bluuebunny/crossref_metadata_2025 huggingface dataset:
Rate of Nitrogen Fertigation During Vegetative Growth and Spray Applications of Urea in the Fall Alters Growth and Flowering of Florists' Hydrangeas
Authors: Bi Guihong , Scagel Carolyn F. , Harkess Richard
Published: February 2019

Plants of Hydrangea macrophylla ‘Merritt's Supreme’ were fertigated with 0, 70, 140, 210, or 280 mg·L−1 nitrogen (N) from July to Sept. 2005 and sprayed with 0% or 3% urea in late October to evaluate whether plant N status during vegetative growth influences plant performance during forcing. In late November, plants were manually defoliated, moved into a dark cooler (4.4 to 5.5 °C) for 8 weeks, and then placed into a greenhouse for forcing. After budbreak, plants were supplied with either 0 N or 140 mg·L−1 N for 9 weeks. Plant growth and N content were evaluated in Nov. 2005 before cold storage and plant growth, flowering, and leaf quality parameters were measured in late Apr. 2006. Increasing N fertigation rate in 2005 significantly increased plant biomass by ≈14 g (26%) and plant N content by ≈615 mg (67%). Spray applications of urea (urea sprays) in the fall had no influence on plant biomass but significantly increased plant N content by ≈520 mg (54%). In general, plants grown with 210 and 280 mg·L−1 N during 2005 had the greatest growth (total plant biomass, height), flowering (number of flowers, flower size), and leaf quality (leaf area, chlorophyll content) during forcing in 2006. Urea sprays before defoliation increased plant growth, flowering, and leaf quality characteristics during forcing in 2006. Providing plants with N during the forcing period also increased plant growth, flowering, and leaf quality characteristics. Urea sprays in the fall were as effective as N fertilizer in the spring on improving growth and flowering. We conclude that both vegetative growth and flowering during forcing of ‘Merritt's Supreme’ hydrangea are influenced by both the N status before forcing and N supply from fertilizer during forcing. A combination of optimum rates of N fertigation during the vegetative stage of production with urea sprays before defoliation could be a useful management strategy to control excessive vegetative growth, increase N storage, reduce the total N input, and optimize growth and flowering of container-grown florists’ hydrangeas.
Container Height and Douglas Fir Bark Texture Affect Substrate Physical Properties
Authors: Owen James S. , Altland James E.
Published: February 2019

A study was conducted to quantify the effect of substrate texture on water-holding capacity of douglas fir [Pseudotsuga menziesii (Mirb.) Franco] bark (DFB) in containers of varying height. Medium (less than 2.2 cm) and fine (less than 0.9 cm) DFB were packed into 7.6 cm i.d. aluminum cores 3.8, 7.6, and 15.2 cm tall to determine container capacity (CC) and air space (AS) at varying container heights. Increasing container height resulted in a linear decrease in CC and a linear increase in AS. Fine texture DFB bulk density (Db) increased 18% with increasing container height, whereas Db of medium texture DFB was unaffected. Water-holding capacity decreased 20% and 42% in medium and fine textured DFB, respectively, with increasing container height from 3.8 to 15.2 cm. A second study was conducted to investigate water distribution in a 15.2-cm tall container for a given substrate texture. Polyvinyl chloride cores (15.2 cm tall × 7.6 cm i.d.) were packed with the same substrates, drained to CC, frozen, and sawed into 2.5-cm sections to determine water-holding capacity at each height. A finer substrate texture increased the amount of water throughout the container profile, but percent of total water for each strata remained similar. Container height and plant size (i.e., transplant or salable), in relation to substrate texture, should be considerations when producing containerized crops. In addition, bark texture alters water-holding capacity and water distribution within the container, ultimately affecting water management practices.
Selective Creeping Bentgrass Control in Kentucky Bluegrass and Tall Fescue with Mesotrione and Triclopyr Ester
Authors: Dernoeden Peter H. , Kaminski John E. , Fu Jinmin
Published: February 2019

Creeping bentgrass (Agrostis stolonifera L.; CBG) is a common weed in home lawns and golf course roughs in many regions of the United States. Currently, no herbicides are registered for selective control of CBG in cool-season grasses. The objective of this field study was to evaluate the ability of mesotrione and triclopyr ester to selectively remove CBG from Kentucky bluegrass (Poa pratensis L.) and tall fescue (Festuca arundinacea Schreb.). Mesotrione (0.14 and 0.21 kg·ha−1 a.i.) and triclopyr ester (0.56 and 1.12 kg·ha−1 a.i.) were applied on a 2-week interval two, three, or four times in Connecticut and Maryland in 2005, and three or four times in Maryland in 2006. Two applications of mesotrione at 0.21 kg·ha−1 a.i. provided marginally acceptable CBG control, but three or four applications at 0.14 or 0.21 kg·ha−1 a.i. provided excellent CBG control. Mesotrione elicited little or no injury to Kentucky bluegrass, but generally caused objectionable injury in tall fescue for about 7 to 14 d after each application. Triclopyr applied at 0.56 kg·ha−1 a.i. reduced CBG cover, but the level of control generally was unacceptable, regardless of application frequency. Three or four applications of triclopyr (1.12 kg·ha−1 a.i.) effectively controlled CBG in Connecticut in 2005 and Maryland in 2006. Triclopyr caused no visual injury to tall fescue, regardless of rate or application frequency. Four triclopyr applications to Kentucky bluegrass, however, were phytotoxic and reduced stand density, especially at the high rate (1.12 kg·ha−1 a.i.). Three summer applications of mesotrione (0.14 kg·ha−1 a.i.) or triclopyr (1.12 kg·ha−1 a.i.) provided the best combination of turfgrass safety and CBG control. Chemical names used: [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid (triclopyr ester); 2-[4-(methylsulfonyl)-2-nitrobenzoyl]-1,3-cyclohexanedione (mesotrione)
‘Sisters on Spring Outing’ (Paeonia suffruticosa ‘Zi Mei You Chun’) (Paeoniaceae): A Unique Chinese Tree Peony Cultivar Possessing Side Flowers and Bicolored Floral Discs
Authors: Suo Zhi-li , Zhao Xiao-qing , Zhao Jian-peng , Zhao Xiao-chong , Chen Fu-fei
Published: February 2019

