bluuebunny/crossref_metadata_2025 huggingface dataset:
Reassessing the Salinity Tolerance of Greenhouse Roses under Soilless Production Conditions
Authors: Cabrera Raul I. , Perdomo Pedro
Published: February 2019

The performance of modern greenhouse-grown roses under intensive nutrient and water management practices questions their traditional classification as a salt-sensitive species, and emphasizes the need to reassess their salinity tolerance. Container-grown `Bridal Pink' roses (on R. manetti rootstock) in a peat moss-based growing medium were irrigated, using moderate leaching fractions (25% targeted, 37.5% actual), with complete nutrient solutions supplemented with NaCl at 0, 5, and 10 mm. These salt concentrations affected the electrical conductivity (EC) and Cl concentrations measured in the leachates, but had no significant effects on flower yield and quality over four growth and flowering flushes (§29 weeks). Cumulative yields over this period increased an average of §13% per leachate EC unit. Thereafter, the applied NaCl concentrations were increased 3-fold to 0, 15, and 30 mm and the plants continued to be evaluated for another four flowering flushes. No significant differences in cut-flower yield and quality were observed among salt treatments despite further increases in leachate EC and Na and Cl concentrations. Symptoms of salt injury were visually observed during the last three flowering cycles, and most heavily on the oldest foliage of plants receiving the highest salt concentration (30 mm), but not on the foliage of harvested shoots. The concentration of most nutrients in leaf tissue was not significantly affected by any of the treatments over the course of the experiment. Leaf Na concentrations were not affected by NaCl applications, averaging 42 mg·kg-1 across treatments. Conversely, leaf Cl concentrations increased significantly and cumulatively over time with salt additions, and ranged from 1.0 to 17.5 g·kg-1 (0.1 to 1.75%). Regression analyses revealed that average relative dry weight yields increased with leaf Cl concentrations up to 4.0 g·kg-1 (0.40%), but were depressed at higher concentrations.
Leafminer Resistance in Lettuce
Authors: Mou Beiquan , Liu Yong-Biao
Published: February 2019

Leafminer (Liriomyza langei Frick) is a major insect pest of many important agricultural crops including lettuce (Lactuca sativa L.). The goals of this study were to evaluate lettuce genotypes for resistance to leafminer and to estimate heritabilities of three leafminer-resistant traits. Forty-six lettuce genotypes were evaluated in two tests in insect cages. Wild species (Lactuca serriola L., Lactuca saligna L., and Lactuca virosa L.) had significantly fewer leafminer stings than cultivated lettuce (L. sativa) in both tests. PI 509525 (L. saligna) had few leafminer stings and no flies emerged. Leaf (leaf and romaine) lettuce also showed significantly less stings than head (crisphead and butterhead) types, while differences between leaf and romaine lettuces, and between crisphead and butterhead types were nonsignificant. Broad-sense heritability for number of stings per unit leaf area was relatively high, averaging 65% over the two tests. Heritabilities for egg-hatching period and flies per plant were 10% and 15%, respectively. Stings per unit leaf area from the two tests were highly correlated (r = 0.828), suggesting that resistance was stable over different plant ages and against different pressures of leafminer. These results suggest that genetic improvement of cultivated lettuce for leafminer resistance is feasible.
Evaluation of Gamma-linolenic Acid Composition of Evening Primrose (Oenothera) Species Native to Texas
Authors: Balch S.A. , McKenney C.B. , Auld D.L.
Published: February 2019

The oil of evening primrose (Oenothera sp.) is an important source of gammalinolenic acid (GLA). GLA [C18:3Δ6,9,12] is an unsaturated fatty acid in demand for its nutritional and pharmaceutical application. Oenothera biennis L. is the primary commercial source of evening primrose oil. A study was conducted to determine if species of Oenothera, adapted to Texas, produce GLA levels comparable to O. biennis. This project identified and evaluated the fatty acid composition of eight species of evening primrose native to Texas. GLA levels of 54 accessions evaluated from collected seed ranged from 0.0% to 11.0%. Field experiments were then conducted to determine oil content, fatty acid composition, seed yield, and potential adaptation to commercial production of selected accessions. Mean GLA levels of cultivated seed from these accessions ranged from 0.0% to 10.1%. Mean seed oil content ranged from 7.3% to 21.7%. Of the species examined, O. elata subsp. hirsutissima (A. Gray ex S. Watson) W. Dietrich and O. jamesii (Torrey & Gray) demonstrated GLA levels and seed yields adequate for commercial production. Based on these results, O. elata subsp. hirsutissima and O. jamesii demonstrated sufficiently high GLA levels, oil content, and seed yields to be considered for commercial production.
Smooth Crabgrass Control in Perennial Ryegrass and Creeping Bentgrass Tolerance to Quinclorac
Authors: Dernoeden Peter H. , Bigelow Cale A. , Kaminski John E. , Krouse John M.
Published: February 2019

