bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoperiod, Irradiance, and Cool Temperature Effects on Gymnocalycium, Rebutia, Lobivia, and Sulcorebutia sp. Growth and Flowering
Authors: Erwin John , Gesick Esther , Dill Ben , Rohwer Charles
Published: February 2019

A study was conducted to determine if photoperiod, irradiance, and/or a cool temperatures impacted flowering of selected species in five cactus genera. Gymnocalycium, Rebutia, Lobivia, and Sulcorebutia plants were grown for 4 months under natural daylight conditions (August–November) in a greenhouse maintained at 26 ± 2 °C. Plants were then placed in either of two greenhouses: 1) a greenhouse maintained at 22 °C day/18 ± 1 °C night temperature with an 8-h daylength (SD) or natural daylight plus night interruption lighting (NI; 2200–0200 HR), or 2) a greenhouse maintained at 5 ± 2 °C under natural daylight conditions (8–10 h). After 12 weeks at 5 °C, plants were moved to the SD and NI lighting treatments in the before mentioned greenhouse and additional lighting treatment [natural daylight plus supplemental high-pressure sodium lighting (85–95 μmol·m-2·s-1; 0800–0200 HR)]. In all cases, plants were moved out of lighting treatments after 6 weeks and were then grown under natural daylight conditions in a greenhouse maintained at constant 22 ± 1 °C. Data were collected on the approximate date growth commenced, the date when each flower opened (five flowers only), flower number per plant, and individual flower longevity (five flowers only). Species were classified into photoperiodic and irradiance response groups where appropriate and whether species exhibited a vernalization requirement was reported. Lastly, whether dormancy occurred and what conditions overcame that dormancy was reported.
Photoperiod, Irradiance, and/or Cool Temperature Effects on Lobivia × Chamaecereus Hybrid `Rose Quartz' Flowering
Authors: Erwin John , Gesick Esther , Dill Ben , Rohwer Charles
Published: February 2019

Photoperiod, irradiance, and/or a cool temperature effects on Chamaelobivia hybrid `Rose Quartz' flowering was studied. Two- to 3-year-old plants were grown for 4 months under natural daylight (DL; August–November) in a greenhouse maintained at 26 ± 2 °C. Plants were then placed in either of two greenhouses: a cool temperature house (5 ± 2 °C; natural daylight), or a lighting treatment house (22 °C day/18 ± 1 °C night temperature, respectively). The lighting treatment house had eight light environments: 1) short day (SD; 8 h; 0800–1600 HR); 2) SD+25–35 μmol·m-2·s-1; 3) SD+45-50 μmol·m-2·s-1; 4) SD+85-95 μmol·m-2·s-1; 5) DL plus night interruption lighting (NI; 2200–0200 HR; 2 μmol·m-2·s-1 from incandescent lamps); 6) DL+25-35 μmol·m-2·s-1 (lighted from 0800–0200 HR); 7) DL+45-50 μmol·m-2·s-1; and 8) DL+85-95 μmol·m-2·s-1. Supplemental lighting was provided using high-pressure sodium lamps. Plants were placed in the cool temperature environment for 0, 4, 8, or 12 weeks before being placed under lighting treatments. All plants received a 6-week lighting treatment and were then placed in the finishing greenhouse (22 ± 2 °C). Data were collected on the date when each flower opened (five only), the flower number per plant, and flower longevity (five only). Vernalization interacted with photoperiod to affect flowering. Unvernalized plants exhibited an obligate long-day requirement for flowering. Vernalized plants exhibited a facultative long-day requirement for flowering. The impact of vernalization, photoperiod, and irradiance on flower number, time to flower, and longevity will also be discussed.
Update on Nitrogen BMP Efforts with Tomato Production in Florida
Authors: Ozores-Hampton Monica , Simonne Eric , McAvoy Eugene , Stansly Phil , Shukla Sanjay , Roka Fritz , Obreza Tom , Cushman Kent , Gilreath Phyllis , Parmenter Darrin
Published: February 2019

Florida tomato growers generate about $600 million of annual farm gate sales. The Florida Vegetable and Agronomic Crop Water Quality/Quantity Best Management Practices Manual was adopted by rule in the Florida Administrative Code in 2006 and describes cultural practices available to tomato growers that have the potential to improve water quality. By definition, BMPs are specific cultural practices that are proven to optimize yield while minimizing pollution. BMPs must be technically feasible, economically viable, socially acceptable, and based on sound science. The BMP manual for vegetables endorses UF-IFAS recommendations, including those for fertilization and irrigation. Current statewide N fertilizer recommendations for tomato provide for a base rate of 224 kg/ha plus provisions for supplemental fertilizer applications 1) after a leaching rain, 2) under extended harvest season, and 3) when plant nutrient levels (leaf or petiole) fall below the sufficiency range. An on-farm project in seven commercial fields was conducted in 2004 under cool and dry growing conditions, to compare grower practices (ranging from 264 to 468 kg/ha of N) to the recommended rate. Early and total extra-large yields tended to be higher with growers' rate than with the recommended rate, but these differences were significant only in one trial. The first-year results illustrated the need for recommendations to be tested for several years and to provide flexibility to account for the reality of local growing conditions. Working one-on-one with commercial growers provided an opportunity to focus on each farm`s educational needs and to identify specific improvements in nutrient and irrigation management.
Application of Hydrated Lime to Hydrogen Cyanamide-treated Grapevines Reduces Lemon Leaf Abscission in Neighboring Lemon Orchards
Authors: Ali Anwar G. , Lovatt Carol J.
Published: February 2019

