bluuebunny/crossref_metadata_2025 huggingface dataset:
Subsoiling and Its Effects on Root Yield and Quality of `Beauregard'
Authors: Jester W.R. , Taylor B. , Schultheis J.R. , Adams D.E.
Published: February 2019

Five studies were conducted from 1997 to 1999 to determine the effects of subsoiling on root quality (i.e., root length and shape) and on yield of `Beauregard' sweetpotato. The statistical design for all five studies was a completely randomized block design with six replications (four in Goldsboro in 1997). All studies were conducted on Norfolk fine sandy loam soils. Two studies were done in 1997, one in Kinston and the other in Goldsboro, N.C.; two studies in 1998, one in Kinston and the other in Goldsboro; and one in 1999 in Kinston, N.C. Common treatments in the studies consisted of no subsoiling, V shank subsoil, 30 cm below row (56 cm from peaked ridge) and V shank subsoil, 46 cm below row (71 cm from peaked ridge). Roots were longer, had more creases, and were more misshapen due to ripping (regardless of subsoiling depth) in the 1997 Kinston test. No differences were detected in root quality due to subsoiling in the other four tests. Marketable and total yields were increased in both tests in 1997 with subsoiling; however, a similar yield increase was not obtained with subsoiling in 1998 and 1999. Jumbo yields were increased in Kinston in 1997 and Goldsboro in 1998 with subsoiling; the better response was obtained with 30-cm-depth subsoiling. Jumbo yields in 1999 were the same regardless of treatment. Canner and cull yields were similar in all tests across treatments. Yields may be increased with subsoiling in certain circumstances (i.e, drought or soils with hard pans), and can result in more off-shape roots and longer roots. It appears from these studies that yields may be increased with subsoiling; however, more off-shape roots may be produced, especially under dry conditions or where fields are not routinely subsoiled.
Tolerance of Cucurbits to the Herbicides Clomazone, Ethalfluralin, and Pendimenthalin. I. Summer Squash
Authors: Grey Timothy L. , Bridges David C. , NeSmith D. Scott
Published: February 2019

Field studies were conducted in 1993, 1994, and 1996 to determine the tolerance of several cultivars of zucchini and yellow crookneck squash (Cucurbita pepo L.) to various rates and methods of application of clomazone, ethalfluralin, and pendimethalin. Applying herbicides preplant soil incorporated (PPI), preemergence (PRE), at seedling emergence (SE), or early postemergence (EPOT) resulted in plant injury that varied from 0% to 98%. Ethalfluralin and pendimethalin (PPI) at 1.12 kg·ha–1 a.i. resulted in the greatest stand and yield reductions across all cultivars. Fruit number and weight declined for all cultivars in 1993 and 1994 as the amount of pendimethalin applied PRE was increased. Zucchini (`Senator') fruit size was significantly reduced for the first three harvests in 1993 by PRE application of pendimethalin or PPI application of ethalfluralin, at all rates. Yellow squash (`Dixie') fruit size was unaffected by herbicide treatment for any harvests during 1993 or 1996. Yellow and zucchini squash yield, fruit number, and average fruit weight were equal to, or greater than, those of the untreated control for PRE clomazone using either the emulsifiable concentrate formulation (EC) during 1993, 1994, and 1996 or the microencapsulated formulation (ME) during 1996. Foliar bleaching and stunting by clomazone was evident in early-season visual observations and ratings, but the effect was transient. Foliar bleaching by clomazone PPI (1.12 kg·ha–1 a.i.) was more evident in `Senator' zucchini, and yield was significantly reduced in 1993. These effects of clomazone PPI were not evident in 1994 for either `Elite' or `Senator' zucchini squash. Chemical names used: 2-[(2-chlorophenyl)methyl]-4, 4-dimethyl-3-isoxazolidinone (clomazone); N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl) benzenamine (ethalfluralin); N-(1-ethylopropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin).
A Method to Screen Pome Fruit for Resistance to Skin-chewing Insects and to Analyze Feeding Trends
Authors: Chervin Christian , Franz Peter , Kulkarni Sarita , Whitmore Steve , McGregor Graeme
Published: February 2019

Insect feeding traces on fruit are a major concern to orchardists. Breeding fruit for insect resistance is becoming more important as available pesticides are limited by more stringent regulations, problems of insect resistance, and residue limits. We present a method to analyze fruit skin damage via treatment of video images. This aspect has not been well studied to date, but would allow a more rapid assessment of fruit resistance to insects in breeding programs. The method uses equipment available on the world video and computer markets. Over 24 hours, larvae of lightbrown apple moth [Epiphyas postvittana Walker (Lepidoptera: Tortricidae)] were permitted to chew restricted areas of skin on the pear cultivars Sensation Red Bartlett, Packham's Triumph, Doyenne du Comice, Beurre d'Anjou, and Corella (Pyrus communis L.); Twentieth Century (Pyrus pyrifolia Burm. Nak.); Ya Li (Pyrus ×bretschneideri Rehd.); and F1 hybrids of `Packham's Triumph' × `Twentieth Century'. Optimum experimental conditions and statistical analyses are described and sensitivity of the various cultivars is discussed. The method allowed us to identify some highly resistant and sensitive pear hybrids. The ability to rapidly screen F1 hybrids for insect resistance may encourage breeders to incorporate such a factor in breeding programs, and should hasten the release of resistant cultivars. The application of this technique in the orchard is discussed. The method also allows the analysis of various aspects of larval feeding, such as number and size of wounds, which may be responses to various fruit skin defense systems.
Survey of Hazelnut Cultivars for Response to Eastern Filbert Blight Inoculation
Authors: Lunde China F. , Mehlenbacher Shawn A. , Smith David C.
Published: February 2019