Smooth crabgrass [Digitaria ischaemum (Schreber) Schreber ex Muhlenb.] is an invasive weed of cool-season turfgrasses. Previous research has demonstrated that quinclorac is an effective postemergence herbicide for crabgrass control, but performance has been erratic in some regions. Furthermore, quinclorac may elicit objectionable levels of discoloration in creeping bentgrass (Agrostis stolonifera L.). The objectives of this 3-year field study were to determine optimum rates and timings of quinclorac applications that provide consistent levels of effective crabgrass control and to assess creeping bentgrass quality responses to quinclorac. To evaluate crabgrass control, quinclorac was applied in early-, mid- and late-postemergence timings at various rates to a perennial ryegrass (Lolium perenne L.) turf. Similar treatments were applied to creeping bentgrass to determine if application timing and rate influenced the level and duration of discoloration. Quinclorac was applied alone or was tank-mixed with either urea (N at 6.1 kg·ha-1) or chelated iron (Fe)+nitrogen (N) (FeSO4 at 1.1 kg·ha-1+N at 2.2 kg·ha-1) to determine if they would mask discoloration. Crabgrass control generally was more effective in the early- and midpostemergence application timings. A single application of quinclorac (0.84 kg·ha-1) was effective where crabgrass levels were moderate, but sequential (i.e. multiple) applications were required where crabgrass levels were severe. The most consistent level of crabgrass control where weed pressure was severe occurred with three, sequential quinclorac (0.37 or 0.42 kg·ha-1) applications. Creeping bentgrass exhibited 2 to 11 weeks of unacceptable discoloration in response to sequential quinclorac applications. Chelated Fe+N was more effective than urea in masking discoloration. In general, chelated Fe+N tank-mixed with quinclorac masked discoloration and turf had quality equivalent to untreated bentgrass on most, but not all rating dates. Chemical names used: 3,7,-dichloro-8-quinolinecarboxylic acid (quinclorac).
`Umatilla Russet' and `Russet Legend' Potato Yield and Quality Response to Irrigation
Authors: Shock C.C. , Feibert E.B.G. , Saunders L.D. , James S.R.
Published: February 2019

`Umatilla Russet' and `Russet Legend', two newly released potato (Solanum tuberosum L.) cultivars were compared with four established cultivars (`Russet Burbank', `Shepody', `Frontier Russet', and `Ranger Russet'). Potatoes were grown under four, season-long, sprinkler irrigation treatments in three successive years (1992-94) on silt loam soil in eastern Oregon. At each irrigation, the full irrigation treatment received up to the accumulated evapotranspiration (ETc) since the last irrigation. Three deficit irrigation treatments had progressively less water. The new cultivars `Umatilla Russet' and `Russet Legend' performed as well as or better than the other cultivars in the full irrigation treatment, with `Umatilla Russet' showing a higher yield potential at the higher water application rates than `Russet Legend'. All cultivars produced more U.S. No. 1 tubers than `Russet Burbank', except in 1993, an unusually cool and wet year. `Russet Legend' was the only cultivar showing a tolerance to deficit irrigation. In two out of the three years, `Russet Legend' was as productive of U.S. No. 1 yield over most of the range of applied water as `Shepody', `Frontier Russet', and `Ranger Russet' were at the higher end of the applied water range. Chemical names used: 0,0-diethyl S-[(ethylthio) methyl] phosphorodithioate (phorate); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin); and 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1methyl-ethyl) acetamide (metolachlor).
Impact of Fungal Gummosis on Peach Trees
Authors: Beckman T.G. , Pusey P.L. , Bertrand P.F.
Published: February 2019

Peach tree fungal gummosis caused by Botryosphaeria dothidea [(Moug.:Fr.) Cos & de Not.] is widespread throughout the southeastern United States. Until recently, its economic impact on peach [Prunus persica (L.) Batsch] has been impossible to estimate, since no effective controls were known. Significant, though not total, suppression of gummosis on `Summergold' peach trees was achieved with an intensive 5-year spray program with captafol. Captan was far less effective than captafol. Both trunk diameter and fruit yield were negatively correlated with disease severity. After eight growing seasons, trees treated with captafol were 18% larger than the untreated trees. Yield of mature captafol-treated trees was 40% to 60% high er than that of untreated ones. Following termination of the spray program after 5 years, disease severity gradually increased on both captafol- and captan-treated trees. However, through eight growing seasons, disease severity was significantly lower on captafol-treated trees. This study demonstrates that peach tree fungal gummosis significantly depresses tree growth and fruit yield on susceptible peach cultivars.
Host Range of a Select Isolate of the Ericoid Mycorrhizal Fungus Hymenoscyphus ericae
Authors: Gorman Nicole R. , Starrett Mark C.
Published: February 2019

Studies were conducted to examine the host range of a select isolate of the ericoid mycorrhizal fungus Hymenoscyphus ericae (Read) Korf and Kernan [American Type Culture Collection (ATCC) #32985]. Host status was tested for 15 ericaceous species, including: Calluna vulgaris (L.) Hull, Enkianthus campanulatus (Miq.) Nichols, Gaultheria procumbens L., Kalmia latifolia L., Leucothoe fontanesiana Sleum., Oxydendrum arboreum (L.) DC.,Pierisfloribunda (Pursh) Benth. & Hook.,Rhododendron calendulaceum (Michx.) Torr.,Rhododendron carolinianum Rehd., Rhododendron catawbiense Michx., Rhododendron maximum L., Rhododendron mucronulatumTurcz., Vaccinium corymbosum L., and Vaccinium macrocarpon Ait. Arbutus unedo L., an ericaceous species that forms arbutoid, not ericoid, mycorrhizae, was used as a negative control. All of the species were colonized by the ericoid isolate with the exception of Enkianthus campanulatus and the negative control. Inoculation with this isolate of H. ericae resulted in a significant increase in shoot growth. However, intensity of root colonization was not correlated to amount of shoot growth. In fact, an increase in growth was observed in the two species that lacked fungal colonization.
Minimizing Stem Elongation During Spray Applications of Gibberellin4+7 and Benzyladenine to Prevent Leaf Chlorosis in Easter Lilies
Authors: Ranwala Anil P. , Legnani Garry , Miller William B.
Published: February 2019

