bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison Study on Soil Physical and Chemical Properties, Plant Growth, Yield, and Nutrient Uptakes in Bulb Onion from Organic and Conventional Systems
Authors: Lee Jongtae , Hwang Sunkyoung , Lee Seongtae , Ha Injong , Hwang Haejun , Lee Sangdae , Kim Juyeon
Published: February 2019

This study aimed to compare agricultural practices, soil physical and chemical properties, growth characteristics, and nutrient uptake of bulb onions from organic and conventional farms in southeastern Korea during the 2011–12 growing season. Soil and plant samples were collected from eight certified organic fields managed organically for more than 5 years and eight conventional fields adjacent to the organic fields. The amounts of nutrients applied to onion fields were approximately two times greater with the conventional methods than with organic methods. However, the soil physical and chemical properties were not significantly different between the organic and conventional systems, except for NO3-N in early May. Growth characteristics were significantly different in early April with organic bulb yield of 55.9 t·ha−1, which was 21.8% lower than conventionally produced onions. Yield reduction in organic onions was the result of lower large-sized (8 cm or greater) bulb yield compared with conventional production. In the conventional system, phosphorus (P) and potassium (K) content of leaf tissue in early April, and nitrogen (N) and P content of bulb tissue in early May were higher than those in the organic system. Uptake of all nutrients was greater in the conventional onions compared with the organic onions, except for leaf tissue at harvest. In conclusion, organic onions began to grow and absorb soil nutrients later than the conventional onions in the initial vegetative growth stage. Moreover, it led to an organic onion producing a lower bulb yield. To accelerate the initial growth of the organic onion plant, agricultural practices need to be modified. Modifications that may help include using larger sized seedlings at transplanting, covering the plants with nonwoven fabric or transparent plastic film to increase warmth during winter, and harvesting the onions 1 week later than the conventional onions.
Progress Toward Increasing Intake of Dietary Nutrients from Vegetables and Fruits: The Case for a Greater Role for the Horticultural Sciences
Authors: Simon Philipp W.
Published: February 2019

Diet is implicated globally in the cause and severity of many diseases, including cancer, heart disease, and diabetes, and a large body of medical evidence indicates that consumption of healthier foods can alleviate both the incidence and severity of not only these diseases, but also obesity, which is a causal factor for many chronic diseases. The 2010 Dietary Guidelines for Americans indicated that several nutrients are underconsumed in the United States, including folate, magnesium, potassium, dietary fiber, and vitamins A, C, and K. Vegetables and fruits are major sources of several of these micronutrients and minerals as well as many other phytonutrients. Despite these health benefits, vegetable and fruit intake by U.S. consumers is significantly lower than recommended by dietary guidelines (less than 40% of recommended intake) and has not risen in the past decade. Collaborations between horticultural plant breeders, production and postharvest scientists with food scientists, nutritionists, medical scientists, marketing specialists, and social scientists are needed to develop plans and take action to stimulate increased vegetable and fruit intake. Increased intake may have a positive impact not only on the health of consumers, but would also increase the economic value of horticultural commodities and raise the profile of horticultural sciences. Horticultural approaches to address this important challenge, and opportunity, must be developed.
Assessing Nutritional Changes in a Vegetable Over Time: Issues and Considerations
Authors: Farnham Mark W. , Grusak Michael A.
Published: February 2019

For many decades plant breeders have worked to improve vegetable crops for numerous economically important traits, like host plant resistance to disease, yield, and vegetable quality. Most improvements have been made with little knowledge as to how, or if, nutritional or phytonutrient concentrations might also be indirectly altered in the process. There have been some reports suggesting that concentrations of nutrients in vegetables have been reduced over time, possibly related to introductions of new cultivars. However, for most vegetables, current evidence indicating changes in nutrient concentrations, and specifically mineral concentrations, is circumstantial at best. To effectively test whether changes may have occurred over time as new cultivars replace older ones, appropriate field studies must be conducted wherein harvested produce from “old” vs. “new” crop cultivars is analyzed by appropriate methods and compared directly. Numerous considerations and issues such as 1) the set of cultivars to be used in field tests; 2) how nutritional concentration will be expressed; and 3) the evolution, history, and consumption changes of the crop under study must be addressed in making such direct comparisons and interpreting results.
Efficient In Vitro Screening for Higher Soil pH Adaptability of Intersectional Hybrids in Blueberry
Authors: Tsuda Hirotoshi , Kunitake Hisato , Aoki Yo , Oyama Akiko , Tetsumura Takuya , Komatsu Haruki , Yoshioka Katsunori
Published: February 2019

We tested efficient in vitro methods for screening the genotypes with higher pH tolerance using multiple shoots of intersectional hybrids between Vaccinium corymbosum ‘Spartan’ and V. bracteatum. The response of the four hybrid clones tested to different pH levels was clone-dependent in vitro. An apparent difference was found in the rooting rate among the hybrid clones even at higher pH levels; the rooting rates of JM4 (91%) at pH 8.0 indicated a significantly high value compared with other clones (JM1: 24%, JM2: 9%, JM3: 8%, ‘Spartan’: 0%). Furthermore, JM4 showed constantly high rooting rates (91% to 100%) at all pH levels with no significant differences. Similar differences in the root characters of the hybrids were also confirmed by checking the viability of roots using fluorescein diacetate (FDA)/propidium iodide (PI) staining after dipping the roots of in vitro-produced shoots in liquid medium at different pH levels for 6 hours. These results suggest that an in vitro screening method using the rooting rate of multiple shoots and the viability test of roots by FDA/PI staining as a marker could become a very useful tool for the selection of germplasm with tolerance to higher pH within a short time using small planting spaces. In addition, JM4, which showed a high rooting rate at pH 8.0, could be useful in breeding new cultivars with higher pH tolerance.
The Number of Emitters Alters Salt Distribution and Root Growth in Potted Gerbera
Authors: Valdés Raquel , Miralles Julián , Ochoa Jesús , Bañón Sebastián , Sánchez-Blanco María Jesús
Published: February 2019

