bluuebunny/crossref_metadata_2025 huggingface dataset:
Variance Component Analysis of Parthenocarpic Character in a Processing Cucumber (Cucumis sativus L.) population
Authors: Sun* Zhanyong , Lower Richard L. , Staub Jack E.
Published: February 2019

The incorporation of genes for parthenocarpy (production of fruit without fertilization) has potential for increasing yield in pickling cucumber (Cucumis sativus L.). The inheritance of parthenocarpy in cucumber is not well understood, and thus a genetic analysis was performed on F3 cross-progeny resulting from a mating between the processing cucumber inbred line 2A (P1, gynoecious, parthenocarpic, indeterminate, normal leaf) and Gy8 (P2, gynoecious, non-parthenocarpic, indeterminate, normal leaf). A variance component analysis was performed to fruit yield data collected at two locations (designated E-block and G-block) at Hancock, WI in 2000. The relative importance of additive genetic variance compared to dominance genetic variance changed across environments. The additive genetic variance was 0.5 and 4.3 times of dominance genetic variance in E-block and G-block, respectively. The estimated environmental variance accounted for ≈90% of the total phenotypic variance on an individual plant basis in both locations. Narrow-sense heritability estimated on an individual plant basis ranged from 0.04 (E-block) to 0.12 (G-block). Broad-sense heritability estimated on an individual plant basis ranged from 0.12 (E-block) to 0.15 (G-block). The minimum number of effective factors controlling parthenocarpy was estimated to range between 5 (G-block) to 13 (E-block). These results suggest that the response to direct selection of individual plants for improving parthenocarpy character will likely be slow and difficult. Experiment procedures that minimize the effect of environment on the expression of parthenocarpy will likely maximize the likelihood of gain from selection.
Introgression of Big Vein Tolerance from Lactuca virosa L. into Cultivated Lettuce (Lactuca sativa L.)
Authors: Hayes* Ryan J. , Ryder Ed , Robinson Bert
Published: February 2019

Big vein (BV) disease of lettuce is caused by soil borne fungal vectored viruses, and reduces marketability through head deformation. Tolerant cultivars reduce BV frequency, but no resistant cultivars exist. L. virosa L. is highly resistance. The objectives were to 1) determine if L. virosa P.I.s exhibit variation for resistance, and 2) determine if resistance is transferable to lettuce. Seedlings were inoculated with root macerate of BV infected plants, transplanted to BV infested soil, and greenhouse grown for 3 months. Twelve plants in each of 1,2, or 3 reps of Great Lakes 65 (GL65-susceptible), Pavane (Pav-tolerant), L. virosa (11 accessions), and BC1 F2 through F5 families of lettuce cultivars x L. virosa accession IVT280 were tested. The percentage of BV afflicted plants was recorded. In hybrid families, BV free plants from tolerant families were selected and advanced. No BV was found in L. virosa. Variation for tolerance was observed in BC1 F2 and F3 families; 33% had greater tolerance than Pav (17% afflicted). Additional tests identified 11 BC1 F3 families (14%) with greater tolerance than Pav (42% afflicted). Subsequent BC1 F4 and F5 generations however, were more susceptible than Pav. Lactuca virosa is highly resistant, but resistance did not transfer to hybrid progeny. Variation for tolerance was observed in BC1 F2 and F3 families, but later generations were susceptible. Interactions or linkage of genes for developmental processes and BV resistance may hinder introgression. Introgression will continue using congruity backcrossing and a greater diversity of L. virosa.
Greenhouse and Nursery Media Analysis Proficiency Testing
Authors: Newman* Steven E. , Miller Robert O.
Published: February 2019

Greenhouse and nursery managers rely on testing laboratories with the expectations of accuracy and consistency. The Greenhouse and Nursery Media Analysis Proficiency (GNMAP) Testing program was initiated to provide laboratories servicing greenhouses and nurseries with inter-laboratory quality control. The GNMAP program operational guidelines are based on those outlined under ISO 9000, ISO/IEC Guide 43 and Draft ISO/IEC Guide 24, which describe the requirements for proficiency testing. Nine laboratories enrolled in the program in 2003 and submitted results for root zone media and fertilizer solutions. Data analysis provided the minimum, maximum and median values; median absolute deviation (MAD); overall reproducibility (Rd); individual reported lab values; repeatability (Rp) of lab value (CV for the individual lab); and mean lab value reported. The Rd was calculated from the median of all lab Rp values and is a measure of intra-lab variance. A measure of inter-lab variance was determined by calculating the relative median deviations (RMD = MAD/Median × 100). For one of the media distributed, results for the saturated media extract included median pH values from 4.3 to 6.9 with MAD values averaging 0.1 across the three samples. The electrical conductivity (EC) median values ranged from 0.36 to 4.57 dS/m with RMD averaging 31% of the median. The main variability between laboratories for the majority of the macro cations was closely aligned with measured EC. Cations (K, CA and Mg) concentrations ranged from 17 to 502 mg/L with Ca typically in the greatest concentration. Cation inter-lab precision, based on the RMD ranged from 9-32% across the three substrate samples. The greatest RMD was 31.8% for Ca and 9.2% for K. The Rd values for the cations averaged 5%.
Temperature Effects on Flower Induction of Two Phalaenopsis Orchid Hybrids
Authors: Blanchard* Matthew G. , Runkle Erik
Published: February 2019

