses between ‘Emerald’ (Z. japonica × Z. pacifica Goudsw.) × Z. japonica. These grasses were evaluated in adjacent experiments with 18 progeny in one and 13 in another. Plots were maintained under golf course fairway conditions and experienced natural infestations of the bluegrass billbug in 2009 and 2010 with larval damage primarily evident in June and continuing throughout the remainder of the growing season. ‘Meyer’ suffered the highest level of damage on each of six rating dates, ranging from 17% to 38% of the experimental plot area affected. Among the zoysiagrass progeny, damage ranged from 0% to 35% with most showing less than 15% damage. Overall, zoysiagrass progeny associated with reciprocal crosses of Z. japonica × Z. matrella or ‘Emerald’ × Z. japonica were less susceptible to bluegrass billbug than ‘Meyer’.
Allelopathic Effects of Sunnhemp (Crotalaria juncea L.) on Germination of Vegetables and Weeds
Authors: Skinner Emillie M. , Díaz-Pérez Juan Carlos , Phatak Sharad C. , Schomberg Harry H. , Vencill William
Published: February 2019

Sunnhemp (Crotalaria juncea L.) is a tropical legume that could be an important summer cover crop in the southeastern United States, but it has the potential for suppressing both crops and weeds. Allelopathic effects of sunnhemp on weeds, vegetable crops, and cover crops were evaluated in greenhouse and growth chamber experiments. In the greenhouse, ground dried sunnhemp residues (applied mixed with the soil at 1.6% w/w) reduced percent germination of lettuce (Lactuca sativa L.) and smooth pigweed (Amaranthus hybridus L.) to a similar degree as that caused by cereal rye (Secale cereale L. subsp. cereale) residues (applied at 1.5% w/w). The allelopathic activity of sunnhemp was greater in the leaves than in the roots or stems. In growth chamber studies, the mean reduction in germination (relative to the control) caused by sunnhemp leaf aqueous extracts was: bell pepper (100%), tomato (100%), onion (95%), turnip (69%), okra (49%), cowpea (39%), collard (34%), cereal rye (22%), sweet corn (14%), Austrian winter pea (10%), crimson clover (8%), cucumber (2%), and winter wheat (2%). In lettuce, carrot, smooth pigweed, and annual ryegrass, sunnhemp aqueous leaf extract reduced seedling length to a degree similar as that produced by rye aqueous leaf extract. Sicklepod [Senna obtusifolia (L.) H.S. Irwin & Barneby CA] germination was not inhibited by any of the sunnhemp or rye aqueous extracts. In conclusion, sunnhemp reduced the germination percentage and seedling growth of various crop species. The allelochemical activity in sunnhemp was primarily in the leaves and remained active at least 16 d after harvest under dry conditions. Sunnhemp's allelochemical effect may be a useful attribute for weed management in sustainable production systems. However, plant growth in the field in crops such as bell pepper, tomato, onion, and turnip may be impacted as a result of allelopathic activity of sunnhemp residues. Thus, weed management may be more effective when sunnhemp is grown in rotation with crops that tolerate the allelochemicals from sunnhemp, resulting in optimization of the rotation effects.
A Cytosolic Heat Shock Protein Expressed in Carrot (Daucus carota L.) Enhances Cell Viability under Oxidative and Osmotic Stress Conditions
Authors: Ahn Yeh-Jin , Song Na-Hyun
Published: February 2019

The expression and function of DcHsp17.7, a small heat shock protein expressed in carrot (Daucus carota L.), was examined under oxidative and osmotic stress conditions. Comparative analysis revealed that DcHsp17.7 is a cytosolic Class I protein. Sequence alignment showed that DcHsp17.7 has the characteristic α-crystalline domain-containing consensus regions I and II. Under oxidative [hydrogen peroxide (H2O2)] and osmotic (polyethylene glycol) stress conditions, DcHsp17.7 accumulated in carrot leaf tissue. To examine its function under these abiotic stress conditions, the coding sequence of DcHsp17.7 was introduced into Escherichia coli and expressed by isopropyl β-D-1-thiogalactopyranoside treatment. Under both oxidative and osmotic stress conditions, heterologously expressed DcHsp17.7 enhanced bacterial cell viability. The expression level of soluble proteins was higher in transgenic cells expressing DcHsp17.7 when compared with controls under these stress conditions. These results suggest that DcHsp17.7 confers tolerance to both oxidative and osmotic stresses and thereby functions as a molecular chaperone during the stresses examined.
Growth, Morphology, and Quality of Rooted Cuttings of Several Herbaceous Annual Bedding Plants Are Influenced by Photosynthetic Daily Light Integral During Root Development
Authors: Currey Christopher J. , Hutchinson Veronica A. , Lopez Roberto G.
Published: February 2019

