bluuebunny/crossref_metadata_2025 huggingface dataset:
Substrates, Wounding, and Growth Regulator Concentrations Alter Adventitious Rooting of Baldcypress Cuttings
Authors: King Andrew R. , Arnold Michael A. , Welsh Douglas F. , Watson W. Todd
Published: February 2019

In previous studies, baldcypress [Taxodium distichum (L.) Rich.] clones were selected for tolerance to high pH soils, drought and salt exposures, and ornamental characteristics. The objective of the current research was to determine the treatment combinations that yielded optimum root quantity (percentage) and rooted cutting quality (root number, length, dry mass, and shoot dry mass) on vegetative cuttings for a representative clone. Cuttings were treated with factorial combinations of one of four potassium salt of indole-3-butyric acid (K-IBA) concentrations [0, 5,000, 10,000, 15,000 mg·L−1 (0, 20.72, 41.44, 62.16 mm, respectively)], wounded or not wounded (1-cm long basal incision), and rooted in one of three substrates (100% perlite, 100% peatmoss, or 50% perlite:50% peatmoss). Data indicated a tradeoff between potential rooting quantity and root quality measurements in response to different substrates. Although rooting percentages were affected by substrates only at P ≤ 0.10 (53% in 100% perlite versus 36% in 100% peatmoss), there were highly significant (P ≤ 0.0001) differences in rooted cutting potential among substrates as measured by the percentage of cuttings with basal callus. Cuttings placed in 100% perlite callused at 85%, whereas cuttings placed in 100% peatmoss callused at ≈53%. The 100% peatmoss treatment, however, yielded cuttings with significantly greater root quality for all measurements, except root number per cutting. Wounding cuttings proved to have deleterious effects on root quality measurements. Total root length was ≈14.5 cm for non-wounded cuttings and ≈10.8 cm for wounded cuttings. Increasing K-IBA concentrations did not significantly (P ≤ 0.05) affect rooting or callus percentages but did significantly affect root dry mass, total root length, and average root length per cutting. Total root length increased from 10.8 cm at 0 mg·L−1 K-IBA to 16 cm at 15,000 mg·L−1 K-IBA. Mean root number per cutting increased from ≈1.6 with wounded cuttings planted in 100% peatmoss to ≈3.1 with non-wounded cuttings planted in 100% perlite. Results suggested that high-quality softwood baldcypress cuttings should not be wounded, should be treated with 15,000 mg·L−1 K-IBA, and grown in a substrate with intermediate water-holding capacity to achieve an acceptable balance between rooting percentage and rooted cutting quality objectives.
Response of ‘Captiva’ St. Augustinegrass to Shade and Potassium
Authors: Cai Xiaoya , Trenholm Laurie E. , Kruse Jason , Sartain Jerry B.
Published: February 2019

The effects of potassium (K) on stress tolerance of turfgrass have been documented for some environmental stresses but not for shade tolerance. ‘Captiva’ st. augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] was evaluated in this research project to determine the effects of K and shade on turf performance. The study was conducted at the University of Florida Envirotron Turfgrass Research Laboratory in Gainesville, FL. Grasses were planted in 15.2-cm plastic pots in a climate-controlled glass house. Two consecutive studies were conducted, the first from 20 May to 24 Oct. 2009 and the second from 18 Jan. to 20 June 2010. Grasses were placed in either full sun or under shade structures covered with woven black shadecloth to provide 30%, 50%, or 70% shade. Potassium was applied as potassium chloride (KCl) (0–0–62) at four rates (0, 0.6, 1.2, or 2.4 g·m−2) every 30 days. In both trials, turf visual quality and color scores and dry weight (DW) of shoot and root were lowest at 70% shade and highest at 30% shade. Turf visual quality score increased as K rate increased. Leaf length increased and leaf width decreased as shade level increased. Leaf tissue total Kjedahl nitrogen (TKN) and K concentration increased as shade level increased from 0% to 70%. Thatch DW was greatest at 70% shade and lowest at 30% shade. In the first trial, turf treated with a higher K rate had longer leaf length and greater root DW. Results from this study showed that ‘Captiva’ could maintain acceptable visual quality at up to 50% shade and that K at 2.4 g·m−2 may help turfgrass grow in a shaded environment by improving turf visual quality score, root growth, and leaf tissue K concentration. Additional field plot research should be conducted to verify these responses.
Integration of Georeferencing, Habitat, Sampling, and Genetic Data for Documentation of Wild Plant Genetic Resources
Authors: Volk Gayle M. , Richards Christopher M.
Published: February 2019

Plant genetic resource collections provide novel materials to the breeding and research communities. Crop wild relatives may harbor completely novel forms of allelic variation for biotic and abiotic resistance as well as masked genes for improved quality and production. This variation has been shaped by the environment from which the plant materials were collected. With detailed original source information, genetic assessments of germplasm collections can go beyond the basic measurements of collection diversity and breeding for simple traits to assessments of natural variation in environmental contexts. Availability of detailed documentation of passport, phenotypic, and genetic data increases the value of all genebank accessions. Inclusion of georeferenced sources, habitats, and sampling data in collection databases facilitates interpretation of genetic data for genebank accessions with wild origins.
Cold Temperature Tolerance of Trunk and Root Tissues in One- or Two-year-old Apple Rootstocks
Authors: Moran Renae E. , Sun Youping , Geng Fang , Zhang Donglin , Fazio Gennaro
Published: February 2019

