bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of GUS Reporter Gene System for Aphanomyces Root Rot Screening in Pea
Authors: Coyne Clarice J. , Muehlbauer Fred J.
Published: February 2019

Aphanomyces root rot of pea (Pisum sativum) in many pea-growing regions. The genetic resistance to this fungal pathogen is quantitatively inherited and confers levels of tolerance to the disease. Genetic gains in selection have been hampered by the difficulty of differentiating the highly tolerant from tolerant lines in segregating populations. Reporter gene systems have been useful in studying genetic resistance to other soil-borne pathogens. We have transformed an isolate of Aphanomyces euteiches, the causal pathogen, with a reporter gene β-glucuronidase (GUS) and a selectable marker gene, hygromycin phosphotransferase or neomycin phosphotransferase. The transformed lines constitutively express GUS as determined fluorimetrically by measuring the conversion of 4-methylumbelliferyl glucuronide to 4-methlyumbelliferone. The efficacy of this GUS enzyme assay will be compared with an indirect enzyme linked immunosorbant assay (ELISA) and visual disease development ratings in inoculated seedlings of three populations recombinant inbred lines of pea segregating for tolerance.
Transformation of Nicotiana alata Link and Otto. with an Autoregulatory Senescence-inhibitor Gene Construct
Authors: Schroeder Kenneth R. , Stimart Dennis P.
Published: February 2019

Leaf explants of Nicotiana alata Link and Otto. were surface disinfested and cultured on Murashige and Skoog (MS) medium containing 2.66 μm N6-benzyladenine (BA) to promote shoot proliferation. After 5 weeks, proliferated shoots were removed and remaining callus saved. Callus was inoculated with Agrobacterium tumefaciens encoding a senescence-specific promoter SAG12 cloned from Arabidopsis thaliana fused to a Agrobacterium tumefaciens gene encoding isopentenyl transferase which catalyzes cytokinin synthesis. Following inoculation, the callus was cocultivated for 6 days on BA medium. Selection for transgenics was done on BA medium plus 100 mg Kanamycin and 400 mg Ticarcillin (antibiotics) per liter. Proliferating shoots were rooted on MS medium containing antibiotics. Rooted cuttings were transplanted to soil, acclimated and flowered in the greenhouse. Transgenics were outcrossed to a commercial N. alata hybrid. Seed was germinated in vitro on half-strength MS medium plus antibiotics. Segregation of transgenics to nontransgenics was 1:1. Evaluation of leaf senescence on 5-month-old plants showed 2 to 14 times fewer senesced leaves on the transgenic than the nontransgenic plants.
`Maurine Blue' and `Florida Blue': Heat-tolerant Lisianthus [Eustoma grandiflorum (Raf.) Shinn.]
Authors: Harbaugh Brent K. , Scott John W. , Rubino David B.
Published: February 2019

Seedlings of commercial lisianthus cultivars form rosettes when grown at 25 to 28°C. Rosetted plants have a basal cluster of leaves, very short internodes typical of biennials, and do not bolt or flower for months without being exposed to 3 to 4 weeks at <15 to 18°C to reverse heat-induced rosetting. Semirosetted plants develop when seedlings are grown at a constant 22 to 25°C or at <22°C night with >28°C day. Semirosetted plants have one or more side shoots which may elongate and flower, but plants flower unpredictably and are of poor quality as cut flowers or potted plants. `Maurine Blue' and Florida Blue' were released from the Univ. of Florida in 1995. To our knowledge, they are the first heat-tolerant lisianthus cultivars. Seedlings and plants can be grown at 28 to 31°C without rosetting. `Maurine Blue' ranged in height from 38 cm (summer) to 67 cm (spring) during 1994 and 1995 production trials in Florida. `Maurine Blue' has potential for use as a tall bedding plant if sold as green transplants, a flowering potted plant if grown with three plants per 15-cm-diameter pot with a growth retardant, or as a bouquet-type cut flower. `Florida Blue' plants (38 cm) grown in an 11.5-cm square pot (0.65-L) with capillary mat irrigation were similar in height to `Blue Lisa' (32 cm) and taller than `Little Belle Blue' (22 cm) and `Mermaid Blue' (24 cm). `Florida Blue' was designated as a semi-dwarf cultivar with an intended use as a bedding plant. Growth retardants would be useful for production in pots <10 to 12 cm in diameter. Complete descriptive information, photographs and pedigrees will be presented.
Prunus mahaleb Seedling Populations as Improved Rootstocks for Sweet Cherry
Authors: Bliss F.A. , Almehdi Ali A.
Published: February 2019

Seedlings of Prunus mahaleb are often used as rootstocks for sweet cherry (P. avium) scion cultivars in commercial orchards. While they are desirable based on ease of propagation and economical production of nursery stock, seedlings may be variable resulting in nonuniform compound trees, and they are susceptible to several important diseases. Seedling sources have shown substantial variability for population uniformity of plant growth, and reaction to crown gall, powdery mildew and Phytophthora root rot. Segregating families also vary for pollen fertility, inbreeding response and control of scion growth. Multiple screening for favorable trait combinations is underway to develop improved sources of cherry rootstocks.
Analysis of S-allele Genotypes of Japanese Apple Cultivars
Authors: Komori Sadao , Soejima J. , Ito Y. , Bessho H.
Published: February 2019