Potted gerberas were grown in a greenhouse with one, two, or four emitters (1.2 L·h−1) per pot and irrigated with water of two levels of salinity (1.5 dS·m−1 and 3 dS·m−1). All pots received the same volume of water. The aim was to determine whether the number of emitters per pot affects the distribution of roots and salts in the substrate (100% coconut fiber). We determined the electrical conductivity (EC) distribution at three different heights (upper, middle, and lower). We also studied the roots and EC horizontal distribution in four quadrants (southeast, southwest, northwest, and northeast). Shoot growth, leaf damage, plant water status, and photochemical capacity of photosystem II were also studied. Two or four emitters per pot reduced the leaching fraction compared with that observed with one emitter, improving both the amount and homogeneity of substrate moisture. In the two saline conditions used, the salt concentration in the substrate was irregular both vertically and horizontally, and the presence of roots in the horizontal quadrant sides was heterogeneous. Both of these behaviors decreased as the number of emitters per pot increased. Root growth was weakly related with the soluble salt content in the root zone. When saline water is used, two emitters per pot are to be recommended because the difference between using two and four emitters was very slight. The use of only one emitter reduced shoot and root growth and encouraged salt damage to leaves.
Propagation for the Conservation of Pityopsis ruthii, an Endangered Species from the Southeastern United States
Authors: Wadl Phillip A. , Rinehart Timothy A. , Dattilo Adam J. , Pistrang Mark , Vito Lisa M. , Milstead Ryan , Trigiano Robert N.
Published: February 2019

Pityopsis ruthii is an endangered species endemic to the Hiwassee and Ocoee Rivers in Tennessee. As part of a recovery effort focused on P. ruthii, vegetative propagation and in vitro multiplication and seed germination techniques were developed. Plants were vegetatively propagated using greenhouse stock plants and wild-collected stems. Rooting occurred with and without auxin treatments but was greatest when 0.1% indole-3-butyric acid (IBA) talc was applied to the vegetative cuttings; rooting was lowest when flowering stems were used. Pro-Mix BX substrate provided the most consistent rooting. In vitro multiplication was accomplished by the removal of lateral shoots from in vitro-grown plants that were rooted on Murashige and Skoog (MS0) basal medium with 270 clones produced from a single individual after 4 months. Nineteen clones were transplanted and secured with bonded fiber matrix into their natural habitat and 14 survived for 1 year. To avoid genetic swamping of native populations with the introduction of large numbers of genetically identical individuals through clonal propagation, seed-based propagation efforts were explored. Open-pollinated seeds were collected, disinfested and germinated, and seedlings established on MS medium. Seeds were submersed in 70% ethanol for 1 minute and briefly flamed. Seeds were surface-sterilized in a range [10% to 50% (v/v)] Clorox® bleach solutions with vigorous shaking for 20 minutes, rinsed three times in sterile water, and germinated on MS0. Removal of pappus from seeds was required for successful disinfestations, but the bleach concentration was not critical. Successful propagation is a step toward the conservation and recovery of P. ruthii and should allow future reintroduction projects.
Screening the Cucumber Plant Introduction Collection for Young Fruit Resistance to Phytophthora capsici
Authors: Colle Marivi , Straley Elizabeth N. , Makela Stephanie B. , Hammar Sue A. , Grumet Rebecca
Published: February 2019

Fruit rot caused by Phytophthora capsici is a major constraint in cucumber (Cucumis sativus) production. In an effort to identify a source of resistance, we developed a more streamlined detached fruit method for high-throughput screening and tested the U.S. cucumber PI collection for fruit rot resistance. A total of 1076 PI collections, from 54 geographic locations around the world, along with the susceptible commercial cultivar, Vlaspik, were grown in the field and tested for resistance to P. capsici. Using the knowledge gained from our prior studies regarding greater susceptibility of young fruits compared with older fruits, very young fruits (≈3 to 4 days post-pollination) were collected and inoculated with zoospore suspensions of P. capsici isolate OP97. From the screens performed in 2011 and 2012, 99% of the tested PIs were rated as moderately or highly susceptible based on symptom development and pathogen growth at 5 days post-inoculation. The cv. Vlaspik control showed consistent high susceptibility to P. capsici with a mean symptom rating of 8.0 on a 9-point scale. A set of 28 PIs was chosen for further testing in the greenhouse or field in 2013. The disease ratings of PIs rescreened in 2013 were much lower compared with that of the full collection of PIs. Three accessions, PI109483, PI178884, and PI214049, showed consistent low mean disease ratings and may be considered as possible sources of resistance to young cucumber fruit infection by P. capsici. Evaluation of the S1 progeny of PI109483 suggests that the resistance is heritable and should allow for development of useful breeding materials that can be used for developing P. capsici-resistant cucumber cultivars.
Climate, Winter Chill, and Decision-making in Sweet Cherry Production
Authors: Measham Penelope F. , Quentin Audrey G. , MacNair Nicholas
Published: February 2019

