bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterosis and Inbreeding Depression for Yield of Pickling Cucumber (Cucumis sativus L.) Hybrids
Authors: Cramer Christopher S. , Wehner Todd C.
Published: February 2019

Currently, both hybrid and inbred pickling cucumber cultivars are being grown commercially in the United States. Heterosis for yield in pickling cucumber has been previously reported. However, heterosis has not been repeatable in other studies. The objective of this study was to determine the existence of heterosis and inbreeding depression for yield in pickling cucumber. Six pickling cucumber inbreds (`Addis', `Clinton', M 12, M 20, `Tiny Dill', `Wisconsin SMR 18') were hybridized to form four F1 hybrid families (`Addis × M 20, `Addis' × `Wis. SMR 18', `Clinton' × M 12, M 20 × `Tiny Dill'). Within each family, F2, BC1A and BC1B generations were also formed. Thirty plants of each generation within each family were grown in 3.1-m plots for four replications in the spring and summer seasons of 1996 at the Horticultural Crops Research Station in Clinton, N.C. Data were collected at once-over harvest for total, marketable, and early yield in terms of number (1000 fruit/ha) and weight (Mg/ha). In addition to yield, a fruit shape rating was collected for each plot. High parent heterosis for yield (total and marketable fruit weight) was only observed for `Addis' × `SMR 18' grown in the summer season. The three other families did not exhibit heterosis for total, marketable, and early yield. Heterosis for shape rating was not observed for any family. `Addis' × `Wis. SMR 18' also exhibited inbreeding depression for total fruit weight, marketable fruit weight, early fruit number, and early fruit weight during the spring season and for marketable fruit number and marketable fruit weight during the summer season.
Downy Mildew Resistance of the Cucumber Germplasm Collection in North Carolina Field Tests
Authors: Wehner Todd C. , Shetty Nischit V.
Published: February 2019

Downy mildew [Pseudoperonospora cubensis (Berk. & Curt.) Rostov] is an important disease in most cucumber (Cucumis sativus L.) production areas of the world. Resistant cultivars are available, but higher levels are needed if yield losses are to be avoided. The objective of this experiment was to test all available plant introduction accessions, cultivars, and breeding lines (collectively referred to as cultigens) of cucumber for downy mildew resistance under field conditions in North Carolina. Cultigens were tested in 2 years and two replications under natural field epidemics of the disease. Mean ratings for downy mildew leaf damage ranged from 1.3 to 9.0 on a 0 to 9 scale. The most resistant nine cultigens originated from the U.S., and were primarily adapted cultivars or breeding lines. The most-resistant cultigens, for which multiple-year data were available, were Gy 4, `Clinton', PI 234517, `Poinsett 76', Gy 5, `Addis', M 21, M 27, and `Galaxy'. The most-susceptible cultigens for which multiple year data were available, were PI 288995, PI 176952, PI 178886, and PI 211985. We classified 17 cultigens as highly resistant (1.3 to 3.0), 87 as moderately resistant (3.3 to 5.0), 311 as moderately susceptible (5.3 to 7.0), and 248 as highly susceptible (7.3 to 9.0) for the 663 cultigens with multiple-year data. No plant introduction accessions were found to be more resistant than the most-resistant elite cultivars and breeding lines tested.
Specific Genomic Regions in Common Bean Condition Resistance to Multiple Pathogens
Authors: Miklas Phillip N. , Stone Valerie , Urrea Carlos A. , Beaver James S.
Published: February 2019

A genetic linkage map of 170 RAPD markers mapped across 79 recombinant inbred lines (Dorado and XAN-176) reveal genomic regions that condition multiple disease resistance to fungal (Ashy Stem Blight—Macrophomina phaseolina), viral (bean golden mosaic virus—BGMV), and bacterial (common bacterial blight—Xanthomonas campestris pv. phaseoli) pathogens of common bean (Phaseolus vulgaris). A genomic site on linkage group US-1 had a major effect, explaining 18%, 34%, and 40% of the variation in phenotypic reaction to ashy stem blight, BGMV, and common bacterial blight disease, respectively. Adjacent to this region was a QTL conditioning 23% of the variation in reaction to another fungal pathogen, web blight (Thanatephorus cucumeris). A second genomic site on linkage group US-1 had minor affect on multiple resistance expression to the same fungal (15%), viral (15%), and bacterial (10%) pathogens. It is unknown whether these specific genomic regions represent a series of linked QTL affecting resistance to each disease separately or an individual locus with pleiotropic effect against all three pathogens.
RAPD Molecular Markers for the Gene Controlling Seedling Lethality and Plant Crippling in Common Beans
Authors: Dávila Martha , Coyne Dermot , Singh Shree , Jung Guenhwa
Published: February 2019

The genes involved in F1 seedling abnormal development and lethality in inter-gene pool crosses have been designated as Dl1 (MesoAmerican=MA) and Dl2 (Andean=A) (Shii et al., 1980, J. Hered. 71:218–222). The different degrees of leaf crippling (C) in segregating populations of crosses was due to the interaction between the Dl1 or Dl2 loci, growing environment, and the lcr allele (Singh and Molina, 1996, J. Hered., In press). The objective was to identify RAPD markers linked to the genes for crippling (lcr) and seedling lethality (Dl) using the bulked segregation analysis procedure for F2 of MA × A crosses. Crosses were made between C lines, FB 10413-24-2, WA 7807-305, and TY 5578-220 and normal (N) parents and tester stocks for Dl1 and Dl2 genes. The F2 FB 10413-24-2 × Carioca segregated 13 N:3C. F3 families segregated 3N:1C. RAPD marker OPB-10 was linked to Lcr at 31.2 cM. F3 families segregated 1N:3C. RAPD marker OPO16 was linked to Dl1 at 27 cM. The F2 WA-7807-305 × Rio Tibagi segregated 3N:1C. RAPD marker OPS-03 was linked to Lcr at 32.6 cM.
Breeding Great Northern and Pinto Dry Beans with Multiple Disease Resistance Combined with Improved Seed Quality, Adaptation, Yield, and Plant Type
Authors: Coyne D.P. , Steadman J.R. , Lindgren D.T. , Nuland David , Smith Durward , Stavely J.R. , Reiser J. , Sutton L.
Published: February 2019