Ninety hazelnut (Corylus sp.) genotypes were surveyed for response to the eastern filbert blight pathogen [Anisogramma anomala (Peck) E. Müller] following greenhouse inoculation using a combination of enzyme-linked immunosorbent assay (ELISA) and visual inspection for cankers. Most were cultivars of the European hazelnut (Corylus avellana L.) and a few were interspecific hybrids. Six genotypes did not display signs of the pathogen or symptoms of disease: `Closca Molla', `Ratoli', `Yoder #5', `Potomac', `Medium Long', and `Grand Traverse'. `Closca Molla' and `Ratoli', both minor Spanish cultivars, are superior in many respects to `Gasaway', which has been extensively used as a completely resistant parent in breeding. `Potomac' and `Yoder #5' have C. americana Marsh. in their pedigrees, `Grand Traverse' is one-quarter C. colurna, and the origin of `Medium Long' is uncertain. The random amplified polymorphic DNA (RAPD) marker generated by primer UBC 152, which is linked to the single dominant resistance gene of `Gasaway', is absent in these six genotypes, and thus they appear to be novel sources of genetic resistance to this devastating disease.
Plant Growth Regulators and Mowing Height Affect Ball Roll and Quality of Creeping Bentgrass Putting Greens
Authors: Fagerness Matthew J. , Isgrigg John , Cooper Richard J. , Yelverton Fred H.
Published: February 2019

Questions exist as to whether growth-inhibiting chemicals mimic the effects of reduced mowing heights on putting green ball roll. An experiment was initiated during Spring 1997 to investigate ball roll and visual quality parameters of putting greens maintained at 3.2, 4.0, or 4.8 mm with plant growth regulator (PGR) treatments applied monthly over the course of 1 year. Additional experiments were conducted during Fall 1995 and 1996 and Spring 1996 to investigate diurnal PGR effects on ball roll. All experiments were conducted on pure stands of `Penncross' creeping bentgrass (Agrostis palustris Huds). Treatments included trinexapac-ethyl and paclobutrazol, both inhibitors of gibberellin biosynthesis. In the one-year experiment, mowing height was inversely related to ball roll. However, compromises in turfgrass visual quality and shoot density in `Penncross' turf mowed at 3.2 mm make this a questionable mowing height in areas with severe summer conditions. Ball roll during summer months was reduced by PGRs, suggesting that PGRs have little potential as alternatives to decreasing mowing height for increased ball roll. Paclobutrazol reduced turfgrass quality and shoot density during summer months, suggesting that it be used with caution. Other PGRs, particularly trinexapac-ethyl at 0.05 kg·ha–1 a.i., increased afternoon ball roll by as much as 5% to 10% in diurnal experiments. Use of PGRs on creeping bentgrass putting greens may therefore produce short-lived increases in ball roll with subtle to negative effects on bentgrass growth over more extended periods of time. Chemical names used: 4-(cyclopropyl-α-hydroxymethylene)-3,5-dioxocyclohexane carboxylic acid ethylester (trinexapac-ethyl); (+/–)-(R*,R*)-β-[(4-chloro-phenyl)methyl]-α-(1,1dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).
A Comparison of Visual vs. Instrumental Measurement of Color Differences in Bentgrass Turf
Authors: Landschoot Peter J. , Mancino Charles F.
Published: February 2019

This study was conducted to determine: 1) if the Minolta CR-310 Chroma Meter can detect color differences among bentgrass (Agrostis stolonifera L., A. capillaris L.) cultivars maintained as a turf; 2) how the CR-310 parameters of hue angle, lightness, and chroma compare with visual color assessments; and 3) if the CR-310 can provide consistent color measurements among evaluators. Differences were detected among cultivars with respect to hue angle, lightness, and chroma. Hue angle and chroma were significantly correlated with visual color assessments when data were averaged across all evaluators. Lightness was not strongly associated with visual color assessment. Differences were found among evaluators for visual color assessment, lightness, and chroma, but not for hue angle measurements. Thus, hue angle appears to be the most consistent CR-310 parameter for measuring color of bentgrass turf. These results indicate that the CR-310 can be used to evaluate the color of bentgrass cultivars maintained as a turf and provides consistent hue angle measurements among evaluators, regardless of experience in rating turf color. The CR-310 is probably best used for measuring relative color differences and may be useful if cultivars of similar color are desired in blended turfs.
Field Evaluation of Herbicide-resistant Transgenic Broccoli
Authors: Waterer D. , Lee S. , Scoles G. , Keller W.
Published: February 2019

This study examined the field performance and herbicide resistance of lines of broccoli (Brassica oleracea Italica Group) generated from plants transformed for resistance to the herbicide glufosinate by Agrobacterium-mediated gene transfer. Seedling vigor and vegetative growth characteristics of the first recombinant generation (R1) produced by selfing the transformed lines were comparable to those of the F1 parent (cv. Cruiser) and an equivalent nontransformed F2 line. In hand-weeded trials, marketable yields of the R1-transformed lines were comparable to the parental line or the corresponding nontransformed F2 line. A single application of the recommended rate of the nonselective herbicide glufosinate slowed the growth and reduced yields of nontransformed broccoli, but had little effect on head quality or yields of most transformed lines. Inheritance of herbicide resistance in the R1 progeny of the R0 transgenic plants followed standard Mendelian ratios for a completely dominant trait controlled by a single gene. The results confirm the potential for improvement of broccoli through the incorporation of herbicide resistance by gene transfer technology. Chemical name used: 2-amino-(4-hydroxymethylphosphinyl)butanoic acid (glufosinate, phosphinothricine).
Humic Acid Seed and Substrate Treatments Promote Seedling Root Development
Authors: Hartwigsen Jack A. , Evans Michael R.
Published: February 2019