Previous research in our laboratory provided evidence that hydrogen cyanamide (HC) applied to grapevines (Vitis vinifera) to stimulate budbreak resulted in ethylene production, which, in addition to HC drift at application, caused abscission of leaves in neighboring `Eureka' lemon [Citrus limon (L.) Burm. F.] orchards. Foliar-applied hydrated lime [Ca(OH)2] at 140 kg per 2337 to 2807 L·ha-1 to commercial `Thompson Seedless', `Perlette', `Red Flame', or `Princess' vineyards 2–48 h after HC treatment reduced leaf abscission from 2-year-old'Eureka' lemon trees placed inside the vineyards, with no negative effects on budbreak or yield of any grape cultivar. Hydrated lime is an effective inexpensive tool that grape growers can use to protect neighboring lemon orchards.
Genetic and Environmental Variation of Glucosinolate Content in Chinese Cabbage
Authors: Kang Ji Yeon , Ibrahim Khalid E. , Juvik John A. , Kim Doo Hwan , Kang Wha Jeung
Published: February 2019

Strong evidence exists to suggest that increased consumption of glucosinolates from Brassica vegetables is associated with reduced risk of cancer induction and development. Development of elite germplasm of these vegetables with enhanced levels of glucosinolates will putatively enhance health promotion among the consuming public. To evaluate levels of glucosinolate phenotypic variation in Chinese cabbage tissue and partition the total phenotypic variation into component sources (genotype, environment, and genotype-by-environment interaction), a set of 23 Brassica rapa L. var. pekinensis genotypes were grown in two different environments (field plots and greenhouse ground beds). Gluconasturtiin and glucobrassicin were found to account for ≈80% of total head glucosinolate content. Significant differences were found in glucosinolate concentrations between the lowest and highest genotypes for glucobrassicin (6-fold) and for gluconasturtiin (2.5-fold). Analysis of variance showed that for the three major glucosinolates (gluconasturtiin, glucobrassicin, and progoitrin), the genotypic effects described most of the phenotypic variation (62% averaged over the three compounds). The next most important factor was genotype × environment interaction (29%), whereas variation affiliated with the environment was found to be relatively minor (8%). These results suggest that genetic manipulation and selection can be conducted to increase glucosinolate content and the putative health promotion associated with consumption of Chinese cabbage.
Strawberry (Fragaria ×ananassa Duch.) Growth and Productivity as Affected by Temperature
Authors: Kadir Sorkel , Sidhu Gaganpreet , Al-Khatib Kassim
Published: February 2019

Thermotolerance of photosynthesis and productivity in `Chandler' and `Sweet Charlie' strawberry plants (Fragaria ×ananassa Duch.) exposed to three temperature regimes was studied. Net CO2 assimilation rate (A), variable chlorophyll fluorescence (Fv), efficiency of photosystem II (Fv/Fm), relative chlorophyll content, plant growth, and fruit yield and quality were measured. High temperature (40 °C day/35 °C night) was more detrimental to photosynthesis and productivity than the moderate or low temperature (30/25 or 20/15 °C). Net CO2 assimilation rate in both cultivars was markedly reduced by 40/35 °C, although there was slight decline in `Sweet Charlie' at 30/25 °C. `Chandler' maintained significantly higher A rates than `Sweet Charlie' for at least three weeks of heat stress, indicating that `Chandler' might tolerate longer exposure to high temperature. In parallel to the decrease in A rate, intercellular CO2 concentration (Ci) and instantaneous water use efficiency (WUE) were significantly decreased at high temperature. `Chandler' leaves were cooler and transpired more than `Sweet Charlie' leaves, suggesting that each cultivar adopted different heat resistance mechanisms at 40/35 °C. There were changes in Fv and Fv/Fm with increasing temperature, indicating irreversible damage to photosystem II at 40/35 °C might have occurred. The trend of reduction in stomatal conductance (gS) in both cultivars at high temperature did not coincide with the reduction in A rates. Decline in A rates at high temperature was more related to changes in Fv/Fm than to gS activity. The optimal temperature for vegetative growth was 30/25 °C. Reduction in A rate at high temperature resulted in reduction in total leaf area (LA), shoot, root, and leaf biomasses. Strawberry roots were more responsive than shoot growth to temperatures above 20/15 °C. Fruit yield for `Chandler' was higher at 20/15 °C than at 30/25 °C, suggesting that `Chandler' might have a higher source-to-sink relationship at 20/15 °C than at 30/25 °C. Fruit skin color was temperature dependent only for `Chandler'. A quadratic relationship between flower development and duration of exposure to 30/25 °C for both cultivars was observed; more than two weeks of 30/25 °C can be detrimental to flower development. Regardless of the cultivar and duration of exposure, 40/35 °C was the temperature regime most detrimental to fruit set.
Transmission of Xylella fastidiosa through Pecan Rootstock
Authors: Sanderlin R. S. , Melanson R. A.
Published: February 2019

Xylella fastidiosa Wells et al., the pathogen that causes pecan [Carya illinoinensis (Wangenh.) C. Koch] bacterial leaf scorch disease, was demonstrated to be highly transmissible through graft unions from infected rootstock into new growth developing from scions. Infected rootstocks were obtained by inoculation of pecan seedlings in pots with in vitro cultures of the pathogen. If rootstock infection occurs in nature, transmission of the pathogen into tissue growing from scions could serve as a significant source of introduction of the disease into pecan orchards. Because symptom development in infected trees typically begins in midsummer and grafting takes place in the early spring, it would be difficult to identify infected rootstock before grafting. Commercial pecan growers sometimes attempt to eliminate bacterial leaf scorch from trees by regrafting to other cultivars. The high rate of transmission from infected rootstocks observed in this test and the lack of knowledge of cultivars with resistance to the disease makes this practice ineffective.
`Solar Fire' Hybrid Tomato: Fla. 7776 Tomato Breeding Line
Authors: Scott J.W. , Olson S.M. , Bryan H.H. , Bartz J.A. , Maynard D.N. , Stoffella P.J.
Published: February 2019