Several experiments were conducted to find effective ways of utilizing gibberellin4+7 (GA4+7) and benzyladenine (BA) to prevent leaf chlorosis during greenhouse production of Easter lilies (Lilium longiflorum Thunb.) while minimizing the undesirable side effects on stem elongation. On an absolute concentration basis, GA4+7 was much more effective than BA in preventing leaf chlorosis. Excessive levels of GA4+7, however, tended to cause stem elongation. When applied at around the visible bud stage, if the foliage was well covered with the spray solution, 25 mg·L-1 of GA4+7 was adequate for maximum protection against leaf chlorosis. Increasing the GA4+7 concentration above 25 mg·L-1 gave no additional benefit on leaf chlorosis. Two possible modes of GA4+7 uptake during a foliar spray application (absorption through leaves and stems, and root uptake of the extra run-off) were studied in terms of their relative contribution to leaf chlorosis and stem elongation. Although both modes of uptake prevented leaf chlorosis, foliar uptake was much more effective than root uptake. However, GA4+7 taken up by the roots contributed mainly to stem elongation. When sprayed to leaves on only the lower half of the plant, a 10-mL spray of either 25 or 50 mg·L-1 of each GA4+7 and BA was enough for complete protection against leaf chlorosis. Increasing volumes had no additional benefit on leaf chlorosis, but increased the chances of unwanted stem elongation.
Dollar Spot and Brown Patch Incidence in Creeping Bentgrass as Affected by Acibenzolar-S-Methyl and Biostimulants
Authors: Lee Joon , Fry Jack , Tisserat Ned
Published: February 2019

There is interest in identifying cultural practices that may reduce fungicide requirements of creeping bentgrass (Agrostis palustris Huds.) putting greens. Our objective was to evaluate the plant defense activator ASM in combination with 12 biostimulants for the potential to reduce dollar spot (Sclerotinia homoeocarpa F.T. Bennett) and brown patch (Rhizoctonia solani Kuhn) in a blend of `Cato: `Crenshaw creeping bentgrass during 2000 and 2001. The experimental design was a split-plot with ASM as the whole plot, and biostimulants as the subplots. ASM was applied biweekly as a.i. at 35 g·ha-1 and biostimulants were applied according to manufacturers recommendations. Sclerotinia homoeocarpa infection centers were reduced by 38% with ASM, but levels were >1500/m2 in Aug. 2000, and turf quality was unacceptable through most of the study period. No suppression of brown patch occurred with ASM. None of the biostimulants reduced dollar spot or brown patch in creeping bentgrass when compared to biweekly applications of soluble N at 4.9 kg·ha-1. Dollar spot suppression achieved with ASM warrants additional studies to determine how it might be used to reduce fungicide inputs on creeping bentgrass putting greens. Chemical name used: acibenzolar-S-methyl (ASM).
Remontant Flowering Potential of Ten Hydrangea macrophylla (Thunb.) Ser. Cultivars
Authors: Adkins Jeffrey A. , Dirr Michael A.
Published: February 2019

Floral induction of 10 Hydrangea macrophylla (Thunb.) Ser. cultivars (`All Summer Beauty', `Dooley', `Endless Summer', `Générale Vicomtesse de Vibraye', `Lilacina', `Mariesii Variegata', `Mme. Emile Mouillère', `Nikko Blue', `Penny Mac', and `Veitchii') was evaluated to determine the remontant flowering potential. Cultivars exhibiting superior flowering potential could facilitate year-round production of florist s hydrangea and expand the geographic adaptation of hydrangeas in the landscape. Plants were tested under either 8-hour inductive short-day (SD) or 24-hour noninductive extended-day (ED) photoperiods at 24 ± 2 °C. Floral induction of H. macrophylla occurred under both SD and ED but was more rapid under SD than under ED. Shoot length and total number of nodes were significantly different for cultivars, photoperiods, and harvest dates. Significant differences in the floral initiation and development were observed among cultivars. `Penny Mac', `Endless Summer', `Lilacina', `Mme. Emile Mouillère', and `Nikko Blue' displayed significantly greater floral meristem development under SD than all other cultivars. Over the nine-week period, only `Dooley', `Endless Summer', and `Penny Mac' floral development was affected significantly greater by SD photoperiods than ED photoperiods. All others cultivars showed similar floral development under SD and ED. Stage of meristem development was highly correlated with number of nodes, but not with shoot length.
Densely Planted Okra for Destructive Harvest: I. Effects on Yield
Authors: Wu Yaying , Kahn Brian A. , Maness Niels O. , Solie John B. , Whitney Richard W. , Conway Kenneth E.
Published: February 2019