Seed of Pelargonium ×hortorum L.H. Bailey `Freckles' (geranium) and Tagetes patula L. `Bonanza' (marigold) were soaked for 12, 24, or 48 h in solutions containing 0 (deionized water), 5000, 10,000, or 15,000 mg·L-1 humic acid (HA) or nutrient controls (NC) containing similar levels of nutrients prior to planting. Soaking in deionized water (DI) and NC treatments had no significant effect on root fresh weight. However, several of the HA treatments increased root fresh weight of marigold seedlings, and all increased geranium root fresh weight. Percentage of germination and shoot fresh weight were not significantly affected by treatment. Seed of Cucumis sativus L. `Salad Bush' (cucumber), Cucurbita pepo L. `Golden Summer Crookneck' (squash), `Freckles' geranium and `Bonanza' marigold were sown into 15-cell plug trays (5 mL volume), and the substrate was drenched with DI, 2500 or 5000 mg·L-1 HA, or 2500 or 5000 mg·L-1 NC. DI and NC treatments did not affect root fresh weight. However, cucumber, squash, and marigold seedlings germinated in substrate drenched with 2500 and 5000 mg·L-1 HA and geranium seedlings germinated in substrate drenched with 2500 mg·L-1 HA had significantly higher root fresh weight than did seedlings from all other treatments. Percentage of germination and shoot fresh weight were not significantly affected by treatment. `Salad Bush' cucumber and `Golden Summer Crookneck' squash seedlings germinated on germination towels soaked with 2500 or 5000 mg·L-1 HA, had significantly higher root fresh weight than did seedlings germinated on towels soaked with DI or NC solutions. Treatment with HA did not affect shoot fresh weight or the number of lateral roots. However, HA treatment increased the total length of lateral roots. The increase in lateral root growth occurred primarily in lateral roots developing from the lower hypocotyl.
Molecular Detection of Jujube Witches' Broom Phytoplasmas in Micropropagated Jujube Shoots
Authors: Tian J.B. , Guo H.P. , Bertaccini A. , Martini M. , Paltrinieri S. , Pastore M.
Published: February 2019

Jujube (Zizyphus jujuba Mill.) witches' broom (JWB) is the most important disease in the areas of jujube cultivation in China, where it occurs every year. Micropropagated shoots of the three most important cultivars (`Lizao', `Junzao', and `Muzao') in the National Jujube Gene Pool, collected at the Pomology Institute of Shanxi province, were tested for the presence of phytoplasmas. Phytoplasma ribosomal (16Sr) general and specific primer pairs were used in direct or nested polymerase chain reaction (PCR). Positive results were obtained only from symptomatic micropropagated samples of `Lizao' and from phytoplasma controls. Restriction fragment length polymorphism (RFLP) analyses of PCR products with several restriction enzymes revealed that the phytoplasmas infecting the symptomatic plants belong to the 16SrRNA group V subgroup B. The positive correlation between symptoms and the presence of phytoplasmas was verified in tissue culture. Samples from apparently healthy shoots of `Junzao', `Muzao', and `Lizao' were free of phytoplasmas.
Application of Spectroscopy for Measuring Leaf Nitrogen, Chlorophyll and the Other Pigments in Pinot Noir Grape
Authors: Ding* Pinghai , Cortell Jessica M. , Fuchigami Leslie H.
Published: February 2019

Nitrogen is one of the most important nutrition factors affecting grapevine growth performance and berry quality. Leaf pigments contents and leaf areas are the important indicators of grapevine nitrogen status and plant performance. In order to find a efficient way to nondestructively measure leaf nitrogen and pigments status, the SPAD meter, CCM-200 and CM-1000 chlorophyll meter in comparisons with FOSS NIR system were used in measuring leaf nitrogen, leaf chlorophyll, carotenoids, flavonoids and anthocyanins in 7-year-old Pinot Noir grape with different rate of N treatments. The results indicate that the reading of all these meters have a good relationship with leaf N, leaf chlorophyll and leaf area. But the accuracy among these meters was different, in which the accuracy of FOSS NIR is better than that of the SPAD meter, CCM-200 and CM-1000. There is the good relationship between leaf nitrogen contents, leaf area, leaf chlorophyll and carotenoids contents. Flavonoids and anthocyanins have the inverse relationship with leaf N contents and leaf area. FOSS NIR system can be use for nondestructive assessing nitrogen, leaf chlorophyll, carotenoids, flavonoids and anthocyanins whereas the other meters can only used for nondestructive assessing leaf nitrogen and leaf chlorophyll. These results indicate it is possible to use nondestructive spectral methods as the precision viticulture tools to manage vineyards nitrogen fertilization and grapevine performance.
Effects of Reversed Day/Night Temperatures on a Doritaenopsis Hybrid Orchid
Authors: Wang* Yin-Tung
Published: February 2019