Winter injury to the root systems of fruit trees can cause significant tree losses and yield reductions in the northern regions of the United States and Canada. To compare the root and trunk cold temperature tolerance, a series of experiments were conducted using ungrafted apple rootstocks. ‘Geneva® 11’ (G.11), ‘Geneva® 30’ (G.30), ‘Geneva® 41’ (G.41), ‘P.2’, and ‘Budagovsky 9’ (B.9) apple (Malus ×domestica Borkh.) rootstocks had root tissue hardiness similar to ‘M.26’, but ‘Geneva® 935’ (G.935) had greater cold-hardiness than M.26 when based on shoot regrowth in ungrafted trees. The LT50 of M.26 and P.2 roots ranged from –12 to –14 °C. The LT50 was –13 °C for B.9, –13.4 to –14.6 °C for G.30, and –12 °C for G.11. The LT50 of G.41 was one of the highest in one experiment, –8 °C, and one of the lowest in another, colder than –15.0 °C. The LT50 of G.935 roots was the lowest and ranged from –16 to –19 °C. Compared with M.26, trunk cold-hardiness in December was greater in B.9 and P.2 and was similar in G.30. Cold-hardiness of G.11 in December was mixed with less injury in the xylem but more injury in the phloem compared with M.26. In October, M.26 and G.935 trunks had little injury after exposure to –24 °C.
Pollination of ‘Hortblue Petite’ Blueberry: Evidence of Metaxenia in a New Ornamental Home-garden Cultivar
Authors: Miller Shirley , Alspach Peter , Scalzo Jessica , Meekings John
Published: February 2019

‘Hortblue Petite’ (Vaccinium corymbosum L.) is a compact, small-statured tetraploid blueberry that was introduced to the New Zealand retail sector as a garden ornamental in 2005. Pollination requirements for ‘Hortblue Petite’ have not previously been investigated and this study was undertaken to better understand compatibility with other blueberry cultivars. Pollen donor effects on fruit weight were significant; pollen from large fruiting cultivars produced bigger fruit in ‘Hortblue Petite’, adding support toward metaxenia occurring in blueberry. Outcrossing with other tetraploids was most successful in terms of fruit set, berry weight, and yield potential. Number of viable seeds per berry was less with self-pollination and with crosses using pollen from a hexaploid rabbiteye type. The data indicated that the best yields would be obtained from using either open-pollinated flowers or a large-fruited cultivar such as ‘Nui’.
Peach Blossom String Thinner Performance Improved with Selective Pruning
Authors: Schupp James R. , Baugher T. Auxt
Published: February 2019

Hand-thinning of fruit is among the most labor-intensive orchard practices and consequently contributes significantly to peach (Prunus persica) production costs. Prior research conducted by the authors on string blossom thinners for managing peach tree cropload demonstrated that this new technology reduces labor requirement and also improves fruit size. Studies were conducted over two seasons in peach orchards trained to perpendicular V or open-center systems to evaluate possible pruning strategies to improve tree canopy access by string thinners. The objectives were to demonstrate if modifications in fruiting shoot orientation, pruning detail, and/or scaffold accessibility improved flower removal, reduced follow-up hand-thinning requirement, and/or increased fruit size. Blossom removal was improved by either detailed pruning or partial pruning (elimination of all shoots on the side of a limb inaccessible by the thinner spindle) in both training systems. Flower density and fruit set measurements revealed greater differences among pruning treatments compared with hand-thinned control treatments with both fruiting shoot orientation pruning modifications and detail pruning resulting in improved thinning. Thinning efficacy was unaffected by scaffold angle but increased as canopy accessibility ranking increased. Follow-up hand-thinning time was reduced by all treatment, system/cultivar, and year combinations except standard pruning in an open center-trained 2009 trial. Detail pruning consistently improved fruit size compared with hand-thinned control and other pruning treatments in both perpendicular V- and open center-trained orchard plots. The best treatments resulted in a thinning savings of $120/ha to $282/ha in perpendicular V plantings and $26/ha to $46/ha in open-center plantings. Realized economic savings beyond hand-thinning alone ranged from $473/ha to $2875/ha in perpendicular V trials and $28/ha to $293/ha in open-center trials.
In Vitro Culture of Immature Zygotic Mango Embryos and Plantlet Development
Authors: Pérez-Hernández Juan Bernardo , Grajal-Martín María José
Published: February 2019

In vitro culture of immature embryos may assist mango breeding in the production of hybrid plant material. However, zygotic embryo culture techniques have not been successfully developed for mango. To recover in vitro zygotic plants through embryo culture, ‘Lippens’ and ‘Keitt’ were used as a source of model immature embryos. Excised embryos were incubated in a liquid maturation medium to test different culture systems and media composition. Subsequent germination allowed for the recovery of complete in vitro plantlets. Variables included during artificial embryo maturation, independently or through paired interactions, significantly affected all the parameters measured for embryo development and characterization of the plantlets. Main effects of culture system (i.e., static versus agitation) and coconut water supply (20%) were responsible for up to 85.5% of total treatment variation. Direct and inverse interactions observed between culture system and either coconut water supplement or sucrose content (45 or 60 g·L−1) contributed to define the best combination of factors to improve embryo growth and plant formation. Complete plantlets could be obtained at a frequency above 83% for both cultivars at the end of the in vitro phase at a developmental stage that allowed acclimatization to greenhouse conditions.
Environmental Variance Components of Fruit Ripening Date as Used in Both Phenotypic and Marker-assisted Selection in Japanese Pear Breeding
Authors: Nishio Sogo , Yamada Masahiko , Sawamura Yutaka , Takada Norio , Saito Toshihiro
Published: February 2019