Cuttings of herbaceous annual bedding plants must be rooted in late winter and early spring when ambient outdoor photosynthetic daily light integrals (DLIs) are at seasonally low levels. We evaluated the effect of DLI during root development on growth, morphology, and quality of nine popular vegetatively propagated annual bedding plant species. Cuttings of Angelonia angustifolia Benth. ‘AngelMist White Cloud’, Argyranthemum frutescens (L.) Sch. Bip. ‘Madeira Cherry Red’, Diascia barberae Hook. f. ‘Wink Coral’, Lantana camara L. ‘Lucky Gold’, Nemesia fruticans (Thunb.) Benth. ‘Aromatica Royal’, Osteospermum ecklonis (DC.) Norl. ‘Voltage Yellow’, Scaevola L. hybrid ‘Blue Print’, Sutera cordata Roth. ‘Abunda Giant White’, and Verbena Ruiz ×hybrida ‘Aztec Violet’ were harvested and propagated in a glass-glazed greenhouse with 23 °C air and substrate temperature set points. After callusing (≈5 mol·m−2·d−1 for 7 days), cuttings of each species were placed under one of three different fixed-woven shade cloths providing ≈38%, 61%, or 86% shade or no shade with 16 h of supplemental light for 14 days. There were no clear trends across species for stem length in response to DLI. Stem caliper of Argyranthemum, Diascia, and Nemesia increased by 35%, 119%, and 89%, respectively, as DLI increased from 1.2 to 12.3 mol·m−2·d−1. Depending on species, total, shoot, and root dry mass increased by 64% to 465%, 50% to 384%, and 156% to 1137%, respectively, as DLI increased from 1.2 to 12.3 mol·m−2·d−1. The quality index, an objective, integrated, and quantitative measurement of rooted cutting quality, increased for all species by 176% to 858% as DLI increased from 1.2 to 12.3 mol·m−2·d−1. Our results indicate that providing a DLI of ≈8 to 12 mol·m−2·d−1 after callusing increases both growth and quality of rooted cuttings.
Use of an Active Canopy Sensor and SPAD Chlorophyll Meter to Quantify Geranium Nitrogen Status
Authors: Wang Yun-wen , Dunn Bruce L. , Arnall Daryl B. , Mao Pei-sheng
Published: February 2019

This research was conducted to investigate the potentials of normalized difference vegetation index (NDVI), a Soil-Plant Analyses Development (SPAD) chlorophyll meter, and leaf nitrogen (N) concentration [% dry matter (DM)] for rapid determination of N status in potted geraniums (Pelargonium ×hortorum). Two F1 cultivars were chosen to represent a dark-green leaf cultivar, Horizon Deep Red, and a light-green leaf cultivar, Horizon Tangerine, and were grown in a soilless culture system. All standard 6-inch (15.24-cm) pots filled with a medium received an initial top-dress application of 5 g controlled-release fertilizer (15N–9P–12K), then plants were supplemented with additional N in the form of urea at 0, 50, 100, or 200 mg·L−1 N every few days to produce plants ranging from N-deficient to N-sufficient. The NDVI readings of individual plants from a NDVI pocket sensor developed by Oklahoma State University were collected weekly until the flowering stage. Data on flower traits, including number of pedicels (NOP), number of full umbels per pot (NOFU), total number of flowers per pot (TNF), number of flowers per pedicel (NOF), and inflorescences diameter (IFD), were collected 3 months after initial fertilizer treatment. After measuring flower traits, pedicels were removed from each pot, and SPAD value, NDVI, and leaf N concentration (g·kg−1 DM) were measured simultaneously. Cultivar and N rate significantly affected all but two flower and one N status parameters studied. The coefficient of determination R2 showed that NOP, NOFU, and TNF traits were more related to the N rates and the status parameters studied for ‘Horizon Tangerine’ than for ‘Horizon Deep Red’. For the latter cultivar, NOP and TNF traits were highly related to NDVI and SPAD values than N rates and leaf N content parameters. Correlation analysis indicated that the NDVI readings (R2 = 0.848 and 0.917) and SPAD values (R2 = 0.861 and 0.950) were significantly related to leaf N content (g·kg−1 DM) between cultivars. However, sensitivity of the NDVI and chlorophyll values to N application rate in geranium was slightly less than leaf N content. Strong correlations (R2 = 0.974 and 0.979, respectively) between NDVI and SPAD values were found within cultivars. The results demonstrated NDVI and SPAD values can be used to estimate N status in geranium. Because the pocket NDVI sensor will be cheaper than the SPAD unit, it has an advantage in determining N content in potted ornamentals.
Morphological Variations in Buddleia Induced by Gamma Ray Irradiation
Authors: Dai Wenhao , Magnusson Victoria
Published: February 2019

