bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrating Host Resistance and Plant Protectants to Manage Pythium Root Rot on Geranium and Snapdragon
Authors: Múnera Johanna Del Castillo , Hausbeck Mary K.
Published: February 2019

Root rot caused by Pythium spp. is a significant disease on greenhouse-grown crops and negatively affects the floriculture industry. To develop strategies that limit Pythium root rot on geranium and snapdragon, greenhouse trials were conducted to test plant protectants and cultivars. Seven fungicides and two biological control agents were evaluated on plants inoculated with P. aphanidermatum, P. irregulare, or P. ultimum. Disease severity was assessed using a scale of 1 (healthy, no disease symptoms) to 5 (plant death) from 5 to 45 day postinoculation (dpi). The area under disease progress curve (AUDPC) values differed significantly (P < 0.0001) among Pythium spp. and treatment. The interaction between plant protectants and Pythium spp. was also significant. For geranium, mefenoxam (trade name: Subdue Maxx) and Streptomyces lydicus WYEC108 (trade name: Actinovate) effectively controlled Pythium root rot. For snapdragon, treatment efficacy varied depending on the Pythium sp. When 11 geranium cultivars were inoculated with P. aphanidermatum, none were completely resistant to the pathogen. However, when P. irregulare was used to inoculate these geranium cultivars, Nano White Hybrid and Bulls Eye Cherry were similar to the uninoculated control. When 12 snapdragon cultivars were inoculated with P. aphanidermatum or P. irregulare, no cultivar was completely resistant to either pathogen, but Twinny White and Candy Showers Yellow were least susceptible to both. Integrating effective fungicides with less susceptible cultivars can limit disease caused by Pythium spp.
Evaluating Grafted Watermelon for Verticillium Wilt Severity, Yield, and Fruit Quality in Washington State
Authors: Wimer Jesse , Inglis Debra , Miles Carol
Published: February 2019

Verticillium wilt caused by Verticillium dahliae is a serious disease for watermelon growers in Washington State. Grafting represents a possible alternative disease management strategy, but little is known about rootstock resistance to verticillium wilt or the performance of grafted watermelon in the different production regions of the state. In this study, verticillium wilt severity, yield, and fruit quality were evaluated at three contrasting field sites in Washington using verticillium wilt-susceptible ‘Sugar Baby’ (diploid) watermelon grafted onto four commercial rootstock cultivars (Marvel, Rampart, Tetsukabuto, and Titan); nongrafted ‘Sugar Baby’ was included as the control. Verticillium dahliae soil densities varied at each site (<1.0, 5.7, and 18.0 colony-forming units (cfu)/g soil at Othello, Eltopia, and Mount Vernon, respectively). Area under disease progress curve (AUDPC) values differed significantly among treatments at Eltopia and Mount Vernon. Nongrafted ‘Sugar Baby’ had the highest AUDPC value at all three sites, while ‘Sugar Baby’ grafted onto ‘Tetsukabuto’ had the lowest AUDPC value at Eltopia and Mount Vernon. Nongrafted ‘Sugar Baby’ also had the lowest fruit weight per plant at all sites, but ‘Sugar Baby’ grafted onto ‘Tetsukabuto’ had the highest fruit weight per plant at Eltopia and Mount Vernon. Marketable fruit weight per plant did not differ among treatments at Othello. Yield was negatively correlated with AUDPC values at both Eltopia and Mount Vernon. Fruit number per plant was only significantly impacted at Eltopia, where ‘Sugar Baby’ grafted onto ‘Tetsukabuto’ had more fruit per plant than all other treatments except ‘Sugar Baby’ grafted onto ‘Rampart’. Fruit quality (flesh firmness, total soluble solids, and lycopene content) was unaffected by grafting at either Othello or Eltopia, except for increased flesh firmness for ‘Sugar Baby’ grafted onto ‘Marvel’ and ‘Titan’ as compared with nongrafted ‘Sugar Baby’ at Eltopia. At season’s end, plants were sampled from all treatments at Eltopia and Mount Vernon and assayed for V. dahliae. Microsclerotia typical of this organism were observed in all samples. Results from this study indicate that verticillium wilt of watermelon can be successfully managed by grafting when the V. dahliae soil density exceeds 5.0 cfu/g in Washington. In addition, grafting does not reduce fruit quality and using certain rootstocks can improve the quality of flesh firmness at certain locations.
Paclobutrazol or Ancymidol Effects on Postharvest Performance of Potted Ornamental Plants and Plugs
Authors: Ahmad Iftikhar , Whipker Brian E. , Dole John M.
Published: February 2019