It not clear how a prolonged period of cool days and warm nights affect Phalaenopsis hybrids which take up CO2 mainly at night. The `Lava Glow' clone of the hybrid Doritaenopsis (Phal. Buddha's Treasure × Doritis pulcherrima) 15 cm in leaf span were subjected to day/night (12 h each daily) temperatures of 30/25, 25/30, 25/20, or 20/25 °C at 170 umol.m-2 .s-1 PPF. After nine months, plants under the higher average daily temperature (ADT) produced more leaves. Those grown at 30/25 °C had the largest leaf span and total length of the new leaves. Plants under 30/25, 25/30, 25/20, or 20/25 °C had 5.0, 4.7, 3.6, and 2.8 new leaves and 72, 61, 42, and 28 cm in total new leaf length, respectively. Cool days and warm nights resulted in smaller leaf span and reduced leaf growth, particularly at 20/25 than at 25/30 °C. Within a given ADT, cooler days resulted in shorter leaves. Leaves produced by plants at the lower ADT had a smaller length to width ratio and the more desirable oval shape. The most striking effect of 20/25 °C was that 14 out of 15 plants bloomed, whereas only 5 plants under 25/20 °C and none in the 30/25 or 25/30 °C treatment flowered. In a second experiment, 18-22 cm plants were subjected to 30/20, 20/30, 25/15, or 15/25 °C. After 29 weeks, similar results were obtained. All plants under 15/25 °C bloomed, whereas none in the other treatments produced flowers. Long-term exposure to 15/25 °C resulted in slow leaf production and undesirable small leaves. These results suggest that, with day temperatures in the 20-15 °C range, nights 10-5 °C warmer are not desirable for rapid vegetative growth. However, cool days and warm nights may be used to effectively induce the flowering process.
Conservation-driven Propagation of an Epiphytic Orchid (Epidendrum nocturnum) with a Mycorrhizal Fungus
Authors: Zettler Lawrence W. , Poulter Sarah B. , McDonald Kris I. , Stewart Scott L.
Published: February 2019

Seeds of an endangered epiphytic orchid from Florida (Epidendrum nocturnum Jacquin) germinated in vitro with a mycorrhizal fungus [Epulorhiza repens (Bernard) Moore] using a technique normally applied to terrestrial orchids (symbiotic seed germination). Seeds from two sources (Fakahatchee Strand, Fla. Panther NWR) were sown on either modified oats medium (MOM) or standard oat medium (SOM) and inoculated with the fungus. Significant differences in germination were detected between the two seed sources. MOM had a significant effect on mean leaf length during incubation in vitro (F
(1278) = 23.81, P > 0.000), but media had no significant effect on leaf number. After 48 days in vitro, all leaf-bearing seedlings were exposed to light and then transferred to greenhouse conditions ex vitro on sterile Sphagnum moss with or without half-strength Miracle-Gro (Scotts, Port Washington, N.Y.) commercial fertilizer. After 163 days ex vitro, seedlings on Sphagnum without Miracle-Gro displayed highest survivorship (>90%), whereas Miracle-Gro-exposed seedlings from standard oat agar experienced low (44%) survivorship. Healthy seedlings with a mycotrophic capability were obtained 1 year after sowing. A total of 43 seedlings were subsequently reintroduced into the Florida Panther NWR in Nov. 2005, 16 months after sowing. The symbiotic technique may, therefore, have practical merit for conservation of E. nocturnum and other epiphytic orchids threatened with extinction.
Micronutrient Availability in Fresh and Aged Douglas Fir Bark
Authors: Buamscha M. Gabriela , Altland James E. , Sullivan Daniel M. , Horneck Donald A.
Published: February 2019

Annual vinca [Catharanthus roseus (L.) G. Don ‘Peppermint Cooler’] plugs were transplanted to containers filled with Douglas fir [Pseudotsuga menziesii (Mirbel) Franco] bark (DFB) in May and June 2005 (Expts. 1 and 2, respectively). Treatments were arranged in a 2 × 3 factorial with two DFB ages (fresh and aged) and three micronutrient sources (DFB alone, 10% by volume yard debris compost, or 0.9 kg·m−3 Micromax fertilizer). Plants were measured for shoot dry weight and foliar color. Substrate and foliar samples of each plant were analyzed for 13 essential macro- and micronutrients plus substrate pH and EC. Douglas fir bark alone appears to provide sufficient micronutrients for annual vinca grown at pH 4.7 to 5.7 over a 2-month period. In Expt. 1 there were no differences in shoot dry weight or foliar color regardless of DFB age or micronutrient source. At the end of Expt. 2, plants in aged DFB were larger than those in fresh DFB, but differences were primarily the result of nitrogen availability. None of the treatments developed color symptoms that could be associated with micronutrient deficiency. Micronutrient availability in DFB should be considered in container fertilizer management plans.
Effects of Foliar Applications of Smoke-Water and a Smoke-isolated Butenolide on Seedling Growth of Okra and Tomato
Authors: Kulkarni Manoj G. , Ascough Glendon D. , Van Staden Johannes
Published: February 2019

The ecologic significance of smoke-related seed germination is now well recognized. Consequently, smoke solutions and a pure butenolide, the active compound from smoke that stimulates germination of a number of plant species, show great potential for enhancing the growth of vegetable crops. Achieving maximum production and better and faster growth of the seedlings has always been a priority for vegetable growers. This study therefore highlights the effects of foliar application of smoke-water and a butenolide on seedling growth of okra [Abelmoschus esculentus (L.) Moench] and tomato (Lycopersicon esculentum Mill.). Treating okra seedlings with smoke-water (1:500 v/v) showed a significant (P < 0.05) increase in shoot/root length, shoot fresh/dry weight, number of leaves, total leaf area, and stem thickness compared with the control treatment. Treatment of okra seedlings with smoke-water significantly (P < 0.05) increased the absolute growth rate (AGR) per week. However, the seedling vigor index (SVI) did not improve as a result of no change in root fresh weight. On the other hand, foliar application of smoke-water and butenolide showed a pronounced effect on the seedling growth of tomato. Most of the growth parameters examined for both the treatments were significantly (P < 0.05) increased, resulting in a significantly (P < 0.05) higher SVI and AGR than the control. This study indicates that the foliar application of smoke-water or butenolide may be a useful and inexpensive technique for enhancing seedling growth of vegetable crops.
Survey of Hazelnut Germplasm from Russia and Crimea for Response to Eastern Filbert Blight
Authors: Molnar Thomas J. , Zaurov David E. , Goffreda Joseph C. , Mehlenbacher Shawn A.
Published: February 2019