Buddleia species is commonly used as a perennial for landscaping as a result of its heavy flowers and long bloom period. However, this species has a few concerns such as lack of flower color, excessive growth, and an invasive nature. Attempts to improve Buddleia using conventional breeding methods have resulted in limited success. In this study, mutagenesis by gamma ray irradiation was used to induce genetic variations. In vitro shoot tips of two Buddleia cultivars, B. davidii ‘Potters Purple’ and Buddleia ‘Lochinch’, were exposed to 0 to 150 Gy gamma rays and then recovered in Murashige and Skoog (MS) medium supplemented with 2.5 μM benzyladenine (BA). Shoots that recovered from the gamma ray treatment were rooted in half-strength MS medium with 0.5 μM naphthalene acetic acid (NAA) and grown in the greenhouse. The growth of shoot tips was inhibited after they were exposed to gamma rays. An average of 50.8% of shoots treated with 50 Gy gamma rays were recovered, whereas only 9.7% and 6.5% of shoots recovered when exposed to 100 and 150 Gy gamma rays, respectively. After transfer to the greenhouse, a few plants showed reduced growth with some dying before they reached the flowering stage. Various variations including characteristics of leaves (shape, size, hairs), stems (shape, internode length, branching), flowers (color, size, and structure), and plant stature were observed. This research demonstrates that in vitro mutation induction using gamma ray irradiation could be a useful protocol to develop new cultivars or genetic materials for further breeding of Buddleia or other related species.
In Vitro Development of the Rare and Endangered Moss Molendoa hornschuchiana (Hook.) Lindb. ex Limpr. (Pottiaceae, Bryophyta)
Authors: Vujičić Milorad , Sabovljević Aneta , Šinžar-Sekulić Jasmina , Skorić Marijana , Sabovljević Marko
Published: February 2019

The high mountain pottioid moss Molendoa hornschuchiana (Hook) Lindb. ex Limpr. is a very rare and critically endangered bryophyte species in Europe in need for ex situ conservation. A 25-year-old herbarium sample was used to revive and propagate this species for further reintroduction and introduction to potential natural habitats. The reviving of “dead” herbarium specimen was achieved by disposing of axenical organisms as well as adjusting condition for developing secondary protonema, bud inductions, and optimization of gametophyte propagation in vitro condition.

The influence of exogenously added growth regulators on the morphogenesis of this species was studied. The plants were cultured in the two basic types of media, viz., BCD and half-strength Murashige and Skoog (MS) supplemented with different concentrations (0.01–0.3 μM) of indole-3-butyric acid (IBA) and N6-benzyladenine (BA) under a 16-h photoperiod. The influence of growth regulators on gametophores multiplication in vitro as well as on protonemal diameter was recorded. Well-developed gametophores were obtained on BCD medium, whereas on half-strength MS medium, secondary protonema was produced, both on hormone-free and supplemented substrate exclusively. Based on multiplication index in vitro, maximum development of gametophores was realized on BCD medium supplemented with 0.3 μM IBA and 0.1 μM BA. However, the widest diameter of secondary protonema was obtained on BCD medium enriched with low concentration of both BA (0.01 and 0.03 μM) and constant concentration of IBA (0.03 μM). Chemical names used: indole-3-butyric acid (IBA), N6-benzyladenine (BA), Murashige and Skoog medium (MS).
Optimizing Substrate Moisture Measurements in Containerized Nurseries
Authors: Daniels Alex B. , Barnard David M. , Chapman Phillip L. , Bauerle William L.
Published: February 2019

The primary goal of this study was to determine the optimum number of substrate moisture sensors needed to accurately determine substrate water content for 10 tree species in a containerized nursery. We examined variation in volumetric water content (VWC, m3·m−3) within containers, within species, among species, and over time. Across time, differences among species were not significant (P = 0.14). However, differences among time periods and the interaction effect between species and time periods were significant (P < 0.001). Seasonal differences in within-species variation were also evident in nine of the 10 species. In an attempt to understand species-specific mechanistic factors that influence within-species variation in VWC, we accounted for physiological and morphological differences affecting transpiration with a spatially explicit mechanistic model, MAESTRA. Neither estimated transpiration rate per whole crown or m2 of leaf area could explain variation in VWC. Based on our results, we recommend species-specific sensor deployment and report sensor quantities that estimate the mean substrate VWC of each species within a confidence interval of ± 5% VWC. Given the economic value of water and its control on biomass production, we conclude that nursery managers can maintain optimal substrate moisture with minimal sensor deployment.
Pollenizer and Cultivar Influence Seed Number and Fruit Characteristics in Olea europaea L.
Authors: Farinelli Daniela , Pierantozzi Pierluigi , Palese Assunta Maria
Published: February 2019

