bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth Substrate and Nutrient Salt Environment Alter Mannitol-to-Hexose Partitioning in Celery Petioles
Authors: Stoop Johan M.H. , Pharr David M.
Published: January 2019

The fleshy parenchyma tissue of celery [Apium graveolens L. var. dulce (Mill.) Pers.] petioles is the major storage tissue for the sugar alcohol mannitol and for the hexoses, glucose and fructose. In this study, we found that plants grown in the soilless mixture, Promix, fertilized weekly with a nutrient solution, or grown in a hydroponic container culture, differed in carbohydrate composition. However, plant growth was not affected. Higher mannitol and lower hexose concentrations were present in petioles from plants grown hydroponically. This was true in petioles that did not differ in total soluble carbohydrate concentration. The ratio of mannitol to hexose concentration in petioles was ≈2-fold higher for hydroponically grown plants compared to Promix-grown plants, and the higher ratio was maintained during the entire 12-week experimental period. Carbohydrate partitioning was also affected by petiole development within the plant. Sucrose and hexose concentrations were highest in mature petioles, whereas mannitol was relatively high in all petioles except the oldest ones. Because the mineral solution applied to the Promix-grown plants had a lower total salt concentration compared to hydroponically grown plants, we postulated that the salt concentration of the mineral solution might be an important factor affecting C partitioning in celery petioles. When plants were grown hydroponically at two different salt concentrations [electrical conductivity (EC) = 2.7 and 6.0 mS·cm-1], high mannitol-to-hexose ratios were observed in celery petioles of plants grown at high salt concentration (EC = 6.0 mS·cm-1), a result supporting the hypothesis that the salt environment might alter mannitol and hexose concentrations in a coordinated way. These data are consistent with the hypothesis that elevated mannitol levels may be a significant component of plant adjustment to salt stress, possibly adding osmotic adjustment and preventing inactivation of metabolic processes.
Inhibition of Ethylene Biosynthesis and Action in Cut Carnations (Dianthus caryophyllus L.) by Aminotriazole
Authors: Altman Steven A. , Solomos Theophanes
Published: January 2019

Treating `Elliott's White' cut carnations with 50 or 100 mm aminotriazole for 4 days inhibits the respiratory climacteric and significantly extends vase life. Aminotriazole induced time- and concentration-dependent inhibition of ethylene evolution and onset of the ethylene climacteric by inhibiting ACC synthase activity. Flowers treated with 50 or 100 mm aminotriazole for 2 days exhibited concentration-dependent increases in ethylene evolution, respiratory activity, ACC synthase activity, and petal ACC content in response to the application of exogenous ethylene at 10 μl·liter-1. Senescence-associated morphological changes, increased ACC synthase activity, ACC content, and ethylene evolution were completely inhibited in flowers treated for 4 days with 100 mm aminotriazole. Although treatment with 50 mm aminotriazole for 4 days did not completely inhibit components of the ethylene biosynthetic pathway, no morphological or respiratory responses to the application of exogenous ethylene at 10 μl·liter-1 were observed, a result indicating that prolonged aminotriazole treatment inhibited ethylene action. Chemical names used: 3-1H-amino-1,2,4-triazole-1-yl (aminotriazole), 1-aminocyclopropane-1-carboxylic acid (ACC).
Physiological Mechanisms of Drought Resistance in Four Native Ornamental Perennials
Authors: Chapman Douglas S. , Augé Robert M.
Published: January 2019

Understanding physiological drought resistance mechanisms in ornamentals may help growers and landscapers minimize plant water stress after wholesale production. We characterized the drought resistance of four potted, native, ornamental perennials: purple coneflower [Echinacea purpurea (L.) Moench], orange coneflower [Rudbeckia fulgida var. Sullivantii (Beadle & Boynt.) Cronq.], beebalm (Monarda didyma L.), and swamp sunflower (Helianthus angustifolius L.). We measured a) stomatal conductance of leaves of drying plants, b) lethal water potential and relative water content, and c) leaf osmotic adjustment during the lethal drying period. Maintenance of stomatal opening as leaves dry, low lethal water status values, and ability to osmotically adjust indicate relative drought tolerance, with the reverse indicating drought avoidance. Echinacea purpurea had low leaf water potential (ψL) and relative water content (RWC) at stomatal closure and low lethal ψL and RWC, results indicating high dehydration tolerance, relative to the other three species. Rudbeckia fulgida var. Sullivantii had a similar low ψL at stomatal closure and low lethal ψL and displayed relatively large osmotic adjustment. Monarda didyma had the highest ψL and RWC at stomatal closure and an intermediate lethal ψL, yet displayed a relatively large osmotic adjustment. Helianthus angustifolius became desiccated more rapidly than the other species, despite having a high ψL at stomatal closure; it had a high lethal ψL and displayed very little osmotic adjustment, results indicating relatively low dehydration tolerance. Despite differences in stomatal sensitivity, dehydration tolerance, and osmotic adjustment, all four perennials fall predominantly in the drought-avoidance category, relative to the dehydration tolerance previously reported for a wide range of plant species.
Genetic Transformation of Peach Tissues by Particle Bombardment
Authors: Ye Xiaojian , Brown Susan K. , Scorza Ralph , Cordts John , Sanford John C.
Published: January 2019