Common bacterial blight (CBB), rust (RU), and white mold (WM) are serious diseases of great northern (GN) and pinto (P) beans in Nebraska and Colorado. The bacterial diseases halo blight (HB) and brown spot (BS) are sporadic. Severe Fe-induced leaf chlorosis (Fe ILC) occurs on calcareous sites. Separate inoculated disease nurseries are used to screen for resistance to the pathogens causing the above diseases. Yields and seed quality of lines are also determined in non-disease trials. Sources of exotic resistance to the above pathogens and to Fe ILD have been identified and their inheritance determined. A non-structured recurrent selection scheme has mainly been used, occasionally with a backcross program, to combine high levels of the desired traits. Selection for highly heritable traits such as seed size, shape and color, maturity, plant architecture, and RU resistance occurs in early generations while traits of low heritability, such as CBB resistance, WM avoidance, yield, seed coat cracking resistance, and canning quality, are evaluated in separate replicated tests over several years and finally for yield in on-farm-trials. A number of multiple disease resistant, high-yielding, well-adapted GN and P lines are or will be released; P `Chase' (on about 30,000 acres in 1996) and GN WM 3-94-9 (for possible release).
Development of Pinkeye-type Southernpeas with Green Cotyledons
Authors: Fery R.L.
Published: February 2019

A breeding program was initiated in 1990 to develop a pinkeye-type southernpea [Vigna unguiculata (L.) Walp.] cultivar homozygous for the gc gene conditioning green cotyledons. The pinkeye is the leading cultivar class of southernpea grown in the U.S., and there is considerable interest in converting pinkeye germplasm to green cotyledon phenotypes because a cultivar homozygous for the gc gene can be harvested at the near-dry seed stage of maturity without loss of the seed's fresh green color. Seeds containing embryos homozygous for the gt gene are easily identified, and this ability to select in the seed stage greatly facilitated breeding efforts. A total of 25 advanced breeding lines (F9 and F10) were evaluated in preliminary field tests in 1995, and the experimental line US-858 was selected for seed multiplication, field testing, and raw product evaluation in 1996. The results of 1996 replicated yield trials conducted in South Carolina and seed multiplication plantings grown in El Salvador, Georgia, and Florida indicate that the maturity, seed, and yield characteristics of US-858 are comparable to those of the leading pinkeye-type cultivars. Raw product evaluations were conducted at a commercial freezing facility in Georgia, and the results indicate that US-858 produces an excellent processed product. The results of field inoculation tests conducted in Georgia indicate that US-858 is resistant to blackeye cowpea mosaic virus, the major pathogen of southernpea in the U.S.
Random Amplified Polymorphic DNA Analysis of Garlic (Allium sativum L.) Germplasm Collection
Authors: Jenderek M.M. , Schierenbeck K.A. , Hannan R.M.
Published: February 2019

Maintenance of garlic (A. sativum L.) germplasm collections is based on year-to-year vegetative propagation of individual accessions. Several accessions are phenotypically similar, often originating from the same region of the world, but have been collected by different people at different times. These accessions are currently maintained as separate and unique samples, but may represent genetic duplication in the collection. In order to identify genetic duplication in the USDA collection, 45 garlic Plant Introduction accessions from the garlic USDA germplasm collection were analyzed for RAPD marker polymorphism. The samples originated from 20 countries worldwide. RAPD bands were generated by 20 decamer primers, using 100-ng DNA template, and 38 PCR amplification cycles. Polymorphism between accessions was defined as presence or absence of particular bands at given loci. However, a few distinguishing RAPD markers were established for selected accessions, identifying additional molecular markers to wholly assess the similarities or polymorphism of the garlic collection units is necessary.
Lipoxygenase POTLX-1 and POTLX-2 Genes are Expressed during Potato Tuber Initiation and Development
Authors: Kolomiets Mikhailo V. , Hannapel David J. , Gladon Richard J.
Published: February 2019

Plant lipoxygenases (LOXs) (linoleate:oxygen oxidoreductase, EC 1.13.11.12) catalyze the oxygenation of polyunsaturated fatty acids such as linolenic and linoleic acids. Some of the final products of LOX-catalyzed reactions are traumatin, jasmonic acid (JA), methyl jasmonate (MJ), and C-6 volatile compounds, and they serve hormone-like regulatory and defense-related roles in plants. Recently, it has been proposed that LOXs play a role in potato tuberization processes because JA, MJ, and structurally similar tuberonic acid and tuberonic acid glycoside have been shown to be tuber-inducing substances. In order to study possible lipoxygenase involvement in potato tuberization, we have isolated, sequenced, and characterized the expression pattern of two cDNA clones, designated POTLX-1 and POTLX-2, that represent similar, but distinct, LOX genes. Within the scope of our experiments, northern hybridization studies with mRNA extracted from various organs of `Superior' potato plants indicated that the expression of these two genes is restricted to developing tubers and roots only. Moreover, there is a positive correlation between POTLX-1 and POTLX-2 mRNA accumulation and the stage of potato tuber development, and this implicates LOX in tuberization processes. Accumulation of their transcripts was not detected in leaves, flowers, stems, shoot tips, or axillary buds. These results indicate that the isozyme forms encoded by these two genes are tuber-specific, and they are good candidates to study LOX involvement in potato tuberization processes. Treatment of potato leaves with abscisic acid, MJ, gibberellic acid, auxin (NAA), and cytokinin (BA) did not trigger transcriptional activation of either of these genes.
Transformation of Carrot (Daucus carota L.) with Genes Involved in Carbohydrate Metabolism and Partitioning via Hypocotyl Tissue Cultures
Authors: Qin Mingbo , Lee Chiwon W. , Borovkov Alex Y. , Duysen Murray E.
Published: February 2019

