bluuebunny/crossref_metadata_2025 huggingface dataset:
Root Growth of Seedlings and Microcuttings of Western Black Cherry Grown in Compacted Soil
Authors: Oddiraju Venu G. , Beyl Caula A. , Barker Philip A.
Published: February 2019

Seedlings and microcuttings taken from two western black cherry (Prunus serotina var. virens Ehrh.) trees, one with profuse roots and one with scant roots, were grown in either normal or compacted soil to determine if the variation in the growth of fine and coarse roots under conditions of compaction could be attributed to genetic factors or method of propagation. An image processing system [Image Capture and Analysis System (ICAS)] was used to classify and measure the roots. There was a significant reduction in the surface area of fine roots, total surface area, and root dry weight after 12 weeks of compaction, but the effect on coarse roots was nonsignificant. Initial differences in the larger surface area of coarse roots of seedlings vs. for those of microcuttings disappeared over the course of the experiment. However, the surface areas of fine roots and the total surface area were significantly larger and root dry weight was higher for seedlings than for microcuttings, even at the end of the 12-week treatment period. The surface areas of fine and coarse roots, total surface area, and dry weight of roots were similar at the end of the experiment, regardless of genotype.
In Vitro Shoot-apex Grafting of Mulberry (Morus alba L.)
Authors: Ma Fengtong , Guo Chunhui , Liu Yurong , Li Minxia , Ma Tiejun , Mei Lixin , Hsiao Andrew I.
Published: February 2019

A protocol to achieve in vitro shoot apex grafting of Morus alba is described. Decoated seeds were incubated at 26C on Murashige and Skoog (MS) medium in 0.2% Gelrite for 10 days in darkness and 2 weeks with a 16-hour daily photoperiod. The shoots were excised from seedlings, and the shoot bases were soaked in 500 μm IBA for 30 min. The shoots were transferred to a vermiculite support medium moistened with half-strength MS salts and were incubated at 26C in darkness for 10 to 12 days. Seedling stems, now ≈8 mm in circumference, were used as rootstocks. Shoot apex scions 1 to 2 mm long were taken from adult plants of several major commercial cultivars of M. alba. The average successful frequency of in vitro shoot-apex grafts was 75% to 80%, indicating that thickening the circumference of rootstock stems was a critical factor. Chemical name used: indole-3-butyric acid (IBA).
High-frequency Shoot Regeneration from Roots of Japanese Persimmon
Authors: Tetsumura Takuya , Yukinaga Hisajiro
Published: February 2019

Microshoots of Japanese persimmon (Diospyros kaki L. cv. Jiro) were rooted in vitro. The roots were excised and cultured on solidified Murashige and Skoog medium. After 20 days of culture, adventitious shoots formed spontaneously and directly from the roots. Of all the tested cytokinins, 10–5 m zeatin in combination with 10–8 m IAA was the most effective in stimulating production of adventitious shoots. CPPU and 2iP also were effective cytokinins. Addition of a high concentration of auxin, especially 2,4-D, to the medium inhibited adventitious shoot formation. The percentage of root segments forming adventitious shoots increased with increasing segment length. Almost all of the longest roots (4 to 6 cm) formed adventitious shoots. Chemical names used: 6-benzyladenine (BA); 2,4-dichlorophenoxyacetic acid (2,4-D); indole-3-acetic acid (IAA); 2-isopentenyladenine (2iP); N-phenyl-N′-(2-chloro-4-pyridyl)urea (CPPU).
Breeding Aspects in Alstroemeria L.
Authors: De Jeu Marjo J. , Kamstra Silvan , Kuipers Anja , Jacobsen Evert
Published: February 2019

The genus Alstroemeria L. is endemic in South America, mainly in Chile and Brazil. Crossing barriers of mainly postfertilization origin hampered widely inter-specific hybridization. Culturing the ovules 2 days after pollination in an hormone-free MS medium with 9% saccharose for 6 weeks and hereafter transfer to a MS medium with 3% saccharose gives germination of the fertilized ovules. In a diallel cross with 5 Chilean and 2 Brazilian species 39 combinations failed, whereas after early ovule culture hybrid plants were obtained in 27 of the incongruous combinations. The rate of success varied between 0.4%–22.5% depending on the species combination. The hybrids were tested in in vitro stage for their true hybridity using isozyme analysis and/or genomic in situ hybridization of chromosomes (GISH). This method can easily be applied in hybrids between Chilean and Brazilian species. Backcrosses were made using the ovule culture again and in the combination (A. aurea × A. inodora) × A. inodora plants were obtained although the pollen fertility was very low (1%–5%). By using species-specific repetitive probes in in situ hybridization (FISH) chromosome specific patterns were obtained enabling us characterizing the backcross hybrids for their chromosome constitution. By this method we can identify our breeding material for special traits linked with identified chromosomes.
Resistance of Pelargonium Species to the Fungal Pathogen Botrytis cinerea
Authors: Uchneat Michael S. , Craig Richard
Published: February 2019