`Solar Fire' is a heat-tolerant hybrid tomato (Solanum lycopersicum L. formerly Lycopersicon esculentum Mill.) with resistance to all three races of Fusarium wilt incited by Fusarium oxysporum f. sp. lycopersici Sacc. Snyder & Hansen. It has superior fruit-setting ability in comparison with most existing cultivars under high temperatures (>32 °C day/>21 °C night), and the fruit crack less under the rainy field conditions often present in the early fall Florida production season. Fla. 7776 is the pollen parent in `Solar Fire', providing much of the heat tolerance in this hybrid. It has large fruit-providing breeders with a parent to produce heat-tolerant hybrids with two heat-tolerant parents.
A Quantitative Real-time Polymerase Chain Reaction Assay for Botrytis aclada in Onion Bulb Tissue
Authors: Coolong Timothy W. , Walcott Ronald R. , Randle William M.
Published: February 2019

A real-time polymerase chain reaction (PCR) assay has been developed for the detection and quantification of Botrytis aclada (Fresenius), a causal agent of neck rot in onion (Allium cepa L.) bulbs. The assay uses TaqMan probe-based chemistry to detect an amplicon from the L45-550 region of B. aclada while using a DNA sequence from the onion serine acetyl transferase gene (SAT1) as a control. The assay detection limits for B. aclada and onion were 10 pg·μL−1 of genomic DNA. The detection limit for lyophilized B. aclada mycelium was 1 μg. The presence of onion tissue in the samples did not affect the performance of the real-time PCR assay. The assay distinguished among different amounts of B. aclada mycelium growing on onion disks that were inoculated with 0, 102, or 104 B. aclada conidia. Visual observations during the incubation period corresponded with changes in real-time PCR results. This assay could be used to determine the amount of B. aclada mycelium in bulbs during growth, harvest, and storage, thus giving researchers an objective and efficient tool by which to quantify the growth rate and virulence of B. aclada strains in vivo.
Irrigation Strategies for Greenhouse Tomato Production on Rockwool
Authors: Saha Uttam K. , Papadopoulos Athanasios P. , Hao Xiuming , Khosla Shalin
Published: February 2019

To address the concern that irrigation provides sufficient water to match the crop needs, while not impeding oxygen availability to the roots, we conducted an experiment to develop suitable irrigation schedule(s) for greenhouse tomato (Lycopersicon esculentum Mill.) on rockwool. The experimental treatments incorporated the electrical conductivity (EC) of the nutrient solution in the rockwool slab (slab-EC) along with the water content (WC) in the rockwool slab (slab-WC) as the irrigation decision-making variables. They were: slab-WC ≤ 70% or slab-EC ≥ 1.4× normal or more (T1), slab-WC ≤ 70% or slab-EC ≥ 1.7× normal or more (T2), slab-WC ≤ 80% or slab-EC ≥ 1.4× normal or more (T3), slab-WC ≤ 80% or slab-EC ≥ 1.7× normal or more (T4), and the combined weight loss (WL) 700 g or more (T5) and WL 500 g or more (T6), in which “normal” means the feed solution EC as recommended in the seasonal fertigation schedule for a spring–summer tomato crop. The data on early-season marketable yield, total seasonal marketable yield, and fruit grades indicated the superiority of treatments T1, T2, and T6 over T3, T4, and T5. Better root growth was observed with T1, T2, and T6 and this was also associated with minimized nutrient solution leaching; furthermore, these plants had an abundance of coarse and fine roots, higher photosynthesis and transpiration, higher marketable yield, and a higher water use efficiency. Our results thus established that irrigation based on either a slab water content 70% or less or a 500-g weight loss is the best strategy for rockwool-grown greenhouse tomatoes in the spring–summer season. A variation in slab-EC between 1.4 and 1.7× normal, at a slab-WC of 70% or less, would have no significant effect on root growth, water use, marketable yield, or fruit grades.
Evaluation of Drought Tolerance and Avoidance Traits for Six Creeping Bentgrass Cultivars
Authors: McCann Stephen E. , Huang Bingru
Published: February 2019

The objectives of this study were: 1) to compare drought responses between the more recently developed creeping bentgrass cultivars to standard cultivars and 2) to determine differential drought tolerance and avoidance characteristics associated with cultivar variation in drought resistance. Six cultivars of creeping bentgrass (Agrostis stoloniferia) (‘Penn A-4’, ‘Independence’, ‘Declaration’, ‘L-93’, ‘Penncross’, and ‘Putter’) were maintained in growth chambers at 20 °C day/15 °C night either well-watered or exposed to drought stress by withholding water for 17 days. Cultivars varied in turf performance and physiological responses (leaf relative water content and photochemical efficiency) to drought stress, which was reflected in their differences in drought tolerance (osmotic adjustment) and drought avoidance traits (water use rate and efficiency, root viability, root length, and number). ‘Penn A-4,’ ‘Independence,’ and ‘L-93’ generally performed better than other three cultivars under drought conditions, mainly through maintaining higher water use efficiency, root viability, root elongation, or root production. The majority of physiological parameters evaluated suggested that of the six creeping bentgrass cultivars examined in this study, the three cultivars with better ability to survive drought stress used mainly avoidance traits related to water use and water uptake.
Detection of Genetic Variation in Wild Populations of Three Allium Species Using Amplified Fragment Length Polymorphisms
Authors: Phillips Nathan C. , Larson Steven R. , Drost Daniel T.
Published: February 2019