A study was initiated to characterize key enzymes that influence sweetness in carrot (Daucus carota L.) roots. Sucrose synthase (SS), sucrose phosphate synthase (SPS), and UDP-glucose pyrophosphorylase (UDPL) genes were isolated from potato (Solanum tuberosum L.) and cloned in an anti-sense orientation into Agrobacterium tumefaciens Bin19, which has a CaMV 35S promoter. Seedling hypocotyl sections of selected carrot lines were pre-incubated on B5 medium for 2 days, co-cultivated with A. tumefaciens Bin 19 for additional 3 days, and then transferred to a modified B5 medium containing 50 g/mL kanamycin and 400 g/mL carbenicillin. In 4 weeks, 18.6%, 33.3%, and 26.7% of the cultures from a breeding line (W204-C) were found to be transformed, respectively, with SS, SPS, and UDPL as determined by kanamycin resistance. In contrast, no kanamycin-resistant calli were obtained from a commercial cultivar (Navajo) in these transformation studies. The transformed calli proliferated in the medium containing 50 g/mL kanamycin and 400 g/mL carbenicillin, whereas non-transformed calli died in the same medium. These transformed calli are currently being used to regenerate plants via asexual embryogenesis using a suspension culture. The influence of these additional genes on sugar metabolism and accumulation in root tissues of transformed carrots will be characterized in the future.
Outcrossing Techniques for Producing Artichoke Seed
Authors: Mayberry K.S. , Principe J.A. , Schrader W.L.
Published: February 2019

The artichoke, Cynara scolymus, is normally propagated by cuttings from mother plants; however, it is possible to produce some types of artichokes from seed. Methods used for producing open-pollinated seed of onion and carrots may be suitable for producing artichoke seed. Outcrossing in artichokes occurs because of differences in maturity of the staminate and pistillate phases within flowers. Producing artichoke seed by simple inbreeding techniques is usually not successful because of vigor loss and low pollen production, low seed production, and late maturity of progeny. Outcrossing is the preferred method of creating a new variety. The cultivar `Imperial Star' was developed by crossing a thornless French line with an Italian line that had sharp woody spines, and a uniform, olive-green color. The French line was a bright green with some light purple at the base of the bracks. The F1 generation from this cross had good hybrid vigor, and produced abundant seed and pollen. The F2 generation segregated widely with many recombinant types that neither parent showed (e.g., extreme thorniness of leaves and petioles). Two plants were selected for sibling pollination. Subsequent generations of siblings within this type produced higher percentages of the desired type—glossiness, earliness, and high seed yield. Subsequent sibling crossing led to the selection of `Imperial Star', PVP. 9000179.
Inheritance and Linkage Analysis of a Blotchy Root Pigment Phenotype in Red Beet
Authors: Watson J.F. , Goldman I.L.
Published: February 2019

The primary pigments in red beet are the betalains, which include the red-violet betacyanins and the yellow betaxanthins. The recent adoption of betalain pigments from red beet as an alternative to synthetic food dyes has heightened interest in genetic modification of pigment production. Dominant alleles at two tightly-linked loci (R and Y) condition production of betalain pigment in the beet plant; however, several alleles at the R locus influence pigment amount and distribution. A mutant phenotype, characterized by irregular sectors of blotchy red and white root color, arose spontaneously in the beet breeding nursery. The blotchy mutant plant was used in crosses with non-blotchy inbred lines to characterize its inheritance. Chisquare goodness-of-fi t tests of segregation data in backcross and F2 generations for several genetic backgrounds did not deviate from the hypothesis that a single recessive gene controls the blotchy phenotype. Linkage analysis was conducted to determine if the blotchy phenotype was conditioned by a new locus or an allele at a previously described locus. Our data indicate the bl gene resides at a newly described locus linked to R and Y. Maximum likelihood estimation revealed a linkage distance between R and Y of 8.95 ± 0.49 cM. The linkage distance between R and BL was calculated at 13.99 ± 1.18 cM, and the overall linkage between Y and BL was determined to be 28.8 ± 4.2 cM. Our data suggest the RYBL genomic region plays a critical role in the genetic control of betalain biosynthesis.
Effect of Nursery Stock Type and Size on Growth of Three Deciduous Shrub Species in Containers
Authors: Iles Jeffery K.
Published: February 2019