Large natural genetic diversifications have occurred among Chinese tree peony cultivars under the natural and artificial selections on the flower for ornamental and medicinal uses in the past over 1500 years in China. Paeonia suffruticosa ‘Zi Mei You Chun’ X.Q. Zhao & J.P. Zhao & X.Z. Zhao & X.C. Zhao & Q.X. Gao & Z.Q. Zhao & J.X. Zhao & Z.L. Suo (Paeoniaceae) is a unique cultivar possessing side flowers and bicolored floral disc belonging to the Central Plains tree peony cultivar group of China. This natural mutant is not only an outstanding ornamental, but also a valuable material for scientific research on evolution of tree peony cultivars, metabolic pathways of pigments in the floral disc, origin of floral disc in Paeoniaceae, and other issues in plant evolutionary and developmental genetics.
‘Raider Azure’ Mealy Blue Sage (Salvia farinacea var. farinacea Benth.)
Authors: McKenney Cynthia B. , Balch Sandra A. , Hegemann Victor , Metz Susan P.
Published: February 2019

Native wildflowers provide a rich germplasm resource for continued plant improvement. Over the past 10 years, native accessions of Salvia farinacea var. farinacea Benth. have been collected and introduced into an ornamental breeding program. Texas Tech University announces the release of a new mealy blue sage cultivar named ‘Raider Azure’. ‘Raider Azure’ is intended for use as a drought-tolerant native ornamental for demanding landscapes. It has been trialed for use as a perennial bedding plant where it has displayed attractive violet–blue flowers and a vigorous growth habit, which is common in this species. The extended bloom period for mealy blue sage suggests the cultivar ‘Raider Azure’ is well suited for full sun bedding displays in a variety of locations.
Exploration and Inventory of Native Orchid Germplasm in West Borneo, Indonesia
Authors: Siregar Chairani
Published: February 2019

Borneo (Kalimantan) is the third largest island in the world. It is rich with various indigenous orchid species that grow epiphytically, terrestrially, or saprophytically in the forests. Its rain forests are also home to some rare species such as some Aërides sp., Bulbophyllum sp., Cymbidium sp., Dendrobium sp., Dimorphorchis sp., Grammatophyllum sp., Paphiopedilum sp., Phalaenopsis sp., Paraphalaenopsis sp., and Vanda sp., all of which have a very high economic value. These species are endangered and some of them may have not yet been found or discovered, because of the loss of habitat resulting from fire, forest damage, illegal logging, and orchid hunting either by domestic or foreign collectors. Until recently, there are only a few records on the orchid native to West Borneo. For this reason, a research was conducted to identify and create an inventory of all orchid species that exist in West Borneo before they become extinct along with their habitat and to conserve them ex situ. This research was conducted in 10 counties and one municipal city in West Borneo, and inventory was done through exploration. Orchids found were recorded and identified into their genera and their species by visual examination of vegetative and floral characteristics, respectively. A total of 197 species of orchids from 66 genera were identified, and among those, 27 species live as terrestrials, 169 species live as epiphytes, and one species lives as both an epiphyte and terrestrial.
In Vitro Propagation of Traditional Italian Hazelnut Cultivars as a Tool for the Valorization and Conservation of Local Genetic Resources
Authors: Bacchetta Loretta , Aramini Maria , Bernardini Claudia , Rugini Eddo
Published: February 2019

The hazelnut (Corylus avellana) is one of the most important crops in the Mediterranean basin. The availability of efficient and reliable in vitro propagation could valorize the local genetic resources. Different studies have been carried out for the definition of an efficient hazelnut micropropagation protocol. These have usually been performed on the most important cultivars, but the application of the micropropagation protocol to the minor ones has produced contradictory results and the technique sometimes had less success than the traditional one. The aim of this work was to gather knowledge and additional information on the in vitro performance of some minor cultivars in comparison with the most used for micropropagation. A revised procedure for the specific medium formulation is suggested. The sterilization and culture establishment phases are discussed in detail. The role of zeatin and 6-benzylamminopurine (BA) in shoot proliferation in the Italian traditional cultivars is compared to improve this phase. The rooting stage proves to be one of the most crucial steps in achieving a large-scale commercial application of hazelnut micropropagation.
Water-soluble Antioxidant Potential of Turkish Pepper Cultivars
Authors: Frary Anne , Keçeli M. Ali , Ökmen Bilal , Şιğva Hasan Ö. , Yemenicioğlu Ahmet , Doğanlar Sami
Published: February 2019