Three wild onion species native to the intermountain west in the United States—Allium acuminatum, A. brandegei, and A. passeyi—show horticultural potential, but little is known about patterns of genetic diversity among localized populations and geographical regions. We examined amplified fragment length polymorphisms (AFLP) within and among five Allium acuminatum, four A. brandegei, and three A. passeyi collection sites in Utah. These three congeners with contrasting abundance and distribution patterns provide an opportunity to investigate the role of geographic distance, altitude, and rarity in patterns of genetic divergence. The collection sites were selected along an altitudinal gradient to reflect ecogeographic variation. Individual plants from each of the 12 sites were genotyped using six AFLP primer combinations detecting DNA variation within and among all three species. Genetic differences between species were high enough to render comparisons among species impractical, so each species was analyzed separately for differences between populations and variability within populations. Similarity coefficients were significantly greater within collection sites versus among collection sites indicating divergence between populations. Within-population genetic diversity was not correlated with elevation for any of the three species. Analysis of molecular variance revealed that 66% (A. acuminatum), 83% (A. passeyi), and 64% (A. brandegei) of observed variation is found within populations. Genetic divergence among populations (ФST) was higher in the widely distributed species, suggesting that interpopulation gene flow may be negatively correlated with range size. Allium acuminatum and A. brandegei individuals cluster into groups corresponding strictly to collection sites based on neighbor-joining analysis of the total number of DNA polymorphisms between individual plants. Allium passeyi populations, however, had less overall genetic variation between populations. Genetic isolation by distance appeared responsible for much of the variability among populations, although there was one notable exception showing significant differences between two geographically close populations in A. acuminatum.
Genetic Variation in Early Growth and Bud Production among Natural Populations of Fraser Fir
Authors: Emerson Jennifer L. , Frampton John , McKeand Steven E.
Published: February 2019

A series of open-pollinated progeny tests of Fraser fir [Abies fraseri (Pursh) Poir.] was analyzed to determine natural variation among six geographic seed sources and to estimate genetic parameters for traits important in Christmas tree production. Highly significant differences were found among seed sources and families within sources (P ≤ 0.0001) for height after 4 years in the field. The individual-tree within-population heritability values for the traits measured in Year 4 ranged from 0 to 0.44, with height having the highest heritability, overall tree quality having a heritability of 0.14, and bud and branching traits having varying heritabilities. Heritability values for height at age 4 varied greatly among the six sources, from 0.15 for the Black Mountains to 0.67 for the Great Smoky Mountains. Highly significant seed source × site interactions as well as family within source × site interactions existed for height. Stability variance analysis, after removing the environmental heterogeneity, showed significant instability across the test sites for two of the six seed sources for height after 4 years, and some rank changes occurred. The high heritability values for height indicate that economically important genetic gains can be made in Fraser fir for Christmas tree production because of the importance of height in determining Christmas tree value.
Effects of Stratification, Germination Temperature, and Pretreatment with Gibberellic Acid and Hydrogen Peroxide on Germination of ‘Fry’ Muscadine (Vitis rotundifolia) Seed
Authors: Conner Patrick J.
Published: February 2019

Germination of muscadine seed has frequently been low and irregular in the University of Georgia breeding program. A systematic study was undertaken to determine the best seed treatments and germination conditions for muscadine seed. Open-pollinated seeds of ‘Fry’ muscadine were used for all treatments. Stratification of seeds was performed by placing dry seed in damp vermiculite at 4 °C for periods of 0, 30, 60, and 90 d. The 90-d stratification period gave the highest germination percentage, with successively lower germination in the shorter stratification treatments. Pretreatment of seeds before stratification with three rates (0.5, 1.0, and 2.0 M) of hydrogen peroxide (H2O2) and four rates (1, 2, 4, and 8 g·L−1) of gibberellic acid (GA3) were used in an attempt to promote germination. Low rates of H2O2 (0.5 M) and GA3 (1 g·L−1) were beneficial in some instances, whereas high rates of GA3 were detrimental. Nicking the seedcoats before stratification and soaking seeds in running water after stratification were ineffective in promoting germination. Germination temperatures of 32/22 °C (8 h/16 h) were superior to 22/22, 27/22, and 37/22 °C.
Postharvest Performance of ‘Pacific Rose™’ Apple Grown Under Partial Rootzone Drying
Authors: Zegbe Jorge A. , Behboudian M. Hossein , Clothier Brent E. , Lang Alexander
Published: February 2019

Quality and storability of ‘Pacific Rose™’ apple grown under partial rootzone drying (PRD) were studied over 2 years. The treatments were commercial irrigation (CI) and PRD, which were applied by watering one side of the tree row throughout the season (Expt. 1) or by alternating irrigation between two sides of the tree row when volumetric soil water content ranged between 0.18 and 0.22 m3·m−3 (Expt. 2). The PRD and CI fruit had similar quality attributes at harvest and after storage except that the former had lower weight loss during storage in Exp. 1 and a lower firmness after storage in Exp. 2. Compared with CI, PRD saved water by 0.15 mega liters per hectare in Exp. 1 and by 0.14 mega liters per hectare in Exp. 2. We recommend PRD for humid environments similar to ours.
Ionizing Irradiation Using Electron Beam to Control Importation of Biothreat Agents in Geranium Cuttings Inhibits Rooting
Authors: Mackay Wayne A. , Pemberton Brent , Maxim Joseph , Pillai Suresh D.
Published: February 2019