Effects of paclobutrazol and ancymidol on postharvest performance and growth control of potted sunflower (Helianthus annuus L.), zinnia (Zinnia elegans Jacq.) and marigold (Tagetes erecta L.), petunia (Petunia ×hybrida Vilm.) plugs, respectively, were studied. Paclobutrazol was applied as a drench at 0, 1.0, 2.0, or 4.0 mg of a.i. per 15.2-cm pot for sunflower and 0, 0.5, 1.0, or 2.0 mg per 12.5-cm pot for zinnia, while ancymidol was applied at 0, 40, 80, and 160 mg·L−1 with a volume of 0.21 L·m−2 as a foliar spray for marigolds or petunia plug crops. With an increase in paclobutrazol dose or ancymidol concentration, plant growth (plant height and diameter, shoot fresh or dry weight) was controlled for all species tested. Use of 1.0–2.0 mg paclobutrazol per pot produced 21% to 28% shorter plants with 12% to 15% smaller plant diameter, 13% to 19% less shoot fresh weight, 15% to 21% less dry weight, and darker green foliage color for potted sunflower than nontreated plants. Treatment with 1.0–4.0 mg paclobutrazol per pot delayed first wilting by 0.7–1.4 days compared with nontreated plants. For zinnia, 0.5–1.0 mg paclobutrazol controlled plant growth, produced dark green foliage, and extended shelf life by delaying first wilting by 2.6–3.9 days and second wilting by 1.4–2.0 days than nontreated plants. For marigold and petunia plugs, 40–80 mg·L−1 ancymidol provided ample growth control with darker green foliage; however, postharvest longevity was extended only when plugs were sprayed with 160 mg·L−1 ancymidol. During simulated storage and shipping, plant growth retardants maintained darker green foliage for potted sunflower, zinnia, and marigold plugs and prevented postharvest stem elongation of petunia plugs. In summary, use of plant growth retardants effectively controlled excessive plant growth and extended shelf life of potted plants and plugs.
A Novel Regeneration System for Tamarillo (Cyphomandra betacea) via Organogenesis from Hypocotyl, Leaf, and Root Explants
Authors: Kahia Jane , Sallah Peter Kanze , Diby Lucien , Kouame Christophe , Kirika Margaret , Niyitegeka Simeon , Asiimwe Theodore
Published: February 2019

Cyphomandra betacea (Cav.) is commonly known as Tamarillo or tree tomato. This species is mainly used for its edible fruits which have a high nutritional value and contain relatively high amounts of proteins, vitamins B6, C, E, and provitamin A. The cultivation of Tamarillo in Rwanda is facing major challenges caused mainly by viral diseases such as Tamarillo mosaic virus (TaMV). These diseases are difficult to control and are transferred through vegetative propagation, often resulting in heavy productivity losses and poor-quality fruits. Thus, this study was conducted to evaluate the possibility of using tissue culture as an alternative propagation method. Tamarillo seeds were sterilized using a commercial bleach and germinated in vitro to get clean starting explants. Explants (hypocotyls, leaves, and roots) were cultured on semisolid Murashige and Skoog (MS) media supplemented with 6-benzylaminopurine (BA), N6-2-isopentyl adenine (2iP), 6-furfurylaminopurine (kinetin) evaluated at 5, 10, 20, 40 µM, and thidiazuron (TDZ), evaluated at 0.1, 0.5. 1.0 1.5 µM in separate experiments. Data were collected on the number of microshoots and roots 2 months after culture and analyzed using the Statistical Software for Social Sciences (SPSS) Software version 8. The results showed that the growth regulators evaluated had a significant (P ≤ 0.05) effect on plantlet regeneration from leaf and hypocotyl explants. The media supplemented with BA 40 μM was the most effective in inducing multiple shoots from leaf explants producing 4.67 ± 0.15 shoots per explant. Root explants showed the least morphogenic responses for all the parameters evaluated. The regenerated plantlets were transplanted to the greenhouse and a survival rate of 90% was recorded. During this study, a simple, reproducible, single-step protocol was developed. These results would be useful for mass propagation of Tamarillo.
Ameliorative Effects of Plant Growth Promoting Bacteria on Water-yield Relationships, Growth, and Nutrient Uptake of Lettuce Plants under Different Irrigation Levels
Authors: Sahin Ustun , Ekinci Melek , Kiziloglu Fatih Mehmet , Yildirim Ertan , Turan Metin , Kotan Recep , Ors Selda
Published: February 2019

The aim of this study was to determine the effects of selected plant growth-promoting rhizobacteria (PGPR) on some physiological characteristics, plant growth, yield, and plant nutrient content of lettuce grown under different irrigation levels. Field experiments were carried out as split plot based on randomized complete block design with three replications. Three irrigation levels, I1 = 100% (control), I2 = 75%, and I3 = 50% of the field capacity (FC), were determined at the 0–15 cm soil depth by time-domain reflectometry (TDR), as main plots and three levels of bacterial species consisting of no bacterial inoculation (control), Bacillus megaterium TV 6D (B1), Bacillus subtilis TV 12H (B2) as sub plots in 2012 and 2013. Physiological characteristics, plant growth, yield, and plant nutrient content of lettuce was significantly affected by PGPR and irrigation quantities. Results showed that decreasing irrigation quantities significantly decreased the growth, dry and fresh head weight, and yield of lettuce in both years. Moreover, lower irrigation levels caused a decrease in leaf relative water content (LRWC), stomatal conductance (SC), and plant nutrient element content, but an increase electrolyte leakage (EL) and lipid peroxidation [malondialdehyde (MDA)]. However, PGPR inoculations significantly increased the growth, nutrient element content, LRWC, SC, and yield but decreased EL and MDA of lettuce plants grown under lower irrigation levels. The results of the study suggested that PGPR inoculations could alleviate the deleterious effects of lower irrigation conditions on the growth and yield of lettuce plants.
The Effect of Deficit Irrigation and Crop Load on Leaf and Fruit Nutrition of Fertigated ‘Ambrosia’/‘M.9’ Apple
Authors: Neilsen Gerry H. , Neilsen Denise , Guak Sung-hee , Forge Tom
Published: February 2019