In this work, 29 pepper cultivars that represent the diversity of types and varieties grown in Turkey were analyzed for water-soluble antioxidant capacity and phenolic and vitamin C contents. In addition, 14 non-Turkish cultivars were tested for comparison. Significant diversity was observed in the different cultivars with the most variation (7.4-fold) seen for total antioxidant capacity, which ranged from 2.57 to 18.96 mmol Trolox/kg. Vitamin C content for the peppers ranged from 522 to 1631 mg·kg−1, a 3.1-fold difference, whereas total phenolic content for the pepper cultivars ranged from 607 to 2724 mg·kg−1, a 4.5-fold difference. When cultivars were grouped by morphology/use, it was found that some types had significantly more variation and higher antioxidant activities than other types. Thus, for water-soluble antioxidant capacity, most variation was seen in long, blunt-ended Çarliston types, whereas long, pointed Sivri peppers had the highest mean capacity. Bell-shaped Dolmalιk and Sivri peppers had the most variation for phenolic content, but fancy Süs and Sivri types had the highest means for this trait. Dolmalιk types showed the most variation for vitamin C content, whereas Süs and Sivri peppers had the highest means for this character. All three parameters were significantly and positively correlated with the strongest correlation between total antioxidant capacity and phenolic content (r = 0.71). The presence of significant variation for antioxidant content in Turkish germplasm indicates that this material can be used for improvement and genetic mapping of nutritional content in pepper.
Vegetative and Floral Chilling Requirements of Four New Kiwi Cultivars of Actinidia chinensis and A. deliciosa
Authors: Wall Clint , Dozier William , Ebel Robert C. , Wilkins Bryan , Woods Floyd , Foshee Wheeler
Published: February 2019

Kiwifruit (Actinidia deliciosa A. Chev. and Actinidia chinensis Planch) require winter chilling to complete rest and growing degree hours to grow. This study was conducted to compare the chilling requirement and growing degree hours for budbreak and floral development of two female cultivars of A. chinensis, ‘Golden Sunshine’ and ‘Golden Dragon', two female cultivars of A. deliciosa, ‘AU Fitzgerald’ and ‘Hayward', and two male cultivars of A. deliciosa, ‘AU Authur’ and ‘Matua'. In 2005 and 2006, shoot cuttings were made from dormant 1-year canes at nodes 6 to 20, starting from the basal end of canes and held in cold storage at 4 °C. Cuttings were removed from storage and flowering was forced in a greenhouse maintained at 25 °C. Maximum budbreak was determined to be 700 h for ‘Golden Sunshine’, 800 h for ‘Golden Dragon’ and ‘AU Fitzgerald’, and 900 h for ‘Hayward’, ‘Matua’, and ‘AU Authur’. Growing degree hour to first budbreak were 9,500 h for ‘Golden Dragon’ and 15,000 h for ‘Golden Sunshine’, with the correlation of determination too low for the other cultivars. The high heat requirement for ‘Gold Sunshine’ would reduce the risk of injury by late spring frosts. Bloom period of both male cultivars overlapped with bloom periods for all cultivars except ‘Golden Dragon’ for fully mature vines in the field.
Iron Induces Root and Leaf Ferric Chelate Reduction Activity in Grapevine Rootstock 140 Ruggeri
Authors: Siminis Charalambos I. , Stavrakakis Manolis N.
Published: February 2019

Ferric chelate reduction (FCR) activity of roots and leaves was determined in the grapevine rootstock 140 Ruggeri under iron (Fe)-deficient and Fe-sufficient conditions. Micropropagated plants were subjected to 0 or 40 μm Fe(III) EDTA in hydroponic culture. After 10 days of treatments, Fe-deficient plants had a lower level of root FCR activity and chlorophyll content compared with Fe-sufficient plants. Iron supply (20 μm) to Fe-deficient plants caused a rapid increase of root FCR activity (five times higher than initial values) and plants restored leaf chlorophyll content, whereas those not supplied with Fe retained reducing activity at low levels. In Fe-sufficient plants, root FCR activity decreased gradually when Fe was removed from the nutrient solution, reaching the same low levels as the Fe-deficient plants. Iron-sufficient plants displayed constitutively elevated root-reducing capacity for 3 weeks in culture under Fe-sufficient conditions. In Fe-deficient plants, root FCR activity was confined at the apical region of the lateral roots, whereas in Fe-treated plants, activity was detected along almost the whole length of the lateral roots. Root hair development, from the aspect of length and density, proved to be independent of the Fe status of rootstock plants. Leaf FCR activity was measured in mesophyll protoplasts from in vitro-growing Fe-deficient and Fe-sufficient plants. Mesophyll protoplasts reducing activity in Fe-deficient plants appeared to be decreased 43.5% or 40.3%, on a protoplast number or protein basis, respectively, in comparison with that in protoplasts from Fe-sufficient plant leaves. The results suggest that Fe is one of the agents inducing root and leaf FCR activity in grapevine rootstock 140 Ruggeri, altering furthermore its localization pattern in roots.
WholeTree Substrate and Fertilizer Rate in Production of Greenhouse-grown Petunia (Petunia ×hybrida Vilm.) and Marigold (Tagetes patula L.)
Authors: Fain Glenn B. , Gilliam Charles H. , Sibley Jeff L. , Boyer Cheryl R. , Witcher Anthony L.
Published: February 2019

A substrate component (WholeTree) made from loblolly pine (Pinus taeda L.) was evaluated along with starter fertilizer rate in the production of greenhouse-grown petunia (Petunia ×hybrida Vilm. ‘Dreams Purple’) and marigold (Tagetes patula L. ‘Hero Spry’). Loblolly pine from a 12-year-old plantation were harvested at ground level, chipped, and further processed through a hammer mill to pass a 0.64-cm screen. The resulting WholeTree (WT) substrate was used alone or combined with 20% (WTP2) or 50% (WTP5) (by volume) Canadian sphagnum peatmoss and compared with an industry standard peat-lite (PL) mix of 8 peatmoss : 1 vermiculite : 1 perlite (by volume). Substrates were amended with 1.78 kg·m−3 dolomitic lime, 0.59 kg·m−3 gypsum [CaSO4-2(H2O)], 0.44 kg·m−3 Micromax, 1.78 kg·m−3 16N–2.6P–9.9K (3- to 4-month release), and 1.78 kg·m−3 16N–2.6P–10.8K (5- to 6-month release). A 7N–1.3P–8.3K starter fertilizer (SF) was added to each substrate at 0.0, 1.19, 2.37, or 3.56 kg·m−3. Container capacity (CC) was greatest for PL and decreased as the percentage of peatmoss in the substrate decreased with WT having 35% less CC than PL. Conversely, air space (AS) was greatest for the WT and decreased as percentage of peatmoss increased with PL containing 33% less AS than WT. In general, petunia dry weight was greatest for any substrate containing peatmoss with a SF rate of 2.37 kg·m−3 or greater. The exception was that petunia grown in WT at 3.56 kg·m−3 SF had similar dry weight as all other treatments. Marigold dry weight was similar for all substrates where at least 2.37 kg·m−3 SF was used.
Cooling and Long-day Lighting Influences Growth and Flowering of Phlox paniculata L. ‘Ice Cap’ Used for Cut Flowers
Authors: Garner James M. , Armitage Allan M.
Published: February 2019