Okra [Abelmoschus esculentus (L.) Moench] was grown at various highly dense (HD) plant populations for destructive harvest, and compared with control plants grown at spacings of 90 × 23 cm and harvested repeatedly by hand. Our objectives were to identify a HD plant arrangement and an optimum harvest timing to maximize marketable fruit yield per hectare with a single destructive harvest, and to evaluate the potential for regrowth of cut plants followed by one or more subsequent harvests. Within HD treatments, marketable fruit weight per hectare tended to increase as the plant population density increased. Spacings of 30 × 30 cm and wider were not dense enough for the destructive harvest system due to a low marketable yield potential. Wide spacings did favor regrowth of cut plants in two experiments, but total marketable yields were still highest with the highest plant populations tested. Delaying destructive harvest until many overmature fruit were present did not consistently affect marketable fruit yield, but always decreased the proportion (by weight) of marketable fruit to total harvested fruit. Overall, percentages of marketable yield obtained by destructive harvests of plots with HD plant populations were low relative to the cumulative marketable yield from control plots. The lack of concentrated fruit set in okra remains a limiting factor for destructive harvest. However, the labor-saving potential of this system should stimulate further research.
Densely Planted Okra for Destructive Harvest: II. Effects on Plant Architecture
Authors: Wu Yaying , Kahn Brian A. , Maness Niels O. , Solie John B. , Whitney Richard W. , Conway Kenneth E.
Published: February 2019

Research was conducted to develop a cultural system that would permit a destructive mechanical okra [Abelmoschus esculentus (L.) Moench] harvest. This paper reports on studies to determine the responses of okra plant architecture to various highly dense (HD) plant populations, and to consider the implications of those responses for destructive mechanical harvest. Growing okra in plant arrangements more densely planted than the control (which was spaced at 90 × 23 cm) did not affect overall plant heights. The position of the first bloom or fruit attachment and of the first marketable fruit attachment tended to become higher on the stem as plant population density increased, especially when comparing plants from the 15 × 15 cm spacing to control plants. The number of marketable fruit per plant was usually unaffected by plant population. Branch number and defruited dry weight per plant decreased as plant population density increased. Plant architecture did not affect the ability of an experimental mechanical harvester to recover marketable fruit from three different okra cultivars grown in a HD arrangement. The lack of concentrated marketable fruit set, rather than plant architecture, was the main limiting factor to the success of densely planted okra for destructive harvest.
Effect of Insect Growth Regulators on Citrus Mealybug [Planococcus citri (Homoptera: Pseudococcidae)] Egg Production
Authors: Cloyd Raymond A.
Published: February 2019

Greenhouse trials were conducted in 2000-2001 to evaluate the indirect effects of insect growth regulators, whether stimulatory or inhibitory, on the egg production of female citrus mealybug [Planococcus citri (Risso)]. Green coleus [Solenostemon scutellarioides (L.) Codd] were infested with 10 late third instar female citrus mealybugs. The insect growth regulators kinoprene, pyriproxyfen, azadirachtin, buprofezin, and novaluron were applied to infested plants at both the high and low manufacturer recommended rates. Beginning two days after treatments were applied, plants were monitored daily to determine when female mealybugs began to oviposit. Individual mealybugs were removed from plants, placed into glass vials containing 70% isopropyl alcohol when female mealybugs started to oviposit, and dissected to determine the number of eggs. Overall, there were no consistent patterns to suggest that the insect growth regulators and different rates tested had any effect on the egg production of citrus mealybug females. Although, in one instance, the insect growth regulators kinoprene and pyriproxyfen actually lowered citrus mealybug egg production. In addition, the insect growth regulator buprofezin numerically increased female citrus mealybug egg production.
Relationship between Trichoderma Soil Populations and Strawberry Fruit Production in Previously Fumigated Soils
Authors: de los Santos B. , Barrau C. , Blanco C. , Arroyo F. , Porras M. , Medina J.J. , Romero F.
Published: February 2019

Several preplant soil fumigation treatments were repeated over a period of three years on strawberry (Fragaria ×ananassa Duchesne) crops, at two different places in the province of Huelva (southwestern Spain). The influence of these treatments on Trichoderma soil populations and on populations of soilborne pathogens was examined every year by isolating soil onto selective media. No strawberry pathogens were detected but Trichoderma soil populations increased each year after the treatment. Significant differences were noted between the treatments and also compared to the control. The largest populations were observed after treatments with methyl bromide and chloropicrin, and so resulting in a higher production. Chemical name used: trichloronitromethane (chloropicrin).
Resistance to Western Flower Thrips Feeding Damage in Impatiens Populations from Costa Rica
Authors: Warnock Daniel F.
Published: February 2019

Western flower thrips (WFT) [Frankliniella occidentalis (Pergande)] is a pest of greenhouse-grown floriculture crops worldwide. To determine if plant resistance varied in three populations of impatiens (Impatiens wallerana Hook. f.) collected near San Vito, Costa Rica, 59 genotypes were evaluated for resistance to feeding by WFT. Individual insect-free plants of each genotype were inoculated with 20 laboratory-reared WFT. Thrips were allowed to feed on individual plants for a 4-week period followed by visual evaluations to estimate feeding damage. Feeding damage varied among genotypes. Thirty-seven genotypes had feeding damage levels similar to the susceptible control, while 22 entries were significantly more resistant than the susceptible control. Of the 22 genotypes with some level of resistance, six genotypes were commercially acceptable, having mean visual ratings below 4.0 on a 1 to 9 evaluation scale. Five of these six genotypes were seedlings from a single population and represented 13.9% of the seedlings in that population. The remaining seedling was from a second San Vito population. The plants in these populations identified as having acceptable levels of damage may be useful in a breeding program designed to enhance resistance to WFT feeding damage. Because WFT feeding damage varied among genotypes, the potential for improving impatiens resistance to WFT exists within available germplasm.
Utility of Blueberry-derived EST-PCR Primers in Related Ericaceae Species
Authors: Rowland Lisa J. , Dhanaraj Anik L. , Polashock James J. , Arora Rajeev
Published: February 2019