Cross-incompatible combinations among the main cultivars in apple are rarely reported in Japan. Recently, however, most new Japanese cultivars are progenies of `Ralls Janet', `Delicious', `Golden Delicious', `Jonathan', and `Indo'. Cross incompatibility in apple, therefore, will become a serious problem in the near future. Since the analysis of the S-allele genotypes were not performed, especially in Japanese apple cultivars, the fruit set percentage were examined in several combinations of `Hatsuaki' (`Jonathan' × `Golden Delicious') and `Iwakami' (`Fuji' × `Jonathan') progenies using back crossings. As a result, we found that `Golden Delicious' and `Jonathan' had no common S-allele, while `Fuji' and `Jonathan' had one common S-allele. These facts were used as basics for the S-allele genotype analysis, and fruit set percentage and seed number per fruit were investigated on a large scale. The cross seedlings between `Delicious' and `Jonathan', `Ralls Janet' and `Jonathan', `Iwakami' and `Golden Delicious', `Golden Delicious' and `Delicious', `Hatsuaki' and `Fuji', `Hatsuaki' and `Delicious', `Hatsuaki' and `Jonathan', and `Hatsuaki' and `Golden Delicious' were analyzed. In addition, incompatibility between `Redgold' and `Kinesei' (`Golden Delicious' × `Ralls Janet'), `Senshu' (`Toukou' × `Fuji') and `Iwakami', and progenies of `Northern Spy' also were analyzed. As a result, we have found the existence of six alleles and 15 genotypes, and we have established S-allele standard cultivars and strains as follows: (Sa, Sb) = `Golden Delicious'; (Sa, Sc) (4)-354, (4)-425; (Sa, Sd) = `Toukou'; (Sa, Se) = `Redgold', `Kinsei'; (Sa, Sf) = `Narihokou', (4)-4195; (Sb, Sc) = `Hatsuaki', `Kuifua', `Sekaiichi'; (Sb, Sd) = `Tsugaru', (4)-300; (Sb, Se) = (4)-150, (4)-743; (Sb, Sf) = `Northern Spy', M.9, `Umezawa'; (Sc, Sd) = `Jonathan', `Himekami'; (Sc, Sf) = `Fuji', `Shinkou'; (Sd, Se) =; (Sd, Sf) = `Senshu', `Iwakami'; (Se, Sf) = `Ralls Janet'.
Utilization of Identified Simple Sequence Repeats (SSRs) in Malus ×domestica (Apple) for Germplasm Characterization
Authors: Szewc-McFadden Amy K. , Lamboy Warren F. , McFerson James R.
Published: February 2019

To comprehend genetic identity and relatedness in Malus germplasm held in situ and ex situ, we are employing simple sequence repeat (SSR) DNA fragment information in combination with passport and horticultural data. SSRs offer certain advantages for characterizing large arrays of germplasm efficiently. They are abundantly dispersed throughout plant genomes and are exceedingly polymorphic. In addition, they can be PCR-amplified and detected by automated fluorescence-based technology. A size-fractionated DNA library of M. ×domestica cv Golden Delicious was screened to identify SSR loci. Eight loci were found to be reliably informative and were used to prepare locus-specific primer pairs. Characterization of the 75 M. ×domestica accessions included in the core subset of the USDA-ARS Malus germplasm collection revealed six of the eight loci were polymorphic within the array. The number of alleles per locus ranged from two to 21. Throughput was enhanced by multiplexing, allowing simultaneous use of two or three primer pairs. With improved genetic characterization of Malus germplasm, we intend to better develop and relate the core subset to the rest of the collection and to in situ Malus genetic resources. SSR markers appear to be an efficient and reliable tool to expedite this process.
Partitioning of Isozyme Diversity in Wild Populations of Malus sieversii L. and Implications for Germplasm Collection
Authors: Lamboy Warren F. , Yu Jing , Forsline Phil L. , Weeden Norman F.
Published: February 2019

One of the primary progenitors of the cultivated apple (Malus ×domestica) is M. sieversii, a species native to the forested regions of Central Asia. Despite the horticultural importance of M. sieversii, little is known about its genetic variation. In this study, isozyme diversity at 18 loci was determined for 259 open-pollinated offspring belonging to 31 different maternal half-sib families collected from 14 different populations in 4 regions of central Asia. Genetic diversity statistics were computed from the resulting allele and phenotype frequencies. Cluster analysis of half-sib families showed that there was some grouping based on geographic region, but 16 of the half-sib families were most closely related to half-sib families from other regions. AMOVA, the analysis of molecular variance, indicated that most of the enzyme variability (85%) was attributable to differences among half-sib families within populations, none could be assigned to populations within regions, and 15% was due to differences among regions. In addition, no alleles were found that were both fixed in a region and unique to that region. These results suggest that plants belonging to M. sieversii effectively form a single panmictic population. Thus, a thorough sampling of a few large populations will efficiently capture most of the genetic diversity present in wild M. sieversii.
Heritability of Rosette Resistance in Blackberry
Authors: Gupton Creighton L. , Smith Barbara J.
Published: February 2019

A study was conducted to determine if blackberry cultivars Humble, Rosborough, and Brazos transmit rosette (incited by Cercosporella rubi) resistance and to estimate heritability (h2). Plants of parents and offspring involving these cultivars were rated for rosette severity on a whole plant basis from 0 = no rosette to 7 = all buds infected or plant dead. An estimate of h2 was computed by regression of cross means on parental means. The mean rosette severity rating of plants from crosses was always intermediate between the cultivar and other parents. Only `Humble' transmitted enough rosette tolerance to be usable although `Rosborough' crosses were more tolerant than the other parents. The h2 estimate of 0.48 was fairly high but low variability among parents other than `Humble' would suggest little progress from mass selection.
Prospects for Fingerprinting the USDA–ARS Cold-hardy Vitis Germplasm Collection using Simple Sequence Repeat (SSR) Markers
Authors: Lamboy Warren F. , Alpha Christopher G.
Published: February 2019