Botrytis cinerea is an economically important fungal pathogen of Pelargonium species. We are currently studying this plant–pathogen interaction to identify mechanisms of host resistance. Our ultimate objective is to develop commercial Pelargonium genotypes with enhanced resistance to this pathogen. Though all stages of production may be affected by this pathogen, we are investigating foliar and floral resistance of mature plants. Through simple assays, over 200 genotypes have been evaluated for foliar resistance, and more than 100 genotypes have been evaluated for floral resistance. Resistant and susceptible control genotypes have been identified for diploid and tetraploid P. ×hortorum and P. peltatum; these genotypes are being investigated to elucidate mechanisms of resistance. The diploid ivy accession 86-23-1 and the tetraploid zonal geranium `Fox' have the greatest foliar resistance among the genotypes evaluated. The diploid P. ×hortorum `Ben Franklin' has the greatest floral resistance among the evaluated genotypes. Foliar and floral resistance appear to be inherited as separate traits. Foliar resistance is manifested as a two day delay in symptom expression when compared to susceptible genotypes. Foliar resistant accession 86-23-1 has a cuticle with 150% the mass of other Pelargonium genotypes. This difference may be responsible for the observed resistance. Cuticle mass does not appear to be important in floral resistance.
Pretransplant Temperature Regime and Container Size Alter Strawberry Plant Morphology
Authors: Bish Eric B. , Cantliffe Daniel J. , Chandler Craig K.
Published: February 2019

Containerized strawberry transplants offer an alternative to problematic bare-root transplants, which often have variability in flowering and vegetative vigor. Containerized transplants were propagated in three different container cell sizes (75, 150, and 300 cm3) and grown at two different temperature regimes for 2 weeks prior to planting (25/15 and 35/25°C day/night). Bare-root transplants from Massachusetts and Florida were graded into small, medium, and large plants based on crown size (8, 12, and 16 mm respectively). Plug transplants grown at 25/15°C had greater root dry weights than transplants grown at 35/25°C. Root imaging analysis (MacRHIZO) showed that the differences in dry weight were due to root area, not root tissue density. Crown dry weight increased with increasing cell size. Plug transplants grown at 25/15°C flowered earlier and had greater production than any other treatment. The 75 cm3 cell size grown at 35/25°C produced greater December strawberry production than larger cell sizes at the same temperature regime; however, the 75 cm3 cell size had decreased January strawberry production while the larger cell sizes had increased production. Larger plug cell sizes had significantly greater production than smaller plugs throughout the season, whereas larger bare-roots had greater production only early in the season. Containerized plug transplants therefore offers a viable alternative to problematic bare-root transplants.
What it Means to be a Certified Professional Horticulturist
Authors: Gilbertson-Ferris Terry
Published: February 2019

ASHS established a Certified Professional Horticulturist program in 1992 through ARCPACS. Most plant science-related disciplines have their certification programs based in ARCPACS. Professional Certification establishes and promotes professionalism within a discipline. In an era when the general public tends to question the credibility of the scientific community, certification is a valuable tool to establish one's credentials to society. To become certified, the ASHS Certified Professional Horticulturist program required individuals to meet core educational curriculum requirements, document experience in the field, and provide professional references documenting one's professional abilities. Individuals must adhere to the professional Code of Ethics and document continuing education involvement in order to maintain their certification.
Expanding Horticulture Programs through Off-campus Partnerships
Authors: Schutzki Robert E. , Gruber Susan , Norman L. Andrew
Published: February 2019

Michigan State Univ. (MSU) offers 10 certificate programs through the Institute of Agricultural Technology. These programs are campus based, approximately three semesters in length, and include a professional internship. Efforts were made in horticulture to expand programs into major population centers through joint programs with community colleges. Cooperative agreements were developed with Grand Rapids Community College and with Northwestern Michigan College in Traverse City. Issues addressed in the agreements include recruiting, admissions, advising, financial aid, integration of curriculum from both institutions, distance-learning delivery through the CODEC system, instructional commitments from campus-based and adjunct faculty, procedures for transfer to bachelor's degree program at MSU, and graduation. The symbiotic relationship between the institutions has expanded curriculum opportunities in the local areas, increased accessibility to MSU Horticulture programs, and better serves the nontraditional student. Outreach efforts for academic programs complement the traditional outreach that has occurred through the Cooperative Extension Service.
Using Focus Groups for Landscape Horticulture Curriculum Revision
Authors: Barton S.S. , Smith W.G. , Swasey J.L.
Published: February 2019

Curriculum revision for science-oriented degrees can be based on input from research journals and discipline-oriented society meetings, but the professional nature of a landscape horticulture degree requires more detailed industry input. The curriculum revision at the Univ. of Delaware started with discussions amongst faculty who were concerned with the current plant science curriculum. A mail survey of alumni from 1984 to 1993 and employers of Univ. of Delaware Plant and Soil Sciences Dept. graduates was conducted in 1994. Survey results were evaluated and incorporated into the development of two curricula: plant biology and landscape horticulture. Focus groups were used to seek industry input for the landscape horticulture curriculum. Two focus groups—established professionals in the landscape horticulture industry and recent graduates from the Plant and Soil Sciences Dept. with landscape horticulture positions—were convened in December 1995. Focus group members received a packet of information about the department including the proposed curricula prior to the meeting. A group of faculty presented information about departmental facilities, faculty, academic opportunities and practical experiences and accomplishments. The previous survey results and proposed curricula were reviewed. A professional facilitator, using a moderator's guide prepared by faculty members, led each focus group discussion. Tapes from each discussion were transcribed and summarized. Original transcriptions and executive summaries were distributed to focus group participants and faculty. Suggestions from focus group participants were incorporated into the final curriculum. Problems associated with the focus group technique include a reluctance of faculty to accept outside opinions, a reluctance to publicly air departmental concerns, and the cost associated with a professional facilitator and rented facilities. However, the focus group technique provided significant feedback in a short period of time and helped build liaisons with industry constituents by including them in the process. Several focus group participants will be invited to join an advisory council for the department.
A Taste of the Tropics Spices Up Student Interest
Authors: Storey J. Benton
Published: February 2019