The effectiveness of detected quantitative trait loci (QTLs) and molecular markers associated with them in tree fruit breeding is measured by the percentages of the variance associated with detected QTL effects accounting for not phenotypic variance, but genetic variance of the trait. The genetic variance can be obtained by subtracting environmental variance from the phenotypic variance. Once accurate environmental variance components are obtained for a given selection field, environmental variances under any number of replications and measurement repetitions can be estimated. We estimated environmental variance components of fruit ripening date measured by days in a Japanese pear (Pyrus pyrifolia Nakai) breeding field in the National Institute of Fruit Tree Science, Tsukuba, Ibaraki, Japan. We estimated variance among fruits within a tree (σf2) as 25.6, among trees within a genotype (σt2) as 0.2, among years (σy2) as 9.4, associated with genotype × year interaction (σgy2) as 7.9, and associated with tree × year interaction (σty2) as 1.2. Because σf2 was the largest environmental variance component, increasing the number of fruit evaluated would most effectively reduce the environmental variance, and tree replication would not because of very small σt2 and σty2. The 95% confidence limit of a genotypic value was ± 10 days in the evaluation of five fruits on a single tree in a year and ± 7 days over 2 years. Broad-sense heritability in a family, each offspring in which was evaluated using five fruits on a single tree in a single year, was estimated at 0.83 for three full-sib families analyzed.
Host Plant Resistance to Tomato spotted wilt virus (Bunyaviridae: Tospovirus) in Tomato
Authors: Riley David G. , Joseph Shimat V. , Kelley W. Terry , Olson Steve , Scott John
Published: February 2019

Commercially available cultivars of tomato Solanum lycopersicum L. were field-tested for resistance to Tomato spotted wilt virus (TSWV) over a 5-year period (from 2006 to 2010) at the Coastal Plain Experiment Station at Tifton, GA. Selected cultivars were transplanted each year into staked, black plastic mulch beds on drip irrigation in the spring of each year when the incidence of Tomato spotted wilt (TSW) tended to be highest. The presence of TSWV was confirmed by double antibody sandwich (DAS) enzyme-linked immunosorbent assay (ELISA). Also, the presence of thrips vectors was monitored using beat-cup sampling of foliage and flower samples. Tomato cultivars with the Sw-5 resistance gene provided high levels of control of TSW expression over all 5 years. However, these genotypes had no apparent effect on the thrips vectors, western flower thrips, Frankliniella occidentalis (Pergande), and tobacco thrips, Frankliniella fusca (Hinds), that transmit TSWV. Overall, the top 15 commercial tomato cultivars based on consistent TSW resistance and ranked from highest marketable fruit yield were: ‘Tycoon’, ‘Tous 91’, ‘Talladega’, ‘Red Defender’, ‘BHN 444’, ‘Nico’, ‘Carson’, ‘BHN 685 (Roma type)’, ‘Picus’, ‘Redline’, ‘Tribute’, ‘Quincy’, ‘BHN 640’, ‘BHN 602’, and ‘Top Gun’.
Concentrated Exogenous Abscisic Acid Drenches Reduce Root Hydraulic Conductance and Cause Wilting in Tomato
Authors: Astacio Manuel G. , van Iersel Marc W.
Published: February 2019

Previous work has shown that exogenous abscisic acid (ABA) applications can reduce transpiration, delay wilting, and thereby extend the shelf life of unwatered plants. Paradoxically, we have seen that drenches with concentrated ABA solutions may actually induce wilting. These wilting symptoms occur despite the presence of ample water in the substrate, suggesting that ABA may interfere with the ability of roots to take up water. Our objective was to develop a better understanding of this wilting effect using tomato (Solanum lycopersicum) as a model. In the first study, ABA drenches (125–2000 mg·L−1) reduced transpiration and water use compared with the control plants, yet the relative water content (RWC) of the leaves of ABA-treated plants was lower than that of control plants at 24 h after the ABA drench. Control plants had a leaf RWC of 97%, whereas plants treated ABA had a RWC of 57% to 62%. ABA concentrations of 500 mg·L−1 or higher caused the plants to wilt within 24 h despite the presence of ample water in the substrate. Leaf ABA concentrations 24 h after the ABA application ranged from 2.6 (control) to 62.6 nmol·g−1 fresh weight (FW) in the 2000-mg·L−1 ABA treatment, indicating effective transport of ABA from the roots to the leaves. The reduced leaf RWC suggests that ABA drenches are limiting water transport through the roots to the leaves. The effects of ABA on the hydraulic conductance of the roots and stems of tomatoes were quantified to determine if ABA drenches limit water transport through the roots. The cumulative volume of water conducted by the root systems during a 4-day period ranged from 36.7 mL in the control treatments to 8.1 mL in roots systems drenched with 1000 mg·L−1 ABA, a reduction of 78%. When the conductance study was repeated using decapitated roots and excised stems, root water flux was again reduced by ABA, but water flux through internodal stem sections did not show an ABA effect. Results suggest that ABA-induced wilting is caused by a reduction in root conductance and we hypothesize that ABA affects aquaporins in the roots, limiting water uptake.
Stimulation of Short-term Plant Growth by Glycerol Applied as Foliar Sprays and Drenches under Greenhouse Conditions
Authors: Tisserat Brent , Stuff Amy
Published: February 2019