The commercial production of potted flowering orchids has increased tremendously in the past decade, and is now the second most valuable potted flowering crop in the United States. Phalaenopsis spp. comprise a large percentage (75% to 85%) of the potted orchid sales in the U.S. due to their long flower life and ease of scheduling to meet specific market dates. Constant air temperatures above ≈26 °C inhibit flowering of most Phalaenopsis hybrids, and a 25/20 °C day/night temperature regimen is used commercially to induce flowering. However, the relative promotion of flowering by constant versus fluctuating day/night cool temperatures (<25 °C) has not been well described. Phalaenopsis Miva Smartissimo × Canberra `450' and Brother Goldsmith `720' were grown at constant temperatures of 14, 17, 20, 23, 26, and 29 °C, and day/night temperatures of 20/14, 23/17, 26/14, 26/20, 29/23, and 29/17 °C;. Plants were grown in glass greenhouses with a constant photoperiod of 12 h, and shading was provided so that the maximum instantaneous irradiance was ≤150 μmol·m-2·s-1. After 6 weeks at the various temperature setpoints, ≥80% of plants of both cultivars had VI when grown at a constant 17, 20, or 23 °C, and at the 23/17 °C day/night regimen. None of the plants were reproductive within 6 weeks when grown at a constant 26 or 29 °C, or at the 26/14, 26/20, 29/17, or 29/23 °C day/night temperature setpoints. Therefore, temperature during the day and night both influence flowering of these two Phalaenopsis orchid hybrids.
Effect of Far-red Light on Inhibiting Anthocyanin Formation in the Leaves of Hanabusaya asiatica
Authors: Yoo* Dong-Lim , Nam Chun-Woo , Suh Jong-Teak , Ryu Seung-Yeol , Lee Seung-Woo
Published: February 2019

Hanabusaya asiatica has beautiful flowers as ornamental pot plant. It's a famous Korean endemic perennial plant in Korea. Recently many research items has been studying for developing cultivation technology of H. asiatica as a new commercial pot plant. Many endemic plants have much problems associated with maintaining quality for commercial plant. In H. asiatica, as a result of accumulation of anthocyanin in the leaves at reproductive stage, the leaf veins turn to brownish black and whole leaves become to necrosis and dry after all. This study was carried out to find out the suitable method for preventing the accumulation of anthocyanin in leaves by light quality. H. asiatica was treated three light quality, blue, far-red + blue, far-red and control on the middle stage of vegetative growth. Light quality sources were made by diodes. Light quality treatments were done in growth chamber. The photoperiod was 16 hours. Light quality treatments were done for 4 hours as daylight extension after 12 hours lighting by fluorescent lamps. Far-red lighting treatment was very effective to prohibit the formation of anthocyanin in the leaves. Blue lighting treatment was increased the anthocyanin accumulation but blue lighting treatment with far-red showed preventing the formation of anthocyanin. In these results, far-red lighting was very effective for preventing the action of cryptochrome by blue lighting on the anthocyanin formation in the leaves of Hanabusaya asiatica.
Soil Water in Amended Landscape Soils
Authors: McBee* Oren , Smalley Timothy J. , Radcliffe David E.
Published: February 2019

This study determined the effect of soil amendments on plant available water (PAW) and readily available water (RAW). Intact soil cores were collected from a Cecil sandy clay loam soil landscape planting beds that had been amended annually for 5 years with 5 cm (25% by volume) of pine bark and broiler litter. Soil cores were also collected from a landscape bed that had been amended once in April 2000 with 5 cm (25% by volume) of Permatill (expanded slate). The results of this study indicated that amending soil with pine bark or broiler litter compost increased soil porosity, drainage, aeration and PAW. The volumetric RAW (cm3·cm-3) did not differ among treatments, but amending the soil with pine bark or broiler litter did increase the gravimetric RAW (g·g-1). Permatill increased drainage and aeration, but did not increase available water to plants.
Seasonal Effects of Transplanting on Growth and Pre-bud Break Root System Regeneration of Northern Red Oak and Willow Oak
Authors: Richardson-Calfee Lisa , Harris* J. Roger , Fanelli Jody
Published: February 2019

Seasonal effects on transplant establishment of balled-and-burlapped (B&B) shade trees are not well documented. Early post-transplant root growth and above-ground growth over 3 years were therefore documented for November- and March-transplanted northern red oak (Quercus rubra L.) and willow oak (Q. phellos L.). Survival of red oak was 100% for both treatments. Survival of November- and March-transplanted willow oak was 67% and 83%, respectively. No new root growth was observed outside or within the root balls of either species upon excavation in January. However, new root growth was evident when subsamples were excavated the following April for November-transplanted trees of both species, indicating that root system regeneration of November-transplanted trees occurs in late winter and/or early spring, not late fall and/or early winter. November-transplanted red oak, but not willow oak, had grown more roots by spring bud break than March-transplanted trees. While height growth of willow oak was nearly identical between treatments after 3 years, November-transplants exhibited greater trunk diameter increase for all 3 years. Overall, season of transplant had little effect on height and trunk diameter increase of red oak, even though November-transplanted trees grew more roots prior to the first bud break following transplant. Among the willow oaks that survived, season of transplanting had little effect on height growth, but November transplanting resulted in greater trunk diameter increase. However, considering the mortality rate of November-transplanted willow oak, March may be a better time to transplant willow oak in climates similar to southwest Virginia.
Topping and Pruning Effects on Yield and Fruit Size of Navel Orange
Authors: Kallsen* Craig E.
Published: February 2019