Growers naturally adapt and manage production for unpredictable and variable seasonal climates; however, the projected changes in climate introduce a new concern with increased variability in the frequency and severity of extreme climatic events and sustained changes in temperature. This study addresses the complexity of providing clear winter chill information in a form that facilitates grower assimilation and application of that information, ultimately to assist decision-making around variety selection and management. This study established the chill requirement for two commonly grown sweet cherry (Prunus avium L.) varieties: ‘Kordia’ and ‘Sweetheart’, and explored the uniformity of bud burst in each. It was found that varieties required different chill hours and that ‘Sweetheart’ reached mean time to, and maximum total bud burst, faster than ‘Kordia’, but no subsequent impact on uniformity of maturity at harvest. There was no significant difference in uniformity of burst between the two varieties. The results obtained by matching chill accumulation to tree phenology showed that cherry-producing regions in Australia will experience sufficient chill to support the production of the variety ‘Sweetheart’ with an increase in mean winter temperature of 1 °C. Regions in Western Australia and Queensland will become marginal, or not suitable, for ‘Kordia’.
An In Vitro Germination Technique for Some Stone Fruit Species: the Embryo Isolated from Cotyledons Successfully Germinated without Cold Pre-treatment of Seeds
Authors: Şan Bekir , Yildirim Adnan Nurhan , Yildirim Fatma
Published: February 2019

Seeds of temperate fruit species need a long time to germinate as a result of their requirement of stratification or cold treatment. Therefore, fast and uniform germination techniques are desirable and important for fruit tree propagation and especially for breeding studies. The effects of combinations of benzylaminopurine (BAP) and gibberellic acid (GA3) on in vitro embryo germination of apricot, peach, and wild cherry were determined without seed cold pretreatment. The results showed that no germination was recorded in all the seeds with testa. In the seeds without testa, no germination (wild cherry) or limited germination (less than 10%) was recorded. When the embryos separated from cotyledons were cultured, successful germination was obtained for all species. In general, the addition of different combinations of BAP and GA3 into the Murashige and Skoog (MS) medium significantly increased the germination ratios of embryos without cotyledons in all species. For wild cherry, the best treatment (66.7% germination) was MS media containing 0.5 mg·L−1 BAP + 2.0 mg·L−1 GA3 or 0.5 mg·L−1 BAP + 4.0 mg·L−1 GA3. For peach, the best treatment (86.7% germination) was MS medium supplemented with 0.5 mg·L−1 BAP + 3.0 mg·L−1 GA3. For apricot, the best treatment (93.3%) was MS media containing 0.5 mg·L−1 BAP + 3.0 mg·L−1 GA3, 1.0 mg·L−1 BAP + 1.0 mg·L−1 GA3, or 1.0 mg·L−1 BAP + 2.0 mg·L−1 GA3.
Drying and Shade Effects on Spearmint Oil Yields and Composition
Authors: Zheljazkov Valtcho D. , Astatkie Tess , Jeliazkova Ekaterina
Published: February 2019

‘Native’ spearmint (Mentha spicata L.) is one of the two most widely grown spearmints in the United States and in other countries. Recent studies demonstrated the feasibility of growing ‘Native’ spearmint as a cash crop for north–central Wyoming. Transportation and energy costs of commercial mint production can be reduced by drying the spearmint in windrows in the field for a few days after harvest and before oil extraction. This method of drying mint has been a common practice in the traditional mint production regions of the world. However, there is a knowledge gap regarding the effect of this drying method on the yield and composition of ‘Native’ spearmint oil. Field and laboratory experiments were conducted in Wyoming to evaluate the effects of drying duration in days after harvest (DAH: 0, 1, 2, 3, 4, 7, or 11) and drying conditions (shade and sun) on the yield of essential oil (EO) and on the concentrations of different oil constituents (beta-pinene, myrcene, limonene, eucalyptol, cis-sabinene hydrate, 4-terpineol, cis-dihydro carvone, cis-carveol, carvone, iso-dihydro carveol acetate, beta-bourbonene, beta-caryophyllene, alpha-humulene/transbeta-farnesene, and germacrene D). Neither drying duration nor drying condition had a significant effect on oil yield. The average yield of essential oil was 0.25 g of oil per 100 g of fresh weight. Drying duration and drying conditions had a significant effect on the composition of EOs. The concentrations of myrcene and germacrene-D were higher in the EOs from plants dried under shade (3.2% and 2.4%, respectively) than the EOs from plants dried under direct sun (3% and 2.2%, respectively). The concentration of beta-pinene was higher in plants dried under direct sun than under shade (0.92% vs. 0.88%). Carvone ranged from 51% to 53% in the oil and was higher in EOs from plants dried for 1 and 2 DAH and lower in EOs from plants dried for 7 days. Drying of ‘Native’ spearmint under direct sun in Wyoming for up to 11 DAH can be used as an effective tool to reduce transportation and energy costs without affecting oil yields.
Resistance to Botrytis cinerea and Quality Characteristics during Storage of Raspberry Genotypes
Authors: Harshman Julia M. , Jurick Wayne M. , Lewers Kim S. , Wang Shiow Y. , Walsh Christopher S.
Published: February 2019