Pelargonium × hortorum ‘Tango Dark Red’, ‘Tango Pink’, ‘Americana Red’, and ‘Rocky Mountain Lavender’ unrooted cuttings were subjected to Electron beam (E-beam) irradiation at 0 (control, no treatment), 0.61 ± 0.04, 0.83 ± 0.07, or 1.02 ± 0.01 kGy (mean ± se, n = 4) in Expt. 1 and 0 (control, no treatment), 0.08 ± 0.00, 0.16 ± 0.00, 0.31 ± 0.00, or 0.57 ± 0.02 kGy (mean ± se, n = 4) in Expt. 2. Cuttings exposed to E-beam irradiation other than the control treatment did not root or form callus and exhibited a change in leaf color from green to red and eventually yellow. Our results suggest that the use of ionizing irradiation for preventing the accidental importation of biothreat agents through unrooted Pelargonium cuttings is not feasible.
Determining Sex and Screening for the Adventitious Presence of Transgenic Material in Carica papaya L. Seed Germplasm
Authors: Matsumoto Tracie K. , Zee Francis T.P. , Suzuki Jon Y. , Tripathi Savarni , Carr James , Mackey Bruce
Published: February 2019

Papaya ringspot virus (PRSV) is a devastating disease that has a detrimental impact on both commercial papaya production and Caricaceae germplasm conservation. In 1998, the PRSV coat protein transgenic line 55-1 and derived progeny were released to growers in Hawaii. The transgenic varieties have provided durable and practical control of the disease that have saved the papaya industry. However, like with transgenic crops throughout the world, there is public concern about the possibility of cross-contamination of these transgenic materials into nontransgenic lines. As the designated germplasm repository for Caricaceae, we are responsible for maintaining the genetic integrity of each accession. Therefore, we have developed a protocol using polymerase chain reaction for detection of the adventitious presence of the 55-1 transgene insertion event in both parental plants and their progeny seed populations. This protocol assures a 99.9% confidence level of obtaining seeds that are 99.5% transgene-free. The protocol developed in this study is not typical for most seed validation techniques because there is a higher than normal producer risk resulting from the potential of large numbers of seeds not meeting the stringent criteria. However, we believe this is necessary to ensure the genetic integrity of seeds stored in the repository.
Interspecific Analysis of Xylem Freezing Responses in Acer and Betula
Authors: Byard Stephanie , Wisniewski Michael , Li Jianhua , Karlson Dale
Published: February 2019

Temperate woody plants have evolved two methods for coping with seasonal exposure to subzero temperatures. Supercooling is a freeze-avoidance strategy in which cells can avoid intracellular freezing below subzero temperatures. Nonsupercooling is a freeze-tolerance strategy in which the growth of extracellular ice crystals is promoted and intracellular water is withdrawn. Thus, nonsupercooling species have also evolved adaptations to tolerate intracellular dehydration, which results from the formation of extracellular ice. The goal of our study was to provide the first broad characterization of freezing response within two representative woody genera (Acer and Betula) in relation to the evolution of the freezing response trait. Although all of the examined Acer species (nine) exhibited xylem supercooling response, only five of 14 Betula species were identified as supercooling species. When the characterized freezing responses were overlaid onto a phylogenetic tree, the supercooling freezing response was revealed as an ancestral trait in Betula.
Planting Depth During Container Production and Landscape Establishment Affects Growth of Ulmus parvifolia
Authors: Bryan Donita L. , Arnold Michael A. , Volder Astrid , Watson W. Todd , Lombardini Leonardo , Sloan John J. , Valdez-Aguilar Luis A. , Cartmill Andrew D.
Published: February 2019

Planting depth during container production may influence plant growth, establishment, and subsequent landscape value. A lack of knowledge about the effects of common transplanting practices may lead to suboptimal performance of planted landscape trees. Planting depth, i.e., location of the root collar relative to soil grade, is of particular concern for posttransplant tree growth both when transplanted to larger containers during production and after transplanting into the landscape. It is unknown whether negative effects of poor planting practices are compounded during the production phases and affect subsequent landscape establishment. This study investigated effects of planting depth during two successive phases of container production (10.8 L and 36.6 L) and eventual landscape establishment using lacebark elm (Ulmus parvifolia Jacq.). Tree growth was greater when planted at grade during the initial container (10.8 L) production phase and was reduced when planted 5 cm below grade. In the second container production phase (36.6 L), trees planted above grade had reduced growth compared with trees planted at grade or below grade. For landscape establishment, transplanting at grade to slightly below or above grade produced trees with greater height on average when compared with planting below grade or substantially above grade, whereas there was no effect on trunk diameter. Correlations between initial growth and final growth in the field suggested that substantial deviations of the original root to shoot transition from at-grade planting was more of a factor in initial establishment of lacebark elm than the up-canning practices associated with planting depth during container production.
Nursery Worker Turnover and Language Proficiency
Authors: Mathers Hannah M. , Acuña Alejandra A. , Long Donna R. , Behe Bridget K. , Hodges Alan W. , Haydu John J. , Schuch Ursula K. , Barton Susan S. , Dennis Jennifer H. , Maynard Brian K. , Hall Charles R. , McNeil Robert , Archer Thomas
Published: February 2019