In two studies, rooted cuttings of Phlox paniculata L. ‘Ice Cap’ (summer phlox) were cooled for 0, 4, 8, 12, or 16 weeks. Plants were forced in a glasshouse averaging 18 °C nights under extended-day and night-interruption lighting from incandescent lamps providing a minimum of 14 μmol·s−1·m−2 at plant level or continuous lighting from metal halide (HID) lamps providing a minimum of 400 μmol·s−1·m−2 at plant level. The influence of cooling duration on forcing days to flower, flowering stem counts, and flowering stem length was evaluated. Cooling plants promoted longer stems, higher flowering stem yields, and decreased days to flower when forced under long days provided by incandescent lamps, but when forced under HID lamps, days to flower for cooled plants were similar to those of noncooled plants regardless of cooling duration. Phlox forced in extended daylighting flowered in fewer days, had longer stems, and produced more flowering stems than those forced in night-interruption lighting. With continuous HID lighting, stem lengths and stems harvested per plant increased in a linear manner as cooling increased from zero to 16 weeks. Stem lengths ranged from 63.6 cm for noncooled plants to 96.3 cm for those receiving 16 weeks cooling, and flowering stem yields ranged from seven stems per plant for noncooled plants to 13 for those cooled 16 weeks. Phlox forced under HID lights flowered in substantially fewer days and had longer stems than those forced under incandescent lamps.
Reconciling pH for Ammonia Biofiltration and Cucumber Yield in a Recirculating Aquaponic System with Perlite Biofilters
Authors: Tyson Richard V. , Simonne Eric H. , Treadwell Danielle D. , White James M. , Simonne Amarat
Published: February 2019

Integrating hydroponic and aquaculture systems (aquaponics) requires balanced pH for plants, fish, and nitrifying bacteria. Nitrification prevents accumulation of fish waste ammonia by converting it to NO3
–-N. The difference in optimum pH for hydroponic cucumber (Cucumis sativa) (5.5 to 6.0) and nitrification (7.5 to 9.0) requires reconciliation to improve systems integration and sustainability. The purpose of this investigation was to: 1) determine the ammonia biofiltration rate of a perlite trickling biofilter/root growth medium in an aquaponic system, 2) predict the relative contribution of nitrifiers and plants to ammonia biofiltration, and 3) establish the reconciling pH for ammonia biofiltration and cucumber yield in recirculating aquaponics. The biofiltration rate of total ammonia nitrogen (TAN) removal was 19, 31, and 80 g·m−3·d−1 for aquaponic systems [cucumber, tilapia (Oreochromis niloticus), and nitrifying bacteria (Nitrosomonas sp. + Nitrobacter sp.)] with operating pH at 6.0, 7.0, and 8.0, respectively. With the existing aquaponic design (four plants/20 L perlite biofilter/100 L tank water), the aquaponic biofilter (with plants and nitrifiers) was three times more effective at removing TAN compared with plant uptake alone at pH 6.0. Most probable number of Nitrosomonas sp. bacteria cells sampled from biofilter cores indicated that the aquaculture control (pH 7.0) had a significantly higher (0.01% level) bacteria cell number compared with treatments containing plants in the biofilter (pH 6.0, 7.0, or 8.0). However, the highest TAN removal was with aquaponic production at pH 8.0. Thus, operating pH was more important than nitrifying bacteria population in determining the rate of ammonia biofiltration. Early marketable cucumber fruit yield decreased linearly from 1.5 to 0.7 kg/plant as pH increased from 6.0 to 8.0, but total marketable yield was not different. The reconciling pH for this system was pH 8.0, except during production for early-season cucumber market windows in which pH 7.0 would be recommended.
Yield, Mineral Composition, Water Relations, and Water Use Efficiency of Grafted Mini-watermelon Plants Under Deficit Irrigation
Authors: Rouphael Youssef , Cardarelli Mariateresa , Colla Giuseppe , Rea Elvira
Published: February 2019