The effects of aqueous solutions applied as foliar spray and drench applications of glycerol were tested on the ‘Chantenay’ carrot (Daucus carota L.) family Apiaceae, corn (Zea mays L.) family Poaceae, and spearmint (Mentha spicata L.) family Lamiaceae under greenhouse conditions. Foliar sprays and drenches were administered to carrots at concentrations of 0, 1, 3, 5, 10, 25, or 50 ml·L−1. Fresh weights, dry weights, and taproot diameter from carrot seedlings sprayed with a solution containing 5 mL·L−1 (50 mm) glycerol increased 105.6%, 158.4%, and 53.8%, respectively, when compared with untreated carrots. Foliar sprays were administered to corn at concentrations of 0, 0.1, 0.3, 0.5, and 1 ml·L−1 and spearmint at concentrations of 0, 1, 5, and 10 mL·L−1. Growth responses increased in corn and spearmint by using certain glycerol concentrations. Fresh weights, dry weights, and shoot length from corn seedlings sprayed with a solution containing 0.5 mL·L−1 (5 mm) glycerol increased 83.5%, 154.6%, and 90.9%, respectively, when compared with untreated corn. Fresh weights, dry weights, and shoot length from mint plants sprayed with a solution containing 5 mL·L−1 (50 mm) glycerol increased 46.6%, 68.7%, and 102.5%, respectively, when compared with untreated plants. Glycerol applications can stimulate growth responses in diverse plant species.
A Simple and Efficient Protocol for Plant Regeneration and Genetic Transformation of Tomato cv. Micro-Tom from Leaf Explants
Authors: Cruz-Mendívil Abraham , Rivera-López Javier , Germán-Báez Lourdes J. , López-Meyer Melina , Hernández-Verdugo Sergio , López-Valenzuela José A. , Reyes-Moreno Cuauhtémoc , Valdez-Ortiz Angel
Published: February 2019

A simplified protocol to obtain transgenic tomato plants was established. The effects of culture media composition and Agrobacterium concentration were evaluated. The highest shoot-forming capacity index (5.6) was observed when leaf explants were cultured for 6 weeks with 2 mg·L−1 zeatin, 0.1 mg·L−1 indoleacetic acid, and 300 mg·L−1 timentin. Shoot elongation and root formation were performed in one step on growth regulator-free media. The highest percentage (82%) of fully developed plantlets was obtained when shoots were cultured for 4 weeks with 0.5× Murashige and Skoog (MS) media and 15 g·L−1 sucrose. A 100% of plant survival rate was observed after 4 weeks of being transplanted to ex vitro conditions followed by fruit production (15 fruits/plant) after 2 more weeks. Transient expression of β-glucuronidase was visualized in 100% of the leaf explants infected with Agrobacterium at an OD600 = 0.5 and cocultured for 48 h with 2 mg·L−1 benzylaminopurine, 0.1 mg·L−1 naphthaleneacetic acid, and 100 μM acetosyringone. Stable transformation was confirmed by histochemical glucuronidase assay and polymerase chain reaction (PCR) analysis with a total efficiency of 19.1%. The complete protocol, from shoot induction to fruit production of soil-adapted transgenic plants can be accomplished in only 4 months, and it seems to be very useful for both micropropagation and genetic transformation purposes.
Effects of Auxin and Cytokinin on In Vivo Adventitious Shoot Regeneration from Decapitated Tomato Plants
Authors: Tezuka Takahiro , Harada Masashi , Johkan Masahumi , Yamasaki Satoshi , Tanaka Hideyuki , Oda Masayuki
Published: February 2019

Adventitious shoots can be regenerated from the cut surface of the primary shoot and lateral branches in decapitated plants in vivo. This inherent regenerative ability of plants is useful for mass propagation. In the present study, we conducted histological observations of shoot regeneration and applied auxin and cytokinin to decapitated seedlings in four tomato cultivars. The cultivars produced different numbers of adventitious shoots after decapitation; ‘Petit’ produced the largest number of adventitious shoots (78.5 ± 10.2) and ‘Momotaro’ produced the fewest (12.1 ± 3.3). Histological observation of ‘Petit’ revealed that adventitious shoots regenerated from calli formed at the cut surface of stems. Adventitious shoot formation was inhibited by the presence of lateral branches. Shoot regeneration was prevented by application of 1-naphthaleneacetic acid to ‘Petit’. Application of 6-benzyladenine promoted shoot regeneration in ‘Momotaro’. These results suggest auxin synthesized de novo from the lateral branches inhibited shoot regeneration after decapitation and endogenous cytokinin might stimulate shoot regeneration. Chemical names: 1-naphthaleneacetic acid (NAA); 6-benzyladenine (BA)
Soil Carbon Pools, Nitrogen Supply, and Tree Performance under Several Groundcovers and Compost Rates in a Newly Planted Apple Orchard
Authors: TerAvest Dan , Smith Jeffrey L. , Carpenter-Boggs Lynne , Granatstein David , Hoagland Lori , Reganold John P.
Published: February 2019

This study evaluated the effects of in-row groundcovers (bare ground, brassica seed meal, cultivation, wood chip mulch, legume cover crop, and non-legume cover crop) and three compost rates (48, 101, and 152 kg available nitrogen (N)/ha/year) on soil carbon (C) pools, biological activity, N supply, fruit yield, and tree growth in a newly planted apple (Malus domestica Borkh.) orchard. We used nonlinear regression analysis of C mineralization curves to differentiate C into active and slow soil C pools. Bare ground and cultivation had large active soil C pools, 1.07 and 0.89 g C/kg soil, respectively, but showed little stabilization of C into the slow soil C pool. The use of brassica seed meal resulted in increased soil N supply, the slow soil C pool, and earthworm activity but not total soil C and N, fruit yield, or tree growth. Legume and non-legume cover crops had increased microbial biomass and the slow soil C pool but had lower fruit yield and tree growth than all other groundcovers regardless of compost rate. Soils under wood chip mulch had elevated earthworm activity, total soil C and N, and the slow soil C pool. Wood chip mulch also had the greatest cumulative C mineralization and a high C:N ratio, which resulted in slight N immobilization. Nevertheless, trees in the two wood chip treatments ranked in the top four of the 13 treatments in both fruit yield and tree growth. Wood chip mulch offered the best balance of tree performance and soil quality of all treatments.
Water and Agriculture in a Changing Climate
Authors: O'Neill Michael P. , Dobrowolski James P.
Published: February 2019