Mature, fruiting ‘Ambrosia’/‘M.9’ apple [Malus ×sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] trees were subjected over three growing seasons to a split-plot experimental design involving four irrigation main plot treatments and three subplot crop load treatments with six replicates. This semiarid production region is traditionally irrigated 01 May to 01 Oct. during which time an average of ≈ 15 cm of precipitation occurs. Irrigation treatments were applied through 2 × 4 L⋅h−1 emitters per tree and included I1: daily application of 100% evapotranspiration (ET); or I2: 50% daily ET; or I3: 50% ET applied to one side; and I4: 50%, 25%, or 18% ET-application, applied every second day, 2007–09, respectively. Crop load treatments were imposed annually ≈4 to 5 weeks after full bloom to create low (2.5, 3, and 3.75 fruits/cm2 trunk cross-sectional area (TCSA), medium (4.5, 6, and 7.5 fruits/cm2 TCSA), and high crop loads (9, 12, and 15 fruits/cm2 TCSA), 2007–09, respectively. Leaf and fruit nutrient concentration was affected more by crop load than by any deficit irrigation strategy. Increased crop load increased concentrations of leaf nitrogen (N), calcium (Ca), and fruit Ca in 2 of 3 years and consistently decreased concentrations of leaf and fruit phosphorus (P) and potassium (K) and, in 2 of 3 years, fruit boron (B). Reductions in seasonal water applications (as with I4) reduced leaf P in 2 of 3 years. But, when significant, (usually only 1 of 3 year) increased fruit Ca, magnesium (Mg), P, K, and B concentrations. Crop load also had a dominant effect on fruit nutrient removal rates expressed as kilograms per hectare. High crop load increased removal of all measured nutrients in most years. In contrast, imposition of deficit irrigation strategies often (2 of 3 years) reduced fruit P, Mg, and B removal rates but had little effect on N, Ca, and K. Cumulative evidence suggests that deficit irrigation applied to N, P, K, and B fertigated high density ‘Ambrosia’ apple orchards in combination with crop load reduction to maintain fruit size should usually not create additional nutrient problems. However, low fruit Ca concentrations may occur if the crop is very low. Fertigation of 20 g K/tree/year was insufficient for older trees because inadequate K occurred in all treatments by the third year.
Calcium Chelated with Amino Acids Improves Quality and Postharvest Life of Lisianthus (Eustoma grandiflorum cv. Cinderella Lime)
Authors: Saeedi Reza , Etemadi Nematollah , Nikbakht Ali , Khoshgoftarmanesh Amir H. , Sabzalian Mohammad R.
Published: February 2019

Lisianthus is one of the most important specialty cut flowers in the world. Various greenhouse conditions and inadequate evapotranspiration can disturb the transport of calcium and impair its uptake by plants. This study aimed to compare the effects of calcium amino acid chelates and calcium chloride (CaCl2) on flower production, quality, and postharvest life of cut ‘Cinderella Lime’ lisianthus. Therefore, nutrient solutions containing calcium amino acid chelates (1%) were prepared using calcium and equal concentrations of lysine, threonine, or methionine. The control treatment was a solution without amino acids and calcium. Calcium concentrations of flowering stems were significantly higher in plants treated with calcium amino acid chelates than those treated with amino acids or the control treatment. Treatment with calcium methionine chelate led to significantly higher flower numbers compared with treatment with free amino acids and the control treatment. Moreover, calcium amino acid chelates effectively improved the fresh and dry mass of the flowering stems in comparison with the control plants. In summary, among all calcium sources, calcium lysine chelate could most effectively enhance the postharvest life of lisianthus cut flowers.
Effects of Genotype and Isolate on Expression of Dollar Spot in Seashore Paspalum
Authors: Steketee Clinton J. , Martinez-Espinoza Alfredo D. , Harris-Shultz Karen R. , Henry Gerald M. , Raymer Paul L.
Published: February 2019

Seashore paspalum (Paspalum vaginatum Swartz) is a warm-season turfgrass species primarily used on golf courses and athletic fields, and is often impacted by the disease dollar spot caused by Sclerotinia homoeocarpa F.T. Bennett. Dollar spot is the most common and economically important turfgrass disease in North America, and current management of this disease relies heavily on frequent fungicide applications. An alternate management strategy is host plant resistance, but a better understanding of the interactions between pathogen isolates and the host species is needed to effectively incorporate this resistance into elite seashore paspalum genotypes. The goal of this study was to gather host plant/isolate response data that could be used to develop an effective and efficient screening protocol for resistance to this important disease. Five genotypes of seashore paspalum (‘Aloha’, ‘SeaIsle 2000’, ‘SeaIsle 1’, ‘SeaIsle Supreme’, and 05-1743) varying in dollar spot resistance were inoculated with five isolates of S. homoeocarpa in repeated field studies during 2012 and 2013. Isolates used were from three warm-season and one cool-season turfgrass species. Inoculated plots were evaluated visually and using digital image analysis (DIA) for disease development over time and for number and area of infection centers at two rating dates each year. Statistical differences among the seashore paspalum genotypes and inoculation/isolate treatments were detected for area under the disease progress curve (AUDPC) values, number of infection centers, and infection center area. A significant interaction between seashore paspalum genotype and S. homoeocarpa isolate effects was not observed, indicating that host plant resistance genes are likely not isolate specific. Using this information, breeders should be able to use one highly virulent S. homoeocarpa isolate to screen for host plant resistance in seashore paspalum.
Age Cohort Influences Brand Recognition, Awareness, and Likelihood to Buy Vegetable and Herb Transplants
Authors: Behe Bridget K. , Huddleston Patricia , Sage Lynnell
Published: February 2019