The U.S. nursery and landscape industry generates 1.9 million jobs and had an annual payroll of greater than $3 billion in 2002, yet little is known about nursery and landscape workers. This lack of information is even more pressing considering that labor generally accounts for greater than 40% of production costs and 31% of gross sales. Labor shortages, immigration reform, and legal status of employees are widely reported as the industry's most critical issues. We hypothesized that relevant data regarding the nursery industry workforce may raise an appreciation of the industry's diversity, increase political power and public awareness, and help stakeholders evaluate policy decisions and plan corrective strategies in a more informed manner. A total of 4466 self-administered questionnaires were sent in 2006, attempting to reach 30 nurseries in each of nine states with 1561 returned (35% response rate). Hispanics constituted 70% of the average nursery workforce, including general laborers (76%), crew leaders (61%), and sales/managers (others) (21%). Across firms, labor retention was less than 51% after 5 years and only 22% of employees understood English, raising questions regarding availability and access to training. Sixty percent of nursery employees had not received work-related training, although 81% of men and 72% of women were interested, and an association between training and employee retention existed. The highest rated training topic of interest was English/Spanish (respective of Spanish/English primary language respondents). There was a positive correlation between developing fluency and worker turnover, making the laborer attrition rate even more unfavorable for employers who not only lost employees with acquired experience, but also with acquired English skills.
Marker-assisted Selection for Coupling Phase Resistance to Tomato spotted wilt virus and Phytophthora infestans (Late Blight) in Tomato
Authors: Robbins Matthew D. , Masud Mohammed A.T. , Panthee Dilip R. , Gardner Randolph G. , Francis David M. , Stevens Mikel R.
Published: February 2019

Tomato spotted wilt virus (TSWV) and Phytophthora infestans (late blight) in tomato (Solanum lycopersicum) have a worldwide distribution and are known to cause substantial disease damage. Sw-5 (derived from S. peruvianum) and Ph-3 (derived from S. pimpinellifolium) are, respectively, TSWV and late blight resistance genes. These two genes are linked (within 5 cM on several maps) in repulsion phase near the telomere of the long arm on chromosome 9. The tomato lines NC592 (Ph-3) and NC946 (Sw-5) were crossed to develop an F2 population and subsequent inbred generations. Marker-assisted selection (MAS) using three polymerase chain reaction-based codominant markers (TG328, TG591, and SCAR421) was used in F2 progeny with the goal of selecting for homozygous coupling-phase recombinant lines. From 1152 F2 plants, 11 were identified with potential recombination events between Ph-3 and Sw-5; of those, three were male sterile (ms-10). F3 progeny were generated from the remaining eight F2 recombinants, and resistance to both pathogens, or Ph-3 and Sw-5 in coupling phase, was confirmed in three of those. Recombination was suppressed fivefold in our F2 population to 1.11 cM between genes when compared with published maps of the same region. However, MAS was an efficient tool for selecting the desirable recombination events for these two pathogen resistance genes.
Influence of Hail Net and Reflective Foil on Cyanidin Glycosides and Quercetin Glycosides in ‘Fuji’ Apple Skin
Authors: Jakopič Jerneja , Štampar Franci , Veberič Robert
Published: February 2019

The objective of this work was to compare the contents of cyanidin glycosides and quercetin glycosides in the skin of apples grown with or without hail nets and using reflective foil or not. Under hail nets, photosynthetically active radiation was 10% to 30% lower in comparison with the control treatment. Covering the orchard floor with reflective foil had a positive effect on lighting, particularly on the lower parts of the fruit. Fruit coloration depends on the contents of anthocyanins copigmented with flavonols, the synthesis of which is light-dependent. The content of the main cyanidin glycoside in ‘Fuji’ apple, cyanidin galactoside, was lowest in the control treatment as well as concentrations of cyanidin arabinoside and two other cyanidin pentosides. Reflective foil caused a higher cyanidin glycoside content. Among flavonols, quercetin galactoside, quercetin glucoside, quercetin pentoside, quercetin arabinofuranoside, quercetin xyloside, quercetin rutinoside, quercetin rhamnoside, and quercetin were detected. Hail net and reflective foil both affected the increasing quercetin–glycosides contents. The highest amounts were achieved in the treatment under the hail net, where the orchard floor was covered with reflective foil. We also analyzed catechin, epicatechin, and chlorogenic acid. The lowest amounts of these were measured in the skin of fruit grown on trees under hail nets. In the control treatment, contents of those phenolic compounds were equal or higher, whereas the highest concentrations were detected in the treatments using reflective foil, where lighting was also higher in comparison with the treatments without it.
Effect of 9-Hydroxy-10-oxo-12(Z), 15(Z)-octadecadienoic Acid (KODA) on Endodormancy Breaking in Flower Buds of Japanese Pear
Authors: Sakamoto Daisuke , Nakamura Yuri , Sugiura Hiroyoshi , Sugiura Toshihiko , Asakura Toshikazu , Yokoyama Mineyuki , Moriguchi Takaya
Published: February 2019