Raspberries are a delicate, high-value crop with an extremely short shelf life exacerbated by postharvest decay caused by Botrytis cinerea Pers. European red raspberry (Rubus idaeus L.) is the most widely grown variety. Yellow (R. idaeus L.), black (R. occidentalis L.), and purple raspberries (R. ×neglectus Peck. or R. occidentalis ×idaeus hybrids) are available mainly at local markets and U-pick farms. To compare the postharvest quality of the raspberry color groups, pesticide-free fruit from cultivars and breeding selections of red, yellow, purple, and black raspberries were examined for oxygen radical absorbance capacity (ORAC), phenolics, anthocyanins, soluble solids, titratable acids, pH, color, firmness, decay and juice leakage rates, ethylene evolution, and respiration. There were significant correlations between decay rate and physiochemical properties. Both decay and leakage rates were correlated with weather conditions before harvest, but each color group responded differently to different weather factors. There were no correlations among changes in color, firmness, decay, or juice leakage rates. All the other color groups were less acidic than the familiar red raspberry. Yellow raspberries had the worst decay rates but the best leakage rates. Black and purple raspberries, with the highest phenolics and anthocyanins and the lowest ethylene evolution rates, resisted decay the longest but bled soonest.
Hydration Efficiency of Traditional and Alternative Greenhouse Substrate Components
Authors: Fields Jeb S. , Fonteno William C. , Jackson Brian E.
Published: February 2019

Wettability is a major factor in determining whether a material can be effectively and efficiently used as a component in greenhouse substrates. Poor wettability can lead to poor plant growth and development as well as water use inefficiency. This research was designed to test the wettability and hydration efficiency of both traditional and alternative components of substrates under different initial moisture contents (MCs) and wetting agent levels. Peatmoss, perlite, coconut coir, pine bark, and two differently manufactured pine tree substrate components (pine wood chips and shredded pine wood) were tested at 50% and 25% initial MC (by weight). The objective of this research was to determine the effects of initial MC and wetting agent rates on the wettability and hydration efficiency of these substrate components. Each component received four wetting agent treatments: high (348 mL·m−3), medium (232 mL·m−3), low (116 mL·m−3), and none (0 mL·m−3). Hydration efficiency was influenced by initial MC, wetting agent rate, and inherent hydrophobic properties of the materials. Wetting agents did increase the hydration efficiencies of the substrate components, although not always enough to overcome all cases of hydrophobicity.
Transmission Efficiency of Candidatus Liberibacter asiaticus and Progression of Huanglongbing Disease in Graft- and Psyllid-inoculated Citrus
Authors: Albrecht Ute , Hall David G. , Bowman Kim D.
Published: February 2019

Candidatus Liberibacter asiaticus (Las) is a phloem-limited bacterium associated with huanglongbing (HLB), one of the most destructive diseases of citrus in Florida and other citrus-producing countries. Natural transmission of Las occurs by the psyllid vector Diaphorina citri, but transmission can also occur through grafting with diseased budwood. As a result of the difficulty of maintaining Las in culture, screening of citrus germplasm for HLB resistance often relies on graft inoculation as the mode of pathogen transmission. This study evaluates transmission efficiencies and HLB progression in graft-inoculated and psyllid-inoculated citrus under greenhouse and natural conditions in the field. Frequencies of transmission in graft-inoculated greenhouse-grown plants varied between experiments and were as high as 90% in susceptible sweet orange plants 6 to 12 months after inoculation. Transmission frequency in a tolerant Citrus × Poncirus genotype (US-802) was 31% to 75%. In contrast, transmission of Las after controlled psyllid inoculation did not exceed 38% in any of four experiments in this study. Whereas the time from inoculation to detection of Las by polymerase chain reaction (PCR) was faster in psyllid-inoculated US-802 plants compared with graft-inoculated US-802 plants, it was similar in graft- and psyllid-inoculated sweet orange plants. HLB symptom expression was indistinguishable in graft- and psyllid-inoculated plants but was not always associated with the number of bacteria in affected leaves. The highest number of Las genomes per gram leaf tissue measured in sweet orange plants was one to four × 107 in graft-inoculated plants and one to two × 107 in psyllid-inoculated plants. Highest numbers measured in tolerant US-802 plants were one to three × 106 and two to six × 106, respectively. Compared with artificial inoculation in a greenhouse setting, natural inoculation of field-grown sweet orange trees occurred at a much slower pace, requiring more than 1 year for infection incidence to reach 50% and a minimum of 3 years to reach 100%.
Flower, Fruit, and Petiole Color of American Beautyberry (Callicarpa americana L.) Are Controlled by a Single Gene with Three Alleles
Authors: Contreras Ryan N. , Ruter John M. , Knauft David A.
Published: February 2019

American beautyberry (Callicarpa americana) is a deciduous shrub native to the southeast United States and is grown primarily for its metallic-purple fruit that develop in the fall. There are also pink- and white-fruiting and variegated forms but these traits are rare in nature and there is no information available regarding their inheritance. Also, there is confusion regarding self-compatibility and the presence of apomixis in Callicarpa L. Crosses were performed to investigate the genetics of fruit color, self-compatibility, and apomixis in american beautyberry. Test crosses between C. americana (CA) and C. americana ‘Lactea’ (CAL) suggested that white fruit is recessive to purple. White fruit appears to be controlled by a single recessive gene for which we propose the name white fruit and the gene symbol wft. Although there were only a limited number of progeny grown, crosses between CA and ‘Welch’s Pink’ suggest that purple is dominant to pink. Test crosses between CAL and ‘Welch’s Pink’ are needed to draw conclusions; however, we propose that purple, pink, and white fruit are controlled by an allelic series for which we suggest the gene symbols Wft > wft p > wft. Segregation ratios suggested that all progeny in the study developed through sexual hybridization. All genotypes used in the current study were self-compatible.
The Diversity in Performance of Commercial Olive Clones Selected from the Autochthonous cv. Souri Population for Intensive Irrigated Cultivation
Authors: Ben-Ari Giora , Biton Iris , Mani Yair , Avidan Benjamin , Lavee Shimon
Published: February 2019