Yield, fruit quality parameters and pruning costs were compared among differentially-pruned, mature navel orange trees planted at a density of 222 trees per hectare (90 trees per acre) in 2000, 2001 and 2002. The experiment was designed as a replicated, split block with topping height as the main plot split by three levels of interior pruning as subplots. A tree was reduced in height by mechanical topping to 4.3 m, 4.9 m or left untopped and hand pruned according to one of the three following options: 1. scaffold removal in March of 2000 followed by dead-brushing in 2001, and 2002; 2. dead-brushing only in 2000, 2001, and 2002; or 3. no topping or dead-brushing. Scaffold removal resulted in removal of approximately 50% of the tree canopy. Data were collected from experimental trees surrounded by similarly topped and interiorly pruned border trees. A highly significant positive-linear correlation (r2 = 0.95) was found between the total numbers of fruit produced annually per hectare versus the total number of fruit sized 72 to 88 mm in diameter (i.e. fruit sized such that 88 to 48 may be packed in a standard 17-kg packing carton). This functional relationship existed whether reductions in fruit numbers were the result of severe pruning in March or from, apparently, weather-related year to year variability in fruit set. These results suggest that anything in this orchard that reduces fruit numbers below approximately 250,000 fruit per hectare at harvest (100,000 per acre) will result in a mathematically predictable decrease in the total number of harvested fruit sized 72 to 88 mm in diameter. Trees that were not topped and which had no interior pruning produced the largest number of valuable fruit without additional pruning costs.
Copper Fungicide Spray Timings for Melanose Control in Grapefruit: Comparison of Computer Modelling of Copper Residues vs. Calendar Sprays
Authors: Stover* Ed , Ciliento Scott , Albrigo Gene
Published: February 2019

Grapefruit are susceptible to melanose from initial set until fruit diam. is 6-7 cm, which can span 3 months. Common Indian River melanose-control practice has been application of Cu fungicides at petal fall, with reapplication every three wks. through the infection period. Research data were previously used to develop a computer model to estimate Cu levels on fruit and indicate when reapplication is needed to prevent potential infection. The purpose of this study was to compare melanose control using spray timings suggested by the computer model vs. standard 3 week intervals vs. non-sprayed checks and was conducted over 3 years in mature grapefruit groves near Ft. Pierce, Fla. All applications were made using airblast at 1180 L· ha-1. Melanose and melanose-like Cu injury could not be distinguished and were combined in a melanose/Cu marking (MCM) score for each fruit. Separate fruit samples from the interior and exterior of tree canopies were randomly selected from each tree. In no year was there a significant difference in interior fruit MCM from computer model vs. calendar spray timings when treated with standard rates of Cu fungicide. However, rainfall never occurred when calendar-sprayed fruit were projected to be at low Cu levels. In 2 of 3 yrs. exterior fruit in the non-sprayed checks had less MCM than those from trees treated with Cu, indicating that Cu injury predominated over melanose on exterior fruit. In these fruit, MCM increased linearly with maximum fruit Cu concentration, which was lower on trees managed using the computer model. The computer model appears to be a sound approach to managing melanose, but economic benefit over calendar-based spray timing may only become apparent when practiced over numerous groves and seasons.
Patterns of Sorbitol Metabolism and Availability during Apple Fruit Set
Authors: Archbold* Douglas D. , Nosarszewski Marta
Published: February 2019

Acquiring sufficient carbohydrate is essential for successful apple fruit set. Sorbitol may be the dominant carbohydrate imported by growing fruit, and the rate of sorbitol accumulation may be a function of NAD-dependent sorbitol dehydrogenase (SDH; EC 1.1.1.14) activity. Prior work indicated that SDH activity from whole fruit (seeds plus cortex) increased for 2 or 3 weeks after initiation of fruit growth and then declined through 5 weeks. Using SDH activity assays, an SDH-specific antibody, and SDH-specific probes in Northern analyses, it is evident that SDH is expressed and is active in both apple seed and cortex tissue during the first few weeks of fruit growth. On a per unit protein basis, SDH activity in seeds increased by the pattern described above while that in fruit was generally lower and constant. During this same period of time, the sorbitol content of the expressed sap of apple shoots was analyzed. The sorbitol concentration was 50- to 100-fold higher than the sucrose concentration. The concentrations of both carbohydrates changed in parallel to the change in SDH activity of whole fruit and seeds. The lowest SDH activity and sap sorbitol levels preceded and/or coincided with the beginning of the natural fruit drop (or June drop) period.
Continuous Darkness and Silver Nitrate Promote Anther-derived Callus in Rosa hybrida L.
Authors: Zlesak* David C. , Radatz Corinne M. , Anderson Neil O.
Published: February 2019