Expressed sequence tag-polymerase chain reaction (EST-PCR) markers for DNA fingerprinting and mapping in blueberry (Vaccinium sp.) had previously been developed from expressed sequence tags (ESTs) produced from a cDNA library, derived from RNA from floral buds of cold acclimated plants. Because EST-PCR markers are derived from gene coding regions, they are more likely to be conserved across populations and species than markers derived from random regions of DNA, such as randomly amplified polymorphic DNA (RAPD) or amplified fragment length polymorphism (AFLP) markers. In this study, we tested whether many of the EST-PCR primer pairs developed for blueberry are capable of amplifying DNA fragments in other members of the family Ericaceae. In addition, we cloned and sequenced a selection of 13 EST-PCR fragments to determine if they showed homology to the original blueberry cDNA clones from which the EST-PCR primer pairs were derived. Closely related cranberry genotypes (two wild selections of V. oxycoccus L. and two cultivars of V. macrocarpon Aiton, `Early Black' and `Stevens') and more distantly related rhododendron genotypes (one wild selection each of Rhododendron arboreum Marsh, R. maximum L., and R. ponticum L. and three complex species hybrids, `Sonata', `Grumpy Yellow', and `Roseum elegans') were used. Of 26 primer pairs tested in cranberry, 23 (89%) resulted in successful amplification and eight of those (35%) amplified polymorphic fragments among the cranberry genotypes. Of 39 primer pairs tested in rhododendron, 29 (74%) resulted in successful amplification and 21 of those (72%) amplified polymorphic fragments among the rhododendron genotypes. Approximately 50% of the 13 sequenced EST-PCR fragments were found to be homologous to the original blueberry cDNA clones. These markers should be useful for DNA fingerprinting, mapping, and assessing genetic diversity within cranberry and rhododendron species. The markers which are shown to be homologous to the blueberry cDNA clones by DNA sequencing should also be useful for comparative mapping and genetic diversity studies between some genera of the family Ericaceae.
Vegetative Response of Vitis vinifera to Prohexadione-calcium
Authors: Giudice Danielle Lo , Wolf Tony K. , Marini Richard P.
Published: February 2019

Prohexadione-calcium (prohexadione-Ca) was evaluated for its ability to suppress vegetative growth of grapevines (Vitis vinifera L.) under field conditions. Two or three applications of 250 mg·L-1 prohexadione-Ca reduced primary shoot growth of `Cabernet Sauvignon', but had little effect on other canopy characteristics or cane pruning weights. The reduction of shoot growth was not persistent and shoot hedging was ultimately needed to avoid canopy shading. Similarly, three applications of either 125, 250, or 375 mg·L-1 prohexadione-Ca reduced `Cabernet franc' shoot growth, but again did not eliminate the need for shoot hedging. Cane pruning weights of `Cabernet franc' were unaffected by treatment, and canopy characteristics were generally not improved. Two prebloom and one postbloom application of 250 mg·L-1 prohexadione-Ca were evaluated on `Cabernet franc' and `Chardonnay' in separate field experiments. The prebloom treatments retarded shoot growth of `Chardonnay', but had no effects on `Cabernet franc' shoot characteristics. To retard shoot growth, prohexadione-Ca had to be applied prior to bloom; however, prebloom applications had the potential for severe reductions in crop yield.
A Genetically Confirmed Intersubgeneric Hybrid in Nymphaea L. (Nymphaeaceae Salisb.)
Authors: Les Donald H. , Moody Michael L. , Doran Andrew S. , Phillips William E.
Published: February 2019

A synthetic F1 water-lily hybrid has been obtained for the first time using parental species originating from different subgenera of Nymphaea. The cross was accomplished using Nymphaea gigantea Hook. `Andre Leu' (subgenus Anecphya Casp.) as the maternal parent and a white-flowered variant of Nymphaea colorata Peter (subgenus Brachyceras Casp.) as the paternal parent. Morphologically, the hybrid possesses some characteristics of both parents, some intermediate features, and some unique traits. The cross was confirmed using DNA sequencing and molecular cloning techniques to compare biparentally inherited nuclear genetic markers in the parents and hybrid plant. Each parent possessed distinct alleles that were found to combine in the hybrid. Maternally inherited chloroplast DNA sequences confirmed N. gigantea as the maternal parent of the cross.
Effects of Frequency and Duty Ratio on the Growth of Potato Plantlets In Vitro Using Light-emitting Diodes
Authors: Jao Ruey-Chi , Fang Wei
Published: February 2019

Effects of intermittent light on photomixotrophic growth of potato plantlets in vitro and the electrical savings that could be realized by adjusting the frequency and duty ratio of light-emitting diodes (LEDs) were investigated and compared to the use of conventional tubular fluorescent lamps (TFLs). TFLs provide continuous fluctuating light at 60 Hz and LEDs provide continuous nonfluctuating or intermittent/pulse light depend on the preset frequency and duty ratio. In total, eight treatments were investigated with varying light source, frequency, duty ratio and photoperiod. Results indicated that if growth rate is the only concern, LEDs at 720 Hz [1.4 milliseconds (ms)] and 50% duty ratio with 16-h light/8-h dark photoperiod stimulated plant growth the most. However, if energy consumption is the major concern, using LEDs at 180 Hz (5.5 ms) and 50% duty ratio with 16-h light/8-h dark photoperiod would be the best choice for illuminating potato plantlets without significantly sacrificing plant growth, especially when energy for heat removal is also considered.
Height Control of Poinsettia Using Photoselective Filters
Authors: Clifford Sean C. , Runkle Erik S. , Langton F. Allen , Mead Andrew , Foster Shirley A. , Pearson Simon , Heins Royal D.
Published: February 2019