Rewholesalers, garden centers, and other sellers of deciduous shrubs routinely receive bare-root stock in late winter or early spring for potting; however, bare-root plants are sometimes slow to establish in containers. Potted liners with well-developed root systems show potential for shortening the production cycle and permitting the development of higher-quality plants earlier in the growing season. To study the effect of nursery stock type and size on subsequent growth, two bare-root sizes and one potted liner size of `Cardinal' red osier dogwood (Cornus sericea L.), `Goldflame' spirea (Spiraea xbumalda Burv.), and `James MacFarlane' lilac (Syringa xprestoniae McKelv.) were grown in polyethylene containers of different sizes. Bare-root plants (15 and 30 cm in height) were grown in 2.7- and 6.1-L, and 6.1- and 10.3-L containers, respectively. Potted liners (0.4-L container size) were grown in 6.1- and 10.3-L containers. Plant performance was evaluated 10 and 20 weeks after potting. In general, plant quality ratings increased with container volume for all species. For `Goldflame' spirea and `James MacFarlane' lilac, best plant quality ratings occurred with 30-cm plants grown in 10.3-L containers. But for `Cardinal' redosier dogwood, plant quality ratings were highest and not significantly different for 30-cm bare-root plants and potted liners grown in 10.3-L containers.
Comparison of Pour-through and Ceramic Cup Methods of Extracting Nutrients from a Pine Bark Substrate
Authors: Walden Ronald F. , Niemiera Alex X.
Published: February 2019

The pour-through (PT) nutrient extraction method involves collection of leachate at the container bottom that results from displacement of substrate solution by water applied to the substrate surface. The PT is a convenient and effective means of monitoring the nutritional status of the soilless container substrates used in the nursery industry, but is less convenient for large containers, particularly those used in the “pot-in-pot” system of growing trees in production containers within in-ground socket containers. We describe a simple vacuum method of extracting solution from pine bark in containers using ceramic cup samplers. When N was applied to a pine bark substrate at 56–280 mg/L, extractable N was slightly higher for the PT than for the ceramic cup method. The correlation between applied and extractable N was 0.99 for both methods. Further comparison of pine bark extract nutrient and pH levels for PT and ceramic cup methods will be presented.
Water and Nitrogen Management to Reduce Nitrate-Nitrogen Leaching from Container Crops
Authors: Colangelo David J. , Brand Mark H.
Published: February 2019

Plastic 208-L industrial barrels (14 total) were modified for use as soil-filled lysimeters to study the nitrogen dynamics of a typical container crop production system. The top of each barrel was removed and the bottom was fitted with a drain hole and filter fabric. The drain was then connected via tubing to a 2-L leachate collection vessel made from a length of 15.24-cm-diameter PVC pipe that had been capped on one end. All barrels and connected collection vessels were recessed into a grassed slope. Barrels were filled with homogeneous B and C horizon soil to simulate soil conditions of a typical container nursery. Uniform Rhododendron `Catawbiense Album' plants in 4.5-L containers were arranged atop the barrellysimeters at four plants per barrel. Irrigation/fertilizer treatments included fertilized pulse trickle irrigation (four replications), fertilized overhead irrigation (four replications), and unfertilized controls corresponding to each irrigation treatment (three replications each). All fertilized plants received 10 g of 17N–6P–10K 8- to 9-month controlled-release fertilizer at the beginning of the crop cycle. Leachate from the barrel-lysimeters was collected weekly and total volume, total Kjeldahl N, nitrate-N, and ammonium-N were determined. Peak nitrate-N levels were well above the current drinking water standard for both irrigation treatments at certain times during the year. Cumulative nitrate-N mass output was similar for both irrigation treatments. A nitrogen balance for the complete production system including fertilizer and irrigation water input, plant material, potting media, soil in the lysimeter barrels and leachate output from the barrels has also been determined.
Business Profile of Australian Nurseries
Authors: Brumfield Robin G. , McSweeney Peter F.
Published: February 2019

We surveyed 22 Australian nurseries in 1995 to: 1) develop a profile of Australian nurseries from a production, management, and profitability perspective; 2) compare the data to relevant U.S. benchmarks; and 3) identify trends and potential areas of improvement in the management of Australian nursery enterprises. The study confirmed that Australian nurseries incur high labor costs (38.8% of sales) that are comparable to United States nurseries, while costs of materials and supplies were lower than their U.S. counterparts. Overall, the costs of the surveyed nurseries appeared lower than their U.S. counterparts. Concerns of managers were directed towards recruiting and keeping labor and marketing rather than increasing capital investment to increase production efficiency. Capital expenditures tended to be funded from internal cash flows rather than external borrowings. Many of the nursery managers used relatively simple performance indicators and most business objectives were stated in general terms. Australian nurseries carried more diverse product ranges than the U.S. nurseries. Many of the nurseries adopted quite vigorous marketing strategies with a stronger emphasis on marketing than in those in the U.S. Concerns about the viability of the industry included oversupply, the growth in chain stores business, factors eroding the demand for nursery products and greater regulation.
A Method of Rapidly Assessing Post-disaster Damage to Vegetables and Tropical Fruits
Authors: Lamberts Mary , Balerdi Carlos , Eskelin Karen
Published: February 2019

Producers of perishable commodities periodically experience natural disasters. Growers in Dade County, Fla., have suffered losses from hurricanes, freezes, and floods. Public agencies and grower groups are often asked to provide immediate estimates of loss to both official sources and the news media. Following the Jan. 1997 freeze, a method was developed to provide this information within 1 day of the disaster. This has also been used to estimate job losses for agricultural workers.
Analysis of Volatile Evolution from Scald-developing and Nondeveloping Sides of Apple Fruits
Authors: Whiting M.D. , Paliyath G. , Murr D.P.
Published: February 2019