Curators of plant genetic resources collections must preserve germplasm possessing known useful characteristics as well as material displaying general genetic diversity. In order to ensure that both types of germplasm are included in a collection, germplasm curators require three fundamental types of information about each accession: taxonomic identity, genetic identity, and genetic relationship. Because simple sequence repeat DNA fragments (SSRs) have been successfully used to determine the genetic identity of grape clones, we conducted a study to determine if SSRs would supply all three types of information for the accessions in the cold-hardy Vitis (grape) germplasm collection. SSR fragments were amplified at six different loci for 23 accessions of cold-hardy grape spanning the range of species diversity in the collection. The minimum number of different alleles found at a locus was 9; the maximum was 26. Heterozygosity values ranged between 0.565 and 0.783, while gene diversity values were in the range 0.785 to 0.944. Two hundred fifty-two pairs of plants out of a possible 253 could be distinguished by their SSR profiles. Nei's genetic identities were computed between all pairs of plants and used in a UPGMA cluster analysis. The relationships obtained did not correspond well to expected relationships based on geography and taxonomy. Four species of grapes were represented by two or more accessions in this study. No DNA fragments found at these six loci served to unambiguously distinguish one species from another. Thus, SSR fragments from the six loci studied were useful in determining genetic identity of accessions, but were not helpful in determining genetic relationships or taxonomic identities. We are searching for additional loci that are informative for these types of information. Meanwhile we highly recommend SSRs for determining genetic identity in germplasm resources collections.
Evaluation of Vitis Species Found in Selected Locations of Texas and New Mexico
Authors: Pittcock J. Kim , Durham Richard E.
Published: February 2019

North American Vitis species and hybrids thereof have been the source of rootstocks for V. vinifera for the last century. Collection and evaluation of native Vitis in north-central Texas, western Texas, and New Mexico have been made to determine their current status. Known geographical pockets of grapevines were visited, with specimens taken and identified by comparison to herbarium collections and published descriptions. In locals where more than one species existed, many natural hybrids with varying morphological characteristics have become established. In North Central Texas, two areas were visited. The first was Tarrant, Parker and Wise counties where three grapevine species (V. mustangensis, V. cinerea var. helleri, and V. vulpina) and many hybrids were observed. The second was Wilbarger County where V. acerifolia was found growing in the south while V. ×doaniana was found growing in the north. West Texas was primarily populated with V. acerifolia with the exception of the Silver Falls Canyon area in Crosby County where hybrids of V. acerifolia, V. arizonica and V. riparia were observed. In New Mexico, two areas were visited: San Miquel County (North Central region), where V. acerifolia, V. arizonica, and V. riparia were observed and Eddy County (southern New Mexico) where V. arizonica was observed. A rich diversity of Vitis germplasm appears to remain in these habitats.
Development of Strategies to Evaluate Brassica oleracea L. Vegetable Crops for Wirestem Caused by Rhizoctonia solani
Authors: Farnham Mark W. , Keinath Anthony P.
Published: February 2019

Wirestem, caused by Rhizoctonia solani, is a destructive disease of B. oleracea cole crops and is distributed worldwide. Effective means of wirestem control include soil fumigation and soil treatment with pentachloronitrobenzene, which are increasingly expensive and environmentally undesirable. As a consequence, alternative methods of wirestem control are needed. Thus, we conducted controlled-environment and field experiments to develop methodology to study host-plant resistance and possibly biocontrol agents as potential wirestem control alternatives. Seedlings of 12 cultivars (three each of cauliflower, broccoli, cabbage, and collard) at the four- to five-leaf stage were transplanted to trays in a growth room or into field plots and covered with soil infested with R. solani AG-4 sclerotia. Disease progression (percent of plants healthy, diseased, and dead) was observed every 3 days for 2 weeks in the controlled environments and for 3 weeks in field trials. At the end of two studies, plants were dug with roots intact and rated for disease using a 1 to 10 scale. In all trials, percent healthy plants stabilized at about 2 weeks after inoculation. Incidence of wirestem disease varied among experiments ranging from 70% to 100% diseased, dead plants in controlled environments, and from 51% to 88% and 33% 65% in the two respective field studies. Disease rating was always negatively and significantly correlated with percent healthy plants. Although a genotype × environment interaction was observed, some cultivars (i.e., `Snowcone' and `Snowcrown' cauliflowers) were always severely diseased, while others (i.e., `Viking' broccoli and `Blue Max' collard) were consistently among the least diseased.
Heritability of Root-knot Nematode (Meloidogyne spp.) Resistance in Sweetpotatoes
Authors: Maluf W. R. , Azevedo S. M. , Campos V.P.
Published: February 2019