Most commercial markets require growers of poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch.) to produce plants within strict height specifications. Plant growthretarding chemicals (PGRs) are commonly used to limit internode extension, but in some countries, growers are being pressured to reduce chemical use. Recently, a photoselective film was developed that specifically reduces the transmission of far-red light [(FR), 700 to 800 nm], offering an alternative strategy for height control. Two complementary trials, one in the United Kingdom and one in the United States, showed that plants grown under the FR film for 10 to 12 weeks were ≈20% shorter than control plants growing under neutral density (ND) films transmitting a similar photosynthetic photon flux as the FR film. In the United Kingdom trial, the FR filter delayed time to 50% bract color and first visible cyathia by 6.0 and 3.5 days, respectively, but did not influence time to final harvest. In the United States trial, plants under the FR film had an average of 25% more axillary branches than those under the ND film. In addition, the effects of reduced red [(R), 600 to 700 nm] and blue [(B), 400 to 500 nm] light on internode length, plant biomass, and axillary branching were determined using other photoselective plastics. Compared with plants under the ND film, internode length was 9% or 71% greater in plants grown under environments deficient in B or R, respectively. Our results indicate that poinsettia is highly sensitive to the R: FR ratio, and that spectral manipulation has potential for height control of commercial poinsettia crops.
Hot Water Drench Treatments for the Control of Radopholus similis in Rhapis and Fishtail Palms
Authors: Arcinas A.C. , Sipes B.S. , Hara A.H. , Tsang M.M.C.
Published: February 2019

Exporters of potted nursery stock face strict quarantine regulations against the burrowing nematode, Radopholus similis. Currently, there are no treatments approved by quarantine authorities to disinfest plants of R. similis. Interceptions of the nematode lead to significant economic loss and curtailment of trade, therefore hot-water drench treatments were investigated for quarantine utility. Drenches with 50 °C water were applied for 10 to 16 minutes to two economically important palm species, rhapis (Rhapis excelsa) and fishtail (Caryota mitis). Plants were inoculated with 5,000 mixed life stages of R. similis and allowed to establish for 14 weeks before drench treatments. In rhapis, a moderately good host to R. similis, a 16-minute hot water drench had high efficacy, achieving 99.6% mortality. In fishtail, a poor host, all treatments longer than 10 minutes at 50 °C eliminated R. similis from the plants. Probit regression estimates of the LT99, were 16.9 and 10.3 minutes respectively. However χ2 goodness-of-fit tests were significant (χ2 = 21.136, df = 3, p < 0.0001) for rhapis. Since most observed values were between the 95% fiducial limits, this suggests that the large χ2 value was caused by variability in response or insufficient repetitions rather than an inappropriate model. A χ2 statistic could not be computed for fishtail because poor host status led to variances that were nearly equal to zero. The high efficacy of hot water drenches for the control of R. similis is approaching the Probit 9 standard of 99.9968% mortality required for approval as a quarantine treatment.
Comparison of the Postharvest Quality of Noble Fir Boughs from the United States and Danish Provenances Grown in Denmark
Authors: Chastagner Gary A , Nielsen Ulrik Bräuner , Riley Kathleen L.
Published: February 2019

Postharvest moisture and needle retention of boughs was examined for four Danish and five U.S. provenances of noble fir grown in Denmark. Boughs were displayed indoors under controlled conditions, and data were collected relating to rates of moisture loss and needle retention. Small current-year shoots had moisture and needle loss patterns similar to larger bough material. Postharvest quality of the Danish and U.S. provenance boughs was very similar. There was also a high correlation between the moisture level of the boughs and shoots, indicating that it should be possible to use small shoots to assess differences in moisture retention in future tests.
Biofumigation Potential of Field Pennycress (Thlaspi arvense) Seedmeal
Authors: Vaughn* Steven , Isbell Terry , Weisleder David , Berhow Mark
Published: February 2019

Field pennycress (Thlaspi arvense L.) seedmeal was found to suppress seedling germination/emergence and biomass accumulation when added to a sandy loam soil containing wheat (Triticum aestivum L.), arugula [Eruca vesicaria (L.) Cav. subsp. sativa (Mill.) Thell.] and sicklepod (Senna obtusifolia (L.) H.S. Irwin & Barneby) seeds. Covering the pots with petri dishes containing the soil-seedmeal mixture increased phytotoxicity at the lowest application rate, suggesting that the some of the phytotoxins were volatile. Dichloromethane, methanol and water extracts of the wetted seedmeal were bioassayed against wheat and sicklepod radicle elongation. Only the dichloromethane extract was found to be strongly inhibitory to both species. Fractionation of the dichloromethane extract identified two major phytotoxins, identified by GC-MS and NMR analyses as 2-propen-1-yl (allyl) isothiocyanate (AITC) and allyl thiocyanate (ATC), which constituted 80.9 and 18.8%, respectively, of the active fraction. When seeds of wheat, arugula and sicklepod were exposed to volatilized AITC and ATC, the germination of all three species were completely inhibited by both compounds at concentrations of 5 ppm or less.
Mugwort (Artemisia vulgaris) Rhizome Regeneration in Pine Bark, Soil and Sand Substrates
Authors: Klingeman* William E. , Robinson Darren K. , McDaniel Gary L.
Published: February 2019