Agriculture, in its broadest form, is the greatest consumptive user of water resources in the United States and around the world. Perhaps the greatest challenge facing agricultural producers will be adapting water management to an increasingly variable climate. Adaptation will be extremely difficult, in part because other demands for water (e.g., energy, domestic, industrial, municipal) will continue to increase. Despite considerable improvements in irrigation technology, product development, and other water-saving approaches, agricultural producers will be expected to reduce water consumption and improve or protect water quality of water discharged from agricultural operations. In 2004, the National Institute of Food and Agriculture embarked on an effort to address Agricultural Water Security, ensuring sufficient water of the appropriate quality at the needed time to meet demands for food, fiber, and other agricultural goods and services. This effort identified six broad areas where agricultural research, education, and extension can impact water management to achieve agricultural water security. The six areas are: biotechnology, water reuse, general conservation, irrigation efficiency, water markets and trading, and drought preparedness. We present an overview of the six areas and opportunities for agriculture—and specifically horticultural and specialty crop producers—to adapt to climate change through improved water management.
Soil Water Tension, a Powerful Measurement for Productivity and Stewardship
Authors: Shock Clinton C. , Wang Feng-Xin
Published: February 2019

A fundamental way to schedule irrigation is through the monitoring and management of soil water tension (SWT). Soil water tension is the force necessary for plant roots to extract water from the soil. With the invention of tensiometers, SWT measurements have been used to schedule irrigation. There are different types of field instruments used to measure SWT, either directly or indirectly. Precise irrigation scheduling by SWT criteria is a powerful method to optimize plant performance. Specific SWT criteria for irrigation scheduling have been developed to optimize the production and quality of vegetable crops, field crops, trees, shrubs, and nursery crops. This review discusses known SWT criteria for irrigation scheduling that vary from 2 to 800 kPa depending on the crop species, plant product to be optimized, environmental conditions, and irrigation system. By using the ideal SWT and adjusting irrigation duration and amount, it is possible to simultaneously achieve high productivity and meet environmental stewardship goals for water use and reduced leaching.
Genetic Relationships among Native Species and Hybrid Cultivars of Asian Dendrobium (Orchidaceae) Using Amplified Fragment Length Polymorphism Markers
Authors: Zhu Gen-Fa , Li Dong-Mei
Published: February 2019

This study addresses the phylogenetic relationships among native species and hybrid cultivars of Asian Dendrobium by amplified fragment length polymorphism (AFLP). The plant materials of this study are composed of 37 accessions belonging to native species in China and 63 accessions proposed to be hybrid cultivars originating from Japan and Korea. Eight AFLP primer combinations produced a total of 1658 fragments with an average of 207 fragments per primer pair, of which 1655 bands were polymorphic. Specific AFLP markers were identified in 29 of 100 tested Dendrobium accessions. Unweighted pair group method based on arithmetic average (UPGMA) analysis was performed on Dice's similarity coefficient matrix and also average similarity of each species and cultivar. The tested 100 Asian Dendrobium accessions were grouped into seven clusters with the similarity coefficient of 0.49. A first cluster consisted of 63 hybrid cultivars, 17 species of section Dendrobium, one species of section Formosae, and one species of section Callista. A second, fourth, and seventh cluster included five, three, and two species of section Dendrobium, respectively. A third group comprised five species of section Formosae. A fifth and sixth cluster contained three and two species of section Callista, respectively. These results indicated that the genetic relationships among tested Asian Dendrobium accessions were related to their origins, morphological classification, flower color, and pedigree, to some extent.
Regulation of Chloroplast Ultrastructure, Cross-section Anatomy of Leaves, and Morphology of Stomata of Cherry Tomato by Different Light Irradiations of Light-emitting Diodes
Authors: XiaoYing Liu , ShiRong Guo , ZhiGang Xu , XueLei Jiao , Tezuka Takafumi
Published: February 2019

The chloroplast structural alteration and the photosynthetic apparatus activity of cherry tomato seedlings were investigated under dysprosium lamp [white light control (C)] and six light-emitting diode (LED) light treatments designated as red (R), blue (B), orange (O), green (G), red and blue (RB), and red, blue, and green (RBG) with the same photosynthetic photon flux density (PPFD) (≈320 μmol·m−2·s−1) for 30 days. Compared with C treatment, net photosynthesis of cherry tomato leaves was increased significantly under the light treatments of B, RB, and RBG and reduced under R, O, and G. Chloroplasts of the leaves under the RB treatment were rich in grana and starch granules. Moreover, chloroplasts in leaves under RB seemed to be a distinct boundary between granathylakoid and stromathylakoid. Granathylakoid under treatment B developed normally, but the chloroplasts had few starch granules. Chloroplasts under RBG were similar to those under C. Chloroplasts under R and G were relatively rich in starch granules. However, the distinction between granathylakoid and stromathylakoid under R and G was obscure. Chloroplasts under O were dysplastic. Palisade tissue cells in leaves under RB were especially well-developed and spongy tissue cells under the same treatment were localized in an orderly fashion. However, palisade and spongy tissue cells in leaves under R, O, and G were dysplastic. Stomatal numbers per mm2 were significantly increased under B, RB, and RBG. The current results suggested blue light seemed to be an essential factor for the growth of cherry tomato plants.
The Importance of Determining Carbon Sequestration and Greenhouse Gas Mitigation Potential in Ornamental Horticulture
Authors: Marble S. Christopher , Prior Stephen A. , Runion G. Brett , Torbert H. Allen , Gilliam Charles H. , Fain Glenn B.
Published: February 2019