Tropical horticultural crops can be the spark that builds student interest in horticulture. They are a refreshing alternative to the temperate crops that most of our curricula are necessarily built around. Students who become familiar with production problems and opportunities between 30° north and south latitudes are better equipped to compete in the world economy. HORT 423 covers tropical ecology, soils, atmosphere, and many major crops. Beverage crops studied are cacao, coffee, and tea. Fruit and nut crops include bananas, mango, papaya, pineapple, dates, oil palm, coconut, macadamia, cashew, and Brazil nuts. Spices such as vanilla, black pepper, allspice, nutmeg, mace, cinnamon, cassia, and cloves are studied. Subsistence crops such as cassava, yam, taro, pigeon peas, chick peas, vegetable soy beans, and black beans round out an exciting semester that draws students. HORT 423 is a 3-hour-per-week lecture demonstration course supplemented with slides from the tropical countries. Many students simultaneously enroll in a 1-hour HORT 400 course that is taught during the 1-week spring break in a tropical country. Recent trips have been two each to Costa Rica and Guatemala. These study trips are gaining in popularity. For more information about HORT 423 consult the world wide web at http://http.tamu.edu:8000/~c963/a/h423main.html.
Field Tolerance of Bell Pepper Cultivars to Bacterial Leaf Spot under Epidemic Conditions
Authors: Rowell Brent , Jones R. Terry , Nesmith William
Published: February 2019

Bacterial leaf spot (BLS) caused by Xanthomonas campestris pv. vesicatoria is the scourge that has devastated and continues to limit expansion of both fresh-market and processing pepper production in Kentucky. Fourteen new BLS-resistant varieties and breeding lines were evaluated together with two standard (susceptible) varieties in 1995 at two locations. Twenty advanced lines and commercial varieties were tested at the same locations in 1996. All entries were exposed to an induced BLS epidemic at one location, but were kept disease-free at the second location. Epidemic development was slow and field resistance to four races of BLS was high for all but one of the lines tested, which claimed resistance to races 1, 2, and 3 in 1995. Six entries performed well both under BLS epidemic conditions and in the disease-free environment in 1995. Cultivars with resistance to only race 2 or races 1 and 2 of the pathogen were no different from susceptible checks in terms of yields and disease resistance and were not tested in 1996; combined results form 1995 and 1996 are discussed.
Influence of Nitrogen Fertilization and Plastic Mulches on Insect Populations and Disease Incidence on Bell Peppers (Capsicum annuum)
Authors: Fava E. , Janik D. , Madramootoo C. , Stewart K.A.
Published: February 2019

Production of red bell peppers (Capsicum annuum L. cv. King Arthur) is relatively new to Quebec, and management techniques need to be further developed in terms of insect and disease control as well as fertigation techniques. The purpose of the experiment was to compare the fertigation of peppers using either the conventional method (weekly fertigation) or fertigation based on the readings of the SPAD 502 chlorophyll meter. The experiment compared the effects of these fertigation treatments, with respect to insects and diseases, on either a silver or black mulch. The study done in 1995, demonstrated that using the chlorophyll meter saved 28 kg N/ha compared to the weekly fertigated plants. However, this decrease did not affect the population of insects or the disease incidence on the plants. The main differences occurred between the black and silver mulch treatments for aphid populations. Plants on silver mulch had significantly lower numbers of aphids than the other treatments. Plants on black mulch also had low aphid population compared to plants grown on bare soil. The relationship between silver mulch and viruses or tarnished plant bug were not as apparent. However, the viral infections and tarnished plant bug populations on the plants tended to be lower than those on most of the black mulch treatments. Sunscald was not influenced by mulch or fertigation treatments. This may be partly attributed to the amount of leaf area. The number of fruit invaded by European corn borer was too low to draw any conclusions. Blossom end rot, sclerotinia, and bacterial spot were not present in the field in the 1995 season. The results from the 1996 season should further elucidate these results.
Susceptibility of Seven Tomato Varieties to Spodoptera littoralis (Lepidoptera: Noctuidae) and Colorado Potato Beetle (Coleoptera: Chrysomelidae) Leaf Infestation
Authors: Antonious George F. , Byers Matthew E. , Snyder John C. , Dahlman Douglas L.
Published: February 2019

The development and deployment of crop varieties that resist or tolerate insect attack is one tactic of pest management that can eliminate one or more spray applications per season, a significant savings to the grower. Seven tomato, Lycopersicon esculentum Mill. cultivars (Marmand, Edkawy, VF-145, GS-27, Pakmore-B, Flordade, and UCX) were evaluated under greenhouse conditions for differences in mortality and feeding behavior (leaf-area ingested) of the 4th instar larvae of Spodoptera littoralis (Boisd) and the Colorado potato beetle, Leptinotarsa decemlineata (Say). The most resistant cultivars to S. littoralis during two summer seasons, 1990 and 1991, were Edkawy and UCX (37% mortality) and VF-145 (33% mortality). Mortality was least (20%) on the F1 hybrid GS-27, indicating that GS-27 was the most favorable cultivar for S. littoralis. L. decemlineata larvae reared on excised tomato leaflets of the same varieties indicated similar trends. Factors responsible for greater resistance of Edkawy and UCX to S. littoralis and L. decemlineata are under investigation.
Postharvest Longevity of Antirrhinum majus L. Cut Flowers as Influenced by Backcrosses to a Short-lived Recurrent Parent and Harvest Time
Authors: Schroeder Kenneth R. , Stimart Dennis P.
Published: February 2019