The effect of several pollination combinations of the olive cultivars Ascolana Tenera, Carolea, Leccino, and Picholine on seed quality and seed number and drupe and seed features were evaluated in 2007 and in 2008 in central Italy. The well-known pattern in olive fruit was confirmed by the high percentage of drupes (71.8%, on average) containing one seed with a closed endocarp, as the dispersal unit, optimizing the plant’s investment in seedling survival. Based on the results of the χ2 test of independence, there was a significant maternal and paternal effect on the number of normal seeds per drupe in some years and combinations. Particularly, in 2007, Picholine and Leccino cultivars (as mother) had drupes with two normal seeds (23.7% and 3.1%, respectively, with respect to 10.8% observed in a normal seed pattern), confirming that double-seeding in olive could be cultivar-dependent. Also the specific crosspollination between ‘Carolea’, as a pollenizer, and ‘Ascolana Tenera’ gave rise to a higher proportion of double-seeded drupes in 2007 (39% with respect to 14.3% expected to be in this category). In 2008, although ‘Ascolana Tenera’ produced more drupes with undeveloped seeds (31.9% with respect to 19.7% expected to be in that category), ‘Leccino’ and ‘Carolea’ had drupes with a lower number of undeveloped seed (14.2% and 11.5%, respectively). ‘Maurino’ and ‘Ascolana Tenera’ pollen produced significant effects on ‘Leccino’ drupes by increasing the number of drupes with undeveloped seeds in both experimental years. Double-seeded drupes outweighed those with only one normal seed in ‘Leccino’ and ‘Picholine’. Instead, drupes with undeveloped seeds affected fruit weight, being generally lighter than those with normal seeds. Although the Leccino cultivar, combined with ‘Maurino’ and ‘Ascolana Tenera’, greatly increased the proportion of drupes without normal seed, such condition did not affect their final weight, which was not different from those with one normal seed, suggesting that this variety caused late seed death.
Effect of Nitrogen Source on Pac Choi (Brassica rapa L.) Chemistry and Interactions with the Diamondback Moth (Plutella xylostella L.)
Authors: Johnson Wendy A. , Cloyd Raymond A. , Nechols James R. , Williams Kimberly A. , Nelson Nathan O. , Rotenberg Dorith , Kennelly Megan M.
Published: February 2019

Two greenhouse studies were conducted to examine effects of nitrogen source on primary and secondary metabolism of pac choi (Brassica rapa L. subsp. chinensis cv. Mei Qing Choi) and diamondback moth (Plutella xylostella L.) consumption, development, survival, and body weight. Applications of a liquid organic source of nitrogen (fish hydrolysate fertilizer) were compared with a conventional fertilizer to determine whether nitrogen source directly impacts pac choi chemistry (elemental composition and phenolics) and biomass and indirectly affects diamondback moth fitness parameters. There was no significant effect of fertility treatment on pac choi chemistry or biomass with the exception of percent leaf phosphorus, which was significantly higher in the conventional fertility treatment, and p-coumarin, which was significantly higher in the organic fertility treatment. Diamondback moth also affected plant chemistry. Both calcium (Ca) and magnesium (Mg) were significantly higher in plants infested with larvae compared with uninfested plants. Fertilizer affected diamondback moth fitness with percent survival and cohort development significantly reduced on pac choi associated with the organic fertilizer. However, pac choi receiving the organic treatment was similar in regard to primary nutrients and secondary compounds compared with plants that received a conventional fertilizer.
Seed Development of Cypripedium debile Rchb. f. in Relation to Asymbiotic Germination
Authors: Hsu Rebecca C.-C. , Lee Yung-I
Published: February 2019

The histological and histochemical changes in developing seeds of Cypripedium debile Rchb. f., a native slipper orchid species with horticultural potential, were investigated. The effects of timing for seed collection, culture media, and cultural conditions were also examined. The optimum germination percentage occurred when mature seeds were collected and sowed on 1/4 Murashige and Skoog basal medium. Besides, the liquid culture promoted germination of mature seeds. This finding is contrary to most other Cypripedium species, which are relatively easy to germinate with immature seeds. Moreover, two notable cytological changes of C. debile were observed. First, the suspensor cell protruded beyond the micropyle opening of the inner seedcoat, making the inner seedcoat not substantial. Second, Nile red staining indicated that the deposition of cuticular material on the seedcoat was fragmentary. It is proposed that the less hydrophobic nature of the seedcoat makes mature seeds of C. debile easier to obtain water and nutrients for germination.
Regulated Deficit Irrigation Effect on Yield and Wine Color of Cabernet Sauvignon in Central California
Authors: Costello Michael J. , Patterson W. Keith
Published: February 2019