Physical and biological parameters affecting the efficiency of biolistic transformation of peach were optimized using ß-glucuronidase (GUS) as a reporter gene, such that efficiency of transient GUS expression in peach embryo-derived callus was increased markedly. Transient expression was also obtained in embryonic axes, immature embryos, cotyledons, shoot tips, and leaves of peach. Stable expression of a fusion gene combining neomycin phosphotransferase (NPTII) and ß-glucuronidase activities has been achieved in peach embryo calli. Sixty-five kanamycin-resistant callus lines were obtained from 114 pieces of bombarded calli after 4 months of selection. Nineteen of the 65 putative transformant lines produced shoot-like structures. Seven lines were examined to confirm stable transformation using the colorimetric GUS assay and PCR analysis. All seven lines showed GUS activity. PCR analysis confirmed that, in most of the putative transformants, the chimeric GUS/NPTII gene had been incorporated into the peach genome. The transgenic callus lines were very weakly morphogenic, presumably because the callus was 5 years old and no transgenic shoots developed from this callus. Results of this research demonstrate the feasibility of obtaining stable transgenic peach tissue by biolistic transformation.
Water Use, Growth, and Fruit Yield of `Hosui' Asian Pears under Deficit Irrigation
Authors: Caspari Horst W. , Behboudian M. Hossein , Chalmers David J.
Published: January 2019

Five-year old `Hosui' Asian pear (Pyrus serotina Rehder) trees growing in drainage lysimeters and trained onto a Tatura trellis were subjected to three different irrigation regimes. Weekly water use (WU) was calculated using the mass-balance approach. Soil-water content of control lysimeters was kept at pot capacity, while deficit irrigation was applied before [regulated deficit irrigation (RDI)] and during the period of rapid fruit growth [late deficit irrigation (LDI)]. Soil-water content was maintained at ≈50% and 75% of pot capacity for RDI and LDI, respectively. Deficit irrigation reduced mean WU during RDI and LDI by 20%. The reduced WU was caused by lower stomatal conductance (gs) on deficit-irrigated trees. RDI trees had more-negative diurnal leaf water potentials (ψl). The ψl, gs, and WU remained lower for 2 weeks after RDI was discontinued. RDI reduced shoot extension and summer pruning weights, whereas winter pruning weights were not different between treatments. Except for the final week of RDI, fruit growth was not reduced, and fruit from RDI grew faster than the control during the first week after RDI. In contrast, fruit volume measurements showed that fruit growth was clearly inhibited by LDI. Final fruit size and yield, however, were not different between treatments. Return bloom was reduced by RDI but was not affected by LDI.
Impact of Forcing Summer Asparagus in Coastal South Carolina on Yield, Quality, and Recovery from Harvest Pressure
Authors: Dufault Robert J.
Published: January 2019

The objective of this study was to determine the effect of forcing summer asparagus (May to October) and age at first harvest after transplanting on yield and quality. Ten-week-old `UC 157 F1' asparagus seedlings were field-planted on Sept. 1986 and forced to emerge from 1988 to 1992 by mowing fern in separate replicated plots in May, June, July, August, September, or October. Forcing treatments were not spring-harvested. Forced yields were compared to normal spring harvests (emerging from January to April). Harvesting began for the first time ≈18 or 30 months after transplanting. Spring 1988 yields were greatest of all, but declined yearly for 5 years. Summer forcing in either July or August maintained acceptable yields through 1992. The warmer climate during summer forcing caused most plants to reach the prescribed cutting pressure (eight spears per plant) within a standard 6-week harvest season. Cooler temperatures during spring harvest seasons slowed spear emergence and prevented the plants from reaching prescribed cutting pressure. Forcing in May and June was too stressful to plant recovery after the harvest season by reducing fern regrowth and increasing plant death. Cooler temperatures during October forcing inhibited spear emergence. Forcing in September yielded less than forcing in July and August, but September asparagus would command higher market prices. There was no advantage at any harvest time to delay first harvests from 18 to 30 months after transplanting. Forcing in July through September has potential as an alternative enterprise in coastal South Carolina.
Rootstock and Training System Affect Dry-matter and Carbohydrate Distribution in `Golden Delicious' Apple Trees
Authors: Stutte Gary W. , Baugher Tara A. , Walter Sandra P. , Leach David W. , Glenn D. Michael , Tworkoski Thomas J.
Published: January 2019

A study was conducted to quantify the effects of rootstock and training system on C allocation in apple. Dry-matter distribution was determined at harvest in 5-year-old `Golden Delicious' apple (Malus domestica Borkh.) trees on four rootstocks (MM.111 EMLA, M.7a, M.26 EMLA, and M.9 EMLA) and in three training systems (three-wire palmette, free-standing central leader, and nonpruned). Mobilizable carbohydrate content was determined at harvest and leaf fall in trees from the same planting on MM.111 EMLA and M.9 EMLA in all three training systems. Training system effects interacted with rootstock effects in dry weights of branches and of fruit. Nonpruned system shoot and fruit dry weights reflected known rootstock vigor; whereas, pruned system (three-wire and central leader) shoot dry weights were greatest and fruit dry weights were lowest in trees on M.7a. Rootstock affected the partitioning of dry matter between above- and below-ground tree components, with MM.111 EMLA accumulating significantly more dry matter in the root system than trees on the other rootstocks. Trees in the central leader and the three-wire palmette systems partitioned more dry weight into nonbearing 1-year shoots than trees in the nonpruned system. Root starch content at harvest was greater in trees on MM.111 EMLA than on M.9 EMLA, and root sucrose and sorbitol were less in trees on MM.111 EMLA compared to M.9 EMLA. At leaf fall, starch in young roots was equal in trees on both rootstocks, and sorbitol again was lower in trees on MM.111 EMLA. Harvest starch content of roots, shoots, and branches was lower in nonpruned than in pruned trees. At leaf fall, root, shoot, and branch starch content increased in nonpruned and central leader-trained trees but did not increase in three-wire palmette-trained trees.
High Pollen Loads Can Cause Pistillate Flower Abscission in Walnut
Authors: McGranahan Gale H. , Voyiatzis Demetrios G. , Catlin Peter B. , Polito Vito S.
Published: January 2019