Limited water supply in the Mediterranean region is a major problem in irrigated agriculture. Grafting may enhance drought resistance, plant water use efficiency, and plant growth. An experiment was conducted in two consecutive growing seasons to determine yield, plant growth, fruit quality, leaf gas exchange, water relations, macroelements content in fruits and leaves, and water use efficiency of mini-watermelon plants [Citrullus lanatus (Thunb.) Matsum. and Nakai cv. Ingrid], either ungrafted or grafted onto the commercial rootstock ‘PS 1313’ (Cucurbita maxima Duchesne × Cucurbita moschata Duchesne), under open field conditions. Irrigation treatments were 1.0, 0.75, and 0.5 evapotranspiration rates. In both years (2006 and 2007), marketable yield decreased linearly in response to an increase in water stress. When averaged over year and irrigation rate, the total and marketable yields were higher by 115% and 61% in grafted than in ungrafted plants, respectively. The fruit quality parameters of grafted mini-watermelons such as fruit dry matter and total soluble solids content were similar in comparison with those of ungrafted plants, whereas titratable acidity, K, and Mg concentrations improved significantly. In both grafting combinations, yield water use efficiency (WUEy) increased under water stress conditions with higher WUE values recorded in grafted than ungrafted plants. The concentration of N, K, and Mg in leaves was higher by 7.4%, 25.6%, and 38.8%, respectively, in grafted than in ungrafted plants. The net assimilation of CO2, stomatal conductance, relative water content, leaf, and osmotic potential decreased under water stress conditions. The sensitivity to water stress was similar between grafted and ungrafted plants, and the higher marketable yield from grafted plants was mainly the result of an improvement in nutritional status and higher CO2 assimilation and water uptake from the soil.
Gas Exchange and Growth of Transplanted and Nontransplanted Field-grown Shumard Red Oak Trees Grown with and without Organic Mulch
Authors: Montague Thayne , Fox Lindsey
Published: February 2019

Gas exchange and growth of transplanted and nontransplanted, mulched and nonmulched field-grown Shumard red oak trees (Quercus shumardii Buckli.) were investigated in a semiarid climate. In Spring 2003, 12 field-grown trees were selected for uniformity. Six trees were moved with a tree spade and six trees were undisturbed. In addition, pine bark mulch was applied around three randomly selected transplant and nontransplant trees. Soil volumetric water content, predawn leaf water potential, midday stomatal conductance (g
S) and leaf temperature, and growth data were collected over three consecutive growing seasons. Throughout the experiment, weekly predawn leaf water potential and g
S data indicate transplanted trees with and without mulch were under greater water stress when compared with nontransplanted trees. In addition, nontransplanted trees with mulch were under greater stress when compared with nontransplanted trees without mulch. Each year, transplanted trees and nontransplanted trees with mulch had less apical growth when compared with nontransplanted trees without mulch. Although gas exchange and apical growth of transplanted trees and nontransplanted mulched trees tended to increase each growing season, by experiment termination, gas exchange and apical growth for transplanted trees and nontransplanted trees with mulch did not recover to nontransplanted, nonmulch tree levels.
Inheritance of Major Spathe Colors in Anthurium andraeanum Hort. Is Determined by Three Major Genes
Authors: Elibox Winston , Umaharan Pathmanathan
Published: February 2019

The inheritance of spathe color in anthurium (Anthurium andraeanum Hort.) was studied in 77 crosses involving 59 parental genotypes. The progeny segregation into “colored : white” did not fit the genetic model proposed by Kamemoto et al. (1988), but fit a duplicate recessive epistasis model involving genes O and R, in which either O or R or both in the recessive form would result in white-spathed progeny. The progeny segregation into red or orange group was in agreement with the Kamemoto et al. (1988) model and is determined by the status of the M gene. The dosage effect of particularly the R gene accounted for the differentiation of reds from pinks and oranges from corals. Putative roles for the three genes (M, O, and R) in the flavonoid biosynthetic pathway are postulated.
Rye Mulch Management Affects Short-term Indicators of Soil Quality in the Transition to Conservation Tillage for Cabbage
Authors: Mochizuki Maren J. , Rangarajan Anusuya , Bellinder Robin R. , van Es Harold M. , Björkman Thomas
Published: February 2019

If benefits of conservation tillage can be quantified even in the transition year from conventional tillage, growers will more likely integrate practices that maintain or enhance soil quality and productivity. The management of surface residue is an important component of conservation tillage, especially in cool, rainy climates where vegetable growth and yield reductions have been observed when heavy residue is present. Cereal rye (Secale cereale L.), grown until flowering, was killed with glyphosate and was then cut and removed (stubble treatment) or rolled or chopped to form a surface mulch (mulched treatment) before transplanting cabbage. Rolled mulch increased soil wet aggregate stability by 4% and reduced soil penetrometer resistance by up to 0.5 MPa compared with rye stubble treatments in 2003. In 2004, frequent rains saturated soils and may have accelerated the decomposition of chopped mulch, minimizing treatment effects. Rolled mulch reduced soil temperatures by up to 2 °C in 2003, but June transplanting of cabbage probably minimized the impact of soil temperature. Mulched treatments did not delay cabbage maturity or affect head quality characteristics such as color or uniformity. Although rolled mulch reduced cabbage growth by as much as 30% and yield by 21% in 2003, chopped mulch did not affect growth or yield in 2004. Yield reduction may be overcome by killing the rye relatively early in the spring or retaining only the surface stubble; these strategies may maintain or measurably improve soil quality even in the transition year to conservation tillage.
Release of Available Nitrogen after Incorporation of a Legume Cover Crop in Concord Grape
Authors: Bair Kyle E. , Davenport Joan R. , Stevens Robert G.
Published: February 2019