Regulated deficit irrigation (RDI) is a management strategy that on grape can improve shoot/fruit ratio, water efficiency, and wine quality but has the potential to reduce yield. As part of a study on the influence of RDI on leafhopper density, we evaluated the effects on grape yield, berry size, berry soluble solids, and wine color. The studies were conducted at commercial vineyards in the San Joaquin Valley and in the Paso Robles region, CA, with Cabernet Sauvignon as the cultivar. Water deficits were imposed at either 50% (moderate deficit) or 25% (severe deficit) of standard irrigation (the control) for a period of 3 or 6 weeks and initiated at berry set, leafhopper egg hatch, or veraison. Deficit irrigation decreased berry weight by 16.1% at the San Joaquin Valley site (Aliso) and 11.7% at one of the Paso Robles sites (Frankel) but did not differ at the other site (Steinbeck). Yield was decreased by the deficits by 18.1% at Aliso, 26.7% at Frankel 2001 (but not 2002), and 24% at Steinbeck. Wine color density was increased by 21.8% at Aliso, 34.4% at Frankel 2001 (but not 2002), and did not differ at Steinbeck. Soluble solids did not differ among treatments at any site. There was no difference in berry weight, yield, or color between the moderate and severe deficits. It appears that in central California, RDI such as these are likely to reduce yield but are only one factor among many variables affecting quality such as wine color.
Cultivation and Irrigation of Fernleaf Biscuitroot (Lomatium dissectum) for Seed Production
Authors: Shock Myrtle P. , Shock Clinton C. , Feibert Erik B.G. , Shaw Nancy L. , Saunders Lamont D. , Sampangi Ram K.
Published: February 2019

Native grass, forb, and shrub seed is needed to restore rangelands of the U.S. Intermountain West. Fernleaf biscuitroot [Lomatium dissectum (Nutt.) Mathias & Constance] is a desirable component of rangelands. Commercial seed production is necessary to provide the quantity and quality of seed needed for rangeland restoration and reclamation efforts. Fernleaf biscuitroot has been used for hundreds if not thousands of years in the western United States as a source of food and medicine. Knowledge about fernleaf biscuitroot is confined to ethnobotanical reports, evaluation of some of its chemical constituents, and its role in rangelands. Products derived from fernleaf biscuitroot are sourced from wild plant populations. Little is known about fernleaf biscuitroot cultivation or its seed production. Variations in spring rainfall and soil moisture result in highly unpredictable water stress at flowering, seed set, and seed development of fernleaf biscuitroot. Water stress is known to compromise seed yield and quality for other seed crops. Irrigation trials were conducted at the Oregon State University Malheur Experiment Station at Ontario, OR, a location within the natural environmental range of fernleaf biscuitroot. It was anticipated that supplemental irrigation would be required to produce a seed crop in all years. Fernleaf biscuitroot was established through mechanical planting and cultivation on 26 Oct. 2005 in a randomized complete block design with four replicates; plot size was 9.1 m × 3.04 m wide. Irrigation treatments were 0 mm, 100 mm, and 200 mm/year applied in four equal treatments 2 weeks apart, timed to begin with flowering and continue through seed formation. First flowering occurred in the third year after planting. Seed production increased from the fourth through the sixth year. Optimal irrigation for seed production was calculated as 140 mm/year.
Growth, Physiological Response, and Quality Characteristics of Weeping Fig in Response to Shading Levels and Climatic Conditions
Authors: Scuderi Domenica , Giuffrida Francesco , Toscano Stefania , Romano Daniela
Published: February 2019

The aim of this study was to evaluate the effects of light availability and the climatic conditions on the growth and quality of weeping fig (Ficus benjamina L.). Plants of cv. Danielle were grown under five shading conditions (0%, 20%, 40%, 60%, and 80% reduction of the incident irradiance inside the greenhouse) and two cultivation periods (from May to October and from December to May). The light intensity in no shading treatment ranged from 6.3 to 16.4 MJ·m−2·d−1 in May to October and from 4.6 to 14.5 MJ·m−2·d−1 in December to May. Depending on climatic conditions, the light reduction resulting from shading produced strong differences in the growth of weeping fig. With increasing shading, the dry weight decreased from 282.4 to 113.3 g/plant during the first growth period, which was the period characterized by the highest values of global radiation and temperature, and from 120.8 to 56.8 g/plant during the second period. The effects of reduced light were evident in the plant quality, which is associated with the canopy and leaf characteristics. In particular, as a result of the increase of the apparent quantum yield and reduction of light compensation point, the most shaded plants showed a photosynthetic advantage over the control (0%) at a low irradiance level. Increased shading caused a reduction of plant compactness because of the increase of the internode length and branch insertion angle. Although shading also resulted in a reduction in the leaf number, the plant ornamental value was unaffected because of the highest unit leaf area (+72%) in both of the growth periods. Based on our results, the greatest decrease in irradiance (60% and 80% of shading) reduced the plant growth and compactness more in the growth period characterized by the highest values of global radiation and temperature, whereas the quality of the plants was improved by shading in both of the growth periods.
Determination of Silicon Concentration in Some Horticultural Plants
Authors: Hogendorp Brian K. , Cloyd Raymond A. , Swiader John M.
Published: February 2019