Apple fruits (Malus domestica Borkh. cv. `Red Delicious') stored for 6 months at 2°C in air were analyzed for headspace volatiles by SPME-GC and for surface components by HPLC of hexane extracts. Analysis of headspace volatiles evolved from whole fruit showed five major volatiles that were identified previously as: acetic acid, hexyl ester; hexanoic acid, butyl ester; octanoic acid, propyl ester; hexanoic acid, hexyl ester; and the sesquiterpene, α-farnesene. No significant differences existed in these volatiles between scald-developing and non-scald developing apples. To explore potential differences in volatile evolution, fruit developing scald were cut (axial plane) into scalding and non-scalding halves for analysis. In all cases, volatile emission was much higher from the non-scalding side of the fruit, and the ratio of volatile levels from non-scalding to scalding averaged greater that 2. Various regions of tissue from the same fruit were extracted in hexane for estimation of levels of α-farnesene and its potential catabolites by HPLC. The levels and proportions of the components were nearly identical to those observed during headspace volatile analysis of half fruit. The results suggest that there are potential differences in α-farnesene metabolism an/or permeability of apple cuticle to volatiles between scald-developing and non-scald developing regions of apple fruit.
The Effect of Acclimatization of Fruits on the Control of a CO2-linked Disorder of `Empire' Apples
Authors: Wang Zhenyong , Kossitrakun Manit , Dilley David R.
Published: February 2019

The “scald-like” disorder of `Empire' apples is a CO2-linked disorder. In this study we investigated the factors of acclimatization of preclimacteric fruits at 3°C in air or low O2 levels prior to elevating the CO2 concentration. Fruits were harvested at the immature stage, which had higher potential to suffer the disorder. Establishing CA conditions of 5% CO2 + 1.5% O2 at 3°C within 1 day of harvest resulted in the highest incidence of the `Empire' disorder, followed by 3% CO2 + 1.5% O2 > 5% CO2 + 3% O2 > 3% CO2 + 3% O2. The fruits had to be acclimated at 3°C for 3 to 4 weeks at 1.5% or 3% O2 to become insensitive to 5% or 3% CO2. Holding the fruits in air for 1 week prior to administering 3% or 5% CO2 was insufficient to control the disorder, whereas the fruits tolerated 3% or 5% CO2 after holding the fruits in air for 2 weeks. But, the 2-week delay to CA resulted in accelerating flesh softening. Supplemental carbon dioxide was not necessary for at least 1 month to maintain flesh firmness at near harvest values where fruits were kept at 1.5% O2. Whereas at 3% O2, the presence of 3% or 5% CO2 from the beginning of the storage period was required to retard flesh firmness decrease. Fruits stored for the entire storage duration without CO2 softened markedly. In summary, we conclude that establishing CA conditions of 3% to 5% CO2 with 1.5% or 3% O2 at 3°C within 1 week of harvest can lead to serious incidence of the `Empire' disorder with preclimacteric fruits. Moreover, fruits acclimate better in air than at low O2 levels with respect to tolerating CO2. This suggests a requirement of oxidative metabolism in acclimatization for CO2 tolerance. Beyond 7 days, acclimatization in air at 3°C before CA is established results in excessive flesh softening, even though it does prevent the disorder incidence.
Deleterious Effects of Pure Oxygen on `Gala' and `Granny Smith' Apples
Authors: Solomos Theo , Whitaker Bruce , Lu Changwen
Published: February 2019

Exposure of `Gala' and `Granny Smith' apples to pure oxygen resulted in inhibition of the rise in ethylene evolution and development of visual symptoms of extensive injury akin to that which occurs under the condition of very low oxygen. Analytical data showed that fruit kept under pure O2 accumulated ethanol. In `Granny Smith' apples, the accumulation of ethanol was associated with increases in pyruvate and citrate concentration, and a sharp decrease in isocitrate concentration. These data indicate that an atmosphere of pure O2 inhibited cis-aconitase activity in the fruit, thereby disrupting the TCA cycle. This, in turn, caused an increase in production of ethanol. The possible mechanism by which pure O2 inhibits cis-aconitase will be discussed.
Heat Treatments Delay and Reduce the Ethylene Climacteric in Carnation Flowers (Dianthus caryophyllus L. cv. `White Sim')
Authors: Verlinden Sven , Woodson William R.
Published: February 2019

High-temperature treatments can be used for disinfestation of a variety of horticultural crops. Carnation flowers were subjected to a heat treatment in order to determine if it is a viable option for disinfestation of this crop. Flowers were exposed to 45°C for 24 hr in the dark, while control flowers were held at RT for 24 hr in the dark. Subsequently, the flowers were held at RT in the light and monitored for ethylene production, an indicator of imminent floral senescence. In the heat-treated flowers, the ethylene climacteric occurred at 96 hr after the heat treatment, a delay of 12 hr when compared to the control. Peak ethylene production was decreased by 25% to 30% in heat-treated flowers. Northern blot analysis of the ethylene biosynthetic pathway genes, ACC synthase, and ACC oxidase, showed that the expression of these genes is delayed by 8 to 16 hr in heat-treated flowers. This indicates that the delay and decrease in ethylene production is at least, in part, due to a delay or reduction in the expression of these genes. Further investigation revealed a decreased responsiveness of the petals to ethylene. Petals from heat-treated and control flowers were exposed to 1 ppm ethylene for 0, 0.5, 1, 2, 4, 6, 12, and 32 hr. The heat-treated petals again showed a delay and a decrease in maximum ethylene production after exposure to ethylene. A delay in expression of ACC synthase and ACC oxidase was also observed. The beneficial effects of exposing carnation flowers to high temperatures, a delay in ethylene production, and reduced responsiveness to ethylene, suggest that heat treatments could be used for disinfestation of this crop.
Shoot Proliferation and Growth of Gardenia (Gardenia jasminoides Ellis) in Response to pH and Sugar Concentrations in Vitro
Authors: Al-Juboory Karim H. , Al-Amiry L.K. , Kushad M.M
Published: February 2019