Mugwort, or false chrysanthemum (Artemisia vulgaris L) is a well-adapted invasive plant that presents increasing management challenges to agricultural producers, Green Industry professionals and homeowners across portions of the eastern U.S. The ability of mugwort to regenerate from cut rhizome sections has not been adequately quantified for substrates that are typical of landscapes and nursery fields, container nurseries, and propagation beds. Cut rhizome sections were analyzed by rhizome color, length, and the presence or absence of a leaf scale. Media substrates included pine bark, sand, and soil. Rhizomes darken with time and color did not account for differences in growth among treatments. When grown in pine bark, sand, and soil substrates during 45-d trials, 85%, 78%, and 69% of 2 cm-long rhizome sections produced both roots and shoots. These results contrast with previous research. When rhizome fragments 0.5 cm long did not include a leaf scale, slightly fewer than 31% produced both roots and shoots in soil. Fewer rhizomes survived in soil, but root and shoot fresh masses of soil-grown rhizomes were greater than rhizomes that were regenerated in pine bark and sand. When rhizome sections had a leaf scale, survival, fresh masses of roots and shoots, shoot height, leaf number and root lengths were greater, regardless of substrate type. Root initials emerged in the internode between leaf scales and also adjacent to leaf scales. Shoot emergence preceded root emergence from rhizome sections. Growers, landscape managers and homeowners should scout regularly and initiate aggressive controls when mugwort populations are found.
Nematode Genera Associated with Selected Vegetable Crops in a Tropical Region
Authors: Mateo Cesar A. Martinez , Jimenez A. , Martinez Miguel , Morales-Payan* J. Pablo
Published: February 2019

A survey was conducted in a tropical region under continuous crop production for more than a century in the Dominican Republic, to determine the incidence of nematode genera in the soil and in tomato, eggplant, okra, carrot, cabbage, onion, Sweetpotato, squash, and cucumber roots. Typical crop sequences in the region were tomato, eggplant, or beans, followed by either corn, sorghum, cassava, squash or Sweetpotato, followed by either onion, carrot or cabbage, all the crops being grown with medium to high agrichemical input levels. The genera Meloidogyne, Rotylenchulus, Pratylenchus, Aphelenchus, Helicotylenchus, Tylenchus, and Criconemoides were found in soil and/or crop root samples. Meloidogyne was the most prevalent genus in the soil (41% of the samples) and in roots of squash, cucumber, tomato, Sweetpotato, and carrot (50% of the samples). Rotylenchulus was found in 27% of the soil samples, and in 33% of the tomato, okra, and carrot root samples. Aphelenchus was isolated from 2.5% of the eggplant, onion, and cabbage root samples, and from 11% of the soil samples. Pratylenchus was found only in cucumber roots (13% of the samples) and soil samples (10%). Helicotylenchus, Tylenchus, and Criconemoides were isolated from soil (5%, 4%, and 1% of the samples, respectively), but were not found in crop roots. The incidence of Meloidogyne, Rotylenchulus, Pratylenchus, and Aphelenchus tended to be higher in plots where cucurbits and/or solanaceaous crops were grown more frequently, whereas the presence of Criconemoides seemed to be associated with plots where cassava, corn or sorghum had been grown recently.
Insecticides from Five Chemical Classes Differentially Affect the Plant Growth and Development of Chrysanthemum (Dendranthema grandiflora Tzvelev var. Charm)
Authors: Spiers* James D. , Davies Fred T. , He Chuanjiu , Chau Amanda , Heinz Kevin M. , Starman Terri W.
Published: February 2019

This research focused on the influence of insecticides on plant growth, gas exchange, rate of flowering, and chlorophyll content of chrysanthemum (Dendranthema grandiflora Tzvelev cv. Charm) grown according to recommended procedures for pot plant production. Five insecticides were applied at recommended concentrations at three different frequencies: weekly (7 days), bi-weekly (14 days), or monthly (28 days). A separate treatment was applied weekly at 4× the recommended concentration. Insecticides used were: acephate (Orthene®) Turf, Tree & Ornamental Spray 97), bifenthrin (Talstar®) Flowable), endosulfan (Thiodan®) 50 WP), imidacloprid (Marathon®) II), and spinosad (Conserve®) SC). Phytotoxicity occurred in the form of leaf burn on all acephate treatments, with the greatest damage occurring at the 4× concentration. Photosynthesis and stomatal conductance were influenced primarily by the degree of aphid and/or spider mite infestation—except for acephate and endosulfan treatments (weekly and 4×), which had reduced photosynthesis with minimal insect infestations. Plants receiving imadacloprid monthly had the greatest leaf dry mass (DM). Plants treated with acephate had lower leaf and stem DM with bi-weekly and 4× treatments. Spinosad treatments at recommended concentrations had reduced stem DM, in part due to aphid infestations. The flower DM was not significantly different among treatments. There were treatment differences in chlorophyll content as measured with a SPAD-502 portable chlorophyll meter.
Agroforestry on Small Landholdings in Bangladesh
Authors: Rahman* Lutfor S. , Mir Farid A.
Published: February 2019