Heritabilities for resistance to root knot nematodes (Meloidogyne javanica and Meloidogyne incognita races 1, 2, 3, and 4) were studied in a population of 226 sweetpotato clones of diverse origin. For each nematode isolate tested, 128-cell speedling trays were filled with previously inoculated substrate (30000 eggs/1000 mL substrate). Sweetpotato clones suitably tagged and identified were randomly planted in the cells (one plant/cell), with a total of four plants per clone per isolate. Ninety days after inoculation, sweetpotato plants had their roots washed for substrate removal, and treated with 150 mg·L–1 Phloxine B to stain nematode egg masses. The number of egg masses per root was recorded, and plants were accordingly assigned scores from 0 (highly resistant) to 5 (highly susceptible). Broad-sense heritability estimates were 0.87, 0.91, 0.81, 0.95, and 0.93 respectively for resistance to M. javanica and races 1, 2, 3, and 4 of M. incognita. The frequencies of resistant genotypes were higher for M. javanica and lower for M. incognita race 2. Genotypic correlations (rG) among the resistances to the various Meloidogyne isolates utilized were weak, ranging from 0.11 to 0.57, suggesting independent genetic controls. Clones could be selected, however, with high levels of resistance to all nematode isolates tested. (This work was supported by CNPq, CAPES, FAPEMIG, and FAEPE/UFLA.)
Examination of the Inheritance of Resistance of Colletotrichum orbiculare Race 2 in Cucumber
Authors: Wasilwa L.A. , Morelock T.E. , Correll J.C.
Published: February 2019

Anthracnose of cucurbits, caused by Colletotrichum orbiculare, is composed of three races (race 1, 2, and 2B). The inheritance of race 1 in cucumber is reported to be controlled by a single recessive gene. Although the mode of inheritance to race 2 in cucumber has not been determined, it has been suggested that is quantitatively inherited. Four cucumber cultivars, H19 from two sources [the commercial seed (P1) and the breeders seed (P2)], Pixie (P3), and Marketer (P4), that were considered highly resistant, moderately resistant and highly susceptible, respectively, to race 2 were used as the parents in this study. Crosses between resistant × susceptible and resistant × moderately resistant were made. Some reciprocal crosses also were made. The F1 progeny were then evaluated for resistance to race 2 in a cotyledon assay. Disease severity was assessed 8 days after inoculation using a disease rating scale of 0–7, whereby 0 = healthy plant and 7 = 100% chlorosis or necrosis. All progeny from P1 × P1 were highly resistant (disease severity 19 < 2.5); P2 × P2 and P3 × P3 were highly moderately resistant (disease severity 2.6–4.9); and all P4 × P4 progeny were highly susceptible (disease severity > 5.0) to race 2. All F1 progeny showed a continuum of disease ratings from highly resistant to moderately resistant to race 2. The disease ratings of the F1 progeny would indicate that resistance to race 2 is controlled by multiple genes.
Genetic Basis of Physiological Traits Related to Salt Tolerance in Tomato
Authors: Foolad M.R.
Published: February 2019

Genetic relationships between salt tolerance and expression of various physiological traits during vegetative growth in tomato were investigated. Parental, F1, F2, and backcross progeny of a cross between a salt tolerant (PI174263) and a salt sensitive cultivar (UCT5) were evaluated in saline solutions with electrical conductivity of 0.5 (non-stress) and 20 dS·m–1 (salt-stress). Absolute growth, relative growth, tissue ion content, leaf solute potential and the rate of ethylene evolution by leaf petioles were measured. Growth of both parents were reduced under stress, however, the reduction was significantly less in PI174263 than UCT5 suggesting greater salt tolerance of the former. Under salt-stress, PI174263 accumulated in the leaf significantly less Na+ and Cl– and more Ca2+ than UCT5. The F1 hybrid performed intermediate relative to parents and the backcross populations approached recurrent parents in both growth response and ion accumulation. In all generations, leaf solute potential decreased and the rate of ethylene evolution increased under salt-stress, however, there were little or no differences among generations under either treatment. Across generations growth under salt-stress was positively correlated with Ca2+ and negatively correlated with Na+ accumulation in the leaf. In contrast, growth was not correlated with either leaf solute potential or the rate of ethylene evolution. Generation means analysis indicated that Na+ and Ca2+ accumulations were genetically controlled with additivity being the major genetic components. The results indicated that the inherent genetic capabilities of PI174263 to maintain high tissue Ca2+ levels and to exclude Na+ from shoot were essential features underlying its adaptation to salinity. Thus, tissue ion concentration may be a useful selection criterion when breeding for improved salt tolerance of tomato using progeny derived from PI174263.
Inheritance and Gibberellic Acid Sensitivity of a Dwarf Red Beet Mutant
Authors: Goldman I.L.
Published: February 2019

Few genes have been identified in red beet. A spontaneously occurring dwarf mutant was identified in the late 1970s and again in 1994 in several breeding populations. Mutant plants are characterized by extreme dwarfing of both root and shoot. Young leaves are narrow, thin and strap-like while older leaves are thicker and deeply veined. The shoot axis forms a compressed rosette. Neither the shoot axis nor the root axis of field-grown plants exceeds 3 cm in height. Genetic analysis of F2 and backcross populations revealed the dwarf phenotype is conditioned by a single recessive gene. Several experiments were conducted to determine if the dwarf phenotype was due to a lack of gibberellic acid (GA) production. Exogenous application of GA3 at concentrations ranging from 1 to 1000 ppm on dwarf plants a) following seeding and b) during reproductive growth revealed a linear increase in plant height. Control dwarf plants receiving a water-only treatment were 18% as tall as plants receiving regular application of 1000 ppm GA3. A wild-type phenotype during reproductive growth was recoverable following regular GA3 application.
Heritability Estimates for Sugars, Alcohol Insoluble Solids, and Percent Dry Matter in Baked Sweetpotatoes
Authors: Romaine Durel J. , LaBonte Don R.
Published: February 2019