Stem cuttings of greenhouse-grown gardenia (Gardenia jasminoides Ellis) were surface-sterilized and planted on modified Murashige and Skoog (MS) medium supplemented with 2.0 mg/L (BA) and 0.5 mg/L (NAA). This study examines the effects of pH and various sugars on the growth and proliferation of in vitro-cultured gardenia. The highest average shoot number and shoot length were obtained at pH 4.0 to 5.0. In determining the effect of sugars on shoot proliferation, our findings indicated that sucrose and glucose at 30 and 40 g/L, respectively, produced a higher shoot number when compared to fructose and xylose. In addition, sucrose and glucose produced the highest root number, root length, and rooting percentage, while fructose and xylose had no effect on rooting. Sucrose and fructose produced more calli in comparison to other sugars. Xylose at 40 g/L produced the highest dry weight (18.5%), while xylose at 10 g/L produced the highest fresh weight (94.4%).
Micropropagation and Field Establishment of Hexastylis shuttleworthii (Britten & Baker) Small
Authors: Kitto Sherry , Frett Jeanne
Published: February 2019

Hexastylis shuttleworthii is a highly ornamental shade-tolerant evergreen herbaceous plant native to the southeastern U.S. that is difficult to propagate using traditional methods. Micropropagation would make possible the wider distribution of selected clones. Seeds were surface-sterilized and germinated in vitro. Seedling clones were maintained on a MS basal medium containing 1 mg/L BA and were subcultured monthly. Proliferation of clones 2 and 3, maintained on media supplemented with 1, 2.5 or 5 mg/L BA for 6 months, increased slightly with increasing BA concentration; however, proliferation decreased slightly over the experimental period. Rooting medium (perlite, vermiculite, MetroMix 510, Bacto Growers Mix) did not effect microcutting root production or subsequent plant survival. Microcuttings rooted in vitro (67% survival) generated more leaves compared to microcuttings rooted under humidity domes with mist in the greenhouse (8% survival). After rooting in vitro, multiple-shoot clumps (95%) survived better than individual shoots (29%) under greenhouse conditions. Plants were easily established when planted in raised beds in a lath house.
Omega-3-Fatty Acid Concentration in Portulaca oleraceae L. is Altered by the Source of Nitrogen in Hydroponic Solution
Authors: Palaniswamy Usha Rani , McAvoy Richard , Bible Bernard
Published: February 2019

Omega-3 fatty acids (O3FA) are essential for normal human growth, development, and disease prevention. Purslane (Portulaca oleraceae L.) is an excellent source of the O3FA α-linolenic acid (LNA)—with higher concentrations than any green leafy-vegetable examined to date—and is being considered for cultivation (by USDA-ARS) in an effort to improve the balance of essential fatty acids in the western diet. Twenty-fi ve-day-old seedlings of both a green-leafed and a golden-leafed type of purslane were transplanted into a closed hydroponic system. Nitrogen, at 200 ppm, was provided as NO3 and NH4 forms to yield NO3: NH4 ratios of 1:0, 0.25:0.75, 0.5:0.5, and 0.75:0.25. Treatments were arranged in a randomized complete-block design with five replications. The experiment was repeated. Young, fully expanded leaves were harvested 18 days after treatment initiation, frozen (–60°C), and then analyzed for fatty acids using gas chromatography. Although the two types of purslane did not differ in LNA concentration, the green-leafed purslane produced greater total dry mass than the golden-type. On a leaf dry mass basis, plants grown with a NO3:NH4 ratio of 0.5:0.5 produced 241% and 53% greater LNA than plants grown with NO3:NH4 ratios of 1:0 and 0.75:0.25, respectively. Plants grown with NO3:NH4 ratios of 1:0 and 0.25:0.75 produced similar leaf LNA concentrations. Total dry mass was not affected by the nitrogen treatments.
Alternative Crop-growing Strategies: Use of Winter Cover Crops on Bell Pepper Production
Authors: Ranwala N.K.D. , Brock K. , Ray C.L. , Greene K. , Decoteau D.R.
Published: February 2019

The effects of two winter cover crops, rye and crimson clover, on bell pepper yield were studied. Cover crops were planted in fall and incorporated into the soil prior to bell pepper planting. Both cover crops increased the marketable number and weight of bell peppers, and reduced the cull number of bell peppers compared to fallow (control) treatment. Delaying the harvest increased the marketable yield in both cover crops. Since there was no difference in bell pepper yield between two cover crops, both cover crops can be used effectively for bell pepper production. Use of cover crops may reduce the production costs and harmful effects on the environment by reducing chemical dependency, and increase the crop yield.
Surface Mine Land Reforestation: Using Poultry Litter
Authors: Sibley J.L. , Himelrick D.G. , Dozier W.A.
Published: February 2019

Poultry and coal production are two major industries concentrated in north-central Alabama. Standard surface coal mine reclamation procedures were compared to procedures utilizing poultry litter in an 3.24-ha mine site. Three 0.4-ha plots amended with litter at rates of 25, 50, and 100 mt/ha, were compared to a plot with mineral fertilizer (13N–13–P13K) at standard reclamation rates of 672 kg/ha, and a plot receiving no fertilizer or litter. All plots were amended with ground limestone and disced in 31 cm. A mix of fescue, lespedeza, rye, and clover was broadcast over all plots uniformly. Eight tree species; northern red oak, nuttall oak, willow oak, red maple, yellow poplar, royal paulownia, loblolly pine, and eastern red cedar were planted in all plots at 1482 trees/ha. Forage yields (1995–96) in litter-amended plots were two to three times higher than statewide hay production averages. High litter rates have had no negative effects on ground cover, tree survival, or ground water nitrates (NO3). This project demonstrates broiler litter use as an organic-matter amendment in a self-sustaining reclamation success.
Flowering Response of Anemone coronaria to Photoperiod and Temperature
Authors: Karlsson Meriam
Published: February 2019