The performance of five cv. Souri selections designated as “clones” were compared in two consecutive plots for ≈20 years each and three additional ones for 18 years. Fruit morphology, yield, oil production, and tree growth were monitored. The major results are presented as mean values of five sequential “on” years as well as the characteristic production of young and mature trees. The DNA identity was determined using both simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs). The performance of two “clones,” SLO and SBU, showed stable diverse production characteristics and could be designated as defined clones, although no clear differences of the DNA between them or the other “clones” were apparent. Another “clone,” SGS, was also designated as a true clone as a result of both unique fruit morphology and DNA markers. The differences between the other “clones” were minute in fruit production morphology and oil production as well as on a DNA basis and their designation as being true clones is doubtful.
Isolation, Characterization, and Management of Colletotrichum spp. Causing Anthracnose on Lucky Bamboo (Dracaena sanderiana)
Authors: Sharma Kalpana , Merritt Joyce L. , Palmateer Aaron , Goss Erica , Smith Matthew , Schubert Tim , Johnson Robert S. , van Bruggen Ariena H.C.
Published: February 2019

International trade in ornamental plants has increased worldwide. Dracaena is the genus most frequently imported into the United States and many pests and pathogens currently not in the United States could be imported with Dracaena plant materials. In 2009, lucky bamboo (Dracaena sanderiana) with anthracnose symptoms was found in Florida. The associated fungus, putative Colletotrichum dracaenophilum, is considered a reportable pathogen that originated from Asia. Imported D. sanderiana plants with anthracnose symptoms were collected from a nursery in south Florida in 2011 and retail stores in north Florida in 2012 and 2013. Five isolates of Colletotrichum spp. were isolated from symptomatic D. sanderiana plants and Koch’s postulates were fulfilled for the first time. Polymerase chain reaction was performed on the internal transcribed space (ITS) and 28S rDNA regions of three original isolates and re-isolates and these sequences were compared with sequences of Colletotrichum spp. in GenBank. Sequence analysis indicated that the Colletotrichum isolates obtained from D. sanderiana in Florida belonged to C. dracaenophilum or the C. gloeosporioides species complex. Latent infections on healthy-looking lucky bamboo developed anthracnose lesions within 2 to 3 months. The reaction of several Dracaena species and varieties to the two Colletotrichum species was tested. Colletotrichum dracaenophilum caused the most severe disease on lucky bamboo, whereas one isolate of the C. gloeosporioides species complex was least pathogenic to all of the Dracaena spp. and varieties. Hot water treatments were not effective at controlling latent infections, but application of Azoxystrobin at 0.075 g a.i./L significantly reduced anthracnose development on both latently infected and inoculated lucky bamboo plants.
Effects of Substrate Water Content on Morphology and Physiology of Rosemary, Canadian Columbine, and Cheddar Pink
Authors: Zhen Shuyang , Burnett Stephanie E. , Day Michael E. , van Iersel Marc W.
Published: February 2019

Two experiments were conducted to determine how different substrate volumetric water contents (θ equals volume of water per volume of substrate) affected morphology and physiology of three popular perennials using a capacitance sensor-automated irrigation system. In the first study, rosemary (Rosmarinus officinalis) was grown at one of eight θ set points ranging from 0.05 to 0.40 L·L−1. In the second study, Canadian columbine (Aquilegia canadensis ‘Pink Lanterns’) and cheddar pink (Dianthus gratianopolitanus ‘Bath’s Pink’) were grown at one of nine θ set points ranging from 0.05 to 0.45 L·L−1. Total leaf number and area as well as shoot fresh and dry weight of rosemary plants grown at θ of 0.20 L·L−1 or greater were approximately twice that of those grown at lower θ. Canadian columbine height increased as θ increased. Leaf area of cheddar pink grown at θ of 0.35 L·L−1 or higher was twice that of plants grown at the lowest θ. Shoot dry weight of Canadian columbine was not significantly affected by θ. Shoot dry weight of cheddar pink responded quadratically to increasing θ and peaked at θ of 0.35 L·L−1. θ also significantly influenced photosynthetic activities; net photosynthetic rate (AN) and stomatal conductance (gs) of Canadian columbine increased with increasing θ. AN of cheddar pink also increased as θ increased. Greater water volumes were applied to maintain higher θ set points. Irrigation water use efficiency (IWUE = shoot dry weight ÷ total amount of water applied per plant) of Canadian columbine and cheddar pink was not influenced by θ. Growth of all three plants was reduced when grown at lower θ; in the case of cheddar pink and Canadian columbine, this was attributable at least in part to reduced AN.
Water Use of Hydrangea macrophylla and Gardenia jasminoides in Response to a Gradually Drying Substrate
Authors: O’Meara Lucas , Chappell Matthew R. , van Iersel Marc W.
Published: February 2019