Marketers invest nearly 8% of their advertising budget on in-store marketing because >70% of all buying decisions are made at the point of purchase. Older consumers, especially Baby Boomers (typically classified as persons born from 1950 to 1965) have long been considered a core target market for horticultural products. However, some industry concerns have arisen with regard to the lack of purchasing among younger age cohorts, especially Gen X (born 1966–77) and Gen Y (born 1978–90). Brands help to create the perception of added value while also differentiating products from competitors. Often, brands are one of a few pieces of information consumers use to make product choices. We conducted an online survey in May 2014 to investigate the role of age cohort and brand recognition on the likely to buy (LTB) rating of two herb and two vegetable transplants. We showed study participants images of 16 plants, varying the container color (white, green, and yellow), plant type (basil, parsley, tomato, and pepper), plant brand (generic and three national brands), and price. About equal numbers from three age cohorts (Boomers, Gen X, and Gen Y) were represented in the sample of 566 plant purchasers. We observed that more Boomers had seen (recognized) Brand P, whereas more Gen X and Gen Y participants had seen Brand L. Subjects who had seen the plant brands before the study had a higher mean LTB rating for branded plants compared with those who had not seen the plant brands before the study. Furthermore, both Gen X and Gen Y were more LTB branded plants compared with Boomers. In the conjoint analysis, we found that plant type was the most important product attribute. Price and brand were similarly important but also less important than plant type. All three attributes were more important than container color. Having no brand on the container detracted $0.20 from the perceived value of the plant while the brands added up to $0.15 to the perceived plant value. Future marketing strategies which include branded plants at the point of purchase likely will increase perceived product value and LTB, especially among younger consumers.
Extensive Desiccation and Aging Stress Tolerance Characterize Gaillardia pulchella (Asteraceae) Seeds
Authors: Adegbola Yai Ulrich , Pérez Héctor E.
Published: February 2019

We investigated the response of Gaillardia pulchella seeds to desiccation and aging stress to gain some perspective on the germplasm storage potential and seed vigor of this species. Seed–water relations of mature, freshly harvested G. pulchella seeds were characteristic of desiccation-tolerant species. For example, initial seed water potential (−53 MPa) was well below the lethal water potential limit (−15 MPa) for desiccation-sensitive seeds. Desiccation tolerance was confirmed by high (>70%), rapid (t50 range 4–7 days), and uniform germination following equilibration drying. Likewise, post–saturated salt accelerated aging (SSAA) germination tests indicated a high degree of vigor of fresh seeds. The substantial level of desiccation and aging-related stress tolerance in G. pulchella seeds suggests that these organs potentially display orthodox storage physiology and an ability to endure variable seed bed conditions.
Improving Rooting and Shoot Tip Survival of Micropropagated Transgenic American Chestnut Shoots
Authors: Oakes Allison D. , Desmarais Tyler , Powell William A. , Maynard Charles A.
Published: February 2019

Many hardwood tree species are being threatened by exotic pests, and for some, only genetic engineering can offer a solution before functional extinction occurs. An example of how genetic engineering can be a useful tool for forest restoration is the transgenic american chestnuts, which contain a wheat oxalate oxidase gene conferring resistance to the chestnut blight. Many hundreds of these trees are needed for field trials and eventual restoration plantings throughout its natural range, but production is bottlenecked because of the difficulty of making hardwood trees produce roots through micropropagation. The presence of roots and living shoot tips precede successful acclimatization of tissue culture-produced american chestnut plantlets. In these experiments, we attempted to improve the post-rooting stage of our american chestnut propagation protocol. We examined vessel type, hormone, and activated charcoal concentrations, and using a vermiculite substrate. For plantlets with the best combination of roots and living shoot tips we recommend using semisolid post-rooting medium containing 2 g·L−1 activated charcoal and 500 mg humic acid in disposable fast-food takeout containers. When using vermiculite as a substrate, adding 2.0 g·L−1 activated charcoal to post-rooting medium without a gelling agent was the preferred treatment. Improving the survival rates of the american chestnut plantlets will benefit the american chestnut restoration project by providing more plant material for both ecological studies and eventual restoration, since pursuit of a nonregulated status for these transgenic trees will require extensive field testing. These procedures may also be applicable to other difficult-to-root hardwood trees in transgenic programs, such as american butternut, white oak, and black walnut.
Nitrogen Fertigation Rates Affect Stored Nitrogen, Growth, and Blooming in Iris germanica ‘Immortality’
Authors: Zhao Xiaojie , Bi Guihong , Harkess Richard L. , Varco Jac J. , Li Tongyin , Blythe Eugene K.
Published: February 2019