Six hundred five hazelnut (Corylus avellana L.) seedlings from a diverse germplasm collection made in the Russian Federation and the Crimean peninsula of the Ukraine were inoculated with the eastern filbert blight (EFB) pathogen Anisogramma anomala (Peck) E. Müller and their responses evaluated. Responses were rated on a scale of 0 to 5, in which 0 represents no sign of EFB and 5 represents all branches exhibiting cankers. At final evaluation, eight seedlings showed no signs of the pathogen or symptoms of the disease. Five additional seedlings expressed only very minor signs of the pathogen (rating = 1). The remainder ranged in disease expression from moderately to severely infected to dead with 89.7% (470 of 524) of the surviving seedlings rating 4 or 5. Of the 13 apparently resistant seedlings (rating 0 or 1), seven originated from nuts purchased from roadside vendors near Simferopol, Crimea, Ukraine; five from nuts purchased at an outdoor market near Krasnodar, Russia; and one from nuts obtained from the hazelnut breeding program of the Nikita Botanical Gardens, Yalta, Crimea, Ukraine. Random amplified polymorphic DNA (RAPD) markers generated by the primers UBC 152800 and OP AA12850, which are tightly linked to the single dominant resistance gene ‘Gasaway’, were not present in all 13 resistant seedlings, providing support, along with their geographic origins, that they represent novel sources of genetic resistance to EFB.
Influence of Rhizome Propagule Size on Yields and Triterpene Glycoside Concentrations of Black Cohosh [Actaea racemosa L. syn Cimicifuga racemosa (L.) Nuttal]
Authors: McCoy Joe-Ann , Davis Jeanine M. , Dwight Camper N. , Khan Ikhlas , Bharathi Avula
Published: February 2019

Black cohosh [Actaea racemosa L. syn. Cimicifuga racemosa (L.) Nuttal] is a native North American medicinal plant traditionally harvested for its rhizomes and roots. Black cohosh products were listed in the top 10 selling herbal supplements from 2002 to 2005. As a result of increasing commercial demand, there is a need to develop propagation protocols suitable for production purposes to replace current methods of harvesting from wild populations. The objectives of this study were to 1) determine optimal rhizome propagule division size for successful regeneration, 2) analyze triterpene glycoside concentrations, 3) quantify survival rates after 3 years of production, and 4) evaluate net yield results. Experimental sites included a shade cloth structure in an agricultural research field, a shaded forest interior, and a shaded, disturbed forest edge. Plant emergence, growth, and survival were assessed at each site over a 3-year period. Optimal rhizome division size for propagation was a 10 to 30-g section originating from terminal rhizome portions. Rhizome survival averaged 97% among all treatments tested by year 3 at three sites. No differences in mean triterpene glycoside concentrations were detected between rhizome size classes or sites tested. Mean cimiracemoside concentrations ranged from 0.80 to 1.39 mg·g–1 d/w tissue, deoxyactein 0.47 to 0.92 mg·g–1, and actein 10.41 to 13.69 mg·g–1. No differences in triterpene levels were detected between flowering and nonflowering plants, nor were yields reduced. Net yields from a shade cloth production site were 9 and 17 times higher than a disturbed forest edge and forest site respectively. Black cohosh is a strong candidate for commercial propagation under adequate site selection.
Coloration, Anthocyanin Concentration, and Growth of Croton (Codiaeum variegatum L.) as Affected by Cotton Gin Trash Compost Use in the Potting Medium
Authors: Papafotiou Maria , Avajianneli Barbara , Michos Costas , Chatzipavlidis Iordanis
Published: February 2019

Compost from cotton gin trash was evaluated as a peat substitute in Codiaeum variegatum L. production. Rooted cuttings were grown for 8 months in media containing cotton gin trash compost, sphagnum peatmoss, and perlite in 1:3:4, 1:1:2, and 3:1:4 ratios respectively, and their growth was compared with a control medium of 1 peat : 1 perlite (by volume). Even when 75% of peat in the control medium was replaced by cotton gin trash compost, plant height, leaf number, and leaf size were unaffected, whereas root dry weight was increased in the medium with 25% peat replacement. Although replacement of peat by cotton gin trash compost did not affect quantitative characteristics of croton foliage growth, it affected the foliage color, as plants in media with cotton gin trash compost had more areas colored red in their leaves. The increase of red coloration was proportional to the increase of cotton gin trash compost in the medium. The phenomenon was more intense in the lower leaves than the apical ones. Anthocyanin concentration measurements showed that the gradual increase of cotton gin trash compost level in the growth medium caused a gradual increase of the anthocyanin concentration in the leaves. This effect is discussed in relation to chemical properties of the media, as electrical conductivity, pH, and nutrient concentrations. The gradual increase of cotton gin trash compost level caused an analogous increase of N, P, and K concentrations in the medium. Also, media with cotton gin trash compost had high electrical conductivity at the beginning of the culture period, related to the cotton gin trash compost level, which was reduced to values similar to that in the control medium after 50 days of culture. Na concentration in the media ranged similarly to electrical conductivity. The pH was positively related to cotton gin trash compost level, and media with a high cotton gin trash compost level had increased pH during the culture period compared with the control.
The Use of Plastic Films and Sprayable Reflective Particle Films to Increase Light Penetration in Apple Canopies and Improve Apple Color and Weight
Authors: Glenn D. Michael , Puterka G.J.
Published: February 2019