Over the past three decades, one issue that has received significant attention from the scientific community is climate change and the possible impacts on the global environment. Increased atmospheric carbon dioxide (CO2) concentration along with other trace gases [i.e., methane (CH4) and nitrous oxide (N2O)] are widely believed to be the driving factors behind global warming. Much of the work on reducing greenhouse gas emissions and carbon (C) sequestration has been conducted in row crop and forest systems; however, virtually no work has focused on contributions from sectors of the specialty crop industry such as ornamental horticulture. Ornamental horticulture is an industry that impacts rural, suburban, and urban landscapes. Although this industry may have some negative impacts on the global environment (e.g., CO2 and trace gas efflux), it also has potential to reduce greenhouse gas emissions and increase C sequestration. The work described here outlines the causes and environmental impacts of climate change, the role of agriculture in reducing emissions and sequestering C, and potential areas in ornamental horticulture container-grown plant production in which practices could be altered to increase C sequestration and mitigate greenhouse gas emissions.
In Vitro Shoot Regeneration of Georgia Plume, Elliottia racemosa, from Multiple Genotypes Collected from Wild Populations
Authors: Radcliffe Carrie A. , Affolter James M. , Wetzstein Hazel Y.
Published: February 2019

Georgia plume (Elliottia racemosa, Ericaceae) is a threatened, woody plant endemic to Georgia's Coastal Plain region in the southeastern United States. Populations of the plant have a fragmented distribution within a restricted range and are characterized by low genetic diversity and a lack of sexual recruitment. Georgia plume cannot be effectively propagated using conventional methods. We have developed an in vitro shoot regeneration system that is effective with explants obtained from mature plants in the wild. The objective of this study was to determine the efficacy of using this in vitro protocol to regenerate proliferating shoot cultures from 34 georgia plume genotypes obtained from divergent populations. Young expanding leaves were cultured on Gamborg's media supplemented with 10 μM thidiazuron and 5 μM indole-3-acetic acid. After 8 weeks, tissues were transferred to a shoot elongation medium with 25 μM 2-isopentenyl adenine. Of the 34 genotypes tested, 91% formed shoot primordia and 85% regenerated shoots within 6 months of inoculation. This study verifies that tissue culture can be used to produce adventitious shoots from a wide range of georgia plume genotypes. Within a coordinated conservation program, tissue culture is a feasible system to use for safeguarding and reintroduction of genetically diverse plant material, which may be critical to the survival of this rare species.
Improvements in Hazelnuts in the United States
Authors: Olsen Jeff
Published: February 2019

In the mid-1980s, eastern filbert blight (EFB) fungus, Anisogramma anomala (Peck) E. Müller, was discovered in Oregon's main hazelnut-producing region and now is present throughout the hazelnut-producing area. Oregon State University's (OSU) Hazelnut Breeding Program responded by developing EFB-resistant cultivars, the first of which was released in 2005. The breeding program has also selected for other beneficial traits such as uniform early nut maturation, larger kernel size, and improved kernel quality. A 2008 OSU economic study on the costs of establishing and producing hazelnuts showed that the EFB-resistant cultivars enhanced economic viability of orchards, increasing cumulative cash flow during the 12-year establishment period by $12,243 per hectare. Several completely resistant cultivars have been released from the OSU Hazelnut Breeding program, all of which have ‘Gasaway’ as a resistance source, which transmits a dominant allele at a single locus that provides resistance to EFB. Additional EFB-resistant genotypes have also been identified from a diversity of origins that are being integrated into the OSU breeding program to produce new cultivars expressing multiple sources of genetic resistance. Interest in growing hazelnuts is increasing in other parts of the United States; for example, the Arbor Day Foundation began the Hazelnut Research Project in 1996 in Nebraska. A Hybrid Hazelnut Consortium was formed to join the leading hazelnut researchers in the United States. The Consortium's goal is to create a world-leading research and breeding program to develop hazelnuts as a widely adapted, high-yielding, and low-input sustainable crop that is competitive with annual crops for food, feed, or bioenergy. At Rutgers University, there has been a program of breeding and research for hazelnuts for the eastern United States since 1996. The program currently has ≈11,000 hazelnut seedlings undergoing evaluation. The Rutgers program is also looking for winter-hardy genotypes. They have been working closely with OSU to assess the response of OSU hazelnut selections that are resistant to EFB in Oregon when they are exposed to EFB isolates collected from across the eastern United States. This work has demonstrated the need for cultivars to express multiple sources of resistance and has prompted quarantine on importation of hazelnut plants into Oregon from other states where EFB strains may differ. Rutgers is also searching for new sources of resistance to EFB from seedling populations from Europe with the goal of integrating these sources into American germplasm. More effective Integrated Pest Management for EFB-susceptible hazelnut cultivars has been developed by OSU scientists. They recommend a management program that integrates scouting for and pruning infected tissue, fungicidal sprays, and the use of more resistant cultivars. Advances in hazelnut fertilizer management have included descriptions of patterns of nitrogen uptake, distribution, and use using isotopically labeled nitrogen.
Evaluation of Dry Matter, Protein, Starch, Sucrose, β-carotene, Iron, Zinc, Calcium, and Magnesium in East African Sweetpotato [Ipomoea batatas (L.) Lam] Germplasm
Authors: Tumwegamire Silver , Kapinga Regina , Rubaihayo Patrick R. , LaBonte Don R. , Grüneberg Wolfgang J. , Burgos Gabriela , Felde Thomas zum , Carpio Rosemary , Pawelzik Elke , Mwanga Robert O.M.
Published: February 2019