Narrow-sense heritability (h2) estimates for sugars were determined to assess the feasibility of breeding for a sweeter baked sweetpotato. Roots of parents and half-sib progeny were baked (190°C for 75 minutes) 16 weeks after harvest. Sugars from 10 gram root samples were extracted in ethanol for HPLC sugar quantification. Alcohol insoluble solid (AIS) residues (starch) were also measured from the samples. Dry matter was determined on a separate 10-g sample. Narrow-sense heritability estimates based on variance components analysis for AIS and percent dry matter were 0.20 and 0.32, respectively. Estimates for sugar data were 0.05 for sucrose, 0.52 for maltose, and 0.52 for total sugars (fructose, glucose, sucrose and maltose). These heritability estimates for maltose and total sugars imply a breeder could expect a moderate gain in sweetness over several cycles of selection.
Analysis of Response and Correlated Response to Selection for Salt Tolerance during Germination in Tomato
Authors: Foolad M.R.
Published: February 2019

The effectiveness of directional phenotypic selection to improve tomato seed germination under salt-stress was investigated. Seed of F2 and F3 progeny of F1 hybrids between a salt-tolerant and a salt-sensitive tomato cultivar were evaluated for germination response at three stress levels of 100 (low), 150 (intermediate), and 200 mm (high) synthetic sea salt (SSS). At each salt-stress level, the most tolerant individuals were selected. Selected individuals (F2s or F3s) were grown to maturity and self-pollinated to produce F3 and F4 progeny families. The selected progeny from each experiment were evaluated for germination at four treatment levels of 0 (nonstress), 100, 150, and 200 mm SSS and compared with unselected populations. The results indicated that selections were equally effective at all three stress levels and in both F2 and F3 generations and significantly improved progeny seed germination under both salt-stress and nonstress treatments. Estimates of realized heritability for rapid germination under the various salt-stress levels ranged from 0.67 to 0.76. Analysis of response and correlated response to selection indicated a genetic correspondence of up to 100% between germination at different salt-stress levels. Genotypic family correlations between germination at the low, intermediate, and high salt-stress levels ranged from 0.67 to 0.89 and those between nonstress and salt-stress conditions ranged from 0.25 (between 0 and 200 mm) to 0.71 (between 0 and 100 mm salt). The results indicated that similar or identical genes contributed to rapid germination response of tomato seeds at different salt-stress levels. Thus, selection at one stress level resulted in progeny with improved germination at diverse salt-stress levels.
Evaluation of Oriental Trellis Cucumbers in Trellis and Flat Bed Production Systems
Authors: Shetty Nischit V. , Wehner Todd C.
Published: February 2019

Suitability of commercial production of oriental trellis type cucumber (Cucumis sativus L.) was evaluated using 18 cultivars and breeding lines (referred to as cultigens hereafter). The cultigens (15 oriental trellis and three American slicers) were tested using two systems (trellis and flat bed production) in two seasons (spring and summer) in 1995 at Clinton, N.C. Traits evaluated included total yield, early yield, percentage culls, vine length, leaf area, gynoecious rating, fruit shape, fruit color, fruit length, seed cell size, anthracnose resistance, powdery mildew resistance, and fruit keeping ability. Highest yielding cultigens were `Summer Top', `Tasty Bright', and `Sprint 440'. Those with best fruit quality were `Sprint 440', `Tasty Bright', `Poinsett 76', and `Summer Top'. Most disease resistant was `Poinsett 76'. The best cultigens considering all traits measured were `Sprint 440', `Tasty Bright', and `Summer Top'. Production of cultigens on trellis rather than flat bed resulted in an average increase in total, marketable, and fancy yield of 130%, 160%, and 140%, respectively. Oriental trellis cucumbers can be produced as a less expensive alternative to European greenhouse cucumbers, and to supply consumer demand for this particular product type.
A Prospective Variety of Jute Marlow Corchorus olitorius Linn for Nigeria Consumers
Authors: Makinde Margaret Joke
Published: February 2019

Five promising lines of Jute Marlow (Corchorus olitorius Linn.) were selected from the GeneBank of NIHORT and collections made within the last few years. A comparison of the vegetable characters and seed yields were made and NH87/CO4-1 had significantly higher shoot yields at the seedling stage of 0.31 and l.00 g per plant at 3 and 5 weeks, respectively. The highest dry-seed weight of 6.18 g/plant also makes it attractive for seed growers.
Use of Flow Cytometric Measurement of Nuclear DNA Content to Assess Ploidy Level in Azalea
Authors: Velguth Peter H. , Pellett Harold
Published: February 2019

We evaluated flow cytometric measurement of nuclear DNA content to determine ploidy level in azalea. If ploidy level correlates with DNA content, ploidy level could be determined more readily than by direct chromosome counts and assist in planning crosses and evaluating progeny. Tested plants included azalea cultivars, materials from the azalea breeding project at the Univ. of Minnesota, and species from the Rhododendron Species Botanic Garden and the North Carolina Arboretum. Data compiled from DNA assays of practically all material analyzed fell into distinct groups consistent with their being either diploid, triploid, or tetraploid. Additionally, a known diploid plant of each of four diploid species, together with a natural or derived tetraploid plant of each of these species was obtained. Results showed that the four diploids had a similar DNA content compared to one another. DNA content of the tetraploids was also similar, and the tetraploid's DNA content was approximately twice that of the diploids, as expected. Unfortunately, success with direct chromosome counts in other material has proven elusive, currently precluding direct correlation of DNA amount with ploidy level across other species and cultivars. Although many cases exist in the literature where DNA content has a direct relationship to ploidy level, this does not always hold. Although the majority of plants tested fell into a diploid, triploid, or tetraploid grouping based on DNA content, further study is required to determine the exact relationship between ploidy level and DNA content in azalea.
Horticultural Research at The Holden Arboretum
Authors: Chan Charlotte R. , Marquard Robert D.
Published: February 2019