The role of pollen in abscission of pistillate flowers of Persian walnut (Juglans regia L.) cv. Serr was investigated over a 4-year period by controlled pollinations and pollen counts. Self-pollen, pollen from other walnut selections or cultivars, or dead pollen was applied at high and low doses to pistillate flowers enclosed in pollination bags. Unbagged, open-pollinated flowers and bagged, nonpollinated flowers served as controls. In all cases, presence of pollen significantly increased the probability of pistillate flower abscission (PFA). Dead pollen resulted in as much PFA as live pollen. Counts of pollen grains confirmed that PFA-type flowers had significantly more pollen than normal flowers. In the fourth year `Serr' pollen was applied to unbagged flowers of `Serr' and ten other Persian walnut cultivars, and the amount of PFA on the artificially pollinated flowers was significantly higher than on the open-pollinated flowers, while the control flowers dusted with talc or pine pollen had almost no PFA. These results clearly indicate that excess pollen is involved in pistillate flower abscission in `Serr' walnut and suggests that other cultivars may also be sensitive to pollen load. This phenomenon may have implications in the biology of selfing and evolution.
Effects of Brief Anaerobic Exposures on Carbon Dioxide Production and Quality of Harvested Asparagus
Authors: Torres-Penaranda Ana Victoria , Saltveit Mikal E.
Published: January 2019

Freshly harvested asparagus (Asparagus officinalis L.) spears were exposed to an anaerobic N2 atmosphere for 0, 2, 4, or 6 hours at 2.5 or 20C and then returned to 2.5C. Carbon dioxide production was measured each day, starting 3 days before and ending 11 days after the treatment. Significant increases in CO2 production relative to 0-hour controls were found within 1 day of treatment at 20C and were directly proportional to the duration of the anaerobic exposure. At 2.5C, CO2 production relative to the 0-hour control was stimulated by the 2- and 4-hour treatments and depressed by the 6-hour treatment, with the relative rate of production inversely proportional to the duration of the anaerobic treatment. A decrease in CO2 production occurred 7 days after N2 treatment, regardless of temperature. A sensory panel evaluated effects of treatments on appearance quality 7 and 15 days after treatment and on taste quality 4 days after treatment. Judges could not detect any significant differences between anaerobic treatments and control. No significant difference was found in the percent of decayed asparagus among treatments as detected by visual evaluation 6 days after treatment. It appears that exposure to an anaerobic N2 atmosphere for up to 6 hours was not detrimental to the storability or quality of harvested asparagus spears. These results indicate that cooling with vaporized liquid N2, during which an anaerobic atmosphere could be produced before the spears were significantly cooled, would not reduce subsequent quality or storability.
Effect of Ozone and Storage Temperature on Postharvest Diseases and Physiology of Carrots (Daucus carota L.)
Authors: Liew Chiam L. , Prange Robert K.
Published: January 2019

Effects of ozone and storage temperature on carrots and two postharvest pathogens—Botrytis cinerea Pers. and Sclerotinia sclerotiorum de Bary—were investigated. Pathogen-inoculated and uninoculated whole carrots were exposed to an ozone concentration of 0 (control), 7.5, 15, 30, or 60 μl·liter-1. Treatment chambers were flushed with a total flow rate of 0.5 liters·min-1 (air and ozone) for 8 h daily for 28 days. The experiment was repeated twice at storage temperatures of 2, 8, and 16C. The residual ozone concentration (ozone supplied-exhausted and reacted ozone) increased with ozone supply concentration but was less at higher storage temperatures. A 50% reduction of daily growth rates of both fungi at the highest ozone concentration indicated that ozone was fungistatic. Carrot respiration rate, electrolyte leakage, and total color differences increased with ozone concentration. Ozone-treated carrots were lighter (higher L* values) and less intense (lower chroma values) in color than control carrots.
Early Season Patterns of Carbohydrate Partitioning in Exposed and Shaded Apple Branches
Authors: Grappadelli L. Corelli , Lakso A.N. , Flore J.A.
Published: January 2019

The partitioning of photosynthates labeled by 14CO2 in exposed and shaded `Empire' apple (Malus domestica Borkh.) branches was examined at 1, 3, 5, and 10 weeks after bloom. Extension shoots, nonfruiting spurs, or fruiting spurs were labeled separately to examine which shoot types exported to the fruit at each time. The general partitioning patterns were observed with autoradiography, while label accumulation in fruit was determined by oxidation and scintillation counting. At each treatment time, half of the branches was preconditioned with artificial shade (to 35% full light) for 48 hours before labeling and returned to the shade for a 2-day translocation period. One and 3 weeks after bloom, extension shoots showed little export to fruit; nonfruiting and vigorous fruiting spurs exported label to weak spurs and extension shoot tips. Shade had no major effect on partitioning patterns at 1 and 10 weeks, but essentially eliminated export from extension shoots at 3 weeks and greatly reduced export to fruit 5 weeks after bloom, as observed on the autoradiograms. At 5 weeks after bloom, the shading effect was equal to a 2-week delay in export. By 10 weeks after bloom, all shoot types were exporting most of the 14C fixed to fruit. The photosynthate support of the fruit before fruit set seemed to strongly depend on the spur canopy, especially when the extension shoots were exposed to low light.
Growth and Gas Exchange by Lettuce Stands in a Closed, Controlled Environment
Authors: Wheeler R.M. , Mackowiak C.L. , Sager J.C. , Yorio N.C. , Knott W.M. , Berry W.L.
Published: January 2019