An inbred backcrossing approach was taken to transfer long postharvest keeping time of cut flowers from a white inbred line of Antirrhinum majus L. into a yellow short-lived inbred line. Three backcrosses to the short-lived recurrent parent were done followed by three generations of selfing by single-seed descent. Plants from 56 accessions of BC1S3 through BC3S3 were grown twice (June and August 1995) in a greenhouse and flower stems harvested for postharvest longevity evaluation. Postharvest evaluation was done in deionized water under continuous fluorescent light. Longevity was determined as the number of days from cutting to discard when 50% of the open florets on a flower stem wilted or turned brown. One yellow accession was retrieved that was not significantly different in postharvest longevity from the white long-lived parent. Environment substantially influenced postharvest longevity over harvest dates. Possible causes for variation of postharvest keeping time will be presented.
Effects of Heat Stress on Floral and Vegetative Development in New Guinea Impatiens
Authors: Strope Kerry M. , Strefeler Mark S.
Published: February 2019

Fifty-three commercial New Guinea Impatiens cultivars (Impatiens hawkeri Bull.) from six different breeding series were tested for level of heat tolerance. Five floral (flower number, flower length, flower width, floral dry weight, and flower bud number) and five vegetative characteristics (leaf dry weight, stem dry weight, total dry weight, number of nodes, and number of branches) were evaluated with emphasis placed on continued flowering under long term heat stress. Significant differences among cultivars were found in each data category (P ≤ .0001). Flower number varied from 0 to 6, flower length varied from 10 to 51 mm, flower width varied from 10 to 47 mm, floral dry weight varied from 0 to 0.5 g, and flower bud number varied from 0 to 14. Four heat tolerant (Celebration Cherry Red, Celebration Rose, Lasting Impressions Shadow, and Paradise Moorea) and three nonheattolerant (Lasting Impressions Twilight, Danziger Blues, and Pure Beauty Prepona) cultivars were identified using a Weighted Base Selection Index. These cultivars were used as parents in a full diallel crossing block with reciprocals and selfs. One hundred seedlings from each of 49 crosses were evaluated for heat tolerance. General and specific combining abilities of the parents were evaluated as was heritability. It was found that the four heat tolerant cultivars had higher general combining abilities. Heat tolerance has low heritability and is controlled by many genes. Superior genotypes were identified (selection intensity of 0.05) and retained for further evaluation and breeding efforts.
Reduction of 1-Aminocyclopropane-1-carboxylic Acid (ACC) in Pollen by Expression of ACC Deaminase in Transgenic Petunias
Authors: Lindstrom Jon T. , Lei Chih-Hsien , Woodson William R.
Published: February 2019

Petunia hybrida pollen accumulates significant levels of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) late in development. This pollen ACC is thought to play a role in the rapid burst of ethylene produced by pollinated pistils. To investigate this further, we have expressed the ACC deaminase gene product from Pseudomonas in transgenic petunias under the control of three different promoters including CaMV-35S, LAT52, and TA29 directing construction expression, pollen-specific expression and tapetum-specific expression, respectively. Several transgenic plants expressing the LAT52-ACC deaminase gene exhibited significant reduction of ACC in pollen. Two independent transformants contained only trace amounts of ACC in pollen. In contrast, the other promoters did not lead to reduced ACC in pollen. Pollination of wild-type pistils with pollen from LAT52-ACC deaminase plants elicited increased ethylene similar to wild-type pollen. Fecundity was unaffected by the reduction in pollen ACC content. Taken together, we conclude pollen-borne ACC is not the elicitor of pollination-induced ethylene production by pistils.
Expression of the RolC Gene in Transgenic Plants of Salpiglossis sinuata L.
Authors: Lee Chiwon W. , Wang Lijuan , Ke Shanqiang , Qin Mingbo , Cheng Zong-Ming
Published: February 2019

The phenotypic expression and inheritance of the rolC gene in the transgenic plants of Salpiglossis sinuata L. were investigated. The chasmogamous salpiglossis plants with solid yellow flower color (ccrrDD) were transformed with Agrobacterium tumefaciens strains LBA4404 and EHA101 carrying rolC, GUS, and NPTII genes via a leaf disc co-cultivation system. The transgenic plants were shorter in plant height, produced more branches with a compact growth habit, and developed smaller flowers and narrower leaves as compared to the control plant. While the transgenic plants showed the same corolla color and color shades as the parental line, they became male sterile. A backcross between a male-sterile transgenic plant (ccrrDD plus rolC) and a nontransformed red-flowering line (ccRRDD) produced a progeny with red flower color and the same altered growth habit as the transgenic female parent. Only 4 out of 32 plants in this progeny population showed the negative GUS staining as well as the non transgenic phenotype. These results suggest that at least two copies of the rolC gene were integrated into one homologous chromosome pair during transformation and that a cross-over event may have occurred during meiosis.
Effects of Irrigation and Nitrogen Fertilizer Rate on the Annual Culture of Globe Artichoke in Quebec
Authors: Husain S. , Stewart K.
Published: February 2019