The effect of 9-hydroxy-10-oxo-12(Z), 15(Z)-octadecadienoic acid (KODA) on endodormancy breaking was studied in flower buds of japanese pear (Pyrus pyrifolia Nakai). The optimal concentration of KODA (100 μM) for endodormancy breaking was established over a 2-year period during the endodormancy stage of 2006 and 2007 in japanese pear cultivars Kosui, Natsushizuku, and Hosui. The effect of KODA on endodormancy breaking in flower buds was similar between ‘Natsushizuku’ and ‘Kosui’ but somewhat lower in ‘Hosui’. These results indicate that KODA can be an effective agent for promoting endodormancy breaking of flower buds in ‘Natsushizuku’ and ‘Kosui’. Although not as effective as hydrogen cyanamide, KODA may be preferable at late endodormancy stages because it has no apparent phytotoxicity.
Horticulture and Health in the Middle Ages: Images from the Tacuinum Sanitatis
Authors: Janick Jules , Daunay Marie Christine , Paris Harry
Published: February 2019

Lavishly illustrated late 14th century manuscripts known as the Tacuinum Sanitatis, a guide for healthy living, were based on an 11th century Arabic manuscript known as the Taqwim al-Sihha bi al-Ashab al-Sitta (Rectifying Health by Six Causes) written by the physician and philosopher Ibn Butlan (d. 1063). The expensive, illustrated Tacuinum Sanitatis tomes portray a utopian feudal society in which nobles are engaged in play and romance while feudal laborers work the estate. Rich in horticultural imagery, they include vivid scenes of the harvest of vegetables, fruits, flowers, and culinary and medicinal herbs. Each scene is accompanied by a brief summary of the health aspects of the subject. Although medieval medicine was based on ancient philosophical concepts of Greek sciences, particularly Hippocrates and Galen, these documents connect vegetables and fruits with human health and well-being, similar to modern medicine. Hence, the present-day focus on the connection between horticulture and health can be seen as an extension of ancient and medieval regimens for a healthy lifestyle.
Ornamental Plant Response to Percentage of Reclaimed Water Irrigation
Authors: Yeager Thomas H. , von Merveldt Joseph K. , Larsen Claudia A.
Published: February 2019

Vinca [Catharanthus roseus (L.) G. Don], salvia (Salvia splendens F. Sellow ex Roem. and Schult.), Dwarf Yaupon holly (Ilex vomitoria Ait. ‘Nana’), and ‘Helleri’ holly (Ilex crenata Thunb. ‘Helleri’) were grown in 2.3-L containers with soilless substrates in a greenhouse. Irrigation was applied as needed to the substrate surface or applied to the substrate surface and applied over plant foliage. Irrigation for both application methods was composed of 0%, 25%, 50%, 75%, or 100% reclaimed water (processed sewage) with deionized water composing the remainder. Shoot dry weights of marketable-sized plants were either larger or similar when 100% reclaimed water was used compared with 0% reclaimed water (deionized). Root dry weights exhibited a similar response except for salvia roots that were smaller with 100% reclaimed water irrigation regardless of application method. Leachate NO3-N, phosphorus (P), and potassium (K) generally decreased throughout the experiments for vinca and Dwarf Yaupon holly and were highest at experiment midpoint for ‘Helleri’ holly and lowest for salvia. Leachate electrical conductivities (ECs) were generally highest at experiment termination for vinca and salvia, whereas ECs of Dwarf Yaupon and ‘Helleri’ holly tended to peak at experimental midpoint and then decrease slightly at termination. ECs were usually less than 2 dS·m−1 except at experimental midpoint (4.5 months) for ‘Helleri’ holly. Based on the response of plants in this research, high-quality reclaimed water is a viable water source for annual and woody container-grown nursery crops.
Field Screening of Cowpea Genotypes for Alkaline Soil Tolerance
Authors: Goenaga Ricardo , Gillaspie A. Graves , Quiles Adolfo
Published: February 2019

Cowpea or Southernpea [Vigna unguiculata (L.) Walp.] is an important legume crop used as a feed for livestock, as a green vegetable, and for consumption of its dry beans, which provide 22% to 25% protein. The crop is very sensitive to alkaline soil conditions. When grown at soil pH of 7.5 or higher, cowpea develops severe leaf chlorosis caused by deficiencies of iron (Fe), zinc (Zn), and manganese (Mn) resulting in stunted plant growth and yield reduction. We evaluated in replicated field experiments at St. Croix, U.S. Virgin Islands, and Juana Díaz, Puerto Rico, 24 PIs and two commercial cultivars, some of which have shown some tolerance to alkaline soils in unreplicated, seed regeneration plots of the U.S. cowpea collection. Alkaline soil conditions at St. Croix were too severe resulting in average yield of genotypes at this location being significantly lower and 77% less than that at Juana Díaz. Nevertheless, some genotypes performed well at both locations. For example, PIs 222756, 214354, 163142, 582605, 582840, 255766, 582610, 582614, 582576, 582809, and 349674 yielded in the upper half of the group at both locations. Accession PI 163142 ranked third in grain yield production at both locations and outyielded the iron-chlorosis-resistant controls at St. Croix. These genotypes deserve further attention as potential sources of alkaline soil tolerance.
Single Recessive Gene for Multiple Flowering in Summer Squash
Authors: Paris Harry S. , Hanan Aviva
Published: February 2019

Most summer squash, Cucurbita pepo L., produce one flower bud per leaf axil, whereas some genotypes can produce two or more. The former genotypes are referred to as single-flowering, whereas the latter are referred to as multiple-flowering. The objective was to determine the mode of inheritance of multiple flowering. The zucchini ‘True French’, which is single-flowering, was crossed with Accession 1777, a nearly isogenic line of this cultivar, which is multiple-flowering. Parental, filial, and back-cross plants were grown in pots in the greenhouse and each of their first 15 leaf axils was scored for the number of flower buds. Nearly all F1 plants, regardless of the direction of the cross, and plants resulting from back-crossing to ‘True French’ were single-flowering. Approximately one-fourth of the F2 plants, regardless of the direction of the cross, and half of the plants of the back-cross to 1777 produced two flowers at one or more leaf axils. These results indicate that the ability to produce more than one flower per axil is conferred by a single recessive gene, herewith designated multiple flowering, symbol mf.
Variation of Total Soluble Protein Content in Fruit among Six Greenhouse Tomato Cultivars
Authors: Matsuda Ryo , Kubota Chieri
Published: February 2019