Two studies were conducted in which `Waldmann's Green' lettuce (Lactuca sativa L.) was grown hydroponically from seed to harvest in a large (20-m2), atmospherically closed growth chamber for the National Aeronautics and Space Administration's controlled ecological life support system (CELSS) program. The first study used metal-halide (MH) lamps [280 μmol·m-2·s-1 photosynthetic photon flux (PPF)], whereas the second used high-pressure sodium (HPS) lamps (293 μmol·m-2·s-1). Both studies used a 16-hour photoperiod, a constant air temperature (22 to 23C), and 1000 μmol·mol-1 CO2 during the light period. In each study, canopy photosynthesis and evapotranspiration (ET) rates were highly correlated to canopy cover, with absolute rates peaking at harvest (28 days after planting) at 17 μmol CO2/m2 per sec and 4 liters·m-2·day-1, respectively. When normalized for actual canopy cover, photosynthesis and ET rates per unit canopy area decreased with age (between 15 and 28 days after planting). Canopy cover increased earlier during the study with HPS lamps, and final shoot yields averaged 183 g fresh mass (FM)/plant and 8.8 g dry mass (DM)/plant. Shoot yields in the first study with MH lamps averaged 129 g FM/plant and 6.8 g DM/plant. Analysis of leaf tissue showed that ash levels from both studies averaged 22% and K levels ranged from 15% to 17% of tissue DM. Results suggest that lettuce should be easily adaptable to a CELSS with moderate lighting and that plant spacing or transplant schemes are needed to maximize canopy light interception and sustain efficient CO2 removal and water production.
Genotypic Differences in the Length-Diameter Relationship of Branches of One-year-old Peach and Nectarine Trees
Authors: Kervella Jocelyne , Pagès Loïc , Génard Michel
Published: January 2019

Genotypic variations in the length-diameter relationship of branches among peach and nectarine [Prunus persica (L.) Batsch.] cultivars were investigated. The length and basal diameter of all undamaged first-order shoots from 1-year-old trees of 14 cultivars and one accession were measured. Statistical analysis of the allometric relationship between length and basal diameter of shoots provided evidence of genotypic differences for that relationship, although the diameter of very short shoots did not differ between genotypes. A gradient existed from `Armking' with thin shoots (9 mm in diameter for 85.5-cm-long shoots) to `Flavorcrest' with thick shoots (16.4 mm in diameter for 85.5-cm-long shoots). Early selection for shoot thickness should be possible in breeding programs. The likely consequences of observed shoot thickness variations on the mechanical and hydraulic properties of shoots are discussed.
Histology of Somatic Embryogenesis in Regal Geranium
Authors: Wilson D.P.M. , Sullivan J.A. , Marsolais A.A. , Tsujita M.J.
Published: January 2019

The origin and development of somatic embryos from petiole sections of Regal geranium (Pelargonium ×domesticum Bailey `Madame Layal') were studied using time-series sections at days 0, 4, 8, 14, and 24. Somatic embryos originated as early as day 4 of culture. The proembryo stage resembled that of a zygotic embryo and the somatic embryos developed through the globular, heart-torpedo, and cotyledonous stages characteristic of in vivo zygotic embryogenesis. A suspensor-like structure was observed with some somatic embryos but this was not consistent. Strong evidence is presented to suggest that somatic embryos arose from single subepidermal parenchyma cells.
Phosphorus Effects on Olive Leaf Abscission
Authors: Burnik-Tiefengraber Tjasa , Weis Kitren G. , Webster Barbara D. , Martin George C. , Yamada Hisashi
Published: January 2019

When continuously stem-fed with 75 mm NaH2PO4, `Manzanillo' olive explants showed significant leaf abscission after 48 hours; by that time 1.042 mg·g-1 fresh weight P had accumulated in the abscission zone (AZ). The potential contribution of ethylene to phosphate-enhanced abscission was investigated using aminooxyacetic acid (AOA), an ethylene-synthesis inhibitor, and by measuring ethylene evolution in phosphate-treated explants. In combination with NaH2PO4, AOA did not affect leaf abscission. Though ethylene evolution from explants increased as leaf abscission was initiated, it was about two orders of magnitude less than the concentration necessary to induce leaf abscission as judged by exogenous treatments. Based on leaf-abscission kinetics, we have concluded that the mechanism of P-induced abscission is independent of gross measurement of evolved ethylene, but we cannot rule out ethylene confined to the AZ itself. When evaluated for P-induced leaf abscission, leaves of `Manzanillo' and `Sevillano' abscised earlier than `Ascolano' and `Mission'.
Salinity Tolerance Mechanisms of Six C4 Turfgrasses
Authors: Marcum Kenneth B. , Murdoch Charles L.
Published: January 2019