Legume cover crops can be used to provide nitrogen (N) to organically produced Concord (Vitis labruscana Bailey) grape. The cover crop must be incorporated at a time such that subsequent N mineralization is synchronous with plant demand to maximize the amount of N available to the grape plant. The objectives of this research were to 1) evaluate the effectiveness of hairy vetch (Vicia villosa subsp. villosa L.) and yellow sweet clover [Melilotus officinalis (L.) Lam.] in providing N to organically grown Concord grape, 2) examine the synchronization of N release from mineralization after incorporation of cover crops with plant N demand, and 3) compare soluble, more readily available sources of N to legume cover crops in providing N to grape. This work was conducted on two Concord vineyards, one commercial (COM) and one research (RES) vineyard. Both vineyards were overhead sprinkler-irrigated and plots were established in a Latin square design with four or six replicates of each treatment. Treatments consisted of hairy vetch and yellow sweet clover planted in either the spring or fall, 112 kg·ha−1 N added as either urea or blood meal, and a 0 kg·ha−1 N control. Soils were sampled weekly (0 to 30 cm) from budbreak to cover crop plot treatment establishment and were analyzed for soluble (NO3-N and NH4-N) N. Soluble N release in the plots was monitored with ion exchange membranes (plant root simulators). Grapes were harvested and evaluated for yield and °Brix. Legume and fertilizer treatments resulted in increased N availability from grape bloom until veraison. As a result of rapid nitrification, NH4-N was less useful than NO3-N in determining N mineralization patterns. Available N peaks as high as 40 mg·kg−1 NO3-N were well timed with the critical N demand period for Concord grape. Soluble N sources (urea and blood meal) peaked higher than plant sources. No differences were detected between legume treatments. Legume covers did, however, supply more available N per unit of biomass to the soil than a small grain cover. Yield and oBrix varied by year but not by treatment, suggesting that the cover crop or plant and soil N reserves provided sufficient available N to the grape through the study period.
Evaluation of Irrigation Frequency and Quantity on Leaf Gas Exchange, Growth, and Nitrate Leaching of Coleus in a Simulated Landscape
Authors: Scheiber S.M. , Beeson R.C. , Chen J. , Wang Q. , Pearson B.
Published: February 2019

Solenostemon scutellarioides (coleus) were grown in drainage lysimeters in concurrent experiments to evaluate effects of irrigation quantity and frequency on growth responses, leaf gas exchange, and nitrate leaching. Lysimeters in Expt. 1 were irrigated either with 13 mm daily or 13 mm every other day. Daily irrigation increased mean leachate and doubled nitrate leached compared with every other day (22.9 kg·ha−1 N versus 10.8 kg·ha−1 N, respectively). In Expt. 2, lysimeters were irrigated every 2 days with 13 mm or every 3 days with 18 mm such that total depth applied was equivalent. Irrigation frequency had no effect on irrigation quantity or nitrate leached. In these experiments, assimilation rates, stomatal conductance, and transpiration rates were influenced by day since irrigation with values lower on days without irrigation. However, neither irrigation quantity nor frequency affected final shoot dry weight, root dry weight, height or growth indices (P > 0.05).
Growth, Nitrogen Use Efficiency, and Leachate Comparison of Subirrigated and Overhead Irrigated Pale Purple Coneflower Seedlings
Authors: Pinto Jeremy R. , Chandler Rhiannon A. , Dumroese R. Kasten
Published: February 2019

Pale purple coneflower [Echinacea pallida (Nutt.) Nutt.] was grown within three container volumes (90, 105, and 340 cm3) under subirrigation and overhead irrigation treatments. Subirrigated coneflowers showed increased seedling quality with more biomass (14%), better nitrogen use efficiency (13%), greater nitrogen content (N; 11%), more height (15%), and lower mortality compared with overhead-irrigated seedlings. Plants also showed increasing height, biomass, and N content with increasing container volume. Overhead irrigated coneflowers had more leachate compared with subirrigated seedlings, which produced none. Leachate electrical conductivity and N were monitored throughout the growing season and decreased at similar rates, whereas subirrigation effluent levels remained constant. Subirrigation offers a viable alternative to traditional overhead irrigation systems by producing this native plant with equal or better quality without discharging potentially harmful leachate into the environment.
Nutrient Solution Concentrations of Na2SeO4 Affect the Accumulation of Sulfate and Selenate in Brassica oleracea L.
Authors: Chang Pai-Tsang , van Iersel Marc W. , Randle William M. , Sams Carl E.
Published: February 2019

Dietary sources of selenium (Se) are associated with human health benefits, and Brassica species are good sources of Se in human diets. Selenium and S compete for absorption and accumulation in plant tissues; therefore, the ratios of Se to S in the growing environment determine the accumulation of selenium in plants. To determine responses for Brassica oleracea L., two levels of Na2SeO4 (96 mg·L−1 SeO4
2– and 0.384 mg·L−1 SeO4
2–) were added to nutrient solutions with or without MgSO4·7H2O (96 mg·L−1 SO4
2–). The highest plant fresh weight and S and SO4
2– accumulation were found when plants were grown in the medium with a SeO4
2– to SO4
2– ratio of 1 : 250 (0.384 mg·L−1 SeO4
2– and 96 mg·L−1 SO4
2–). However, the highest accumulation of Se was found when a low level of selenate (0.384 mg·L−1 SeO4
2–) was added to nutrient solutions without S. The activity of glutathione peroxidase (GPx) was regulated by Se status; the highest GPx activity was measured when a high level of SeO4
2– (96 mg·L−1) was supplied to nutrient solutions without S supplementation. The lowest concentration of total glucosinolates was found when adding SeO4
2– to nutrient solutions without S. We saw no difference in plant growth and mineral accumulation when plants were grown with K2SeO4 versus Na2SeO4, suggesting that the growth-inhibiting effect of Na2SeO4 was the result of the SeO4
2– rather than potentially toxic effects of Na+.
Winter Foot and Equipment Traffic Impacts on a ‘L93’ Creeping Bentgrass Putting Green
Authors: Baldwin Christian M. , Liu Haibo , McCarty Lambert B. , Luo Hong , Toler Joe , Long Steven H.
Published: February 2019