The objective of the present study was to examine the effect of a reflective, aluminized plastic film (APF), a reflective, particle-based film applied to the tree (PFT), a reflective, particle film applied to the west side of the tree (PFW), or a particle-based reflective film applied to the grass between tree rows (RPF) on ‘Empire’ apple [Malus domestica (Borkh.)] color and fruit weight in a multiyear study. The APF treatment consistently increased red color and was the only treatment to increase fruit red color from the lower portion of the west side of the tree. The PFT, PFW, and RPF treatments inconsistently improved apple red color. The APF treatment reflected ≈6 times the amount of photosynthetically active radiation (PAR) as the RPF and reflected different red/far-red light ratios (R/FR). In all years, average fruit weight was increased by the RPF, PFT, and PFW treatments compared with the untreated control and APF treatment. The mechanism responsible for the increased fruit weight may be the altered light quality, not quantity, reflected from the RPF treatments. The reflected light has enhanced far-red radiation, which may have beneficial effects on both fruit color and fruit weight. The effect of enhanced far-red radiation on increased fruit weight may be a phytochrome-mediated process affecting dry matter partitioning.
Plant Exploration: From Queen Hatshepsut to Sir Joseph Banks
Authors: Janick Jules
Published: February 2019

The worldwide exchange of fruits has been facilitated by traders, travelers, sovereigns, conquerors, diplomats, missionaries, and botanists. The beginnings of organized plant exploration date to the Pharaohs of ancient Egypt, who, as early as 2000 bce, brought back exotic trees and plants in their foreign campaigns and illustrated them on their temple walls. Queen Hatshepsut (ca. 1500 bce) sent out ships to bring back trees from the land of Punt (northeast African coast). The exchange of plants throughout antiquity was a by-product of trade routes between East and West as well as though the campaigns of conquerors including Alexander, the warriors of Islam, Genghis Khan, and the crusades. The age of exploration starting at the end of the 15th century was inspired by the search for a sea route to the spice-rich East. The encounter of Columbus with the Americas brought about an explosive exchange of New World and Old World plants. The rise of science in the 17th and 18th centuries was associated with botanical exploration involving travels and expeditions, including Hans Sloan to the West Indies, James Cunningham to China, Georg Eberhard Rumpf (Rumphius) to the Moluccas, and Sir Joseph Banks to Newfoundland, Labrador, South America Tahiti, New Zealand, Australia, the Malay Archipelago, Hebrides, and Iceland.
Predicted Crop Value for Nectarines and Cling Peaches of Different Harvest Season as a Function of Crop Load
Authors: Reginato Gabino H. , de Cortázar Víctor García , Robinson Terence L.
Published: February 2019

Several field experiments to assess the effect of tree size and crop load on fruit size and yield efficiency were conducted in cling peach and nectarine orchards of different harvest seasons in Chile. Trees were randomly selected in each orchard and then hand-thinned at the beginning of pit hardening to a wide range of crop loads. The fraction of above-canopy photosynthetically active radiation (PAR) intercepted by the canopy (PAR
i) was determined at harvest. All fruits were counted and weighed and average fruit weight calculated. Crop load and yield were normalized by tree size measured by intercepted PAR
i. For each orchard, the relationship between crop load and fruit size or crop load and yield efficiency was assessed by regression analysis. Fruit size distribution was calculated from fruit size adjusted for fruit load assuming a normal fruit size distribution and valued according to shipment date and price obtained from a Chilean export company. Using crop load as a covariate, fruit size adjusted for crop load was compared for nectarine and peach cultivars. Fruit size adjusted for fruit load and yield efficiency was greater with late season cultivars than the early or midseason cultivars. Predicted crop value (PCV), normalized in terms of PAR intercepted, was calculated for all the cultivars. Large differences in predicted crop value were found for early, midseason, and late ripening nectarines. Early and late ripening cultivars had the highest predicted crop value, especially at lower crop loads and larger fruit sizes. The early season cultivars had high crop value as a result of higher fruit prices, whereas the late season cultivar had high crop value as a result of higher production. With cling peaches, the early season cultivar ‘Jungerman’ had a lower predicted crop value than the late season cultivars ‘Ross’ and ‘Davis’. For cling peaches, the highest PCV was achieved at a relatively high crop load with high yield and small fruit size.
Nutrient Availability in Soil Amended with Pecan Wood Chips
Authors: Tahboub Mohammed B. , Lindemann William C. , Murray Leigh
Published: February 2019

Pecan [Carya illinoinensis (Wangenh.) K. Koch] pruning wood is usually burned, a practice that creates serious environmental concerns. Chipping and soil incorporation of prunings may be an alternative disposal method if nutrient immobilization is not a problem. Our objective was to determine if incorporation of pecan wood chips into soil would affect the availability of nitrogen (N), phosphorus (P), and potassium (K). Pecan wood chips were incorporated into a silty clay soil at rates of 0, 4484, 8968, 13,452, and 17,936 kg·ha−1 in May or June 2002, 2003, and 2004. Some plots received N (ammonium sulfate) at a rate of 0, 15.2, 30.5, 45.7, and 61.0 kg·ha−1 to adjust the C:N ratio of trimmings to 30:1. Wood chip incorporation did not significantly decrease inorganic N regardless of application rate or number of applications. When ammonium sulfate was added to balance the C:N ratio, soil inorganic N increased with the rate of wood chip application, also indicating that N immobilization did not occur. Soil-available P and K were not significantly affected after one, two, or three wood chip applications. Soil-available K increased when ammonium sulfate was added to balance the C:N ratio. Soil incorporation of pecan wood chips does not appear to immobilize N, P, or K, thus providing growers with an environmentally viable means of wood disposal.
Estimating the Relative Abundance of Flush Shoots in Citrus with Implications on Monitoring Insects Associated with Flush
Authors: Hall David G. , Albrigo L.G.
Published: February 2019