As a result of the lack of quantitative data regarding specific water requirements of ornamental species, precision irrigation can be a difficult task for nursery growers. One challenge for growers is that it is not clear how much of the water in soilless substrates is actually available for plant uptake. Substrate moisture release curves (MRC) have been used to predict the amount of plant-available water in soilless substrates, yet there is little information about whether there are differences among species in their ability to extract water from substrates. The objectives of this study were to determine 1) the hydraulic properties of a composted pine bark substrate; and 2) how water uptake in Hydrangea macrophylla and Gardenia jasminoides was affected by decreasing substrate volumetric water content (VWC). As the substrate VWC decreased from 0.38 to 0.17 m3·m−3, substrate matric potential decreased from –4.0 to –69 kPa, whereas hydraulic conductivity decreased from 0.115 to 0.000069 cm·d−1. To measure plant water uptake in a drying substrate, growth chambers were used to provide stable environmental conditions that included continuous lighting to prevent diurnal fluctuations in water use. Water use by H. macrophylla ‘Fasan’ started to decrease at a higher VWC (0.28 m3·m−3) than G. jasminoides ‘Radicans’ (0.20 m3·m−3). Plant water uptake stopped at a VWC of 0.16 m3·m−3 in H. macrophylla and 0.12 m3·m−3 in G. jasminoides. The results show that H. macrophylla is less adept at extracting water from a drying substrate than G. jasminoides. Traditionally, plant-available water in soilless substrates has been studied using substrate MRCs. Our data suggest that substrate hydraulic conductivity may be an important factor controlling water availability to the plants. In addition, there are important differences among species that cannot be detected by only looking at substrate hydraulic properties.
Genetic Diversity and Population Structure of Sardinian Myrtle (Myrtus communis L.) Selections as Obtained by AFLP Markers
Authors: Melito Sara , Fadda Angela , Rapposelli Emma , Mulas Maurizio
Published: February 2019

Myrtle is an aromatic plant typical of the Mediterranean maquis. It is widely exploited in pharmaceutical, cosmetic, and food industries, whereas in Italy, it is mainly used for the production of the typical liqueur. Amplified fragment length polymorphism (AFLP) markers were used to evaluate the genetic variability of some Sardinian Myrtus communis L. candidate cultivars. The AFLP selective amplification produced 138 reproducible AFLP fragments, 96% of which were polymorphic. STRUCTURE analysis divided the myrtle accessions into two main genetic groups (K = 2). The two clusters showed different numbers of individuals. Most of the individuals belonged to Cluster B, whereas only eight genotypes were attributed to Cluster A. Unweighted pair group method with Arithmetic Mean (UPGMA) dendrogram segregated all the myrtle cultivars into five main groups, displaying a partial congruence with the division observed by STRUCTURE analysis. The analysis of the genetic diversity distribution in a candidate cultivar selection displayed a geographical gradient of myrtle from north to south, which reflects the Sardinian shape, and from west to east, which reflects the Sardinian mountain distribution.
Response of 18 Earth-Kind® Rose Cultivars to Salt Stress
Authors: Cai Xiaoya , Sun Youping , Starman Terri , Hall Charles , Niu Genhua
Published: February 2019

Earth-Kind® is a special designation given to select rose cultivars with superior stress tolerance (heat, drought, and pest tolerance) and outstanding landscape performance. The responses of Earth-Kind® roses to high salinity stress are unknown. A greenhouse study was conducted to evaluate 18 Earth-Kind® rose cultivars (Belinda’s Dream, Cecile Brunner, Climbing Pinkie, Ducher, Duchesse de Brabant, Else Poulsen, Georgetown Tea, La Marne, Madame Antoine Mari, Marie Daly, Monsieur Tillier, Mrs. Dudley Cross, Mutabilis, Perle d’Or, Reve d’Or, Sea Foam, Souvenir de St. Anne’s, and Spice) in College Station and 10 of the same 18 cultivars in El Paso in response to two salinity levels at electrical conductivity (EC) of 1.2 (control, nutrient solution) and 10.0 dS·m−1 (EC 10). In both locations, ‘Belinda’s Dream’ and ‘Climbing Pinkie’ in EC 10 had no or little reduction in shoot growth, flower number, and leaf SPAD readings. The net photosynthetic rate (Pn), stomatal conductance (gS), and transpiration (E) did not decrease in these two cultivars at EC 10 in El Paso. In College Station, ‘Mrs. Dudley Cross’, ‘Reve d’Or’, and ‘Sea Foam’ in EC 10 also had no or little reduction in shoot growth, flower number, and leaf SPAD readings. In both locations, ‘Cecile Brunner’ and ‘Else Poulsen’ in EC 10 had severe visual foliar salt damage, and they had the greatest reductions in shoot growth and flower number. In addition to these two cultivars, the lowest relative shoot dry weight (DW) and flower number was observed in ‘Madame Antoine Mari’, ‘Perle d’Or’, ‘Spice’, and ‘Souvenir de St. Anne’s’ in College Station. In summary, ‘Belinda’s Dream’, ‘Climbing Pinkie’, ‘ Mrs. Dudley Cross’, ‘Reve d’Or’, and ‘Sea Foam’ were the most salt-tolerant cultivars, whereas ‘Cecile Brunner’, ‘Else Poulsen’, ‘Madame Antoine Mari’, ‘Perle d’Or’, ‘Spice’, and ‘Souvenir de St. Anne’s’ were the least salt-tolerant among the cultivars investigated.
Comparison of Supplemental Lighting from High-pressure Sodium Lamps and Light-emitting Diodes during Bedding Plant Seedling Production
Authors: Randall Wesley C. , Lopez Roberto G.
Published: February 2019