Although silicon is not an essential element, it is taken up by plants but is rarely quantified. Therefore, this study quantified the silicon concentration in 10 commonly grown horticultural plants including meadow sage (Salvia ×sylvestris), tickseed (Coreopsis verticillata), garden phlox (Phlox paniculata), New England aster (Symphyotrichum novae-angliae), Chinese astilbe (Astilbe chinensis), coral flower (Heuchera hybrid), garden zinnia (Zinnia elegans), French marigold (Tagetes patula), sweet basil (Basil spp.), and rosemary (Rosmarinus officinalis) using a plant alkaline fusion technique, which involved dry-ashing plant tissue samples and measuring color development with a spectrophotometer. Both zinnia and aster accumulated substantially more silicon from the municipal water source and growing medium (5365 and 4797 mg·kg−1 silicon, respectively) than the other plants evaluated, which had concentrations less than 2500 mg·kg−1 silicon. This study is just one of a few in which the silicon concentration in various horticultural plants has been quantified. Consequently, this may lead to better understanding those plants that will or will not benefit from applications of silicon-based fertilizers to promote cold-hardiness and/or plant resistance to fungal pathogens and insect pests.
Influence of Abscisic Acid and Benzyladenine on Fruit Set and Fruit Quality of ‘Bartlett’ Pears
Authors: Greene Duane W.
Published: February 2019

Experiments were conducted to evaluate abscisic acid (ABA) and the combination of ABA and benzyladenine (BA) as a thinner on ‘Bartlett’ pears. Application of 500 mg·L−1 ABA at bloom, petal fall, and at the 10-mm stage resulted in significant fruit thinning at all timings. Application at the 10-mm stage nearly defruited the trees. Rates of ABA between 50 and 500 mg·L−1 were evaluated at 10 mm and the thinning response was quadratic and highly significant. Rates as low as 50 mg·L−1 thinned. BA at 150 mg·L−1 at the 10-mm stage did not thin and when combined with 250 mg·L−1 ABA, no additional thinning was observed, but extensive thinning was done by the ABA alone. When thinning with ABA was achieved, return bloom was also enhanced. Thinning with ABA generally resulted in larger fruit, greater flesh firmness, and higher soluble solids. The russet seen on ABA-treated fruit was attributed primarily to the surfactant used. Extensive leaf yellowing and leaf abscission were noted after ABA application, especially with the 250 mg·L−1 and 500 mg·L−1 and this was considered commercially unacceptable. BA was unable to reverse or modify the leaf yellowing and abscission caused by ABA as it has been shown to do with other plant species.
Necessary Price Premiums to Incentivize Ghanaian Organic Cocoa Production: A Phased, Orchard Management Approach
Authors: Mahrizal  , Nalley L. Lanier , Dixon Bruce L. , Popp Jennie
Published: February 2019

Price premiums necessary to incentivize switching from conventional (inorganic) to organic cocoa (Theobroma cacao) production in Ghana are identified. Optimal, phased-replacement models for orchard management are used to determine when switching from conventional to organic is profitable. The decision is a function of orchard growth stage, price premiums, and yield loss. Results indicate that the net present value (NPV) of organic production under current market conditions is 21% lower than the NPV of conventional production. Analysis shows that, generally, the minimum price premium to convert to organic is just slightly lower, in percentage terms, than the yield reduction caused by growing organically.
Basal Salt Composition, Cytokinins, and Phenolic Binding Agents Influence In Vitro Growth and Ex Vitro Establishment of Magnolia ‘Ann’
Authors: Parris J. Kevin , Touchell Darren H. , Ranney Thomas G. , Adelberg Jeffrey
Published: February 2019

In vitro growth responses of Magnolia ‘Ann’ to basal salt composition, cytokinins, and phenolic binding agents were investigated in a series of experiments to refine micropropagation protocols. Murashige and Skoog (MS), half-strength MS, Woody Plant Medium (WPM), Driver and Kuniyuki (DKW), and Blaydes basal salts in conjunction with 1 g·L−1 activated charcoal (AC) or 1 g·L−1 polyvinylpyrrolidone (PVP) were evaluated as multiplication media. Benzylaminopurine (BAP), meta-topolin (mT), or 6-(γ,γ-dimethylallylamino) purine (2iP) at 2, 4, or 8 μM was investigated to optimize the cytokinin concentration. Murashige and Skoog medium supplemented with 2 μM BAP with no phenolic binding agent was an optimal multiplication medium that yielded 3.2 ± 0.2 shoots with a mean length of 17.2 ± 1.8 mm over an 8-week period. For rooting, microshoots were cultured on half-strength MS media supplemented with 0, 5, 10, or 20 μM indolebutyric acid (IBA) with or without AC. Media containing AC produced elongated microshoots suitable for rooting and ex vitro establishment. Microshoots cultured on medium supplemented with AC also had higher in vitro rooting (16%) and higher ex vitro rooting (75%) compared with those without AC regardless of in vitro IBA concentration.
Soil Quality After Eight Years Under High Tunnels
Authors: Knewtson Sharon J.B. , Kirkham M.B. , Janke Rhonda R. , Murray Leigh W. , Carey Edward E.
Published: February 2019