Creeping bentgrass (Agrostis stolonifera var. palustris Huds.) is desirable as a putting green turfgrass in the transition zone as a result of year-round green color, ball roll, and playability. However, management challenges exist for bentgrass greens, including winter temperature fluctuations. Frosts often cause cancellations or delays of tee time resulting in lost revenue. In response to this winter golf course management issue, a research project was initiated at Clemson University from 1 Dec. 2005 and 2006 to 1 Aug. 2006 and 2007 on a ‘L93’ creeping bentgrass putting green to determine the impacts of foot traffic or mower traffic and time of traffic application on bentgrass winter performance. Treatments consisted of no traffic (control), foot traffic, and walk-behind mower traffic (rolling) at 0700 and 0900 hr when canopy temperatures were at or below 0 °C. Foot traffic included ≈75 steps within each plot using size 10 SP-4 Saddle Nike golf shoes (soft-spiked sole) administered by a researcher weighing ≈75 kg. A Toro Greensmaster 800 walk-behind greens mower weighing 92 kg with a 45.7-cm roller was used for rolling traffic. Data collected included canopy and soil temperatures (7.6 cm depth), visual turfgrass quality (TQ), clipping yield (g·m−2), shoot chlorophyll concentration (mg·g−1), root total nonstructural carbohydrates (TNC) (mg·g−1), soil bulk density (g·cm−3), and water infiltration rates (cm·h−1). Time and type of traffic significantly influenced bentgrass winter performance. On all TQ rating dates, 0700 hr rolling traffic decreased TQ by ≈1.1 units compared with foot traffic at 0700 hr. In December, regardless of traffic application time, rolling traffic reduced bentgrass shoot growth ≈17%. However, in February, chlorophyll, soil bulk density, and water infiltration differences were not detected. By the end of March, all treatments had acceptable TQ. Root TNC was unaffected in May, whereas shoot chlorophyll concentrations were unaffected in May and August. This study indicates bentgrass damage resulting from winter traffic is limited to winter and early spring months and full recovery should be expected by summer.
Intraspecific Genome Size Variation in Pumpkin (Cucurbita pepo subsp. pepo)
Authors: Rayburn A. Lane , Kushad Mosbah M. , Wannarat Wanisari
Published: February 2019

Genome size has recently been reported to vary 16% in pumpkins (Cucurbita spp.). The majority of this variation can be attributed to genome size differences in pumpkins of various taxonomical classes. The purpose of this study was to determine if intraspecific genome size variability could be detected by flow cytometry in Cucurbita pepo subsp. pepo pumpkin cultivars with similar fruit morphology. The pie pumpkins group was chosen for this study because of their similar fruit size, shape, and color. Genome sizes ranged from 1.109 pg in Spooktacular to 1.064 pg in Small Sugar. Spooktacular had a genome size larger than Small Sugar in all three experiments. Therefore, intraspecific genome size variation does exist in C. pepo subsp. pepo among pumpkin cultivars of similar fruit morphology.
Availability of Genotypic Data for USDA-ARS National Plant Germplasm System Accessions Using the Genetic Resources Information Network (GRIN) Database
Authors: Volk Gayle M. , Richards Christopher M.
Published: February 2019

The USDA-ARS National Plant Germplasm System (NPGS) provides critical genetic resources to researchers and breeders worldwide. Users of the NPGS materials need access to data for genetic and descriptive characteristics of the plant materials. New tables and codes have been added to the Germplasm Resources Information Network (GRIN) database to hold raw data relating to molecular markers and alleles. The revised tables accommodate multiple marker types; provide raw data for individuals; accept polyploid data; and provide a record of methods, standards, and control values. A long-term goal is to make the GRIN molecular tables fully interoperable with the National Center for Biotechnology Information database as well as bioinformatic databases (model organism and clade organism databases). The development of this capacity provides critical data infrastructure for future genotype–phenotype association studies and gene discovery.
Field and Greenhouse Response of Red Raspberry Genotypes to Root Rot
Authors: Hoashi-Erhardt Wendy K. , Moore Patrick P. , Windom Gwenyth E. , Bristow Peter R.
Published: February 2019

Red raspberry genotypes (Rubus idaeus L.) were evaluated for resistance to root rot at two field sites in Washington state and in a greenhouse study. Thirteen raspberry genotypes were planted in two field sites naturally infested with Phytophthora fragariae var. rubi Wilcox and Duncan and evaluated over 3 years for growth and symptom expression. In greenhouse pot tests, 14 genotypes were inoculated with an isolate of P. fragariae var. rubi at three inoculum levels and evaluated for growth, root color, and symptom expression using a 1 to 4 rating scale. Eleven of the 14 cultivars were found to be susceptible or very susceptible to root rot in the field and greenhouse. ‘Summit’ and ‘Newburgh’ possessed high levels of resistance to the pathogen. ‘Cascade Bounty’ also showed high resistance to root rot in the greenhouse, but confirmation from a field study is needed. Subjective root ratings of greenhouse-grown plants correlated well with measurements of cane numbers and cane infection in the field. The greenhouse tests were useful in identifying resistant genotypes and very susceptible genotypes but did not always match field results. Observation of at least 3 years in the field was necessary to compare relative reaction with root rot among genotypes.
Summer Cover Crop and In-season Management System Affect Growth and Yield of Lettuce and Cantaloupe
Authors: Wang Guangyao , Ngouajio Mathieu , McGiffen Milton E. , Hutchinson Chad M.
Published: February 2019