Annual bedding plant seedlings or plugs are considered high quality when they are compact, fully rooted transplants with a large stem caliper and high root dry mass. Greenhouses in northern latitudes rely on supplemental lighting (SL) from high-pressure sodium lamps (HPS) during winter months to achieve high-quality, finished plugs. Light-emitting diodes (LEDs) offer higher energy efficiencies, a long operating life, and precise waveband specificity that can eliminate wavebands not considered useful. Seedlings of Antirrhinum, Catharanthus, Celosia, Impatiens, Pelargonium, Petunia, Tagetes, Salvia, and Viola were grown at 21 °C under a 16-hour photoperiod of ambient solar light and SL of 100 μmol·m−2·s–1 from either HPS lamps or LED arrays with varying proportions (%) of red:blue light (100:0, 85:15, or 70:30). Height of Catharanthus, Celosia, Impatiens, Petunia, Tagetes, Salvia, and Viola was 31%, 29%, 31%, 55%, 20%, 9%, and 35% shorter, respectively, for seedlings grown under the 85:15 red:blue LEDs compared with those grown under HPS lamps. Additionally, stem caliper of Antirrhinum, Pelargonium, and Tagetes was 16%, 8%, and 13% larger, respectively, for seedlings grown under the 85:15 red:blue LEDs compared with seedlings grown under HPS lamps. The quality index (QI), a quantitative measurement of quality, was similar for Antirrhinum, Catharanthus, Impatiens, Pelargonium, and Tagetes grown under LEDs and HPS lamps. However, it was significantly higher for Petunia, Salvia, and Viola under 85:15, 70:30, and 100:0 red:blue LEDs than under HPS lamps, respectively. These results indicate that seedling quality for the majority of the species tested under SL from LEDs providing both red and blue light was similar or higher than those grown under HPS lamps.
Oxyfluorfen Strongly Affects Larix occidentalis but Minimally Affects Sagina procumbens in a Bareroot Nursery
Authors: Dumroese R. Kasten , Williams Jasmine L. , Pinto Jeremiah R. , Zhang Peng
Published: February 2019

Our objective was to evaluate oxyfluorfen for control of birdseye pearlwort (Sagina procumbens L.) in a bareroot nursery crop of western larch (Larix occidentalis Nutt.) seedlings. Oxyfluorfen applied at rates up to 0.56 kg a.i./ha in a split-plot experiment with combinations and frequencies of pre- and postemergence sprays gave minimal control of birdseye pearlwort. Although preemergence rates 0.42 kg a.i./ha or greater reduced western larch emergence 10% compared with the control, final seedling inventory was similar for rates 0.42 kg a.i./ha or less. Seedlings receiving 0.42 kg a.i./ha or greater grew 30% more biomass than those that received 0.28 kg a.i./ha or less. When applied postemergence, oxyfluorfen reduced the number of larch seedlings at final inventory 9% and those seedlings had 20% less biomass than the control. Oxyfluorfen applied preemergence increased the amount of bare soil (reduced the weed canopy) throughout the production cycle compared with the control but even the most efficacious treatment combinations still had birdseye pearlwort canopy coverage 63% or greater.
Nitrogen and Fungicide Applications for the Management of Fungal Blights of Carrot
Authors: Saude Catarina , McDonald Mary Ruth , Westerveld Sean
Published: February 2019

Alternaria leaf blight (ALB) caused by Alternaria dauci (Kühn) Groves and Skolko and Cercospora leaf spot (CLS) caused by Cercospora carotae (Pass.) Solheim are the major foliar diseases of carrot in Ontario, Canada. In addition to reducing photosynthetic area, the diseases can weaken carrot tops, which can break during mechanical harvesting, reducing harvested yields. Fungicides are commonly used to manage the disease, but there is potential to reduce fungicide applications through nitrogen (N) management. Trials were conducted on mineral soils from 2006 to 2008 to determine the importance of applied N and fungicide applications to control fungal leaf blights of carrot. Three rates of N (0, 110, and 220 kg·ha−1) and 0, 3, or 5 (2006 and 2007) or 6 (2008) fungicide applications were applied. Leaf blight severity was assessed biweekly throughout the season and at harvest. The severity of both ALB and CLS and combined disease severity index at harvest decreased with increasing N and fungicide application. In some cases, disease severity of carrots treated with high N and no fungicides was equivalent to carrots treated with no N and five fungicide sprays. Total and marketable yield increased with increasing number of fungicide sprays in 2006 and 2007, but N application did not affect yield. Results suggest that severity of ALB and CLS can be minimized through a combination of N and fungicide applications, but rates of N higher than 110 kg·ha−1 may reduce marketable yield through a decrease in stand and an increase in oversized roots.
Rain Garden Filter Bed Substrates Affect Stormwater Nutrient Remediation
Authors: Turk Rebecca L. , Kraus Helen T. , Bilderback Ted E. , Hunt William F. , Fonteno William C.
Published: February 2019