This research is focused on developing production techniques for globe artichoke (Cynara scolymus L.) production in Quebec, Canada. It is a herbaceous perennial grown for its immature flower bud. The globe artichoke is usually propagated vegetatively because plants grown from seed lack uniformity. Furthermore, only a small percentage of plants grown from seed flower due to insufficient cold treatment for vernalization. Artichokes cannot be grown as perennials where winter temperatures are below –10°C. The objectives are to determine the optimum nitrogen fertilizer requirements, and irrigation levels, and to evaluate two widely grown cultivars. Globe artichoke was grown in the greenhouse from seed in March 1995. Seedlings were naturally vernalized and transplanted to the field in mid May on silver plastic mulch. A split-split-plot design was used with three replications. At the rate of 2.5 cm per week water was applied via drip irrigation to one half of the field and the other half received irrigation based on tensiometer readings. The nitrogen treatments were 100, 200, and 300 kg/ha of N of which two-thirds was incorporated preplant. The remainder was applied as a sidedress a month later. In this study, `Imperial Star' (IS) produced uniform plants from seed and a higher percentage of plants produced flower heads (bolted) than `Green Globe Improved' (GG Imp). The harvest period began on 1 Aug. for IS and 9 Aug. for GG (Imp). It ended on 18 Sept. for both cultivars. Eighty-six percent of the IS plants produced buds compared to thirty-nine percent for GG (Imp). Both cultivars produced a high percentage of small buds. Yield from plants that received 2.5 cm of water weekly was greater than the irrigation treatment based on tensiometer readings. Data on nitrogen treatments, days to flowering and harvest, flower bud quality, weight and size of terminal buds, and total yield are being statistically analyzed using SAS.
Wind Protection and Planting Date Affect Snapbean Growth and Yield
Authors: Suratman Mohammed Nazip , Hodges Laurie , Brandle James R. , Hubbard Kenneth G.
Published: February 2019

The effects of windbreak shelter on growth, total, and marketable yield of snapbeans were evaluated during 1994 and 1995. Plantings of `Strike' and `Rushmore' were made at roughly 2-week intervals in exposed plots and plots protected by tree windbreaks. Air and soil temperature, relative humidity, wind speed and direction were monitored continuously and averaged hourly. Wind speed in shelter was 36% and 43% that of open field wind speed in 1994 and 1995 respectively. Air and soil temperatures were higher in sheltered areas. Sheltered plants had significantly higher total dry weight and leaf area index, and significantly greater total internode lengths than exposed plants. For each year, sheltered plant means for both total and marketable seasonal yields were significantly higher compared to exposed plants. Mean pod yields were significantly affected by planting date and cultivar. `Rushmore' produced significantly higher total and marketable yields than `Strike'. The two cultivars responded similarly to sheltered and exposed production environments. Shelterbelts can increase total and marketable yields, with greatest increases early and late in the growing season, an additional advantage since market prices tend to be higher at these times.
Effects of Irrigation System on Pepper Transplant Production
Authors: Galloway Bethany A. , Schultheis Jonathan R. , Monks David W.
Published: February 2019

A study was conducted in Fall 1995 at the Horticultural Greenhouse, North Carolina State University, to examine growth of banana (`Banana Supreme'), bell (`Camelot'), and jalapeno (`Mitla') pepper under overhead (OI), ebb and flood (EF), and float (F) irrigation systems. Plant emergence was fastest in the float system, but slowest in the OI system. Irrigation treatment was highly significant for all weekly sampling dates for root and shoot fresh weight, root and shoot dry weight, root length, stem diameter, height, and leaf area. Stem diameter of F plants was greater than both EF and OI. However, EF and OI plants had similar diameter regardless of sampling date. Root fresh weight did not differ among pepper cultivars. By 39 days after planting (DAP), F plants had 33% greater root fresh weight, by 46 DAP they were almost double, and at 53 DAP they were 44% larger compared to the EF treatment. Float plants had greatest root length, but EF and OI plants had denser root mass (visual observation) in the transplant container cell. At 46 and 53 DAP, EF plants were generally taller than OI plants, and by 60 DAP this difference was almost 30%. Float plants were about double the height of the EF and OI plants and this difference continued until the experiment terminated. Bell pepper had the greatest shoot fresh weight at all sampling dates after 25 DAP, while jalapeno was greater than banana only up to 39 DAP. Beyond 39 DAP, banana pepper fresh weight surpassed jalapeno pepper. By 53 DAP, shoot fresh weight of float transplants were almost 3 times greater than EF or OI plants. Float plants reached a satisfactory size (137 mm height) for transplanting by 8 weeks. Height of EF and OI plants at this time was 68 and 48 mm, respectively. This experiment is being repeated in Spring 1996.
Factors Affecting the Loss of Viability when Maize Grains are Imbibed and then Redried
Authors: Fang Jian , Roos E.E. , Walters C.T. , Moore F.D.
Published: February 2019

Seed hydration and dehydration affects many physiological reactions, including priming, accelerated aging, and desiccation intolerance. Maize grains were repeatedly imbibed and desiccated, or imbibed and held for periods of time to identify the role of each of these factors. Grains were equilibrated to 12% moisture content (mc) and subjected to cycles (up to 14) of hydration (2 hours) and immediate dryback, or one hydration of 2 to 12 hours and dryback. Germination and vigor (root length and leachate conductivity) were determined after each cycle. Grains adjusted to three levels of hydration (27%, 34%, and 40%) were held for up to 10 days in a sealed desiccator. Each day samples were taken and either dried to the original mc prior to evaluation, or evaluated immediately as above. With each cycle of 2 hours of imbibition, seed mc increased (22% to 39%). Root lengths increased (priming effect) during the early cycles of imbibition and dryback. Decline in germination after eight cycles was a result of either accelerated aging or desiccation intolerance. Based on the results of the holding study, both factors contributed to deterioration, but desiccation intolerance was only observed when mc was above 27%. Conductivity of grain leachates was not correlated with loss of germination or vigor in whole grains, but appeared to reflect deterioration in isolated embryos.
Nonchemical Weed Control in Cabbage
Authors: Orzolek M.D. , Murphy J.H. , Otjen L.
Published: February 2019