Haploid (2x) roses derived from modern tetraploid breeding lines would allow for crosses to diploid species at the diploid level. In addition, inheritance studies are easier at the diploid level, using diploids derived from tetraploids possessing economically important traits. Haploidization of 4x roses through anther culture has not been successful due to challenges in callus induction and shoot regeneration. This study investigates rose anther responses to recently reported methods that optimize in vitro adventitious shoot regeneration in rose leaves. Anthers of three cultivars (Akito, Grand Gala, and Orlando) were put in a two-step callus induction (CI) and shoot regeneration procedure with varying CI factors. Experiment one (E1) compared continuous light/dark and silver nitrate (0,30,60 mg·L-1) and experiment two (E2) used the optimal E1 treatment comparing two and four weeks on CI media. Twenty-five anthers per treatment per cultivar were used in E1 and n = 100 for E2. Although no adventitious shoots were generated, callus formed on anther tissue and frequency of formation was variable across treatments. Continuous light resulted in 100% lethality. Darkness and silver nitrate (30 or 60 μm) favored callus generation and significant differences for callus generation were found among cultivars. Darkness and 30 μm silver nitrate were used in E2. Two and four weeks on initiation media were not significantly different for generation of anther-derived callus. Identification of factors which optimize callus formation on rose anthers is a positive step toward reliably generating rose haploids.
Use of RAPD Markers to Assess Genetic Diversity of American Ginseng (Panax quinquefolium L.) Among Wild Populations from the Catskill Mountains of New York State and Other States
Authors: Lim* Wansang , Mudge Kenneth
Published: February 2019

The Catskill Mountains of New York are an important source of wild-collected American ginseng (Panax quinquefolium), and increasingly, of woods-cultivated ginseng. The objective of this study was to assess genetic diversity among eight different wild ginseng populations from the Catskill Mountains and to compare Catskill populations to five wild populations from other states including Kentucky, Tennessee, North Carolina, Pennsylvania, Virginia, and one cultivated population from Wisconsin. Randomly amplified polymorphic DNA markers were used to estimate the genetic difference among the 14 populations using PCR amplified nuclear DNA. Fifteen random primers were selected from a total of 64 random decamer primers by screening bulked DNA samples from the eight Catskill populations. These 15 primers were then used to compare 10 plants each from the eight Catskill populations and three to four plants each from the non-Catskill populations. The 15 primers produced 124 polymorphic bands. The genetic distance within and among populations was estimated using the ratio of discordant bands to total bands. Multidimensional scaling of the relation matrix showed separation of Catskill and non-Catskill population clusters. Significant differences between these groups was confirmed using pooled chi-square tests for fragment homogeneity. Although the eight Catskill populations differed from the non Catskill populations, there were no significant differences among the Catskill populations. This study shows that presence and absence of bands can be used as population specific markers for American ginseng. Although these results do not rule out the possibility that there may be some level of genetic differences among Catskill populations, 10 plants per population was not sufficient to establish such differences.
Seed Production of Field- and Greenhouse-Grown Herbaceous Ornamental Plants: Flowering and Pollinator Effects
Authors: Stieve* Susan M. , Tay David
Published: February 2019

Seeds of herbaceous ornamental accessions conserved by the USDA National Plant Germplasm System (NPGS) are traditionally produced in summer field cages with honey bees (Apis mellifera) when pollinators are required. Efficient methods to produce high-quality seed in greenhouses may allow for year-round seed production. Flower quantities and effects of pollinators on number and weight of seed produced were studied in field cages and greenhouses at the Ornamental Plant Germplasm Center in 2003 in a randomized complete-block experiment. Honey bees, bumblebees (Bombus impatiens), or blue bottle flies (Diptera calliphoridae) were used as pollinators. Field cages and greenhouse compartments with no pollinator were controls. Cultivars used were Antirrhinum majus `Gum Drop', Coreopsis tinctoria `Plains Bicolor', Dianthus chinensis `Carnation' (NPGS accession NSL 15527), Rudbeckia hirta `Indian Summer', and Tagetes patula `Jaguar'. Seeds were harvested, cleaned, weighed, and 100-seed weights calculated. On average Antirrhinum, Dianthus, Rudbeckia and Tagetes produced more flowers in greenhouses, Coreopsis produced more flowers in the field. Coreopsis and Rudbeckia produced more seed per flower on average with field pollination by honey bees, Antirrhinum and Dianthus produced most with bumblebees in the field, and Tagetes produced most with blue bottle flies in the greenhouse. Each genus had similar 100-seed weights on average in all treatments. Results show pollinators other than honey bees are useful for herbaceous ornamental seed production and that seed production in greenhouses may be an alternative method for seed production of herbaceous ornamentals.
Amylase and Endo-β-mannanase Related to the Germination of Eggplant Seeds
Authors: Sung* Yu
Published: February 2019