Tall bearded (TB) iris (Iris germanica L.) has great potential as a specialty cut flower due to its fragrance and showy, multicolor display; however, limited research has been reported on optimal nitrogen (N) nutrient management for TB iris. The objectives of this study were to investigate the effects of N fertilizer rate on plant growth and flowering of ‘Immortality’ iris and determine the influence of both stored N and spring-applied N fertilizer on spring growth and flowering. On 14 Mar. 2012, rhizomes of ‘Immortality’ iris were potted in a commercial substrate with no starter fertilizer. Plants were fertigated with 0, 5, 10, 15, or 20 mm N from NH4NO3 twice per week from 28 Mar. to 28 Sept. 2012. In 2013, half of the plants from each of the 2012 N rate were supplied with either 0 or 10 mm N from 15NH415NO3 twice per week from 25 Mar. to 7 May 2013. Growth and flowering data including plant height, leaf SPAD, number of fans and inflorescence stems, and length of inflorescence stem were collected during the growing season. Plants were harvested in Dec. 2012 and May 2013 to measure dry weight and N concentration in leaves, roots, and rhizomes. Results showed higher 2012 N rates increased plant height, leaf SPAD reading, and number of inflorescence stems at first and second blooming in 2012. Greater 2012 N rates also increased plant dry weight and N content in all structures, and N concentration in roots and rhizomes. Rhizomes (58.8% to 66.3% of total N) were the dominant sink for N in Dec. 2012. Higher 2012 N rates increased plant height, number of fans, and the number of inflorescence stems at spring bloom in 2013. In May 2013, N in leaf tissue constituted the majority (51% to 64.3%) of the total plant N. Higher 2012 N rates increased total dry weight, N concentration, and N content in all 2013 15N rates; however, leaf dry weight in all plants was improved by 2013 15N rate. Percentage of tissue N derived from 2013 15N (NDFF) decreased with increasing 2012 N rate. New spring leaves were the dominant sink (56.8% to 72.2%) for 2013 applied 15N. In summary, ‘Immortality’ iris is capable of a second blooming in a growing season, this second blooming dependent on N fertilization rate in current year. A relatively high N rate is recommended to produce a second bloom.
Measuring Root Hydraulic Parameters of Container-grown Herbaceous and Woody Plants Using the Hydraulic Conductance Flow Meter
Authors: Judd Lesley A. , Jackson Brian E. , Fonteno William C. , Domec Jean-Christophe
Published: February 2019

Root hydraulic conductance and conductivity are physiological traits describing the ease with which water can move through the belowground vascular system of a plant, and are used as indicators of plant performance and adaptability to a given environment. The ability to measure hydraulic conductance of container-grown herbaceous and semiwoody plants with soft conductive tissue was tested using a hydraulic conductance flow meter (HCFM). Although the HCFM is a hydraulic apparatus that has been used on woody plants to measure hydraulic conductance of intact roots, it has never been reportedly used on container-grown horticultural plants. Two herbaceous species, Chrysanthemum L. and Solenstemon scutellarioides Thonn., were grown in containers and hydraulic parameters were measured, including root conductance and root conductivity, as well as physical traits such as stem diameter and dry root mass. The HCFM was easily connected to intact roots even on herbaceous stems and was used to determine hydraulic conductance and conductivity directly on container-grown plants with minimal disturbance on the root system. Chrysanthemums, Buddleja davidii Franch., and Hibiscus moscheutos L. were grown in three different substrates, and both root mass and root hydraulic parameters were determined. Chrysanthemums showed a positive response with increasing root hydraulic conductance with increasing root mass. The substrates used in these studies only had an effect on root biomass of chrysanthemums, but substrates had no differential effect on root hydraulic conductivity.
Response of 10 Aster Species to Saline Water Irrigation
Authors: Wu Shasha , Sun Youping , Niu Genhua , Altland James , Cabrera Raul
Published: February 2019

Asteraceae is one of the largest plant families with many important garden ornamental species. Salt tolerance of 10 aster perennials was evaluated in a greenhouse experiment, including the following: damianita (Chrysactinia mexicana), gregg’s mistflower (Eupatorium greggii), shasta daisy (Leucanthemum ×superbum ‘Becky’), blackfoot daisy (Melampodium leucanthum), lavender cotton (Santolina chamaecyparissus), aromatic aster (Symphyotrichum oblongifolium), copper canyon daisy (Tagetes lemmonii), four-nerve daisy (Tetraneuris scaposa), skeleton-leaf goldeneye (Viguiera stenoloba), and zexmenia (Wedelia texana). Plants were irrigated with nutrient solution at electrical conductivity (EC) of 1.2 dS·m−1 (control) or saline solutions at EC of 5.0 or 10.0 dS·m−1 (EC 5 or EC 10) for 5 weeks. Upon termination, growth parameters, foliar salt damage, relative chlorophyll content [Soil-Plant Analysis Development (SPAD) readings], and mineral concentration were measured. Gregg’s mistflower, skeleton-leaf goldeneye, and lavender cotton were the most salt-tolerant species with less reductions in shoot dry weight (DW) in both EC 5 and EC 10. Considering the relatively severe foliar salt damage (visual quality score of 3.1 and 2.7 at EC 5; 2.4 and 1.6 at EC 10) and mortality rate (10% and 40%) in EC 10, aromatic aster and zexmenia should be avoided where poor quality water may be used for irrigation. Gregg’s mistflower and skeleton-leaf goldeneye had relatively lower leaf sodium (Na) concentrations suggesting that both species can selectively exclude Na. Damianita and the four daisies, i.e., blackfoot daisy, copper canyon daisy, four-nerve daisy, and shasta daisy, were salt sensitive as evidenced by their greater growth reduction, foliar salt damage, and high Na and chlorine (Cl) accumulation in leaves, and should be avoided in landscapes where poor quality water may be used for irrigation.
Garden Chrysanthemum Cell Membrane Thermostability and Flowering Heat Delay Differences Among U.S. and South Korean Germplasm
Authors: Anderson Neil O. , Won Mi-kyoung , Kim Dong-chan
Published: February 2019