The sustainability of soil quality under high tunnels will influence management of high tunnels currently in use and grower decisions regarding design and management of new high tunnels to be constructed. Soil quality was quantified using measures of soil pH, salinity, total carbon, and particulate organic matter (POM) carbon in a silt loam soil that had been in vegetable production under high tunnels at the research station in Olathe, KS, for eight years. Soil under high tunnels was compared with that in adjacent fields in both a conventional and an organic management system. The eight-year presence of high tunnels under the conventional management system resulted in increased soil pH and salinity but did not affect soil carbon. In the organic management system, high tunnels did not affect soil pH, increased soil salinity, and influenced soil carbon (C) pools with an increase in POM carbon. The increases in soil salinity were not enough to be detrimental to crops. These results indicate that soil quality was not adversely affected by eight years under stationary high tunnels managed with conventionally or organically produced vegetable crops.
Doubled Haploid Onion (Allium cepa L.) Lines and Their Impact on Hybrid Performance
Authors: Hyde Peter T. , Earle Elizabeth D. , Mutschler Martha A.
Published: February 2019

Production of double haploid (DH) lines is a rapid method of obtaining completely homozygous inbred lines for numerous crops; however, practical trials testing the use of DH onion lines have been limited. DH onion lines were produced from diverse highly heterozygous material in development within the Cornell onion breeding program. These DH lines were evaluated in multiple replicated trials in onion fields in New York as lines and as parents of hybrids to assess the impact and commercial potential of DH onions. Twenty DH onion lines were compared with open-pollinated cultivars developed from the same source germplasm and with a commercial hybrid over two years. The vegetative vigor of the DH lines was comparable to that of related open-pollinated cultivars, showing minimal, if any, inbreeding depression. Two sets of hybrids were produced using the DH lines as males and two different females that are the female parents of the commercial hybrid controls. Therefore, hybrids in each set are half-sibs, and any performance differences are attributable to their DH male lines. In four replicated trials of these hybrids and controls, the experimental hybrids were either not significantly different or significantly better in measures of vegetative vigor compared with conventional half-sib hybrid controls. The vegetative vigor of DH lines, and their derived hybrids, might result from selection of plantlets without deleterious sublethal genes during gynogenesis. The shortened development time and equivalent quality of DH lines compared with the traditionally bred onion inbreds warrant their use. The increased vigor in hybrid combination could be an additional benefit for onion breeding strategies.
Podophyllotoxin Concentration in Junipers in the Big Horn Mountains in Wyoming
Authors: Zheljazkov Valtcho D. , Cantrell Charles L. , Donega Mateus Augusto , Astatkie Tess , Heidel Bonnie
Published: February 2019

Podophyllotoxin is used for the production of the anticancer drugs etoposide, etopophos, and teniposide. Currently, podophyllotoxin is extracted from the Himalayan mayapple (Podophyllum hexandrum Royle). Some junipers and other species also contain the same natural product and have been explored as a domestic source for this compound. The objective of this study was to screen junipers in the Big Horn Mountains in Wyoming for podophyllotoxin. Twenty junipers (18 accessions of Juniperus horizontalis Moench. and two accessions of J. scopulorum Sarg.) were sampled in Mar. 2012 and analyzed for podophyllotoxin. Podophyllotoxin concentration in the samples varied from 0.058% to 0.673% with five accessions having podophylloxin concentration above 0.5%. This study demonstrated wide variation of podophyllotoxin in J. horizontalis and J. scopulorum in the Big Horn Mountains. Some of the accessions had greater than 0.5% podophyllotoxin making them a feasible source for podophyllotoxin extraction.
Partial Shade, Irrigation, and Added Nutrients Maximize Dry Matter Yield of American Skullcap (Scutellaria lateriflora L.)
Authors: Similien Arsène , Shannon Dennis A. , Wood C. Wesley , van Santen Edzard , Joshee Nirmal , Foshee Wheeler G.
Published: February 2019