The Holden Arboretum, established in 1931, is the largest arboretum in the United States. Its mission is to promote the knowledge and appreciation of plants for personal enjoyment, inspiration, and recreation; for scientific research; and for educational and aesthetic purposes. Of the Arboretum's 3100 acres, 800 acres support collections and display gardens, while the balance comprise natural areas. The collections include nearly 8,000 accessions from 76 plant families; about 700 plant species, some rare or endangered, occupy the natural areas. The education component of the mission connects the Arboretum with the public through school programs, classes, horticultural therapy, and seasonal internships. Two research fellowships are also available. The Holden Arboretum has expanded the research emphasis. The David G. Leach Research Station, part of the Arboretum since 1986, focuses on rhododendron and magnolia breeding and research. Built in 1993, the Horticulture Science Center is a modern research and production facility able to more fully implement and support a broad range of formal horticultural research. The main objective of the research program is to develop superior woody ornamentals for the landscape through hybridization. Additional research emphasizes reproductive biology and using biochemical markers (isozymes and RAPDs) to answer basic questions about the genera under study (Aesculus, Hamamelis, Cercis).
In Vivo and in Vitro Propagation of Selected Cabbage (Brassica oleracea L. var. capitata) Clones
Authors: Pinto José E.B.P. , Souza Clovis M. , Maluf W.R.
Published: February 2019

Hybrid cabbage cultivars can be produced via seed-propagated self-incompatible (SI) inbred lines, or, alternatively, via vegetative propagation of SI clones. Cabbage clones differ in their ability to undergo vegetative propagation, a fact that appears to be related to the degree of differentiation of the axillary buds inside the head. A procedure for in vivo and in vitro propagation is described for cabbage clones known for difficulty in undergoing vegetative propagation. Cuttings from clonal families 800 (easy-to-propagate) and 007 (difficult to propagate) were immersed in indolebutyric acid (IBA—0, 5, 25, and 125 mg·L–1) + boric acid (100 mg·L–1) + sucrose (20 g·L–1) for 15 hours and maintained in glasshouses. Induction of roots was more effective with 125 mg·L–1 IBA supplemented with boric acid and sucrose. This treatment showed the highest frequency of rooting and the largest number of roots per cutting. The in vitro system of propagation was performed on the basal medium of Murashige and Skoog (MS), to which triadizuron (TDZ), benzyladeninepurine (BAP), and kinetin (Kin) were added in different combinations. TDZ was more effective than BAP or Kin in the promotion of shoot regeneration.
Regeneration and Frequency of Tetraploid Variants of Cucumis metuliferus are Affected by Explant Induction on Liquid/Membrane System
Authors: Adelberg Jeffrey
Published: February 2019

Ninety-eight percent of cotyledons of Cucumis metuliferus (PI 482439) regenerated shoot buds in 5 weeks on MS medium with 10 μm BA. Regeneration rates on agar gelled medium and liquid/membrane system were compared after weekly transfers of tissue from liquid/membrane to agar during the 5 weeks of regeneration culture. Number of shoots and buds increased from six (on agargelled medium) to nine per cotyledon when explant on liquid/membrane system for 3 or 4 weeks was transferred to agar gelled medium. Shoot development, rooting, and survival in greenhouse was adequate regardless of whether regeneration was initiated on agar or liquid/membrane system. Tetraploid regenerants were found to be about 9% of the almost 400 regenerants screened. Pollen morphology was a quick and definitive screening technique for tetraploid plants. Frequency of tetraploid plants was similar after 5 weeks of induction on either agar or liquid/membrane system. This frequency decreased by a factor of 10 following transfer of explants from membrane to agar after the first week of induction. Timing of this transfer plays a critical role in eliminating tetraploid variants.
Micropropagation of Chokecherry by Shoot Tip Culture
Authors: Zhang Zhen , Cheng Zong-Ming
Published: February 2019

Chokecherry (Prunus viginiana L.) is an important shrubby species for agroforestry planting in the northern Great Plains states. The X-disease is a serious limiting factor for its utilization. The objective of this research was to produce clonal materials for studying the host and X-disease phytoplasma interactions and for screening X-disease resistant chokecherry germplasms. Shoot tips of 1–2 cm in length were isolated from 1-year old seedling plants, sterilized, and initiated on three basal media supplemented with 5 μm BA and 5 μm IBA. After five weeks, an average of 4.8, 2.2 and 0.3 new shoots were produced on Murashige and Skoog (MS) medium, woody plant medium (WPM) and Knop's medium, respectively. The newly formed shoots were subcultured on MS medium with 5 m BA and 5 m IBA. MS and DKW media gave significantly higher proliferation rates (12–13 shoots after 4 weeks) than WPM (5.5 shoots). Microshoots rooted in half-strength MS medium supplemented with 5 and 10 μm of either IBA or NAA. The shoots were either placed on the medium for 19 days, or for 5 days then transferred to a hormone free medium for 14 days. On the media with IBA, 80% to 90% of the microshoots rooted with an average of 2.4 roots per shoot and there were no differences in rooting percentage and root number. When shoots were exposed to NAA for 5 days, 66.7% of shoots on medium with 5 μm NAA, and 83.3% on the medium with 10 m NAA formed an average of 2.2 roots per shoot; but when the shoots were exposed to NAA for 19 days, 36.4% of shoots on the medium with 5 m NAA and 30% on the medium with 10 μm of NAA formed an average of 0.53 roots per shoot. These rooted shoots are under acclimation to the ambient environment.
Effect of Explant Size and Age on in Vitro Propagation of Curcuma roscoeana Wall.
Authors: Sotthikul Chamchuree , Apavatjrut Pimchai
Published: February 2019