The present study evaluated selected East African (EA) sweetpotato varieties for storage root dry matter and nutrient content and obtained information on the potential contributions of the varieties to alleviate vitamin A and mineral deficiencies. Roots obtained from 89 farmer (white- and orange-fleshed) varieties and one introduced variety (‘Resisto’) were analyzed for storage root quality using near-infrared reflectance spectroscopy technology. Location differences were only significant for starch content. The variance was significant (P < 0.01) for all the traits except sucrose content. Overall, the farmer varieties had higher dry matter, higher starch, and lower sucrose contents than the control clone, ‘Resisto’. It is these qualities that make sweetpotato attractive as a starchy staple in EA. A low population's mean β-carotene content (19.0 ppm) was observed. However, deep orange-fleshed farmer varieties, ‘Carrot_C’, ‘Ejumula’, ‘Carrot Dar’, ‘Mayai’, and ‘Zambezi’, had β-carotene content that can meet 350% or greater of recommended daily allowance (RDA) with 250-g serving to a 5- to 8–year-old child. More but light orange-fleshed farmer varieties ‘K-118’, ‘K-134’, ‘K-46’, ‘KMI61’, ‘MLE162 Nakahi’, ‘PAL161’, ‘Sowola6’, ‘Sponge’, ‘SRT34 Abuket2’, ‘SRT35 Anyumel’, ‘SRT52’, and ‘Sudan’ can provide 50% to 90% RDA of pro-vitamin A for the child. The root minerals’ content was generally low except for magnesium whose content can meet 50% or greater RDA in many farmer varieties. However, in areas with high sweetpotato consumption, varieties ‘Carrot_C’, ‘Carrot Dar’, ‘KRE nylon’, ‘MLE163 Kyebandula’, and ‘SRT49 Sanyuzameza’ can make good intakes of iron, zinc, calcium, and magnesium. In conclusion, some EA farmer varieties can contribute greatly to alleviation of vitamin A deficiency and substantial mineral intakes.
Resistance to Phytophthora and Graft Compatibility with Persian Walnut among Selections of Chinese Wingnut
Authors: Browne Greg T. , Grant Joseph A. , Schmidt Leigh S. , Leslie Charles A. , McGranahan Gale H.
Published: February 2019

Seedlings from seven open-pollinated selections of Chinese wingnut (Pterocarya stenoptera) (WN) representing collections of the USDA-ARS National Clonal Germplasm Repository at Davis, CA, and the University of California at Davis were evaluated as rootstocks for resistance to Phytophthora cinnamomi and P. citricola and graft compatibility with scions of five cultivars of Persian walnut (Juglans regia). Seedlings of Northern California black walnut (NCB) (J. hindsii) and Paradox hybrid (PH) (typically J. hindsii × J. regia) were used as standards. In greenhouse experiments, potted plants of the rootstocks were subjected to intermittent flooding in soil artificially infested with the pathogens. All WN seedlings were relatively resistant to the pathogens (means of 0% to 36% of root and crown length rotted) compared with NCB (44% to 100%) and PH seedlings (11% to 100%). Negligible disease occurred in flooded control soil without the pathogens. In 9-year graft compatibility trials in an orchard, NCB and PH rootstocks supported relatively good survival and growth of all tested scion cultivars (‘Chandler’, ‘Hartley’, ‘Serr’, ‘Tulare’, and ‘Vina’; final scion survival 80% to 100%, mean scion circumference increase 292 to 541 mm), whereas results with WN were mixed. Wingnut rootstocks from all sources were incompatible with ‘Chandler’ (final scion survival 20% to 60%, scion circumference increase 17 to 168 mm). Conversely, all WN rootstocks from all sources were compatible with ‘Tulare’ and ‘Vina’ (final scion survival 80% to 100%, scion circumference increase 274 to 556 mm). Use of the WN rootstocks produced variable results in ‘Hartley’ and ‘Serr’ (final scion survival 10% to 100%, mean scion circumference increase 69 to 542 mm). There was a tendency for more rootstock sprouts on WN selections than on NCB or PH. In a commercial walnut orchard infested with P. cinnamomi, ‘Hartley’ survived and grew markedly better on WN selections than on PH. High resistance to P. cinnamomi and P. citricola was common to all of the WN selections. The results indicate that WN selections may be useful rootstocks for cultivars Tulare and Vina in soils infested with P. cinnamomi or P. citricola and that WN selections may contribute valuable resistance to these pathogens in walnut rootstock breeding efforts.
Irrigation and Nitrogen Management of Artichoke: Yield, Head Quality, and Phenolic Content
Authors: Shinohara Togo , Agehara Shinsuke , Yoo Kil Sun , Leskovar Daniel I.
Published: February 2019