Eight-week-old plants of Anemone coronaria L. `Mona Lisa Series' were transplanted into 10-cm pots and placed in growth chambers at 12, 16, or 20°C and 8, 12 or 16 hr of day length. The irradiance was 12 mol/day per m2. Following the exposure to treatment conditions for 8 weeks, the plants developed in a greenhouse at 16°C and 16 hr of 10-12 mol/day per m2. The fastest appearance of flower buds and flowering were observed for plants grown at 16 hr of day length and 16°C (77 ± 5.4 days from transplant, 133 days from seeding). However, the rate of development was not significantly different from the plants at 12°C and 12 hr of day length (81 ± 3.6 days). Flowering at 20°C required significantly more time at an average 93 ± 9.9 days from transplant. Leaf number at flowering increased with temperature from 9 1.5 leaves at 12°C to 12 ± 3.4 leaves at 16°C and 15 ± 3.4 leaves at 20°C. Flower stem length was significantly longer for plants grown at 12°C or 16 hr of day length (32 ± 0.5 cm) than plants grown at any of the other conditions (26 ± 0.5 cm). The average flower size (length of the petals) was 3.8 ± 0.6 cm for all plants in the study.
Factors Affecting Flowering of Hibiscus spp.
Authors: Warner R. , Erwin J.E.
Published: February 2019

Hibiscus spp. seed were germinated and placed under different photoperiod treatments at 15, 20, or 25± 2°C. Photoperiod treatments were 9 hr, ambient daylight (≈9 hr) plus night interruption lighting (2200–0200 hr, 2 μmol·m–2·s–1 from incandescent lamps), or ambient daylight plus continuous light (100 μmol·m–2·s–1 light from high-pressure sodium lamps). Treatments were terminated at anthesis or after 20 weeks. Variation in flowering form and plant habit were documented and will be discussed. Temperature/photoperiod effects/interactions on plant development will be presented. Species were classified into appropriate photoperiodic groups. Those species with potential as new commercial floriculture crops will be presented.
Effect of Chitosan on Growth and Toxin Production by Alternaria alternata f. sp. lycopersici
Authors: Reddy M.V. Bhaskara , Barka Essaid Ait , Castaigne F. , Arul Joseph
Published: February 2019

The antifungal activity of chitosan, a bioplymer of β-1-4 gluscosamine, against Alternaria alternata, causal agent of black mold of tomato, was investigated. Chitosan was incorporated into potato dextrose broth (PDB) at concentrations of 100, 200, 400, 800, 1600, 3200, and 6400 μg·ml–1, growth and toxin production by the fungus were assessed after a 15-day incubation period. Chitosan significantly affected both growth and toxin production at higher concentrations. However, at lower concentrations, toxin production was affected more than the growth, as evidenced by minimum inhibitory concentrations (MIC) of chitosan derived for toxin production and mycelial growth. Excess sporulation of the fungus was observed in the presence of chitosan, but the spore viability was affected. Chitosan induced aggregation of fungal cells, abnormal shape, excess branching, and hyphal contortion. It also induced leakage of proteins from the fungal cells. The virulence of the toxin in culture filtrate of the fungus from different concentrations of chitosan was assayed by administering on tomato discs. Phospholipid content, electrolyte leakage, xylanase, and pectin methylesterase activity were measured in the culture filtrate administered tomato tissue. Decreased trend in causing electrolyte leakage, phospholipid degradation, and activation of xylanase and pectin methylesterase were observed with increasing concentrations of chitosan. The results showed that chitosan inhibits fungal growth at higher concentrations than toxin production. Further toxin produced at lower concentrations of chitosan was less virulent. Thus chitosan has potential as an antifungal agent.
A Disease Management Program Enhances Bean Production in the Dominican Republic
Authors: Coyne Dermot P. , Santana Eladio Arnaud , Beaver James , Steadman James R. , Lutz Graciela Godoy , Maxwell Douglas , Sutton Lisa
Published: February 2019

Bean golden mosaic (BGM), rust (RU), web blight (WB), and common blight (CB) are major constraints affecting bean yields in the Dominican Republic (DR). The objectives of the USAID DR supported project were to educate graduate students, improve research facilities and equipment, institutionalize the project, and develop a comprehensive bean disease management program. The project trained 25 researchers. A national center for bean improvement (CIAS) was established. Facilities for plant pathology, germplasm storage, and screenhouses were built and equipment and vehicles were acquired. The high-yielding rust-resistant red mottled bean variety `PC-50' was introduced and grown on about 60% of the hectarage. However, BGM became a serious problem with the increase of the white fly population (vector of BGMV) due to increased vegetable production. Under severe BGM, yields were low in plantings made after 15 Dec. The combination of the use of `PC-50', along with a fallow period with delayed planting until early November, reduced the populations of white fly, BGM, RU, and CB and led to a dramatic yield increase of beans and to self sufficiency in beans in the DR. PC-50 became damaged by a new RU race and a resistant line PC-21-SMA (UPR) was released. New bean lines with resistance to BGM, WB, RU, and CBB are being tested for release.
Yield and Disease Resistance of Six Tomato Cultivars Grown in Two Media and Three Calcium Concentrations
Authors: Boone Rebecca S. , Sams Carl E. , Conway William S.
Published: February 2019