Physiological responses to salinity and relative salt tolerance of six C4 turfgrasses were investigated. Grasses were grown in solution culture containing 1, 100, 200, 300, and 400 mm NaCl. Salinity tolerance was assessed according to reduction in relative shoot growth and turf quality with increased salinity. Manilagrass cv. Matrella (FC13521) (Zoysia matrella (L.) Merr.), seashore paspalum (Hawaii selection) (Paspalum vaginatum Swartz), and St. Augustinegrass (Hawaii selection) (Stenotaphrum secundatum Walt.) were tolerant, shoot growth being reduced 50% at ≈400 mm salinity. Bermudagrass cv. Tifway (Cynodon dactylon × C. transvaalensis Burtt-Davey) was intermediate in tolerance, shoot growth being reduced 50% at ≈270 mm salinity. Japanese lawngrass cv. Korean common (Zoysia japonica Steud) was salt-sensitive, while centipedegrass (common) (Eremochloa ophiuroides (Munro) Hack.) was very salt-sensitive, with total shoot mortality occurring at ≈230 and 170 mm salinity, respectively. Salinity tolerance was associated with exclusion of Na+ and Cl- from shoots, a process aided by leaf salt glands in manilagrass and bermudagrass. Shoot Na+ and Cl- levels were high at low (100 to 200 mm) salinity in centipedegrass and Japanese lawngrass resulting in leaf burn and shoot die-back. Levels of glycinebetaine and proline, proposed cytoplasmic compatible solutes, increased with increased salinity in the shoots of all grasses except centipedegrass, with tissue water levels reaching 107 and 96 mm at 400 mm salinity in bermudagrass and manilagrass, respectively. Glycinebetaine and proline may make a significant contribution to cytoplasmic osmotic adjustment under salinity in all grasses except centipedegrass.
Combining Ability for Seedling Root System Size and Shoot Vigor in Interspecific Blueberry Progenies
Authors: Erb W.A. , Draper A.D. , Swartz H.J.
Published: January 2019

Interspecific blueberry (Vaccinium spp.) progenies were examined to determine combining abilities and genetic variability for seedling root system size and shoot vigor and to establish whether a large root system is correlated with good growth when plants are grown on a mineral soil and exposed to a moderate soil water deficit. General combining ability (GCA) variance components for root system size and shoot vigor and specific combining ability variance components for shoot vigor were significant. US226, a tetraploid hybrid of V. myrtilloides Michaux × V. atrococcum Heller, had the highest GCA effect for root system size and the lowest GCA effect for shoot vigor. US75 (V. darrowi Camp × V. corymbosum L.) had the highest GCA effect for shoot vigor and was second in GCA effect for root system size. Comparison of the crosses containing G111 (V. corymbosum) with those containing G362 (V. corymbosum) indicates that selecting for the best V. corymbosum clone to start a breeding program seems as important as selecting the mineral soil-adapted parent. Root system ratings were highly correlated with total dry weight of field-grown plants (r = 0.89). The method used in this study to evaluate seedlings for root system size and shoot vigor could be used to eliminate the less vigorous plants from a population before field planting and to evaluate mineral soil adaptability.
Performance of North American Strawberry Cultivars under Conditions Mimicking California Production Systems
Authors: Rariden John M. , Shaw Douglas V.
Published: January 2019

Runner plants from 16 strawberry (Fragaria ×ananassa Duch.) cultivars were grown using annual Mediterranean production systems to test for differences in productivity, performance traits, and vegetative growth attributes. Genotypes were included from germplasm adapted to four geographic regions: California and northwestern, northeastern, and mid-Atlantic or southeastern United States. The California genotypes were divided further into day-neutral and June-bearing categories. With these treatments, California cultivars had significantly larger plants and grew more rapidly during the fall and winter, had larger fruit, and produced at least twice the quantity of fruit of cultivars from the other regions. Variance components due to region explained 64% and 26% of the phenotypic variance for early and total yield, respectively, whereas differences among cultivars within regions explained 12% and 7% of the variance for these traits. Cultivars from all regions had significantly larger plants and were more productive when treated with 3 weeks of artificial vernalization. However, region × vernalization effects were nonsignificant for all traits, a result suggesting that selection in Mediterranean environments has not adapted germplasm specifically for low vernalization conditions.
Restriction Fragment Length Polymorphism (RFLP) Analysis of Progeny from an Allium fistulosum × A. cepa Hybrid
Authors: Bark Ockyung H. , Havey Michael J. , Corgan Joe N.
Published: January 2019

Allium fistulosum L. (bunching onion) is resistant to many of the important diseases and pests of Allium cepa L. (bulb onion). Although the first interspecific hybrids were generated more than 50 years ago, there is no conclusive evidence that any desirable trait in bunching onion has been successfully transferred to bulb onion by backcrossing. We identified RFLPs in the chloroplast and nuclear genomes to assess DNA transfer from bunching to bulb onion by backcrossing an interspecific hybrid to a bulb onion. Polymorphisms in the chloroplast genome established that the interspecific hybrid and three putative backcross plants had the cytoplasm of a bunching onion. All 57 random cDNA probes detected polymorphisms between the bulb and bunching onion for at least one of two restriction enzymes. The backcross progenies always possessed the bulb-onion fragments and an excess of probes detected the bunching-onion fragments. Only one plant showed an acceptable fit to the expected 1:1 backcross ratio. Significant deviations from expected segregation ratios may be the result of abnormal meiosis in the interspecific hybrid. However, these observations could also be explained by a previously proposed nuclear-cytoplasmic interaction conditioning preferential survival in the bunching-onion cytoplasm of eggs carrying bunching-onion chromosomes.
Influence of Light Level on Performance of the Colorado Potato Beetle on Solanum tuberosum L. and on Resistance Expression in S. berthaultii Hawkes
Authors: França Félix H. , Tingey Ward M.
Published: January 2019