Globe artichoke [Cynara cardunculus L. var. scolymus (L.) Fiori] has been recently introduced as a specialty crop in southwest Texas. Marketable yield, yield components, quality, and phenolic compounds of artichoke heads were investigated in response to three irrigation [50%, 75%, and 100% crop evapotranspiration (ETc)] regimes and four nitrogen (0 to 10, 60, 120, and 180 kg·ha−1) rates under subsurface drip irrigation. Field experiments were conducted over three seasons (2005–2006, 2006–2007, and 2007–2008) at Uvalde, TX. Irrigation was more effective than nitrogen (N) rates to optimize crop yield and head quality. Marketable yields significantly increased at 100% ETc compared with 75% and 50% ETc, whereas a 20% to 35% yield reduction occurred at 50% ETc across seasons. This yield reduction was associated with a decrease in both number of marketable heads and head weight and with reductions in plant physiological responses as measured in the last season. The lack of yield responses to N rates was in part the result of high pre-plant soil NO3-N and NH4-N levels. Total phenolics and chlorogenic acid of artichoke heads increased as the harvesting season progressed and were highest at 50% ETc during mid- and late harvests in one season. Based on these results, we estimate that under these environmental conditions, ≈700 mm (for a bare soil system) of water inputs and 120 kg·ha−1 or less of N (rate depending on soil available N) appear sufficient to obtain high marketable yields, superior size, and nutritional head quality of artichokes.
Rolled Winter Rye and Hairy Vetch Cover Crops Lower Weed Density but Reduce Vegetable Yields in No-tillage Organic Production
Authors: Leavitt Matthew J. , Sheaffer Craig C. , Wyse Donald L. , Allan Deborah L.
Published: February 2019

Winter annual cover crops, winter rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth), can reduce weed density and build soil quality in organic production systems. There is interest in integrating cover crops and reduced tillage with organic vegetable production, but few studies have been conducted in regions with short growing seasons and cool soils such as the upper Midwest. We evaluated no-tillage production of tomato (Solanum lycopersicum L.), zucchini (Cucurbita pepo L.), and bell pepper (Capsicum annuum L.) planted into winter rye, hairy vetch, and a winter rye/hairy vetch (WR/HV) mixture that were mechanically suppressed with a roller–crimper at two locations in Minnesota. Average marketable yields of tomato, zucchini, and bell pepper in the rolled cover crops were reduced 89%, 77%, and 92% in 2008 and 65%, 41%, and 79% in 2009, respectively, compared with a no-cover control. Winter rye and the WR/HV mixture reduced average annual weed density at St. Paul by 96% for 8 to 10 weeks after rolling (WAR) and hairy vetch mulch reduced weeds 80% for 2 to 8 WAR, whereas at Lamberton, there was no consistent effect of cover treatments on weed populations. Winter rye and the WR/HV mixture had higher average residue biomass (5.3 and 5.7 Mg·ha−1, respectively) than hairy vetch (3.0 Mg·ha−1) throughout the season. Soil growing degree-days (SGDD) were lower in cover crop treatments compared with the no-cover control, which could have delayed early vegetable growth and contributed to reduced yields. All cover crop mulches were associated with low levels of soil nitrogen (N) (less than 10 mg·kg−1 N) in the upper 15 cm. Rolled winter annual cover crops show promise for controlling annual weeds in organic no-tillage systems, but additional research is needed on methods to increase vegetable crop yields in rolled cover crops.
Analysis of Strategic Industry Planning and Organizational Opportunities for Mexican Cantaloupe Producers
Authors: García-Salazar J. Alberto , Skaggs Rhonda K. , Crawford Terry L.
Published: February 2019

Cantaloupe [Cucumis melo (L.)] producers in Mexico's Lagunera region harvest and sell their melons in the Mexican domestic market in June, July, and August. These producers and the larger Mexican cantaloupe industry have been economically battered in recent years by increasing competition in the global cantaloupe market, Salmonella contamination, low per-capita consumption relative to U.S. consumers, and historic supply gluts, which result in low prices and profits. A programming model of the region's cantaloupe industry was used to evaluate the impacts of strategic production planning, storage, or flow-to-market supply management. A 20% reduction in regional cantaloupe supply would increase growers’ profits and release land for use in other cropping activities. Cantaloupe storage and strategic production planning would increase producers’ profits but would require costly infrastructure investments. Organization of the regions’ cantaloupe producers to achieve orderly and strategically planned production and marketing would not require costly infrastructure investments and would increase growers’ profits. U.S. marketing orders for fruit, vegetable, and specialty crops are models under which Lagunera region cantaloupe industry planning and coordination could be effected. U.S. marketing orders have allowed producers to manage supply, promote their product to influence per-capita consumption, and deal with product quality and reliability threats.
Willingness to Pay for Optimal ‘Anjou’ Pear Quality
Authors: Gallardo R. Karina , Kupferman Eugene , Colonna Ann
Published: February 2019

In light of increasing consumer demand for optimal fresh fruit quality, experience attributes are crucial to ensure repeated purchases and price premiums. Challenges in offering consistent quality throughout the marketing year make ‘Anjou’ pears an interesting case in which to analyze the effects of experience quality attributes on willingness to pay. We analyzed data from choice experiments conducted along with sensory tests at two different times during the marketing year. Results indicate that individuals are willing to discount between 15.43 cents/kg to 37.48 cents/kg for a one-unit increase in pear firmness and pay between 19.84 cents/kg to 24.25 cents/kg for a one-unit increase in soluble solid concentration. This information would help the industry assign priority to the factors likely enhancing the characteristics leading to repeated sales at price premiums. Also, this information is valuable to related sciences because it provides market information for focusing research portfolios on quality characteristics likely to increase pears’ commercial viability.