Germination of `Fond May' eggplant seeds at 25°C could be increased by after-ripening fruit or fresh seed treated with KNO3 or GA3 or priming. There were high amount of starch and low amount of soluble sugar in after-ripening seed or primed seed. The amount of soluble sugar in after-ripening seed was higher than that in control seed before the radicle protrusion at 25 °C and 25/30 °C. Starch amount in after-ripening seed imbibed at 25/30 °Cwas significantly high. Soluble sugar in un-after-ripening seed imbibed at 25 °C for 2-3 days had higher amount and the high activity of β-amylase was appeared in the second days. Activity of amylase in primed seed imbibed at 25 and 25/30 °C for 3 days increased. The activity of endo-β-mannanase was high in after-ripening or priming or GA3 treated seed at 25 °C.
Mouse Ear Disorder on River Birch Caused by Nickel Deficiency
Authors: Ruter* John M.
Published: February 2019

Mouse ear (leaf curl, little leaf, squirrel ear) has been a problem for growers of container-grown river birch (Betula nigra L.) since the early 1990's. Mouse ear has been noticed in several southeastern States as well as Minnesota, Ohio, Oregon, and Wisconsin, making it a national problem. The disorder is easy to detect in nurseries as the plants appear stunted. The leaves are small, wrinkled, often darker green in color, commonly cupped, and have necrotic margins. New growth has shortened internodes which gives plants a witches-broom appearance. Plants growing in native soil rarely express the disorder. Several common micronutrients have been evaluated with no results. A trial was initiated in June, 2003 to determine if nickel deficiency was the cause of mouse-ear. Symptomatic river birch trees growing in a pine bark substrate in containers were treated with foliar applications of nickel sulfate and a substrate drench. Topdress applications of superphosphate (0-46-0) and Miloroganite, products known to contain nickel, were also applied. At 16 days after treatment (DAT), up to 5 cm of new growth occurred on plants sprayed with nickel sulfate and foliar concentrations of nickel in the new growth increased five fold compared to control plants. At 30 DAT, shoot length increased 60%, leaf area increased 83%, and leaf dry mass increased 81% for trees receiving a foliar application compared to non-treated control plants. Treating trees with a substrate drench alleviated symptoms, whereas treatment with superphosphate and Milorganite did not. Trees receiving a foliar or drench application had normal growth for the remainder of the growing season. Additional studies are underway to refine methods of application, rates, and sources of nickel suitable for use.
Adaptations of Alnus maritima Nodules to Low Oxygen in the Root Zone
Authors: Kratsch* Heidi A. , Graves William R.
Published: February 2019

Alnus maritima (Marsh.) Muhl. ex Nutt. is unique among alders in its degree of preference for low-oxygen soils of wetlands. An actinorhizal species with promise for use in sustainable horticulture, A. maritima develops a root-nodule symbiosis with nitrogen-fixing Frankia. Nodules of other actinorhizal species that are obligate wetland natives are adapted to low oxygen, and expression of hemoglobin is common to these taxa. Our objectives were to determine the range of oxygen tension under which Alnus maritima subsp. maritima fixes nitrogen and to investigate a potential role for hemoglobin in adaptation of nodules to low oxygen. Roots of plants, cultured aeroponically, were subjected to eight oxygen tensions from 0 to 32 kPa. After four weeks, plant dry weight, nodule fresh weight, nitrogenase activity, and photosynthetic rate were measured. In addition, nodules were assayed spectrophotometrically for the presence of hemoglobin. A quadratic function best described the influence of oxygen on plant dry weight, nodule fresh weight, nitrogenase activity, and photosynthetic rate with maximal values above 20 kPa. Alnus serrulata (Ait.) Willd. is sympatric with A. maritima subsp. maritima but is not an obligate inhabitant of wetlands. In a separate experiment, we found higher nitrogenase activity in A. maritima subsp. maritima than in A. serrulata (0.74 vs. 0.26 μmol/h per plant) at hypoxic oxygen tensions. Further, optical absorption spectra of nodule extracts confirmed hemoglobin within nodules of A. maritima subsp. maritima. Our data suggest that hemoglobin contributes to oxygen regulation in nodules of A. maritima subsp. maritima.
Production System Impacts Quality of Cut Poinsettia Stems
Authors: Warnock* Daniel , Fifarek Megan , Lash Heather
Published: February 2019

The development of the Renaissance series of cut poinsettias, Euphorbia pulcherrima, presents unique opportunities and challenges to cut flower producers. This series has curled bracts, long stem length, excellent vase life and is highly marketable. Literature indicates that this crop is suited for pot or bed production, but does not compare methods. This study assessed the impact of production system on final stem quality. Uniform rooted cuttings of `Renaissance Red' obtained from a commercial supplier were transplanted into 30.5-cm pots or a 1.2-× 2.4-m bed containing a soilless media to obtain 2 plants per 0.9 m2. A total of 56 cuttings were used for each production system and grown using standard production techniques. Transplanting occurred on 11 Aug. 11 2003 with plants reaching market stage, two cyathia shedding pollen, about 17 weeks later. To minimize border effects, plants in the outside rows of each production system were discarded. Thus, stem length, stem diameter, bract diameter, floral development, and number of axillary shoots were determined for 30 interior plants in each system. The production systems differentially impacted stem length and number of axillary shoots. Mean stem length in the bed system (89.7 cm) was greater than that observed in the pot system (71.4 cm). Plants in the bed system had significantly fewer axillary branches per plant (0.5) than plants in the pots (2.0). Stem diameters were similar for both systems (11.5 mm and 10.9 mm for bench and pot, respectively) as were bract diameters (14.3 cm and 13.4 cm for pot and bench, respectively). Both systems produced marketable stems; however, stems produced in the bed system had longer stems, fewer axillary branches, and were more uniform than those in the pot system.
Nitrogen Toning and Thidiazuron (TDZ) Improve Pot Plant Quality of Bracteantha bracteata Cultivars
Authors: Beach* Shannon E. , Starman Terri W. , Pemberton H. Brent
Published: February 2019