American skullcap (Scutellaria lateriflora L.), a medicinal plant species valued for its sedative properties associated with flavonoids, is generally harvested from the wild. Scientific information on how field cultivation practices affect dry matter yield is lacking in this species. A 2 × 2 × 3 split plot factorial experiment within a randomized complete block design was conducted on a Marvyn loamy sand (fine-loamy, kaolinitic, Thermic Typic Kanhapludults) in Central Alabama to explore effects of light, irrigation, and nutrient application on dry matter yield of American skullcap. Treatment factors were shade (40% shade vs. no shade), irrigation (applied at 30 kPa vs. no irrigation), and nutrients [no added nutrients vs. nutrients added as chemical fertilizer (100 kg nitrogen, 68 kg phosphorus, 42 kg potassium/ha) or chicken litter (100 kg nitrogen, 50 kg phosphorus, and 123 kg potassium/ha)]. Shade formed the main plot units, whereas irrigation × nutrient factorial combinations were subplots. Skullcap shoots in experimental plots were harvested four times during the course of the two-year experiment (2007, 2008). All growth variables measured, except percent dry matter, performed better under shade than in full sun. Dry matter yield was increased 45% by shade, 61% by irrigation, and 22% by addition of nutrients. A significant irrigation × nutrients interaction was observed at the first and second harvests. Highest yields were obtained with the irrigation + manure and irrigation + fertilizer treatments under shade and the lowest with fertilizer and the control treatments in full sun.
Seed Germination and Seedling Growth of Tomato and Lettuce as Affected by Vermicompost Water Extracts (Teas)
Authors: Arancon Norman Q. , Pant Archana , Radovich Theodore , Hue Nguyen V. , Potter Jesse K. , Converse Chad E.
Published: February 2019

Greenhouse experiments were conducted to evaluate the effects of different concentrations of vermicompost water extracts (teas) and seed soaking duration on germination of tomato (Solanum lycopersicum) and lettuce (Lactuca sativa) seeds. In the first experiment, tomato and lettuce seeds were soaked in vermicompost teas prepared from chicken manure-based vermicomposts for 9 hours. The concentrations of the extracts used were 10%, 5%, 3%, 1% (1:10, 1:20, 1:33, and 1:100 vermicompost-to-water ratio by volume), and 0% (water control). Seeds were sown in peat–perlite medium, and seedlings were harvested after 4 weeks. Soaking seeds in vermicompost teas significantly (P < 0.0001) increased germination percentage and seedling growth of tomato and lettuce compared with control. The response to concentrations of the vermicompost tea was generally linear. In another experiment, tea produced from food waste-based vermicompost was used. Tomato seeds were soaked in 20%, 10%, 5%, 1%, and 0% teas after 24 hours of soaking and sown into a sphagnum moss-based medium. Plant responses were linear and quadratic for germination and growth, respectively, with 1% vermicompost tea increasing germination, whereas 5% vermicompost tea significantly promoted growth. A third experiment was done to evaluate the interaction of a range of vermicompost tea concentrations (20%, 10%, 5%, 1%, and 0%) and length of soaking (24, 12, 8, 4, 1 hours, and 0: no soaking) on the germination of tomato seeds. There was a significant interaction (P < 0.001) between the concentration of vermicompost teas and lengths of soaking. Soaking duration generally had a significantly positive and linear effect on germination of tomato seeds across the concentrations of vermicompost tea. Germination rates of tomato seeds were significantly greater after 8, 12, and 24 hours of soaking. However, within each soaking duration, concentrations of vermicompost teas had variable effects on seed germination. The presence of N-indole-3-acetic acid (IAA), cytokinin, gibberellins, and humic acids in the teas could have been responsible for the faster germination of tomato seeds when soaked at lower concentrations and longer soaking times.
Improving Freezing Tolerance of ‘Chambourcin’ Grapevines with Exogenous Abscisic Acid
Authors: Zhang Yi , Dami Imed
Published: February 2019

The purpose of this study was to develop a protocol to increase freezing tolerance of field-grown ‘Chambourcin’ grapevines (Vitis spp.) using exogenous abscisic acid (ABA). The specific objectives were to determine the optimum concentration and timing for ABA foliar application in ‘Chambourcin’ and to evaluate morphological and physiological changes that lead to increased freezing tolerance in response to foliar ABA application. ‘Chambourcin’ grapevines were treated with a foliar ABA application of concentrations of 0, 100, 200, 300, 400, 500, 600, 700, and 800 mg·L−1 at 50% fruit set stage to evaluate ABA phytotoxicity under field conditions and identify the optimum concentration. In a subsequent experiment, ‘Chambourcin’ grapevines were treated with 400 and 600 mg·L−1 of ABA at different stages of development corresponding to 50% fruit set, 21 days after 50% fruit set, 50% veraison, 20, 30, 40, and 55 days postveraison. ABA concentrations of 700 and 800 mg·L−1 were phytotoxic and caused significant damage to leaves and flowers. Optimum concentrations of ABA did not affect yield components or basic fruit chemical composition, yet it promoted anthocyanin accumulation at harvest. Furthermore, ABA advanced bud dormancy, decreased bud water content, and eventually increased freezing tolerance under simulated freezing tests. The increased freezing tolerance of ABA-treated vines was confirmed by bud injury assessment after a natural freezing event in Jan. 2011. It was also determined that ABA was most effective when applied with an optimum concentration of 400 mg·L−1 20 to 30 days postveraison. It is concluded that exogenous ABA enhanced dormancy and increased freezing tolerance; thus, it has the potential to protect grape cultivars from freezing injury.