Early weed infestation in vegetable crops reduces both early and total marketable yield and quality. Even if escape weeds (12 inches tall or larger) are later killed by a postemergence herbicide application, their skeletons can cause yield loss due to competition for light, temperature modification within the plant canopy, and interference with fungicide and insecticide applications. In addition, weeds can also serve as a reservoir for insect and disease organisms, especially viruses. Experiments in nonchemical weed control in cabbage were conducted at the Horticulture Research Farm, Russell E. Larson Research Center, Rock Springs, Pa., from 1993 to 1995. In addition to weedy and hoed check plots, flaming weeds at 2- to 4-leaf stage of growth with propane gas burners and planting annual ryegrass (Lolium multiflorum) between the rows of cabbage, living mulch, were evaluated during 3 years. The cabbage cultivar Rio Verde was transplanted generally between 15 June and July during each year. Both flaming and living mulch treatments produced yield and head quality similar to the hoed check. Management and timing of ryegrass planting in relation to cabbage establishment is very critical for success with living mulch. Flaming requires straight rows of cabbage or other crop, tractor with driver that can maintain a straight line, and burners that are aligned to burn weeds and not the crop. Results will be discussed.
Rorippa sylvestris, Creeping Fieldcress: A Threat to Production Ornamentals and Its Control
Authors: Elmore C.L. , Kuhns L. , Harpster T.
Published: February 2019

The perennial Brassicaceae specie Rorippa sylvestris has been described as a weed in Scandinavian forest nurseries and in Irish, Canadian, and American nurseries. It was first introduced into Philadelphia, Pennsylvania in about 1818 and has been reintroduced repeated since. It produces little seed unless there are two different introductions together because they are self incompatible. Propagation is principally by rhizome segments from soil or ornamental propagation material. Greenhouse studies to evaluate the depth of emergence of rhizome pieces indicated that 3-cm segments would routinely emerge from depths of at least 24 cm. Allocation to shoot, roots, stems or shoots form rhizomes varied greatly by depth. The greatest shoot weight was from shallow depths with increasing new shoots from rhizomes and stem weights from deeper depths. Preemergence control was excellent with dichlobenil granules at 3 or 6 lb/A, isozaben at 1 or 2 lb/A and the geotextile/herbicide (Biobarrier). The geotextile (Typar) fitted as collars alone were not effective. Trifluralin incorporated into the surface 2 inches at 2 lb/A was effective but did allow some emergence. Trifluralin plus isoxaben or oryzalin plus isoxaben were also effective at rates of 2 plus 0.5, 4 plus 1, or 6 plus 1.5 lb/A, or 3 plus 1, 4.5 plus 1.5, or 6 plus 2 lb/A, respectively, of the two herbicide combinations. Metolachlor at 3, 4.5, or 6 lb/A was ineffective for preemergence control of 3 cm rhizome pieces. Post emergence control was not commercial with 2,4-D, triclopyr, clopyralid or a combination of the latter two, when treated in the 6 to 8 leaf stage with 0.25% or 0.5% solutions. Once creeping field cress is established in ornamentals it is very difficult to control.
The Relationship between Leaf Nitrogen Content and Photosynthesis in Apple Leaves
Authors: Cheng Lailiang , Guak Sunghee , Fuchigami Leslie H.
Published: February 2019

Fertigation of young Fuji/M26 apple trees (Malus domestica Borkh.) with different nitrogen concentrations by using a modified Hoagland solution for 6 weeks resulted in a wide range of leaf nitrogen content in recently expanded leaves (from 0.9 to 4.4 g·m–2). Net photosynthesis at ambient CO2, carboxylation efficiency, and CO2-saturated photosynthesis of recently expanded leaves were closely related to leaf N content expressed on both leaf area and dry weight basis. They all increased almost linearly with increase in leaf N content when leaf N < 2.4 g·m–2, leveled off when leaf N increased further. The relationship between stomatal conductance and leaf N content was similar to that of net photosynthesis with leaf N content, but leaf intercellular CO2 concentration tended to decrease with increase in leaf N content, indicating non-stomatal limitation in leaves with low N content. Photosynthetic nitrogen use efficiency was high when leaf N < 2.4 g·m–2, but decreased with further increase in leaf N content. Due to the correlation between leaf nitrogen and phosphorus content, photosynthesis was also associated with leaf P content, but to a lesser extent.
The Effect of Light Intensity before Harvest on Phenethyl Isothiocyanate Concentration in Watercress (Nasturtium officinale R.Br.) Depends on Photoperiod
Authors: Palaniswamy Usha , McAvoy Richard , Bible Bernard
Published: February 2019