Bracteantha bracteata (Vent.) Anderb. & Haegi (bracteantha) is a vegetative annual produced as a 12.7-cm potted plant in 6 weeks of greenhouse production. A dense leaf canopy produced with a conventional constant-feed fertilization regime (300 mg·L-1 20N-4.4P-16.6K) caused increased disease pressure and lower leaf chlorosis during greenhouse production. During shelf life, lower leaves of plants con-tinued to become chlorotic. The objective was to decrease leaf area and prevent lower leaf chlorosis without affecting harvest time, plant quality or shelf life of two cultivars of three series of bracteantha. The first experiment was to reduce the rate of fertilizer two weeks prior to harvest. Treatments were no fertility reduction (300 mg/liter), 50% reduction (150 mg/liter), and 100% reduction (0 mg·L-1). At harvest, plants were evaluated for shelf life in a growth room at 21.1 ± 1.3 °C and 6 μmol·m-2·s-1 PPF. Five cultivars in the 100% fertility reduction treatment had decreased height and/or width index at harvest and three cultivars maintained higher postharvest quality ratings compared to the other treatments. Separately, the effect of the duration of fertilization was evaluated by terminating fertilization at weekly intervals (0-6 weeks) throughout production. Ceasing fertilization two to three weeks prior to harvest produced plants with lower leaf area without affecting flower number. In another experiment, thidiazuron (TDZ) as a foliar spray at 0, 0.1, 0.5, and 1.0 mg·L-1 was applied to decrease lower leaf yellowing. SPAD-502 chlorophyll meter readings of lower leaves were increased with 0.1 mg·L-1 TDZ treatment compared to the control. Phytotoxic symptoms occurred on plants receiving higher TDZ rates.
Sorting the Heated Mess: Screening Tulip Cultivars for Sensitivity to Heat
Authors: Liou* Susan S.C. , Miller William B.
Published: February 2019

Tulip bulbs are produced in the Netherlands and are shipped to United States during the months of July and August in temperature-controlled shipping containers. Each shipment is often composed of a mixture of many cultivars. Mechanical failure of temperature controls may result in high temperatures that ultimately may reduce forcing quality of the bulbs. When such accidents occur, an immediate decision must be made about whether to invest more time and money on these potentially damaged bulbs. Such a decision is not easy because symptoms of heat damage are often delayed until months later. Research on a single cultivar, `Apeldoorn', has shown that heat stress can cause flower abortion and other abnormalities. However, cultivars undoubtedly vary in their response to heat stress. Thus in the 2002 and 2004 forcing seasons, ≈45 cultivars were screened for response to a standard heat stress of 4 days at 35 °C. Prior to the heat stress, bulbs were held at 17 °C or 9 °C for 4 weeks, mimicking conditions used for late and early forced bulbs, respectively. Flower and leaf height, percent flower abortion, and flowering date were evaluated. Heat stress caused flower abortion and reduced plant height in sensitive cultivars. Across all cultivars, cold storage prior to the heat stress significantly increased bulb's sensitivity to heat stress. Using percent flower abortion, cultivars were grouped into three categories: resistant, moderate, and susceptible. With this information, we hope that damage assessment may become easier and fewer bulbs wasted.
Time to Flowering and Survival of Two Herbaceous Perennials is Affected by Day/Night Temperature Difference
Authors: Dubois* Jean-Jacques B. , Blazich Frank A. , Raper C. David
Published: February 2019

Research by the authors has demonstrated the effect of day/night temperature difference (Tdiff) on plant growth is as substantive as the effect of daily average temperature (DAT). Dependence of plant primary productivity on temperature cannot be assessed with fewer than two data per 24 hours. Thus, the same experimental approach was applied to time to anthesis in Delphinium cultorum Voss `Magic Fountains' and Stokesia laevis L. `White Parasols', and to survival in D. cultorum. Two hundred and seventy seedlings of D. cultorum and 72 plantlets of S. laevis were grown for 56 days in growth chambers under eighteen 12 hour day/12 hour night combinations of six day and six night temperatures (10, 15, 20, 25, 30, or 35 °C). Ninety plants of D. cultorum were harvested after 13, 34, or 56 days, and 36 plants of S. laevis after 34 or 56 days. For each event of interest (anthesis or death), one datum per plant was recorded, consisting of time elapsed when either the event occurred, or the plant was harvested, whichever came first. Each datum was paired with an indicator of whether the plant was harvested prior to the event being observed. Data were analyzed using time—to—event data analysis procedures. Several parametric distributions fitted the data equally well, and both day and night temperature had strong effects on time to anthesis and survival time. However, in contrast with biomass production, DAT was quite sufficient to account for timing of these developmental events in relation to temperature. Addition of Tdiff contributed marginally to the fit to the data, but the magnitude of the effect was considerably smaller. Within the range of temperatures likely to be encountered in cultivation, the effect was negligible.
Evaluation of Hardy Shrub Roses for the Upper Midwest
Authors: Jull* Laura G.
Published: February 2019