Attention to the management of insects that feed on foliar flush growth has increased in Florida citrus as a result of the establishment of invasive plant diseases associated with insects that develop exclusively on flush. Citrus can be monitored to identify peak periods of flush abundance to time insecticide applications for these insects; however, guidelines for quantifying flush abundance are lacking. We therefore investigated sampling procedures for estimating flush abundance. A sampling method was devised to enable a quantitative estimation of flush shoots, defined as any shoot with immature leaves. A sample unit was the area within a 15 × 15 × 15-cm frame slipped into the outer edge of a tree with the end of a branch inside the frame. The number of flush shoots originating within the sample unit was counted. Three sample units were examined per tree in 45 randomly selected trees weekly during 2005 in each of two blocks of trees, one containing young ‘Marsh’ grapefruit (Citrus paradise Macf.) and one containing mature ‘Temple’ orange (tangors) [C. reticulate Blanco × C. sinensis (L.) Osbeck]. A pronounced abundance of flush was generally indicated by means of one or more flush shoots per sample in the particular trees studied. Variation in numbers of flush shoots per sample was similar within and among trees, differed significantly among sample dates, and did not differ significantly between the two blocks of trees overall sample dates. Taylor's power law coefficients indicated that, over all sample weeks, flush shoots were randomly distributed within the young grapefruit trees and only weakly aggregated within the block of mature oranges. Projections indicated that a sampling plan consisting of 40 trees (one sample per tree) would provide density estimates acceptable enough for general estimates at mean densities of one or more shoots per sample. An index of pest abundance based on mean pest density per flush shoot and mean density of flush shoots per sample is proposed.
Hybrid Bluegrass, Kentucky Bluegrass, and Tall Fescue Response to Nitrogen Fertilization in the Transition Zone
Authors: Teuton Travis C. , Sorochan John C. , Main Christopher L. , Samples Thomas J. , Parham John M. , Mueller Thomas C.
Published: February 2019

‘Dura Blue’ and ‘Thermal Blue’ hybrid bluegrass have been selected for heat and drought tolerance. These grasses offer alternatives to traditional Kentucky bluegrass and tall fescue in the transition zone. Experiments were conducted in two locations during 2003 and 2004 at the University of Tennessee in Knoxville, Tenn. Nitrogen (N) was applied at 50, 150, or 300 kg·ha−1 N per year to ‘Apollo’ Kentucky bluegrass, ‘Dura Blue’, and ‘Thermal Blue’ hybrid bluegrass, and ‘Dynasty’ and ‘Kentucky 31’ tall fescue. The main effects of turfgrass and N were significant for color and quality observations. However, their interactions were not significant; therefore, only the main effects are shown. Acceptable turfgrass color (>6) and quality (>6) was observed for all varieties in May, August, and November. All N regimens showed acceptable turfgrass color and quality. However, 150 kg·ha−1 N per year was required to achieve optimum color and quality. ‘Kentucky 31’ produced higher clipping dry weights when N was applied at 50 kg·ha−1 per year than the other varieties. Nitrogen applied at 150 and 300 kg·ha−1 per year on ‘Kentucky 31’ and ‘Thermal Blue’ produced higher clipping dry weights than the other varieties. ‘Dynasty’ and ‘Kentucky 31’ had similar brown patch incidences at each nitrogen level. Increases in brown patch incidence occurred as N levels decreased from 300 (21%) to 50 kg·ha−1 per year (31%) for ‘Dynasty’ and ‘Kentucky 31’. Dollar spot incidence occurred on all bluegrass varieties from 7% to 24%. However, dollar spot decreased with increased N fertility. All turfgrass species tested were acceptable for use in the transition zone.
Distinguishing Creeping Bluegrass (Poa annua var. reptans) Genotypes Using Inter-simple Sequence Repeat Markers
Authors: Carson Troy D. , White Donald B. , Smith Alan G.
Published: February 2019

Poa annua L. has long been a cultivated weed on golf courses. However, the recent development of improved cultivars of creeping bluegrass (Poa annua reptans Hausskn.) has generated an increasing interest in selection and breeding of this species. Inter-simple sequence repeat (ISSR) PCR is a relatively new method for genotype identification and measuring genetic diversity and was employed in this study for differentiating among creeping bluegrass genotypes. The objectives of this study were to test ISSR primers for production of polymorphic fragments and ascertain the applicability of ISSR PCR to distinguish closely related genotypes. Eight primers produced fragments, of which 77.3% were polymorphic, and primers UBC849, UBC850, and UMN001 produced over 75% of the total polymorphic fragments. These three primers had sufficient resolution to distinguish all but two of the diploid creeping bluegrass accessions. This method was a simple, fast, and relatively inexpensive method to produce useful DNA fragments in creeping bluegrass. It is a robust method for detecting polymorphic loci that can be used in the study of genetic relatedness, heritability, or linkage to important traits, development of linkage maps, and marker-assisted breeding.
Waterlogging Tolerance of Kentucky Bluegrass Cultivars
Authors: Wang Kehua , Jiang Yiwei
Published: February 2019