Watercress plants were grown in growth chambers at 15°C or 25°C and either an 8- or 12-hour photoperiod (PP). The photosynthetic photon flux (PPF) was 265 μmol·m–2·s–1 in all chambers, but beginning 1 week before harvest, half of the plants in each chamber were subjected to a higher PPF (434 μmol·m–2·s–1). At harvest, watercress leaves and stems were analyzed for phenethyl isothiocyanate (PEITC) content. Watercress grown at 25°C, the 12-hour PP, and 1 week of high PPF produced the highest PEITC concentration in leaves and stems, and plants grown at 15°C, the 8-hour PP, and the low PPF until harvest produced the lowest PEITC concentration. Plants grown at the 8-hour PP, then exposed to 1 week of high PPF, produced 57.3% and 45.9% greater PEITC at 25 and 15°C, respectively, then plants exposed to the low PPF until harvest. However, plants grown at the 12-hour PP and subjected to 1 week of high PPF produced PEITC levels similar to plants grown under the low PPF at 25 and 15°C. At 25°C, plants grown under the low PPF and the 12-hour PP produced 62% greater dry mass than plants exposed to 1 week of high PPF and the 8-hour PP, but did not differ in PEITC content. Thus, the effect of 1 week of high PPF on PEITC concentration depended on photoperiod.
Using Video Thermal Image Analysis to Monitor Stomatal Opening in Fruit Crops
Authors: Flore James A. , Sage Lynn
Published: February 2019

This study demonstrates that thermal image analysis can be used to localize stomatal opening and closing on leaves of apple, and cherry. An attached leaf was placed in an environmental chamber used for gas exchange and leaf temperature was monitored with cromel-constantan thermocouples, (0.08 mm) pressed against the underside of the leaf, or with an Inframetrics 600 thermal image analyzer that was focused on the upper side of the leaf. Radiation was monitored in the 8–12 μm range and the image was recorded on video tape. A two-degree temperature difference due to stomatal opening was detected. Stomatal opening as monitored by gas exchange was correlated significantly with leaf temperature. Under steady state conditions, stomata from cherry oscillated at 20-minute intervals. Stomata opened and closed uniformly. Factors investigated were light, carbon dioxide, ABA, and water stress. In all cases changes in temperature correlated with stomatal opening and closing. Response time to a change in environment was less than 10 minutes. The practical implications of this study are discussed.
Comparison of Single Leaf and Whole Canopy Gas Exchange Rates of Tomato and Soybean throughout Stand Development
Authors: Stutte G.W. , Yorio N.C.
Published: February 2019

The relationship between whole canopy and single leaf measurements of gas exchange has not been well documented. Two experiments were conducted in the Biomass Production Chamber at Kennedy Space Center (20-m2 growing area) to compare whole canopy versus single leaf net carbon assimilation rate (Anet) measurement of a stand of tomato (Lycopersicon esculentum Mill. cv. Reimann Philipp) and soybean [Glycine max (L.) Merr. cv. Hoyt]. Both crops were grown under a 12/12 hour photoperiod under HPS lamps at PPF of 800 (mol·m–2·s–1, at 26/22°C (light/dark), and constant 65% RH for 90 days. CO2 concentration was controlled to 1200 (mol·mol–1 during the light cycle. Midday measurements of Anet of single leaves were obtained weekly from upper canopy leaves using a portable photosynthesis system. Whole canopy measurements of Anet were calculated daily from CO2 addition data obtained at 5-minute intervals by the BPC monitoring and control system. Single leaf rates exceeded whole canopy rates prior to full canopy coverage then averaged 0.63 of whole canopy for both species during the period of full canopy coverage. Results suggest that reliable estimates of canopy gas exchange can be obtained from single leaf measurements under relatively constant environment conditions.
Changes in Freezing Tolerance, Water Potential, and Gene Expression of Poncirus trifoliata `Rubidoux' Seedlings Exposed to Acclimating Low Temperatures and Long Days
Authors: Tignor Milton E. , Davis John M. , Davies Frederick S. , Sherman Wayne B.
Published: February 2019

Poncirus trifoliata is a comparatively hardy, cross compatible, and graft compliant relative of Citrus. The citrus industry in Florida has suffered immense economic losses due to freezes. Although much research has been done in citrus freeze hardiness, little work has been on the early induction of freeze tolerance by low temperature. Poncirus trifoliata `Rubidoux' seedlings were germinated in perlite under intermittent mist at about 25°C and natural daylight conditions in a greenhouse and grown 2 weeks. See dlings were then transferred into a growth chamber at 25°C and 16 hour daylength for 1 week. Temperature was lowered to 10°C and tissue samples were collected at 0, 6, 24, and 168 hours. Freezing tolerance, at –6.7°C as determined by electrolyte leakage, and stem (leaves attached) water potential, measured using a pressure bomb, were also recorded for a subset of seedlings for the above intervals. After exposure to low temperature for 48 hours a red coloration became visible at the petiole leaflet junction an d at the buds, with subsequent exposure to low temperature the coloration spread to the leaves. Clones for phenylalanine ammonia lyase (PAL), 4-coumarate:CoA ligase (4CL), and chlorophyll ab binding protein (CAB), and chalcone synthase (CHS) were used to probe RNA isolated from P. trifoliata. PAL and 4CL transcripts increased in response to the low temperature. Significant increases in freeze hardiness occurred within 6 hours in the leaves, and increases continued for up to one week. Water potential increased from –0.6 to –2.0 MPa after 6 hours, then returned to –0.6 MPa after 1 week. These data indicate that increases in freezing tolerance and changes in water potential and gene expression can be detected shortly after low temperature treatments are imposed on P. trifoliata seedlings.
Sugars and Chilling Tolerance in Two Cultivars of Dry and Germinating Cucumber Seed
Authors: Jennings Paul H. , Stushnoff Cecil
Published: February 2019