The influence of light level on the expression of resistance in Solanum berthaultii Hawkes (accessions PI 473331 and PI 473334) to the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), was studied by exposing plants to two levels of photosynthetically active radiation: 272 ± 37 μE/m2 per sec and 1025 ± 150 μE/m2 per sec. Over 26 days, shading generally reduced densities of type A and B glandular trichomes, volume of trichome exudate, and phenolic oxidation activity of type A trichomes. In both light regimes, larvae reared on S. tuberosum L. were heavier, developed more rapidly, and had greater survival than those reared on S. berthaultii. Similarly, females reared on S. tuberosum were heavier and produced 10- to 20-fold more egg masses and 68 to 472 times more eggs than those reared on S. berthaultii grown at the same light level. Light level did not affect larval weight, developmental time, survival, adult weight, or fecundity of CPB on either host plant species.
Using Ground Kenaf Stem Core as a Major Component of Container Media
Authors: Wang Yin-Tung
Published: January 2019

Results of a series of experiments showed that the ground, noncomposted woody stem core of kenaf (Hibiscus cannabinus L.) can be used successfully as a container medium amendment for producing potted tropical foliage and woody nursery crops. The growth of Brassaia actinophylla Endl., Hibiscus rosa-sinensis L. `Jane Cowl', and Pittosporum tobira (Thunb.) Ait. `Wheeler's Dwarf' in 70% or 80% kenaf (by volume, the balance being peatmoss or perlite or vermiculite and other nutrients) was similar to or greater than growth in two popular commercial mixes. Undesirable shrinkage of certain kenaf-amended media during plant production was reduced greatly by mixing it with at least 30% peatmoss or by using a coarser kenaf grind. As the portion of peatmoss increased from 0% to 30%, noncapillary porosity and water-holding capacity per container increased. A medium consisting of 50% kenaf, 40% peatmoss, and 10% vermiculite held as much water as a commercial medium. However, plants in most kenaf-amended media required more-frequent irrigation than those in the commercial media.
Dry Weight Partitioning in Three Phenotypes of Red Raspberry
Authors: Popenoe Juanita
Published: January 2019

`Heritage', `Titan', and `Boyne' red raspberries (Rubus idaeus L.) were grown for 3 years and plots were sampled annually for changes in growth. `Heritage' is a primocane- and floricane-fruiting, strongly suckering cultivar; `Boyne' is a floricane-fruiting, strongly suckering cultivar; and `Titan' is a floricane-fruiting, weakly suckering cultivar. Each year in October, plants of each cultivar were dug from two 0.5-m2 plots in each of four rows, separated into roots, crowns, canes (primocanes were harvested in October and floricanes were harvested in July), and leaves, and dried. Fruit were harvested, yields were recorded, and dry weights of subsamples were used to estimate total fruit dry weights. `Heritage' fruit included the primocane and floricane harvests. `Heritage' was more yield-efficient than `Boyne' or `Titan' in that it allocated a higher percentage of total dry weight to fruit and a lower percentage to vegetative parts. Although `Titan' had fewer canes, cane diameter and length were greater. `Boyne' allocated higher percentages of total dry weight to roots than other cultivars. The percentage of total dry weight allocated to fruit was similar for `Boyne' and `Titan' in 1992, but lower for `Boyne' in 1991. Within the cultivars tested, phenotype for suckering did not indicate productivity.
Response of Cucumber (Cucumis sativus L.) and Squash (Cucurbita pepo L. var. melopepo) Roots to Chilling Stress during Early Stages of Seedling Development
Authors: Reyes Eleazar , Jennings Paul H.
Published: January 2019

Roots of `Golden Girl' squash (Cucurbita pepo var. melopepo) and `Encore' cucumber (Cucumis sativus L.), 4- and 3-days-old, respectively, were exposed to 2, 6, 10, and 15C for 24, 48, 96, 144, and 192 hours to compare the sensitivity to chilling temperatures and the subsequent recovery at more favorable temperatures. Seedlings were more sensitive to chilling at 2 and 6C when measured by their ability to resume growth when returned to 26C. Root growth decreased after 48 hours of chilling. Seedlings stressed at 10 and 15C were able to continue root growth at these temperatures and when returned to 26C. However, seedlings at 10C exhibited root-tip browning in both crop species, suggesting disfunction in metabolic pathways that were repressed in seedlings growing at 2C where those symptoms were not present. Effects on root dry weight occurred in the first 24 hours at all temperatures studied. After 96 hours of treatment, seedlings grown at 2 and 6C were irreversibly damaged, as evidenced by their inability to resume growth when returned to 26C. Leakage of electrolytes from squash and cucumber roots increased after 48 hours at 2C. Potassium, Na+, and PO4-2 were lost in greater amounts than Mg+2, Cl-, and SO4-2. No difference in ionic leakage occurred at 10 and 15C, and Ca+2 leakage was not detected at any chilling stress temperature.
Periodicity of Inflorescence Initiation and Development in Nerine bowdenii W. Watson (Amaryllidaceae)
Authors: Theron K.I. , Jacobs G.
Published: January 2019