Tomato has been considered as a potential biological production platform for plant-made pharmaceuticals (PMPs). However, information is limited for protein productivity and dynamics in tomato fruit. As part of our PMP production project, total soluble protein (TSP) content of green and red fruits was analyzed for selected six greenhouse cultivars. The six cultivars consisted of various fruit types (including cluster, cherry, mini plum, and grape types) with sizes ranging from 10 to 150 and from 14 to 188 g fresh weight for green and red fruits, respectively. In fruit TSP content per unit dry weight (DW), approximately seven- to eightfold variation was observed among cultivars for both green and red fruits. There was no significant correlation between fruit TSP content per DW and fruit DW or fruit type over the cultivars irrespective of fruit ripening stage, indicating that fruit weight or fruit type of a cultivar cannot be an indicator of the TSP content per DW. There was also an inconsistent trend in differences in fruit TSP content per whole fruit between green and red fruit among cultivars. Our results suggest that a low-yielding cultivar can produce high TSP content per unit ground area resulting from high TSP content per DW in fruit. A background tomato cultivar or genotype candidate for commercial PMP production should thus be selected from among various fruit types considering both yield potential and fruit TSP content.
Supercooling and Cold-hardiness of Acclimated and Deacclimated Buds and Stems of Persian Walnut Cultivars and Selections
Authors: Aslamarz Asadolah Aslani , Vahdati Kourosh , Rahemi Majid , Hassani Darab , Leslie Charles
Published: February 2019

To study the cold-hardiness of Persian walnut cultivars and selections, three methods were compared: 1) thermal analysis; 2) evaluation of tissue health after controlled freezing; and 3) field observations after a severe midwinter freeze. Stem segments and buds were collected from eight Persian walnut genotypes (four commercial cultivars and four promising Iranian selections). Thermal analysis was conducted using thermoelectric modules (TEM) to measure the high (HTE) and low (LTE) temperature exotherms produced when water and tissues freeze. TEM signals were recorded as the temperature of the samples was decreased at a rate of 2 °C/h. Tissue injury under controlled temperatures was evaluated using pre-chilled stem segments cooled at 2 °C/h to set temperatures ranging from –5 to –30 °C and then held at these temperatures for 16 h. Frozen samples were thawed and visually evaluated for severity of injury. Cold damage under field conditions was evaluated after an unusually severe winter freeze. Twigs from affected trees were removed in mid-February and in April and visually rated for extent of injury and ability to recover. The occurrence of LTEs was correlated with death of the tissues as assessed by tissue browning. Both the capacity to supercool and the cold-hardiness of cultivars and selections tested increased with accumulated seasonal chilling and decreased as they approached spring budbreak. Thermal analysis showed a tendency for buds and stems to exhibit multiple LTEs at peak dormancy. The cultivars and selections were classified into three groups based on their cold-hardiness: sensitive (‘Z30’ and ‘Serr’), semihardy (‘Z53’ and ‘Z67’), and hardy (‘Lara’, ‘Hartley’, ‘Z63’, and ‘Pedro’).
Water-based Cold Protection of Chill-sensitive Foliage Plants in Shadehouses
Authors: Stamps Robert H. , Natarajan Seenivasan , Parsons Lawrence R. , Chen Jianjun
Published: February 2019

Four water-based cold protection systems [under-benches mist (UBM), over-roadways mist (ORM), and two among-plants fog (APF1, APF2)] were evaluated for their water use and effectiveness in protecting ornamental foliage plants from chilling injury (CI) under protected shade structures at three commercial locations in Florida. UBM used a two-stage thermostat-controlled system with mist nozzles on 25-cm above-ground risers combined with an overhead retractable heat curtain. Both ORM and APF1 had seasonally applied polyethylene film cladding and manually controlled irrigation systems. The ORM system had the mist nozzles located 1.8 m high and APF1 and APF2 systems had the low-pressure fog nozzles mounted on 25-cm above-ground risers spaced among the plants. Temperature data loggers were placed outside and inside the northwest sections of the shadehouses. ORM and the two APF systems were evaluated during freeze events in 2006, 2007, and 2008 and UBM only in 2007 and 2008. UBM, ORM, and APF1 successfully kept the shadehouse temperatures above critical chilling temperatures for all of the foliage plants. APF2 protected all foliage crops except for jungle drum “palm” (Carludovica sp.) that sustained CI. At the UBM site, the air temperatures recorded inside the shadehouse were ≈17 °C warmer than outside. Both ORM and APF1 maintained adequately warm temperatures inside the shadehouses; however, the fog system maintained equal or higher temperatures than the mist system and used 86% less water. Inside temperatures were lower with APF2 than APF1 although the emitter type was the same and the water application rates were similar. These temperature differences were attributable to the greater APF2 shadehouse surface area (SA) and volume (V) compared with APF1 and indicate that the SA and V of structures being heated need to be considered when designing water-based low-pressure fog heating systems. The ORM and both fog systems conserved water compared with using the conventional sprinkler irrigation systems. These results show the potential of water-based approaches for maintaining shadehouses above chilling temperatures during freeze events.