Propagation of Curcuma roscoeana in vitro was done successfully by culturing 0.5 × 1.0 mm shoot tips from young buds onto modified MS (1962) + 0.25 mg·L–1 kinetin. The bud-derived new plantlets could be multiplied on a new medium. Stem explants 10 mm in size, measured from base of the plantlets longitudinally cut in half, were the most suitable culture explants providing 2.8 new healthy plantlets/cultured explant. Explants from 4, 6, and 8 weeks old plantlets were more suitable than those of 2 weeks old when grown on agar or in liquid medium. From a histological study, it was found that new buds developed from preexisting meristems. The buds, like root initiation, could also occur directly from initial culture explants, not through callus. The plantlets obtained could successfully be transferred into growing pots, having a 95% survival rate.
Thidiazuron and Benzylamino Purine Stimulation of Apple Shoot Proliferation in Vitro
Authors: Al-Juboory Karim H. , Al-Niami Jabar H.
Published: February 2019

Thidiazuron (TDZ) and benzylamino purine stimulated shoot proliferation on shoot tip explants of wild apple (Malus domestica Borkh) when incorporated in Murashige and Skoog (MS) medium at concentrations of 1.0–10 μm. Shoot numbers obtained with TDZ were greater than the number produced when using BA in the medium but the shoots were shorter than with BA. Increasing TDZ levels increased shoot proliferation with 10 μm. Apple shoots were successfully rooted on MS medium with 2.0 mg·L–1 NAA and then transferred to a mixture of 1 peat: 1 perlite: 1 soil and acclimatized for potting.
Cultural Conditions Affecting the Frequency of Embryoid Formation in Sweetpotato (Ipomoea batatas)
Authors: Norton M.A. , LaBonte D.R.
Published: February 2019

Somatic embryogenesis in sweetpotato is highly genotype dependent. Unfortunately, many desirable agronomic varieties do not produce embryos capable of germination when published protocols are followed. Using one responsive and three recalcitrant cultivars, we examined the effect on embryogenesis of auxin, nitrogen, and carbon; explant source; and desiccation. All cultivars formed proembryonic masses on medium supplemented with either 2,4-D or picloram; picloram favored the growth of nonembryogenic callus. Twenty mm each of ammonium and nitrate promoted the best proembryo formation in all cultivars. Ammonium was essential for embryogenesis; replacing ammonium with proline, glutamine, asparagine, glycine, or casein hydrolysate resulted in poor or no proembryo formation. More proembryos formed on medium supplemented with sucrose than with glucose, fructose, or maltose. Leaf discs from the first fully expanded leaf produced more embryos than younger leaves for all cultivars; discs taken from the lamina produced more embryos than discs including portions of the midrib. Proembryos matured and germinated only after at least 3 weeks on medium containing 5% w/v polyethylene glycol 8000, greater than 3.3 mm myo-inositol, and 1 or 10 μm abscisic acid. More whole plants were obtained from the responsive cultivar Jewel than from the recalcitrant genotypes.
Axillary Shoot Proliferation from in Vitro Culture of Pulmonaria L. Shoots
Authors: Stimart Dennis P. , Mather John C.
Published: February 2019

Actively growing shoots from Pulmonaria L. `Roy Davidson' were cultured in vitro on Murashige and Skoog medium containing benzyladenine (BA) to establish proliferating cultures. BA at 0, 0.4, 0.8, 4.4, 8.8, and 44.4 μm was compared for shoot proliferation and rooting response. Shoot count was highest on 8.8 μm BA with root count highest on 0 or 0.4 μm BA. Subculture 4 weeks later of shoots to the same treatments resulted in highest shoot counts on 44.4 μm BA. Optimum level for micropropagation was 8.8 or 44.4 μm BA. Greatest rooting was at 0 or 0.4 μm BA.
Effect of Quantity and Depth of Media per Culture Container on Shoot Production of Muscadine Grape Cultured in Vitro
Authors: Robacker Carol D.
Published: February 2019

Previous studies indicated that the number of shoots formed per nodal explant varied significantly depending upon the type of culture container used. Amount of media per container and amount of time that media was autoclaved were variables that differed among the containers. To determine the cause for the container effect on shoot number, a study was conducted in which autoclave time and amount of media per container were the same for all tested containers. Media was autoclaved in 500-mL batches for 30 min, then poured in 30-mL aliquots into sterile containers. Containers tested were plastic petri plates, GA-7 Magenta vessels and glass jars. Depth of the medium was 5 mm in plates, 8 mm in vessels, and 12 mm in jars. Nodes from in vitro grown shoots of `Triumph', `Regale', and `Fry' were cultured on Murashige and Skoog salts and vitamins with 2 mg·L–1 BA and 8 g·L–1 agar. Results indicated that the greatest number of shoots formed in the jars. In a second study, nodes were cultured on petri plates containing 30 mL of medium (depth 5 mm) or 70 mL (depth 12 mm). Two to three times more shoots formed on the plates with the greater amount of medium. These studies indicate amount and depth of medium are factors influencing shoot number.
Low-temperature Tolerance Correlates to Seed Leakage in Twenty-eight Cultivars of Chile and with the Size of Seed Company
Authors: Carter A.K. , Stevens R.S. , Hamm J.R. , Hopper N.W.
Published: February 2019