Nerine bowdenii bulbs were sampled from a commercial planting and dissected at 2-week intervals from 9 Oct. 1990 to 12 Nov. 1991. The following variables were recorded: number of florets per inflorescence, differentiation stage of the oldest floret, exterior dimensions of the inflorescence, and the number of leaf primordia between the two innermost inflorescences and between the innermost inflorescence and the vegetative apex. Scanning electron micrographs were made of the inflorescences at different stages of development. The development of the inflorescences of the growth units appeared to be synchronized. When the florets of the outermost inflorescence reached stage Late G (gynoecium elongated, carpels fused), the spathe started to elongate. When florets in the second inflorescence reached stage Mid G (three carpels elongated, not fused), the innermost inflorescence was initiated. Inflorescence development passed through three phases: 1) a floret initiation phase of ≈1 year, when nine to ten florets were initiated, 2) a differentiation phase, also ≈1 year long, when individual florets developed up to stage Late G, and 3) an inflorescence enlargement phase, which lasted ≈4 months and culminated in anthesis. Leaf primordia were initiated at the same rate as florets (one per month) and the vegetative phase for a growth unit was completed within 1 year.
Effects of Soil Moisture, Cultivar, and Postharvest Handling on Pillowy Fruit Disorder in Cucumber
Authors: Navazio John P. , Staub Jack E.
Published: January 2019

Two experiments (1989 and 1990) were designed to characterize the response of cucumber (Cucumis sativus L.) plants with different leaf types [normal leaf (LL) vs. little leaf (ll)] to high soil moisture tension (SMT) and to determine whether hydrocooling would reduce the severity of pillowy fruit disorder (PFD). Comparisons were made among nine cultivars (7 LL and 2 ll) for aboveground vegetative and fruit response, and between two irrigation regimes. High SMT generally caused increased wilt ratings and stomatal conductance and decreased plant dry weight. PFD severity of fruit from watered plots was less [61% (Expt. 1, 1989) and 26% (Expt. 1, 1990)] than of fruit harvested from plots in which water was withheld. The response of the two ll cultivars to moisture stress differed depending on environmental conditions. Increased PFD severity was associated with increased temperature, lower relative humidity (RH), and excluding hydrocooling during postharvest handling. Of the four storage treatments examined, hydrocooling to ≈8.5C then storage at 15C and 85% RH for 4 days produced fruit with the least PFD symptoms. Fruit of `Carolina' (LL) exhibited the highest PFD ratings, while those of `Calypso' (LL) were consistently low compared to other cultivars. Processors can lower PFD incidence and severity by ensuring that adequate moisture is available to plants during fruit enlargement and that harvested fruit are hydrocooled before shipping and storage.
Subcellular Localization of a Basic Peroxidase Isoenzyme in Crisphead Lettuce
Authors: Tena M. Gómez , Pedreño M.A. , Barceló A. Ros , Ferrer M.A.
Published: January 2019

The subcellular localization of a basic peroxidase (EC 1.11.1.7) isoenzyme in crisphead lettuce (Lactuca sativa L.) leaves was studied through subcellular fractionation and protoplast and vacuole isolation. This isoenzyme is mainly located in soluble fractions. Studies using protoplast isolation and vacuole purification indicated that the soluble basic peroxidase isoenzyme is found in the vacuolar sap, probably in equilibrium with the same isoenzyme attached to tonoplast membranes.
Inheritance of Soluble Solids and Pyruvic Acid Content of Bulb Onions
Authors: Lin Mau-Wei , Watson James F. , Baggett James R.
Published: January 2019

Analysis of parents and progeny generations of bulb onion (Allium cepa L.) crosses among parents with differing content of soluble solids (SS) and pyruvic acid (PA) showed that SS and PA are expressed and inherited in a quantitative manner. Distribution of SS and PA in both parents and progenies covered a range of values. Generation means, frequency distributions, deviation from midparent value, and estimates of gene effects all indicated that inheritance of SS and PA was additive, except for small deviations from the additive hypothesis in several individual backcrosses. Estimates of broad-sense heritability ranged from 48% to 53% for PA and 8 % to 56 % for SS. Phenotypic correlations between PA and SS estimated from the F2 generations of two crosses, were moderate and positive (r = 0.50 and 0.42).
Field Emergence of shrunken-2 Corn Predicted by Single- and Multiple-vigor Laboratory Tests
Authors: Parera Carlos A. , Cantliffe Daniel J. , Stoffella Peter J. , Scully Brian T.
Published: January 2019

Poor emergence and seedling vigor are common characteristics of many sweet corn (Zea mays L.) cultivars with the shrunken-2 (sh2) mutant endosperm. A rapid and reliable predictor of sweet corn seed field emergence would improve the potential for high quality crops. Field emergence of seven sh2 sweet corn cultivars grown at seven environments in Florida were correlated with laboratory vigor tests. Factor analysis was used to separate noncollinear vigor tests for subsequent multiple regression models. The best single predictor test (R2 = 0.93***) was an index based on leachate conductivity and germination percentage after a complex stress vigor test involving incubation at 15C. Leachate conductivity after 3 h soaking at 25 or 30C (R2 = 0.9W***), soil cold test (R2 = 0.9***), alternate temperature stress conductivity test (R2 = 0.88***), standard germination test at 30C (R2 = 0.88***), and an index involving incubation at 25C (R2 = 0.88***) were also good predictors of field emergence. Noncollinear tests including the towel germination test at 25 C and an alternate temperature stress conductivity test resulted in the best two factor predictor (r2 = 0.89***), and with glutamic acid decarboxylase activity (GADA) was the best three factor predictor (r2 = 0.93***). The index of conductivity and complex vigor test (ICS) evaluated seed membrane integrity and potential for pathogen infection, respectively, and can be considered as major factors affecting emergence in sh2 sweet corn.
Harvest Pressures Affect Forced Summer Asparagus Yield in Coastal South Carolina
Authors: Dufault Robert J.
Published: January 2019