Global warming has created increased nighttime temperatures both in field and greenhouse production of chrysanthemums during flower bud initiation (FBI) and development, causing heat delay or complete cessation of flowering. Integration of breeding and selection for heat delay insensitivity (HDI) has become imperative for greenhouse (cut, potted types) and must be accomplished on a genotypic basis, similar to winterhardiness. This is a breeding objective in the joint garden chrysanthemum breeding project between the Chungnam Provincial Agricultural Research and Extension Services and the University of Minnesota. The objectives of this research were to test 10 genotypes (cultivars, seedlings) from both breeding programs when grown in low-temperature (LT) and high-temperature (HT) short-day (SD) and long-day (LD) conditions (four environments: LTSD, LTLD, HTSD, and HTLD); determine the extent of heat delay and HDI for visible bud date (VBD), flowering, and other phenotypic traits; evaluate relative injury (RI) and cell membrane thermostability (CMT), and to select future parents with lowered RI values, higher CMT, shorter heat-induced flowering delay, and/or HDI. ‘Magic Ball’ and ‘Minnwhite’ had the shortest plant height in HTLD and HTSD, whereas ‘Geumbangul’ had stability for height in all treatments. Lowest long day leaf numbers (LDLN) occurred under LTSD in seven genotypes. However, both ‘Geumbangul’ and ‘Magic Ball’ had complete stability for LDLN across all environments. Sigmoid curves for RI% and temperature were found for all genotypes and environments with R2 = 0.79–0.89. Only ‘Mellow Moon’ had stability or equal VBDs in HTSD, LTSD, and LTLD conditions. This is the first-ever report of stability for VBD across inductive and noninductive HT/LT treatments. Only ‘Centerpiece’ flowered in all environments and also had 0 day of heat for VBD in LT and 1 day of heat delay in HT, as well as three others (Mn. Sel’n. 01-210-43, ‘Autumn Fire’, and ‘Geumbangul’). Few had linear regressions with positive slopes for heat-induced VBD or flowering delay regressed with RI%; most had no slope (R2 ≈ 0.0) for all treatments (‘Centerpiece’, Mn. Sel’n. 01-210-43), whereas others were negative (‘Mammoth™ Dark Bronze Daisy’, Flw LTLD–LTSD). Surprisingly, one linear regression had a slope of R2 = 1.0 (‘Geumbangul’, Flw LTLD–LTSD). These responses are all novel in chrysanthemums. Selecting the best parents in both breeding programs to maximize stability of all traits across these four environments with minimal crossing and selection across generations could be accomplished by stacking parental traits. A crossing scheme involving just three parents is proposed to incorporate stability for all traits in just a few generations.
Isolation and Characterization of New Polymorphic Simple Sequence Repeat Loci in Chrysopogon aciculatus (Retz.) Trin.
Authors: Zhang Xinyi , Liao Li , Liu Yang , Wang Zhiyong , Liu Jianxiu
Published: February 2019

Chrysopogon aciculatus (Retz.) Trin. is a perennial turfgrass for its low management and resistance. To develop simple sequence repeat (SSR) markers for C. aciculatus, we used four Roche 454 pyrosequencing, combined with the magnetic bead enrichment method FIASCO (fast isolation by amplified fragment length polymorphism of sequences containing repeats) to isolate from the C. aciculatus. A total of 66,198 raw sequencing reads were obtained with 4289 sequences (6.48%) were fit for primer pair design. One hundred microsatellite loci were selected to test the primer amplification efficiency in 20 accessions, and out of these, 11 loci were polymorphic. The amount of observed alleles ranged from three to six, with an average of 3.64. Nei’s genetic diversity values ranged from 0.085 to 0.493, with an average of 0.293. Shannon’s information index values ranged from 0.141 to 0.686, with an average of 0.428. Twenty accessions were clustered into three groups by unweighted pair-group method with arithmetic means (UPGMA). These SSR markers will provide an ideal marker system to assist with gene targeting, cultivar variety or species identification, and marker-assisted selection in C. aciculatus species.
Reproductive Traits of Hermaphroditic Muscadine Cultivars
Authors: Biasi Luiz A. , Conner Patrick J.
Published: February 2019

Native muscadines (Vitis rotundifolia Michx.) are dioecious, but muscadine vineyards are usually planted with a mixture of female plants and hermaphroditic pollenizers. Hermaphroditic cultivars are derived from either of two separate sources original hermaphroditic plants, H1 or H2. Nine hermaphroditic and two female cultivars were studied to determine their potential as pollenizers. Inflorescences of each cultivar were collected in the field to evaluate the number of anthers per flower, the number of pollen grains per anther, and pollen viability and germination in the main and secondary flowering periods. The number of flower clusters per shoot ranged from one to four with most producing two or three flower clusters per shoot. The number of anthers per flower varied by cultivar and cluster position, but in general was between six and eight anthers per flower. ‘Noble’ showed the highest pollen grains production per anther and per flower, reaching 5777 and 39,860, respectively, in the first cluster and ‘Carlos’ produced the least amount of pollen. All cultivars that had secondary flowering showed lower pollen production per anther and per flower as compared with the main flowering period. Optimal muscadine pollen germination media contained 50 mg·L−1 boric acid, 145 mg·L−1 calcium nitrate, 188 g·L−1 sucrose, 10 g·L−1 agar, and 10 mm 2-(N-morpholino)ethanesulfonic acid (MES) pH 6.0. The pollen grain viability of hermaphroditic and female cultivars was high, but pollen grain germination was low in hermaphroditic cultivars and absent in female cultivars. H1-derived cultivars produced more flower buds per cluster and higher germination rates than H2-derived cultivars, indicating they may be better pollenizers. Chemical names used: 2-(N-morpholino)ethanesulfonic acid (MES).
Comparative Organogenic Response of Six Clonal Apple Rootstock Cultivars
Authors: Sun Qingrong , Sun Meijuan , Sun Hongyan , Bell Richard L. , Li Linguang , Zhang Wei , Tao Jihan
Published: February 2019