The study was conducted in three sub-districts of Gazipur district in Bangladesh. It identified the diversity and distribution of tree species and which vegetable crops are grown beneath them, uses of different plants, to identify the problem faced by the farmers. Total of 43 tree plant species are used for fruit and timber were identified in the study area. Based on diversified uses, the major fruit species were jackfruit, mango and coconut. The major timber species were koroi (Albizia procera), raintree (Samanea saman), neem (Azadirachta indica), teak (Tectona grandis) and eucalyptus (Eucalyptus sp.). Total income was found to increase with increase of farm size. A large number of vegetables (32 species) are cultivated in the study area, largely for local consumption. The study showed that stem amaranthus, indian spinach, aroids, sweet gourd, chili pepper, turmeric, eggplant, and radish were grown under shade of jackfruit, mango, date palm, litchi, mahogany, and drumstick trees. The total income from trees in the last five years was higher in the large farm category than that in the tenant category. The major problems faced by the farmers in tree establishment were damage caused by animals which was reported by 68% of the respondents.
Yield and Fruit Quality of Carambola Cultivars Grown at Three Locations in Puerto Rico
Authors: Goenaga* Ricardo , Rivera Edmundo
Published: February 2019

Nine carambola (Averrhoa carambola) cultivars grown on an Oxisol, Ultisol, and Mollisol were evaluated for 2 years under intensive management at Isabela, Corozal and Juana Diaz, Puerto Rico, respectively. There were no significant differences in number and weight of marketable fruits per hectare between Corozal and Isabela; average values for both locations were 249,824 fruits/ha and 29,864 kg/ha. At Juana Diaz these values were 196,254 fruits/ha and 24,339 kg/ha, respectively. There were no significant differences in weight of marketable fruit per hectare among cultivars B-17, Thai Knight, B-10, Sri Kembangan, and Kajang between locations. The average marketable fruit weight for these higher yielding cultivars was 31,457 kg/ha. Cultivar Kari produced significantly longer fruits at all locations, whereas cultivar B-16 produced the shortest fruits. Significantly higher brix values were obtained from fruits of cultivar B-17 at all locations whereas lower values were obtained from those of Arkin.
In Vitro Multiplication of Brazilian Ginseng (Pfaffia spp.) for in Vitro Conservation Purposes
Authors: de Luces Fortes* Gerson Renan , e Silva Ana Carolina Pereira
Published: February 2019

Brazilian ginseng (Pfaffia sp.) is largely known as having anabolic, analgesic, anticancerous, anti-inflammatory, antileukemic properties, and more. Embrapa Genetic Resources and Biotechnology is the major Conservation Center in Brazil. This species could only be stored under in vitro conditions. There are more than two hundred native acessions collected from different locations in the country. So far very few works are found in the literature and there is no specific protocol for in vitro conservation. The aim of this study was to test five different acessions from in vitro collection under one specific nutrient medium. The acessions were catalogued as 2205-12; 2202-04; 2209-11; 2209-10 and 2205-21. One-bud microcutting was inoculated on a MS nutrient medium without growth regulators and added with vitamins, myoinositol (100 mg·L-1), sucrose (30 mg·L-1) and agar (6 mg·L-1). The pH was adjusted to 5.7 before the agar addition. Each treatment was replicated 7 (seven) times and each plot consisted of six test tubes with 5-mL solution. The trial was replicated twice. The evaluations were performed once weekly where the shoot growth was taken along with the number of buds and roots formed. The highest shoot growth were obtained for the acessions 2205-12 and 2209-10. Acession 2209-11 had an intermediate shoot growth and number of buds, but had the highest number of roots per shoot (4.27) compared to 2.14 and 3.75 for acessions 2205-21 and 2209-10, respectively. The highest rate of multiplication was achieved for acessions 2205-12 (4.49) and 2202-04 (4.46) as compared to 3.60 for acession 2205-21. It was clearly shown that acession 2205-21 is a recalcitrant one as in vitro multiplication is concerned. All the acessions rooted in this medium.
Detecting Genes Expressed at Different Stages of Reproductive Arrest in Brassica oleracea
Authors: Duclos* Denise V. , Björkman Thomas
Published: February 2019

Cauliflower (Brassica oleracea var. italica) and Broccoli (Brassica oleracea var. botrytis) differ mainly in the stage of reproductive arrest. Cauliflower curd is an inflorescence meristem, while broccoli arrests just before anthesis. Arabidopsis studies led to the hypothesis that a mutant BoCAL allele arrested cauliflower earlier. Later, a mutant in BoAP1 was found to have similar effects. These partially redundant genes, and several identified since, are present in multiple copies in B. oleracea. Understanding their role in the arrest requires quantification of transcript abundance analysis by real-time PCR. Designing selective PCR primers is a critical first step in the process. Designs were based on alignment among the genes of interest (MADS-box genes BoCAL, BoAP1, FUL, and the non MADS-box genes LFY and TFL1) and their paralogs. The high sequence similarity (some over 95%) makes the target transcripts difficult to distinguish. Therefore, primers were designed mostly for targets in the 3'UTR region in order to gain specificity. Short amplicons, 68bp to 200bp, were required for the high PCR efficiency required to quantify these low-abundance transcripts. Primers were evaluated by conventional RT-PCR and real-time PCR. By altering temperature, Total RNA was isolated from plants that were arrested at three developmental stages, inflorescence meristem (cauliflower), floral meristem (intermediate), and floral bud (broccoli) by varying temperature. RT-PCR products were single bands of the expected size, despite the high homology between genes under study. Real-time melting curve analysis (fluorescence derivative vs. melting temperature) corroborated the presence of a single amplicon. The identity of products was confirmed by sequencing and restriction enzyme digestion.