A hardy shrub rose evaluation trial was planted at three locations in Wisconsin representing U.S.D.A. cold hardiness zones 3, 4, and 5. There were nine replications of each of the 20 different, new or underused rose cultivars located at each location. The roses were then evaluated monthly (May-Nov.) for three years. Monthly data were taken and parameters included: plant height, width, flowers (color, size, amount, duration), insect injury, disease susceptibility, hips (production, size, and color in fall), and amount of winter dieback in spring. Pesticides and winter protection were not used in the trial to properly evaluate for pest resistance and cold hardiness. Pest resistance for roses varied among the cultivars. `Marie-Victorin' was the most severely infected rose by insects. Blackspot and anthracnose were severe (>60% of plant infected) on `Robusta', Red FairyTM, Kaleidoscope™, Cambridge™, and Madison™. Flower amount and continuous bloom occurred on Carefree Delight™, Cambridge™, Madison™, Knockout™, Fire Meidiland™, Mystic Meidiland™, and Red Fairy™. Hip production occurred on many of the cultivars, however, only Carefree Beauty™, `Marie-Victorin', and Mystic Meidiland™ produced colorful orange-red hips. Winter hardiness also varied between the cultivars.
New Golden Leaf Cultivar of Celtis julianae (`Golden Phoenix') and Its Primary Research
Authors: Huang Xuan , Zhao* Liangjun
Published: February 2019

As well as investigating physiological characteristics of the new yellow cultivar of Celtis julianae—`Golden Phoenix' (Julian hackberry, which originally distributed in south of China, is important environmental plant, because there are numerous hairs on surfaces of the leaf, which can absorb dust and clean the air. Julian hackberry is deciduous big tree, more than 25 meters in high, with deep green leaf, red flower and orange fruit, blossoming in April.), differences in leaf color between the new cultivar and the normal Celtis julianae were evaluated. The new cultivar is a natural seed mutant from some cultivated seedlings of Celtis julianae found in 2001. It has golden yellow leaf, average color is Yellow-Green150A mensurating by English Color Card, is significantly more different than those of the normal. It can normally growing but slowly, with smaller plant-size and shorter internode than common plant. The new cultivar's leaf contains less chlorophyll than the normal, but same carotenoid. Its net photosynthetic rate is lower than that of Julian hackberry common cultivates in full sunlight. Shading of leaf to 50% sunlight decreases chlorophyll content and photosynthetic rate compared with full sunlight and sharper in photosynthetic, resulting in deepen green color. Leaves of the new cultivar show higher values of lightness and yellow-green as compared with other normal. Shoot multiplication frequency was highest on woody plant medium containing 1.5 mg 6-BA(benzyladenine)/ml, producing 6 shoots from a single explant, but these are some troubles to root.
Selecting the Best Citrus Rootstock for Young `Valencia' Orange Trees Under Soil Salinity Stress Conditions
Authors: Akl* A.M.
Published: February 2019

This study was conducted during 2002 and 2003 seasons to select the best citrus rootstocks for young `Valencia' orange trees grown under soil salinity stress. Six citrus rootstocks namely Volkamer lemon, Cleopatra mandarin, Troyer citrange, Rough lemon, Egyptian lime, and Sour orange were tested. Four soil salinity levels, namely, 0.0%, 0.1%, 0.2%, and 0.4% were examined. Results showed that growth criteria, plant pigments and percentages of N, P, and K in the leaves of `Valencia' orange onto all citrus rootstocks tended to reduce with raising soil salinity. The harmful effects imposed by soil salinity was `Valencia' orange on Volkamer lemon, Cleopatra mandarin Troyer citrange, Rough lemon, Egyptian lime, and Sour orange, in asending order. Results proved the superiority of Volkamer lemon, Cleopatra mandarin, and Trouyer citrange rootstocks for `Valencia' orange transplants grown under salinity conditions as compared to the other rootstocks. `Valencia' orange on such promising rootstocks could tolerate soil salinity until 0.20% without adverse effects on growth of transplants. Sour orange rootstock seems to be the lowest suitable stock for `Valencia' orange tansplants grown under soil salinity conditions.
Optimization of Long Distance Transportation Conditions for High Quality Tomato Seedlings: Effects of Air Temperature and Light inside Trailers
Authors: Kubota* Chieri , Kroggel Mark
Published: February 2019