Waterlogging (WL) affects the growth and physiological responses of turfgrass. The objectives of this study were to compare the relative WL tolerance of Kentucky bluegrass (Poa pratensis L.) cultivars and to investigate the physiological responses of shoots and roots to WL. Ten cultivars differing in growth habit were subjected to 30 d of WL. The turf quality (TQ) and soil redox potential (Eh), as well as the chlorophyll concentration (Chl), decreased with increasing periods of WL. Among all cultivars, root dry weight (RDW) decreased 16.7% to 39.9% under 10 d and 30.0% to 60% under 30 d of WL, respectively. Waterlogging increased the root electrolyte leakage (REL) from 0.6% to 53.2% under 10 d and from 29.1% to 98.0% under 30 d of WL for all cultivars, respectively. The best correlations were observed between Eh and TQ (r = 0.74), REL and TQ (r = 0.75), RDW and root water-soluble carbohydrate content (RWSC) (r = 0.74), and root oxidase activity and RWSC (r = 0.63), respectively. ‘Moonlight’, ‘Serene’, and ‘Champagne’ showed better tolerance to short-term WL conditions, whereas ‘Kenblue’ and ‘Eagleton’ were the least tolerant cultivars. ‘Limousine’, ‘Unique’, ‘Awesome’, ‘Julia’, and ‘Midnight II’ ranked in the middle group. Variations in WL tolerance among Kentucky bluegrasses could potentially be used for enhancing turfgrass management.
Micropropagation of the Endangered Shrub Pondberry (Lindera melissifolia [Walt.] Blume)
Authors: Hawkins Tracy S. , Schiff Nathan M. , Gardiner Emile S. , Leininger Theodor , Devall Margaret S. , Wilson Dan , Hamel Paul , McCown Deborah D. , Connor Kristina
Published: February 2019

A micropropagation protocol using shoot cultures is described for Lindera melissifolia, a federally listed endangered shrub endemic to the southeastern United States. Stock plants were harvested from native L. melissifolia populations growing in the lower Mississippi Alluvial Valley. In vitro proliferation was on woody plant medium supplemented with 1 μm zeatin. After 6 weeks, zeatin level was increased to 5 μm. Treatment of micropropagated shoots with a liquid auxin (2 indole-3-butyric acid : 1 1-naphthalenacetic acid) resulted in a low mean rooting percentage (≤44%) compared with rooting in the absence of auxins and on a pure peat medium ex vitro, which increased rooting to ≥80%. Time to rooting was 8 weeks. Plants were acclimatized for 2 weeks, then potted in a 2 peat : 1 perlite medium supplemented with superphosphate, 10N–10P–10K, and Milorganite. Micropropagated L. melissifolia stecklings have been successfully outplanted in both controlled and field studies at the Center for Bottomland Hardwoods Research (Stoneville, Miss.).
Histological Evaluation of Early Graft Compatibility in Uapaca kirkiana Müell Arg. Scion/Stock Combinations
Authors: Mng'omba Simon A. , du Toit Elsa S. , Akinnifesi Festus K. , Venter Helena M.
Published: February 2019

Compatibility of scion and stock combinations in Uapaca kirkiana fruit trees has not been evaluated despite noticeable growth irregularities. The objectives of this study were to determine graft compatibility of scion/stock combinations and possible causes of graft incompatibility. Scion, stock, and graft union diameters were measured. Stem sections comprising the graft unions were immersed in formalin acetic acid and then washed in sterile water. These were transversely dissected across the unions and examined under using light microscope. There were considerable growth disorders at the unions, which included significant overgrowth of stocks and unions and constricted unions. There were cracks in the bark across the union in many graft combinations. Anatomic and histological studies showed accumulation of phenol deposits and necrotic tissues, and there was no continuity of vascular tissues above the union. There were also differences in proliferation of callus tissues among grafted partners. Continuity in wood and bark tissues below the unions supported growth of partially compatible partners, whereas isolated parenchymatous tissues at the union supported growth of incompatible partners. There were many necrotic tissues and unfilled areas above the union. Accumulation of phenolic and necrotic cell deposits, poor or a high level of callusing at the union, and possibly specific incompatibility reactions were implicated as the causes of graft incompatibility in U. kirkiana trees.
Heritability and Genetic Variance Estimates for Fruit Weight in Watermelon
Authors: Gusmini Gabriele , Wehner Todd C.
Published: February 2019

Fruit weight in the cultivated watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai var. lanatus] ranges from 1 kg to over 100 kg. In recent years, preference of consumers has shifted toward fruit of smaller sizes than the large sizes traditionally used for parties and picnics. This has produced increased interest in the genetics of fruit weight, especially among watermelon breeders. The objectives of this study were to determine the inheritance of fruit weight. Six adapted cultivars having very large or very small fruit weight were crossed in a half diallel. Field trials were conducted at two locations in North Carolina (Clinton and Kinston). Large-fruited parents had higher phenotypic variance than small-fruited parents. Environmental variance was higher than genetic variance (mean, 7.58 and 3.82, respectively) at Kinston, NC. At Clinton, NC, genetic and environmental variances were similar (mean, 9.45 and 8.99, respectively) for 67% of the families. Narrow- and broad-sense heritability estimates were low to intermediate (mean, 0.59 and 0.41, respectively). A high number of effective factors (mean, 5.4) was found to influence fruit weight in watermelon. Watermelon breeders should use quantitative methods such as recurrent selection for population improvement to change fruit weight in the development of new cultivars.