Various carbohydrates have been shown to be associated with stress tolerance in some plant species. Specifically, the content of soluble sugars have been correlated with desiccation tolerance and winter hardiness. We have previously demonstrated that radicles of cucumber seed become progressively more sensitive to chilling injury during the early stages of germination and that cultivar differences exist. Sucrose, raffinose, and stachyose contents of `Poinsett 76' and `Ashley' seed were determined in dry seed during imbibition and at three stages of radicle emergence. The more chilling-tolerant cultivar (Ashley) contained lower raffinose and higher stachyose contents than the less chilling-tolerant `Poinsett 76'. In both cultivars, the contents of raffinose and stachyose declined dramatically between the 1-mm and 5- to 7-mm stage of radicle emergence. At the 1-mm stage, when cultivar chilling-tolerance differences are most pronounced, `Ashley' appears to have a higher content of stachyose and lower raffinose content.
Programming Flowering of the Phalaenopsis Orchid
Authors: Wang Yin-Tung
Published: February 2019

Blooming Phalaenopsis orchids have become a popular pot plant in recent years. Plants start producing spikes after experiencing cool air in early fall, bloom in early spring, and become limited in supply after April when market demand is strong. Deferring spiking and flowering by maintaining the greenhouse air constantly above 28°C is cost prohibitive. Previous research has discovered that plants must be given light while being exposed to cool air to induce spiking. In Fall 1994, 2-year old Phalaenopsis TAM Butterfly plants were exposed to repeated cycles of 1 day in darkness and another day in light (1D/1L), 4D/3L, 7D/7L, or 0D/7L (continuous lighted control) between 15 Sept. and 16 Dec. Each plant was removed from the treatment once it had started spiking. The control plants bloomed on 20 Jan. 1995, whereas the 4D/3L plants did not reach anthesis until April 17, nearly three months later. Flowering of the 1D/1L and 7D/7L plants was also deferred until early April. The treatments had no adverse effect on flower count or size. In 1995, 3-year old plants were exposed to 0D/7L (control), 2D/5L, 3D/4L, 4D/3L, or 5D/2L from 15 Sept. to 22 Jan. 1996. The control plants spiked on 17 Oct. and bloomed on 8 Feb. 1996 when spikes had just emerged from plants in the 5D/2L treatment. The 5D/2L plants are expected to bloom in late May or early June. The other treatments were not as effective as that in 1994 and resulted in blooming only 2–3 weeks after the untreated control. The results of this research will help producers to stagger or precisely program the time of flowering to meet the market demand.
Anatomical and Morphological Modifications of the Periclinal Chimera Dracaena sanderana `Ribbon' in Response to Four Light Intensities
Authors: Vladimirov Svoboda V. , McConnell Dennis B.
Published: February 2019

Effects of four shade levels (47%, 63%, 80%, and 91%) on growth of D. sanderana `Ribbon' were evaluated. D. sanderana exhibited morphological and anatomical plasticity manifested in differences in all growth parameters examined. Plant growth rate was significantly influenced by the light levels. Under 63% and 80% shade plants grew faster and achieved greater biomass than plants grown under 475% and 91% shade. Leaf variegation was affected by the shade level. Plants grown in 47% and 63% shade had less total variegation than plants grown in 80% and 91% shade. Leaf thickness was greater in plants grown under higher light levels. Marginal leaf growth was suppressed in plants grown in 47% and 63% shade, thus reducing the width of the achlorophyllous margins. The reverse occurred in leaves of plants grown in 80% and 91% shade. The change in variegation pattern occurred very early in leaf ontogeny—during lamina formation and expansion. This change was attributed to differences in relative contribution of the three shoot apical layers under different light conditions. Thus, Dracaena sanderana `Ribbon' when grown in the southeastern United States is shade obligate, with an optimum light intensity level of less than 53% of full sunlight.
Developmental Changes in Soluble and Cell Wall-bound Invertases in Floral Organs of Lilium longiflorum
Authors: Ranwala Anil P. , Miller William B.
Published: February 2019

Easter lily flower buds at five stages of development (stage 1, 3–4 cm in length; stage 2, 6–7 cm; stage 3, 9–10 cm; stage 4, unopened buds, 13–14 cm; and stage 5, open flower 1 day after anthesis) were harvested, and flower organs were dissected for invertase assay. On a fresh weight (FW) basis, anthers had the highest soluble invertase activity (about 10-fold greater) than all other organs reaching to 15 units/g FW by the stage 2. The activity dropped to about 3 units/g FW at stage 3 and 4, and then increased up to 10 units/g FW in open flowers. Specific activity (units per mg of protein) also showed the same trend. On a specific activity basis, sepal invertase activity steadily increased during bud development, but was relatively constant on a fresh weight basis. stigma, style, and ovary, soluble invertase activity expressed on a FW and specific activity basis steadily increased as bud development. Filament soluble invertase activity on FW basis dropped at the stage 2 and 3, while specific activity steadily increased during bud development. Cell wall-bound invertase activity (released with 1 m NaCl) was present in all flower organs. However, soluble activity accounted for the most of total activity in sepal, ovary and filament (about 90%). About 75% of total activity was soluble in anther and style, whereas nearly equal amounts of soluble and cell wall activities were present in the stigma. The cell wall bound invertase activity increased throughout the bud development in sepal, stigma, style, and ovary parallel to soluble activity. Anther cell wall-bound activity fluctuated in a similar pattern as the soluble activity.