Calcium has been linked to disease resistance in fruits and vegetables. The effects of calcium nutrition on six hydroponically grown tomato cultivars (`Switch', `Match', `Blitz', `Caruso', `Trust', and `Celebrity') were evaluated in the fall of 1996. Disease resistance and yield were measured for plants grown in either perlite or pine bark mulch. Plants were fertilized with a 5N–11P–26K water-soluble fertilizer solution containing micronutrients and either 60, 120, or 185 mg·L–1 calcium. Disease resistance was determined by measuring disease lesion diameters on mature green harvested fruit 3 to 5 days after inoculating with Botrytis cinerea Pers.: Fr. There was no significant difference in disease when evaluated by medium, cultivar, or calcium treatment. Foliar analysis by Inductively Coupled Argon Plasma Atomic Emission Spectrophotometer (ICAP) indicated that leaf calcium content ranged from 27,000 to 54,000 μg·g–1 dry weight (leaf above fifth flower cluster), but was not significantly different when analyzed by medium, cultivar, or calcium treatment. There was no significant difference in marketable yield due to medium or calcium treatment. Among cultivars, `Trust' had the highest marketable yield at 2.7 kg per plant, which was significantly different from `Celebrity' at 1.6 kg per plant. This experiment suggests that a cheaper medium (pine bark) and lower calcium levels can be utilized in fall tomato production.
The Influence of Spear Number on in Vitro Rooting of Asparagus (Asparagus officinalis L.)
Authors: de L. Fortes Gerson R. , Müller Nilvane T.G. , Augustin Eliane , Silva João B. , Peters José A. , Flores Rejane
Published: February 2019

Asparagus is a vegetable of great economic importance. It is a dioecius and perennial species mainly propagated by seeds, which makes difficult the breeding work as far as results are concerned. New biotechnological techniques such as tissue culture have been used in order to shorten the release of new cultivars. On the order hand, this process depends mainly on the rooting phase, which, for this species, is to some extent difficult. The aim of this work was to verify the influence of spear number on asparagus rooting. Two genotypes were studied: Clone M14 and cv. Deco, which is a hybrid (M14 × G27). These genotypes were tested with one, two, three, and four spears in a medium containing in mg/L: NAA (0.1); kinetin (2.0); ancymidol (0.5). Sucrose was added to 30 g/L and agar at 6.0 g/L. The pH was adjusted to 5.9. The evaluations were performed 30 days later. Four-spear asparagus rooted better than the others; it was also observed longer roots for this treatment. Clone M14 rooted better than cv. Deco. These results show the importance of the starting explants to improve the in vitro rooting in asparagus.
Plant Regeneration from Axillary Buds of Triploid Watermelon (Citrullus vulgaris Schrad.)
Authors: Guzman S. , Alejandro H. , Farias J. , Michel A. , Lopez G.
Published: February 2019

Watermelon (Citrullus vulgaris Schrad.) is a widely grown crop throughout the tropics and subtropics. In Mexico, it is an economically important crop. In vitro adventitious shoot regeneration of watermelon has been reported from shoot tip culture, leaf, hypocotyl, and cotyledons. Hence, the objective of this study was to evaluate in vitro plant regeneration from axillary buds of triploid watermelon. Axillary buds explants were prepared from shoot of commercial cultivar in field of 60 old day plants. Explants of 2 to 3 mm were incubated 2 weeks on Murashige and Skoog (MS) shoot regeneration medium containing 2.5 mg/L kinetin (KT) or indole-3-butyric acid (IBA), or gibberellic acid (GA3), followed by 3 weeks on shoot elongation medium supplemented with different combinations of the same phytohormones. The percentage of explants (83% to 90%) that produced shoots, expansion in size of explant (0.81–1 cm) and shoot length (6 mm) were highest in MS medium containing KT or IBA. In the shoot elongation step, shoot length (0.9–1 cm) and leaves number (6–7) were highest in MS medium supplemented with 2.5 mg/L of KT or GA3 and 0.2 mg/L IBA, but the better induction of roots in elongated shoot occurred on MS medium with 2.5 mg/L KT and 0.2 mg/L IBA. The results show that axillary buds from watermelon is an alternative for the micropropagation of this crop.
Growth and Performance of Four Summer-ripening Disease-resistant Apple Cultivars on M.27 EMLA, M.26 EMLA, and Mark Rootstocks
Authors: Schupp J.R. , Koller S.I.
Published: February 2019

The growth, productivity, and fruit characteristics of four summer-ripening disease-resistant apple cultivars, (DRCs), `NY 66305-139', `Williams' Pride', `Redfree', and `Dayton' on M.26 EMLA, M.27 EMLA, or Mark rootstocks were compared. `NY 66305-139' was the earliest-ripening cultivar, with the smallest tree size, lowest yield, and the smallest, softest fruit. `Williams' Pride' trees were large, productive, and produced large fruit with the highest red skin color in this trial. The loss of marketable yield of this cultivar, due to moldy core and bitter pit in 1996, raise concerns about its commercial potential. `Redfree' trees were intermediate among the four cultivars in vigor and precocity, and produced high yields of medium-sized fruit. `Dayton' trees were large, high-yielding, and produced the largest, firmest, sweetest fruit; however, the ripening date for `Dayton' was 10 Sept., late for a summer cultivar. Mark and M.26 EMLA produced similarsized trees, while M.27 EMLA produced very small trees. A significant cultivar × rootstock interaction resulted from `Dayton' trees being larger than `Williams' Pride' when both were on M.26, while both cultivars produced similar-sized trees on M.27 or Mark. Of the four cultivars in this trial, we consider `Redfree' to be the best summer DRC for commercial orchards, based upon ripening date, yield, and fruit quality. Mark rootstock was preferable to M.26 or M.27 for the cultivars in this trial, with the best tree growth and precocity.