Increasing numbers of vegetable growers purchase their transplants from specialized transplant producers. Possible deterioration of transplants during transportation limits the market size as well as the potential sources of high quality transplants. To determine best conditions for transportation of seedlings, tomato (Lycopersicon esculentum; `Durinta') seedlings with visible flower buds were placed for 4 days under varied air temperature (6, 12, or the conventional transportation temperature of 18 °C) and light intensity 0 (conventional darkness) or dim light at 12 μmol·m-2·s-1 PAR). Plants were evaluated for visual quality, photosynthetic capacity, growth and ultimately fruit yield. Lower temperatures and illumination significantly maintained visual quality of the seedlings. Lower temperature maintained high photosynthetic capacity of the seedlings during transportation. Growth and development of the seedlings were significantly affected by higher temperature resulting in significantly delayed growth and development. Number of fruits set on the first truss was significantly reduced when seedlings were at 18 °C during transportation. Overall, simulated transport at 6 °C under light showed the best transportability without experiencing negative impact for the 4-day simulated transportation. Seedlings at 6 °C in darkness and at 12 °C under light and in darkness also showed satisfactory transportability. Seedlings at 18 °C exhibited serious quality deterioration of seedlings, delay in early growth and development, loss of flower buds on the first truss and yield reduction, which agrees with the fact that conventional transportation is currently able to be no longer than 3 days in duration.
Phytotoxicity of Copper in Greenhouse Crops
Authors: Zheng* Youbin , Wang Linping , Liu Weizhong , Sutton John , Dixon Mike
Published: February 2019

Copper is one of the essential micro-nutrient elements for plants, but when in excess, is toxic to plants and other living organisms. Electrolytically generated copper and cupric sulphate are increasingly used by the greenhouse industry to control diseases and algae in hydroponic systems. However, there is little information regarding appropriate strategies for employing copper in greenhouse crop production. We investigated the physiological responses, growth and production of several ornamental crops (miniature rose, chrysanthemum and geranium) and greenhouse vegetable crops (pepper, cucumber, and tomato) with respect to Cu2+ concentration in the root zone. Tests were conducted using plants grown in nutrient solution, Promix and rockwool. Results showed that phytotoxic levels of Cu2+ were dependent on the crop species and growing substrate. Plants grown in nutrient solution exhibited symptoms of phytotoxicity at lower Cu2+ concentrations than those on the solid substrates. The ability of copper to control Pythium aphanidermatum and green algae was evaluated under both laboratory and greenhouse conditions. Copper was effective in suppressing green algae in nutrient solution, but did not control Pythium effectively. This presentation is a comprehensive summary of the research conducted over the last three years by our group on copper application in greenhouse systems.
True Firs (Abies sp.): New Conifers for the Midwestern Landscape
Authors: Jones* Grant , Cregg Bert , Schneller Katrina
Published: February 2019

The genus Abies is a member of the family Pinaceae and consists of approximately 55 species found mainly in upper latitudes or higher elevations in the northern hemisphere. Firs generally prefer cool, well-drained sites with acidic soil. Fir trees are occasionally used as landscape trees but are more commonly grown as Christmas trees. Recently, the Michigan State Univ. Forestry Dept. and the Michigan Christmas tree industry initiated a field test of exotic firs (Abies sp.) for potential use as Christmas trees. In the present study we expanded the evaluation of these exotic fir species to include their suitability as landscape trees and to characterize their tolerance to various environmental stresses. We compared foliar nutrition, gas exchange, chlorophyll fluorescence, and shoot morphology of 23 Abies species and hybrids planted at three horticultural research stations in Michigan. Foliar nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), sulfur (S), boron (B), zinc (Zn), and copper (Cu) were correlated (P < 0.05) with soil pH. Species and hybrids varied (P <0.05) in maximum photosynthetic rate, water use efficiency, chlorophyll fluorescence, and the ratio of total needle area to projected needle area. We will discuss the significance of these traits in relation to selecting trees adapted for use in the Midwestern landscape.
Effects of Salinity and Drought stresses on Petunia Transformed for α-Galactosidase Expression
Authors: Locke* Emma L. , Stushnoff Cecil , Pennycooke Joyce C. , Jones Michelle
Published: February 2019

Salinity, drought and temperature frequently limit crop productivity. Transgenic Petunia ×hybrida cv. Mitchell with altered endogenous raffinose family oligosaccharides (RFO) due to over-expression (sense) or under-expression (antisense) of the tomato α-galactosidase gene show that antisense increases in RFO are associated with greater tolerance to freezing stress (Pennycooke et al., 2003). Because vegetative propagules of these antisense lines rooted and established more quickly than their sense counterparts, we hypothesized that antisense lines would also respond to salinity and wilting stress. Salinity treatment plants were exposed to 50-200 mm NaCl graduated 25 mm every 3 days and held at 200 mm for 13 days. Dry-down treatments were watered to pot capacity, then not watered until the onset of wilting. This was repeated in cycles for 26 days. Data were collected on plant growth, root/shoot ratios, and leaf water potential. Fresh and dry weights in four of the six antisense lines exceeded the wild type and sense lines. Osmotic potential for salinity and dry-down plants was 160% to 220% higher than control plants. Pearson correlations revealed that higher osmotic potential was partially associated with higher fresh weight (r = 0.7214, P = 0.02) and root/shoot ratios (r = -0.7414, P = 0.02) in salinity stressed plants. In the dry-down drought stressed plants, osmotic potential was not associated with fresh weight (r = 0.3364, ns) nor root/shoot ratio (r = -0.0431, ns). Salinity stress reduced root mass compared to control and dry down plants. Sense plants grew slowly and were highly variable.