The organogenesis potential is different among cultivars and must be optimized for individual genotype. Shoot organogenesis capacity from in vitro leaves and root organogenesis capacity of in vitro shoots in six clonal apple rootstock cultivars were compared. The shoot organogenesis capacity was highly genotype dependent. ‘GM256’ was found to be the most responsive genotype for shoot regeneration from leaf explants among the cultivars, showing high regeneration percentage on all tested media. The effects of basal medium composition and cytokinins on shoot regeneration were different depending on rootstock genotype. Optimum regeneration occurred on Murashige and Skoog (MS) basal medium for ‘71-3-150’, and optimum regeneration occurred on Quoirin and Lepoivre (QL) basal medium for ‘60-160’ and ‘ПБ’. Thidiazuron (TDZ) was more effective than 6-benzylaminopurine (BA) for Malus prunifolia (Y), whereas TDZ and BA were not significantly different for the other cultivars. All rootstock cultivars showed high root organogenic capacity. The percentage of rooting reached more than 90% and the mean root number per plantlet ranged from three to five. The optimum rooting medium was different for different rootstock cultivars. Optimum root organogenesis occurred on half-strength QL medium for ‘GM256’ and ‘Y’, and for ‘ПБ’ and ‘JM7’ on one-quarter-strength MS medium.
Interspecific and Intergeneric Hybridization in Dissotis and Tibouchina
Authors: Hawkins Susan M. , Ruter John M. , Robacker Carol D.
Published: February 2019

Four species of Dissotis and three species of Tibouchina, two genera of the Melastomataceae family, were crossed in an attempt to create interspecific and intergeneric hybrids. Intergeneric crosses set seed at a rate of 18.1% and interspecific crosses had a 32.3% rate of seed set. Germination was extremely poor, with only four crosses having germinated seed. Crosses produced 31 seedlings. Three of the seedlings were from intergeneric crosses between Dissotis canescens and Tibouchina lepidota. Interspecific crosses produced 25 seedlings from crosses between Dissotis princeps and Dissotis rotundifolia and three seedlings from crosses between D. canescens and D. princeps. The prognosis for conventional breeding for species in Dissotis and Tibouchina is poor due to low seed set, poor germination, and slow growth of progeny.
Fertility Source and Drought Stress Effects on Plant Growth and Essential Oil Production of Calendula officinalis
Authors: Anderson Victoria M. , Archbold Douglas D. , Geneve Robert L. , Ingram Dewayne L. , Jacobsen Krista L.
Published: February 2019

Organic and low-input production systems are increasingly of interest in medicinal plant production, such as Calendula officinalis, a medicinal plant grown for essential oils. However, in these systems the effects of nutrient availability and water stress may act singularly or in combination to affect plant growth and medicinal compound production. This study investigated the effects of organic and conventional fertility sources and drought stress effects on four calendula cultivars. Soil nitrogen (N) status, plant growth, productivity, and essential oil quality and quantity were measured. The plant growth response to increased N availability varied by cultivar, indicating that some cultivars may be better suited to low-input fertility regimes. Fertility source did not significantly affect essential oil quality or quantity. Drought stress reduced plant growth but increased the quality of essential oil, as indicated by the concentrations of specific constituents, although it did not reduce total oil yield. These results indicate that organic and low-input farming systems may significantly reduce plant growth, but may not necessarily affect essential oil yield or quality. As such, the sustainability of medicinal plant production systems may be improved by reductions in water and conventional fertilizers without significant reductions in medicinal compound production.
Micropropagation and Genetic Fidelity of the Regenerants of Aglaonema ‘Valentine’ Using Randomly Amplified Polymorphic DNA
Authors: El-Mahrouk Mohammed Elsayed , Dewir Yaser Hassan , Naidoo Yougasphree
Published: February 2019

The present study reports a simple protocol for in vitro regeneration of Aglaonema ‘Valentine’ using axillary shoot explants for rapid multiplication and production of true-to-type plants. Different concentrations of benzyladenine (BA; 0, 1, 3, 5, and 7 mg·L−1), kinetin (Kin; 0, 1, 3, 5, and 7 mg·L−1), thidiazuron (TDZ; 0, 0.5, 1.0, 1.5, and 2.0 mg·L−1), naphthalene acetic acid (NAA; 0, 0.5, and 1.0 mg·L−1), and indole-3-butyric acid (IBA; 0, 0.5, and 1.0 mg·L−1) were used for shoot regeneration. The highest shoot proliferation (5.0) was obtained on Murashige and Skoog (MS) medium supplemented with 1.5 mg·L−1 TDZ and 1 mg·L−1 NAA. In vitro rooting was easily achieved with 100% at all concentrations of NAA and IBA supplemented to half- or full-strength MS medium. Regenerated plantlets were acclimatized in greenhouse with 100% survival rate. Randomly amplified polymorphic DNA (RAPD) analysis confirmed the genetic fidelity of the regenerated plantlets and mother plant.
In Vitro Seed and Clonal Propagation of the Mediterranean Aromatic and Medicinal Plant Teucrium capitatum
Authors: Papafotiou Maria , Martini Aekaterini N.
Published: February 2019