The effect of summer cover crop and management system on subsequent fall romaine lettuce (Lactuca sativa L.) and spring muskmelon (Cucumis melo L.) growth and yield was evaluated in the Coachella Valley of California from 1999 to 2003. Cover crop treatments included: 1) cowpea [Vigna unguiculata (L.) Walp.] incorporated into the soil in the fall (CPI), 2) cowpea used as mulch in the fall (CPM), 3) sudangrass [Sorghum bicolor (L) Moench] incorporated into the soil in the fall (SGI), and 4) a bare ground control (BG). Management system treatments included: 1) conventional system (CON), 2) integrated crop management (ICM), and 3) organic system (ORG). Cowpea cover crop, either incorporated or used as surface mulch, increased lettuce growth and yield by increasing biomass allocation to lettuce leaf and leaf area growth. Cowpea mulch decreased muskmelon leaf and biomass growth and reduced muskmelon yield. Sudangrass produced more biomass than cowpea and reduced lettuce growth and yield. However, in the following spring, the SGI treatment had the highest muskmelon yield. Lettuce growth was significantly affected by management system, while muskmelon growth at the early stage was unaffected. The organic system reduced both lettuce and muskmelon yield compared with CON and ICM management systems.
Weed Control in Strawberry Runner Plant Nurseries with Methyl Bromide Alternative Fumigants
Authors: Fennimore Steven A. , Haar Milton J. , Goodhue Rachael E. , Winterbottom Christopher Q.
Published: February 2019

Methyl bromide alternative fumigants were evaluated for weed control efficacy in low- and high-elevation strawberry (Fragaria ×ananassa L.) runner plant nurseries. Preplant soil fumigation treatments of methyl bromide plus chloropicrin (MBPic), iodomethane plus chloropicrin (IMPic), 1,3-dichloropropene plus chloropicrin mixture followed by (fb) dazomet, chloropicrin fb dazomet, and a nonfumigated control were evaluated at three California strawberry runner plant nurseries through two production cycles. Fumigant efficacy was measured by weed seed viability bioassays, weed density counts, and time of handweeding. Generally, all alternative fumigant treatments controlled weeds at levels comparable to MBPic. All fumigant treatments, including MBPic, killed more than 95% of common knotweed, common purslane, common chickweed, and strawberry seed. Iodomethane, chloropicrin fb dazomet, and 1,3-dichloropropene plus chloropicrin mixture fb dazomet controlled carpetweed, common lambsquarters, hairy nightshade, palmer amaranth, and prostrate spurge. Handweeding inputs for all fumigants were similar to MBPic at three of four locations. The exception was at the low-elevation nursery in 2000 where handweeding times with MBPic were lower than for IMPic. Treatment and handweeding costs were calculated. The handweeding costs for all treatments were approximately the same. However, the higher iodomethane material cost resulted in a substantially higher treatment cost.
Procedure to Enhance the Recovery Rate of Fungus Gnat, Bradysia sp. nr. coprophila Lintner (Diptera: Sciaridae) Adults from Growing Medium
Authors: Cloyd Raymond A. , Dickinson Amy
Published: February 2019

Fungus gnats, Bradysia spp., are major insect pests in greenhouses and interiorscapes. Management typically involves the use of either insecticides or biological control agents such as entomopathogenic nematodes. Efficacy trials provide information to greenhouse producers on the effectiveness of these management options. However, a simple procedure that rapidly evaluates the performance of control products against fungus gnat larvae is needed. Because fungus gnat larvae inhabit the growing medium, excess or deficient growing medium moisture may reduce adult fungus gnat emergence, thus confounding effects from efficacy trial treatments. Therefore, it is important to determine the amount of moisture and moisture content that results in the highest recovery of fungus gnat adults. We conducted two replicated experiments in a completely randomized design using a range of initial water volumes (treatments) and two larval stages (second and third) of the fungus gnat, Bradysia sp. nr. coprophila. The success of the procedure was based on the number of fungus gnat adults that emerged per treatment. In the first experiment, initial water volumes of 0, 25, 50, 75, 100, 150, and 200 mL were applied to 300 mL of a soilless growing medium consisting of 50% composted pine bark, 20% Canadian sphagnum peatmoss, 10% perlite, and 20% medium coarse vermiculite (SB300 Universal Mix). In general, the highest mean numbers (range, 11.2 to 14.6) of fungus gnat adults were recovered from growing medium treated with 50, 75, and 100 mL of water. In the second experiment, initial water volumes (treatments) of 50, 55, 60, 65, 70, and 75 mL were applied to 300 mL of the soilless growing medium (SB300 Universal Mix). There were no significant differences in the mean number of fungus gnat adults recovered regardless of the larval instar (second instar: 15.8 to 17.7; third instar: 14.4 to 17.4). The final percent moisture content ranged from 65% to 68% for the second instars and 56% to 66% for third instars. This study demonstrates that the highest number of fungus gnat adults may be recovered from soilless growing medium (SB300 Universal Mix) treated with between 50 and 75 mL of water, thus enhancing the confidence in any data set generated when evaluating insecticides or biological control agents for control of fungus gnats.
‘Emerald’ Southern Highbush Blueberry
Authors: Lyrene Paul M.
Published: February 2019

‘Emerald’ is a low-chill tetraploid southern highbush blueberry hybrid that is well adapted to northeast and central Florida and to other areas receiving similar winter chilling (100 to 400 h below 7 °C). Emerald produces a vigorous bush with stout, semierect canes. It has medium to good survival in the field in north Florida. In northeast Florida, ‘Emerald’ flowers from mid-January to mid-February and ripens from mid-April to mid-May. ‘Emerald’ is capable of producing high yields of berries that are large, firm, and medium-dark in color with a small, dry picking scar and good flavor.
Primocane-fruiting Blackberry Breeding
Authors: Clark John R.
Published: February 2019

Primocane-fruiting blackberry breeding was initiated in the early 1990s at the University of Arkansas. The source of this trait is the diploid genotype ‘Hillquist’. Introductions from this effort are the cultivars Prime-Jim® and Prime-Jan®. These genotypes are intended for home-garden use as a result of lack of quality for commercial production. Several traits have been identified that are high priorities in primocane blackberry breeding advancement, including heat tolerance of flowers and fruits, fruit quality, thornlessness, and time of fruit ripening. Progress in addressing these limitations through breeding has been positive and the outlook for further improvement of this type of blackberry is promising.