Twenty-eight seedlots of Capsicum annuum from several commercial seed companies were tested for tolerance to low temperatures. Each cultivar was tested three times at 25, 20, and 15°C in laboratory incubators. It was observed that while high germination percentages (r85%) and fast germination rates were found in several seedlots, the relationship was not strongly linked to type of chile, age of seed, or treatment temperature. Of the 28 seedlots, 14 came from companies which are in the top 10% in volume and sales. The other 14 seedlots were from smaller companies. Seventy-one percent of the seedlots with germination at r85% came from the top ten companies. Ninety-two percent of the seedlots with s85% came from small companies. To further test this finding, we randomly choose six seedlots from a small company and 6 seedlots from a small company. There was a clear delineation in germabiltiy between the small company and the large company. Our results indicate a trend that could have a negative impact on some chile seed markets. Electrical conductivity (EC) is commonly used to detect membrane leakage in seeds. Chile seed from 12 seedlots (6 from the large company and 6 from the small company) were soaked 18 hours at 25 and 5°C. There was a negative correlation (r2 = 0.76) between the 15°C germination at 40 days and the EC. It is important to determine why membrane leakage varies in seedlots from different companies and whether the leakage is due to phenotypic or cultural factors, or due to management practices within the company.
Effect of Humic Acid Seed Treatments on Growth and Development of Seedlings
Authors: Hartwigsen Jack A. , Evans Michael R.
Published: February 2019

Seed of Cucumis sativus and Pelargonium ×hortorum were imbibed for 24 hours in solutions containing 0 (deionized water), 2500, 5000, 10,000, and 20,000 ppm humic acid. Additional treatments included seed which were imbibed in nutrient solutions corresponding to the nutrient content of each humic acid solution as well as an untreated dry control. Percent germination was reduced for geranium seed imbibed in 20,000 ppm humic acid and for cucumber seed imbibed in either 20,000 ppm humic acid or the corresponding nutrient control. Root fresh weights for untreated and water imbibed geranium seed were 0.05 g. Humic acid treatment increased root fresh weights to a maximum of 0.14 g at 5000 and 10,000 ppm. Shoot fresh weights for geranium were 0.12 and 0.10 g for untreated and water imbibed seed, respectively. Humic acid treatment increased shoot fresh weight to a maximum of 0.18 at 2500 ppm. Root fresh weights for cucumber were 0.16 and 0.18 g for untreated and water imbibed seeds, respectively. Humic acid treatment increased root fresh weight to a maximum of 0.33 g at 10,000 ppm. Shoot fresh weights for cucumber were 0.31 and 0.38 g for untreated and water imbibed seed, respectively. Humic acid treatment increased shoot fresh weight to a maximum of 0.43 at 10,000 ppm.
Marigold Growth in Six-packs following Transplanting from Plugs at Several Stages of Development
Authors: Oakley Kay , Geneve Robert , Kester Sharon , Stafford Myra
Published: February 2019

Root and shoot development in Marigold `Little Devil Flame' was studied after being grown for varying lengths of time in 392-count plugs before transplanting to six-pack cells. Seedlings were grown for 0, 5, 10, 15, 20, and 25 days before transplanting to six-packs. All plants were measured at day 25. There was no significant difference in total root length, area and dry weight per plant or in leaf area and shoot dry weight per plant for seedlings transplanted from 0 to 15 days. Both total root dry weight and total shoot dry weight of seedlings transplanted on day 20 was reduced by 32% compared to seedlings that were not transplanted. Total root dry weight of seedlings transplanted at day 25 was reduced by 60% while total shoot dry weight of seedlings was reduced by 56% from those not transplanted. In a separate experiment, the growth rate of seedlings grown in plugs was sigmoidal (r2 = 0.98). Growth rate was significantly reduced between 20 and 25 days in the plug. These results suggest that root restriction in the plug may be a factor in the reduction of seedling growth following transplanting.
Production of Vegetable Transplants with the Controlled Water Table Irrigation System
Authors: Buxton Jack W. , Jia Wenwei
Published: February 2019

Cabbage seed was germinated and grown to transplanting size in a 98-cell tray using an automatic irrigation system based on the principle of maintaining a constant water table (CWT) relative to the growing medium in transplant trays. Seedlings obtained a nutrient solution from a capillary mat with one end suspended in a trough containing the solution. The distance between the nutrient solution surface and the transplant tray bottom was regulated with a water level controller. The nutrient solution was resupplied from a larger reservoir. A polyester material on top of the capillary mat allowed solution movement to the roots but prevented root penetration into the mat. The water table placement below the tray determined the water content in the growing medium. Seedling growth was evaluated using two growing media combined with two water table placements. Excellent quality seedlings were produced; the CWT irrigation system satisfactory provided water and nutrients for the duration of the crop. The only problems observed were dry cells, less than 2%, because of no media–mat contact and algae growth on the media surface using the higher water table. The CWT irrigation system is adaptable to existing greenhouse vegetable transplant production systems. It is automatic and can provide a constant optimum amount of moisture for seedling growing. It can be adjusted for phases of seedling growing such as more water during germination and can create water stress near transplanting time to either harden off or hold plants because of unfavorable planting conditions.