The effect of various pretreatments, culture conditions, and storage time on in vitro germination of seeds, as well as the effect of explant origin and plant growth regulators on in vitro propagation of Teucrium capitatum L. (Teucrium polium sp. capitatum Arcang., Lamiaceae) were examined. Seeds, collected from native plants and stored at room temperature for 3, 7, and 12 months, were cultured for germination in vitro in petri dishes with solid half-strength (½) Murashige and Skoog (1962) growth medium (MS) at 5, 10, 15, 20, 25, and 30 °C, and 16 hours light or continuous darkness. Pretreatments, such as cold stratification, scarification with sandpaper, dipping in concentrated sulfuric acid (H2SO4 > 95%), or dipping in boiling water were tested. Seeds without any pretreatment germinated at lower than 10%. Dipping in concentrated H2SO4 for 15 or 20 minutes was the most effective pretreatment, but still seed germination achieved was low (36%). Seeds preserved their germination capacity for at least 1 year, and germinated satisfactorily at a wide temperature range, from 15 to 25 °C (optimum), while photoperiod did not affect seed germination. Explants excised from in vitro-grown seedlings were established in vitro on MS medium with 1.0 mg·L−1 6-benzyladenine (BA) at much higher rates (≈90%) compared with those collected from plants grown from cuttings in a greenhouse (25%), while explants collected from adult wild plants failed to do so. Explants from seedlings showed strong variability in their response; those excised from branched seedlings formed shoots at significantly higher percentage (90%) at the establishment stage (cultured on MS medium with 0.5–2.0 mg·L−1 BA) than explants excised from unbranched seedlings (36% to 43%), while during subcultures on MS medium with 1.0 mg·L−1 BA, explants from branched seedlings also showed higher multiplication rates than those from unbranched ones. BA at 0.5–2.0 mg·L−1 induced shoot multiplication during both establishment and multiplication stages (7–8 and 14–15 shoots per explant, respectively), while kinetin and 6-γ-γ-(dimethylallylamino)-purine (2iP) were less effective than BA, and zeatin the least appropriate. Microshoot rooting was enhanced by 1-week culture on (½) MS medium with 1.0–4.0 mg·L−1 indole-3-butyric acid (IBA), followed by transfer to auxin-free, (½) MS medium (93% to 98%, 7–8 roots per microshoot), compared with culture on the same medium continuously for 5 weeks (69% to 80%, 5–6 roots per microshoot) or at lower IBA concentrations. Plantlets were acclimatized to ex vitro conditions at 98% on a peat–perlite (1:1, v/v) mixture.
Qualitative Inheritance of External Fruit Traits in Watermelon
Authors: Lou Lingli , Wehner Todd C.
Published: February 2019

Genes for watermelon [Citrullus lanatus (Thunb.) Matsumura & Nakai] fruit traits have been identified since the 1930s. We conducted a study of fruit traits including fruit stripe width, stripe color, rind color, fruit shape, and blossom end shape (concave vs. convex). Ten watermelon cultivars (inbred lines) were used as parents. Several new genes or alleles were discovered. A series of alleles at the g locus is proposed to explain the inheritance of fruit rind pattern: G (medium or dark solid green), gW (wide stripe), gM (medium stripe), gN (narrow stripe), and g (solid light green or gray). The dominance series is G > gW > gM > gN > g. Another series of alleles at the ob locus is proposed for the fruit shape: allele ObE for elongate fruit, which is the most dominant; allele ObR (not the same as the o gene for round) for the round fruit; and allele ob for oblong fruit, which is the most recessive. Gene csm is proposed for the clear stripe margin in the cultivar Red-N-Sweet and is recessive to the blurred stripe margin (Csm) in ‘Crimson Sweet’, ‘Allsweet’, and ‘Tendersweet Orange Flesh’.
Elevated Levels of Potassium in Greenhouse-grown Red Romaine Lettuce Impacts Mineral Nutrient and Soluble Sugar Concentrations
Authors: Barickman T. Casey , Horgan Thomas E. , Wheeler Jennifer R. , Sams Carl E.
Published: February 2019

Lettuce is one of the major crops of the United States and can provide a large portion of income for small to medium size growers. Growing lettuce in adverse environmental conditions can have negative effects on quality. Elevated levels of potassium (K) have been shown to positively influence quality in various fruits and vegetables, such as tomato, pepper, and strawberry. However, research is lacking on the effects of elevated levels of K on leafy vegetables such as lettuce. Therefore, seeds of ‘Cimmaron’ lettuce were sown into a soilless medium and grown in greenhouse conditions at 25/20 °C (day/night). At 27 days after seeding, the plantlets were transferred to 3.8-L plastic nursery pots. Plants were grown under increasing K treatments of 98 (control), 185 (2×), 370 (3×), and 740 (8×) kg·ha−1. Plants were harvested 56 days after seeding. Application of elevated levels of K fertilizer treatments in red romaine lettuce had a positive quadratic effect on plant height increasing 7.0% from the control. Fresh weight (FW) increased 13.0% from the control and dry weight (DW) increased 15.5%. There was linear increase of 30.0% in sucrose concentrations in lettuce leaf tissue. In addition, the increase in K treatments caused an increase of 43.3% in K concentrations in the leaf tissue. In other nutrients, such as Calcium (Ca), Magnesium (Mg), and Sulfur (S), there was a decrease in the leaf tissue of 61%, 52%, and 46% when compared with the control treatment, respectively. The results of the current study suggest that increasing K fertilizer to 185 kg·ha−1 has the best results for plant height, FW and DW, and mineral nutrient concentrations. This study may initiate research that could examine the effects of increasing K fertilizer levels in lettuce or other leafy green vegetables on antioxidant levels and postharvest storability.