Twelve rain gardens were constructed to analyze the effectiveness of three different filter bed substrates to support plant growth and remove nutrients from urban stormwater runoff. The filter bed substrates included a sand-based substrate (sand) composed of (v/v/v) of 80% washed sand, 15% clay and silt fines, and 5% pine bark; a soil-based substrate (soil) composed of (v/v) 50% sandy loam soil and 50% pine bark; and a slate-based substrate (slate) composed of (v/v) 80% expanded slate and 20% pine bark. Coarse particles (6.3 to 2.0 mm) in the soil-based substrate created a large-pore network that conducted stormwater more quickly into and through the rain garden than slate or sand as evidenced by the high infiltration and saturated hydraulic conductivity values. Sand had good overall retention of pollutants except nitrogen (N) possibly as a result of the very small percentage (5%) of organic matter and low cation exchange capacity (CEC). Soil had the lowest remediation of phosphorus (P) and highest concentration of P in its effluent and was similar in N removal efficiency to slate. Slate had the best retention of N and P. Overall, all three substrates functioned in reducing the quantity of pollutants in urban stormwater runoff; yet, the impact of substrate on remediation appeared to lessen by Season 2 because there were few differences between substrate in the effluent nutrient concentration. Substrate did not affect shoot or root growth. Eleven of the 16 species (B. nigra, B. ‘Duraheat’, M. virginiana, M. ‘Sweet Thing’, I. virginica, I. ‘Henry’s Garnet’, J. effusus, P. ‘Shenandoah’, H. angustifolius, H. ‘First Light’, and E. purpureum subsp. maculatum) grew well in the rain gardens and could be used as rain garden plants.
Carotenoid and Tocopherol Composition of an Orange-colored Carrot as Affected by Water Supply
Authors: Ombódi Attila , Daood Hussein Gehad , Helyes Lajos
Published: February 2019

Carotenoids and tocopherols are important phytonutrients of orange-colored carrots. The main goal of this work was to investigate the effects of irrigation on the content and composition of carotenoids and tocopherols in an orange-colored carrot cultivar (Bangor) compared with a rain-fed control. The experiment was conducted for 2 years with a considerably different amount of precipitation during the growing season (576 mm in 2010 and 190 mm in 2011). Six carotenoids and four tocopherols were detected and quantitatively determined. Significant negative correlations were found between water supply and content of total carotenoids and total tocopherols. Irrigation significantly decreased the concentrations of these phytonutrients during the arid year of 2011. Water supply did not affect the carotenoid and the tocopherol composition, which can be an important factor for functional food manufacturers. A significant positive correlation was found between total carotenoid and total tocopherol concentrations, which is very favorable from a nutritional point of view.
Starch Content of Citrus Leaves Permits Diagnosis of Huanglongbing in the Warm Season but Not Cool Season
Authors: Whitaker Douglas C. , Giurcanu Mihai C. , Young Linda J. , Gonzalez Pedro , Etxeberria Ed , Roberts Pamela , Hendricks Katherine , Roman Felix
Published: February 2019

One of the most prominent characteristics of huanglongbing (HLB or citrus greening)-affected citrus trees is the abundant starch accumulation in photosynthetic cells and all other remaining parenchyma cells of aerial parts. Under natural conditions, citrus leaves store very low levels of starch and detectable amounts are only seen as a result of zinc deficiency or accidental girdling of branches. Therefore, leaf starch concentrations over a threshold level should indicate the presence of HLB. In this report, we detailed a comprehensive statistical analysis of starch levels in citrus leaves and compared them with real-time polymerase chain reaction (PCR) detection of the presumptive causal agent Candidatus Liberibacter asiaticus. Starch content was found to reliably predict the PCR results (the proxy for HLB presence) during the “warm season” (June through November) but not in the “cool season” (December through May). During the cool season, starch levels for HLB-positive trees tend to be lower, and 43% of samples were incorrectly classified using Linear Discriminant Analysis (LDA). In contrast, during the warm season, only 8% were misclassified. Furthermore, assuming PCR possibly has error, the total probability of misclassification for HLB status could be controlled using an “uncertain” classification. The temporal pattern of leaf starch is consistent with our understanding of seasonal changes in plant development and bacterial titer.
Antitranspirational Efficacy and Longevity of Abscisic Acid and a Synthetic Abscisic Acid Analog in Pansies (Viola ×wittrockiana)
Authors: Weaver Geoffrey M. , van Iersel Marc W.
Published: February 2019

Physiological antitranspirants can reduce financial risks to growers by temporarily preventing drought stress, improving product quality, and extending the shelf life of ornamental bedding plants. Exogenous abscisic acid (ABA) is an effective antitranspirant that induces stomatal closure in a rate-dependent manner, reducing transpirational water loss in many species. However, it may also cause chlorosis, which reduces product quality. Synthetic ABA analogs have similar effects on stomatal conductance (gS) but are not known to induce chlorosis. We studied the effects of ABA and its analog 8′ acetylene ABA methyl-ester (PBI 429) on gS and net photosynthesis (Pn) in pansies (Viola ×wittrockiana), compared the efficacy and longevity of each compound, and quantified the resulting chlorosis. Plants were treated with spray solutions of ABA (0 to 2000 mg·L−1) and PBI 429 (0 to 200 mg·L−1) and irrigated daily. Gas exchange and leaf chlorophyll measurements were made twice weekly for 2 weeks. Additional measurements were taken once or twice weekly through 47 days. Abscisic acid reduced leaf chlorophyll content and Pn in a rate-dependent manner for 14 days after application but reduced gS for only 11 days, whereas PBI 429 reduced Pn and gS similarly for 7 days and did not reduce leaf chlorophyll content. Reductions in gS and Pn were greatest on the first day after treatment for both compounds. Our results demonstrate that ABA is more effective than PBI 429 at 100 and 200 mg·L−1, but also causes chlorosis, whereas PBI 429 is an effective antitranspirant without this phytotoxic effect.