The purpose of this study was to investigate the effect of different cutting pressures (CP) of 3,6,9, or 12 spears per plant on `UC 157 F1' asparagus yield harvested in spring or forced in July or August. Ten-week-old seedlings were field planted in March, 1987 and forced to emerge from 1989 to 1993 by mowing fern in separate replicated plots in July or August. Forcing treatments were not spring-harvested. Harvesting was terminated if 1) 30 harvests had occurred or 2) 80% of all plants reached cutting pressure treatment levels before 30 harvests occurred. Forced yields were compared to normal spring harvests. Normal emergence time is from January to March. CP treatments affected yield more than harvest time (HT) during the first three harvest years, but, thereafter, HT treatments affected yield more than CP. The most productive HT/CP treatment combinations varied by harvest year as follows: 1989—spring at 9 to 12 spears per plant, July at 12 spears per plant, and August at 9 spears per plant; 1990—forcing in July or August at 12 spears per plant; 1991—forcing in July at 9 to 12 spears per plant; 1992—forcing in July or August at 9 to 12 spears; and 1993—forcing in August at 9 to 12 spears per plant. Total cumulative yields over the 5 year period were highest with forcing in July at 12 spears per plant and August at 9 spears per plant. The productive lifespan of spring-harvested `UC 157 F1' was only three years because of greater stand loss compared to summer forcing.
Nutritional Status in Apples and June Drop
Authors: Abruzzese Alessandro , Mignani Ilaria , Cocucci Sergio M.
Published: January 2019

Apple (Malus domestica Borkh.) trees are often affected by a severe June fruit drop, which is often correlated with competition phenomena involving fruit nutrition. This research was initiated to determine if June drop in `Gloster'/M.9 apple could be correlated with a diminished nutrient availability in developing seeds and fruit. During the test period [30 to 62 days after full bloom (AFB)], the fruit that abscised had a diameter similar to that reached by persisting fruit 13 days earlier. Biochemical parameters related to nutritional status of fruit were measured when an abscission peak occurred 38 days AFB. Persisting fruit (control) and abscised fruit were compared along with fruit that abscise 13 days later. The cortex tissue obtained from the two kinds of abscised fruit showed a higher level of soluble reducing sugars and sucrose and a lower content of K+, acid hydrolyzable polysaccharides, and protein compared to the control. Further, the Ca2+ content was higher in abscised fruit than in controls of the same age, whereas there was no difference when fruit of the same size were compared. Total amino acid level was similar in control and abscised fruit at the same age, but there was a lower amino acid level in abscised fruit of the same size. Histological analysis of cortex tissue indicated that abscised fruit have larger cells with less evident nuclei and thinner cell walls than controls. Compared to control fruit, abscised fruit showed the same average number of seeds and a severe inhibition of seed growth; seeds from both kinds of abscised fruit had the same or higher levels of the parameters measured. No positive correlations were observed between fruit abscission and nutrient content of seeds or fruit.
Postharvest Stimulation of Skin Color in Royal Gala Apple
Authors: Dong Yi hu , Mitra Deepali , Kootstra Arend , Lister Carolyn , Lancaster Jane
Published: January 2019

The red color of Royal Gala apple (Malus domestics Borkh.) skin increased in intensity following irradiation with ultraviolet (UV) and white light. The enhanced red apple color was due to an increase in anthocyanin concentration and the increase was dose dependent. High-performance liquid chromatography analysis showed that the composition of flavonoids in UV treated and natural red colored apple skins was similar. The red apple skin color further increased after storage at 4C in the dark. During the course of irradiation the enzymatic activities of phenylalanine ammonia lyase (PAL) and chalcone isomerase (CHI) increased 10-to 20-fold. Northern analysis showed an increase in PAL transcripts during the irradiation treatment, suggesting that the increase in PAL enzymatic activity was due to de novo synthesis of the enzyme in apple skin cells.
Changes in Water Status of Peach Flower Buds During Endodormancy and Ecodormancy Measured by Differential Scanning Calorimetry and Nuclear Magnetic Resonance Spectroscopy
Authors: Sugiura Toshihiko , Yoshida Mitsura , Magoshi Jun , Ono Sukeyuki
Published: January 2019

Physiological changes in `Hakuho' peach [Prunus persica (L.) Hatsch] flower buds during endodormancy and ecodormancy were investigated based on their water status measured by differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR) spectroscopy. The developmental stage in ecodormancy, which was estimated as the number of days between the sampling date for shoots and the bloom date after forcing, was dominated by absorption of water and was closely related to the water content per dry weight. Two types of water differing in spin-lattice relaxation time (T1) of protons were detected in the flower buds. Water with the shorter T1 was considered to be freezing water as well as that with a longer T1. Nonfreezing water can not be detected by NMR. The change in the longer T1 coincided with the change in the water percentage relative to bud fresh weight and reflected the physiological development in ecodormancy. The shorter T1 value started to increase shortly before rest break and may have some relation with the physiological change at rest break.