bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoperiod, Carbon Partitioning, and Reproductive Development in Rabbiteye Blueberry
Authors: Darnell Rebecca L.
Published: January 2019

Containerized `Climax' and `Beckyblue' rabbiteye blueberry plants (Vaccinium ashei Reade) were exposed to 5 weeks of natural daylengths or shortened daylengths starting 30 Sept. `Beckyblue' plants exposed to short daylengths in the fall initiated more flower buds and had a shorter, more concentrated bloom period than did plants exposed to natural fall daylengths. Reproductive development of `Climax' was not influenced by photoperiod treatments. Leaf carbon assimilation of both cultivars increased under short days. Partitioning of translocated 14C-labeled assimilates to stem tissue increased under short photoperiods for `Beckyblue'; however, partitioning patterns in `Climax' were not affected. Increased carbon fixation and increased partitioning of carbon to stem tissue under short days may contribute to the observed effect of short days on enhancing reproductive development in `Beckyblue'.
Differences in Number and Area of Mesocarp Cells between Small- and Large-fruited Peach Cultivars
Authors: Scorzal Ralph , May Lisa G. , Purnell Beverly , Upchurch Bruce
Published: January 2019

The growth in diameter of large-(`Loring' and `Suncrest') and small-fruited (`Bailey' and `Boone County') peaches [Prunus persica (L.) Batsch] was recorded at weekly intervals from 175 days prebloom to ripening. Samples collected at three dates prebloom, full bloom (FB), and four dates postbloom, including ripe fruit, were sectioned and stained. Total cell count and mean cell size were determined for prebloom ovaries and postbloom mesocarp tissue. Large-fruited cultivars had significantly more cells (up to 3.7 times) than small-fruited cultivars at all sampling dates. Cell sizes increased dramatically with fruit development, but were similar for all cultivars within each sampling date. These results suggest that mesocarp cell count is the major difference between small- and large-fruited peach cultivars and that this difference is determined early in the growth of the ovary.
Influence of Irradiance on Leaf Physiology and Plant Growth Characteristics of Rhododendron × `Pink Ruffles'
Authors: Andersen P.C. , Norcini J.G. , Knox G.W.
Published: January 2019

Leaf physiology and plant growth of Rhododendron × `Pink Ruffles' were compared under conditions of 100% sun and under polyethylene shadecloth with specifications of 69%, 47%, and 29% light transmittance. Net CO2 assimilation (A) and stomatal conductance to water vapor (gs) were often reduced for plants in the 100% sun regime, although few differences existed among the 69%, 47%, and 29% sun treatments. Stomatal conductance was very sensitive to leaf to air vapor pressure deficits (VPD), as evidenced by an 85% increase in gs with a decrease in VPD from 3.2 to 2.2 kPa. Light response curves established for plants after 54 days of exposure to 100% and 29% sun were similar, although A was consistently higher at all levels of photosynthetic photon flux for plants in the 29% sun regime. Maximum A was ≈5 and 6 μmol·m-2·s-1 for 100% and 29% sun-grown plants, respectively; light saturation occurred at ≈ 800 μmol·m-2·s-1 Midday relative leaf water content and leaf water potential were not affected by sun regime. The plant growth index decreased with increasing light level. Leaf, stem, and root dry weights; total leaf number and dry weight; total and individual leaf area; dry weight per leaf; and leaf chlorophyll concentration were reduced in 100% sun, yet few differences existed among the 69%, 47%, and 29% sun treatments. Shoot: root ratio and specific leaf weight were proportional to light level. Plants grown in the 100% sun regime were chlorotic and dwarfed, and plants in 29% sun were not sufficiently compact. One year after transplanting to the field under 100% sun, plants of all treatments were chlorotic and failed to grow.
Variability in Sugars, Acids, Firmness, and Color Characteristics of 12 Peach Genotypes
Authors: Byrne David H. , Nikolic Aleksander N. , Burns Edward E.
Published: January 2019

A wide range of color, sugar, and acid composition was found among 12 peach [Prunuspersica (L.) Batsch] genotypes. Among the high-acid genotypes, a trend of increasing Hunter `a' values, fructose, soluble solids concentration (SSC): titratable acidity (TA) ratio, and decreasing TA and citric acid levels was noted with decreasing mesocarp firmness. Mesocarp firmness was correlated with both skin and flesh `a' values within all genotypes. Among genotypes, the Hunter `a'/firmness relationship varied. `Elberta', a cultivar known to retain a greenish ground color, had a lower Hunter `a' value when soft than did more recent releases such as `Dixiland', `Redhaven', and `Suwanee'. `Sam Houston', a low-acid cultivar, had lower TA and malic, citric, and quinic acid levels than the other cultivars. The dominant acid for all genotypes was malic (50% to 60% of total) with about equal amounts of citric and quinic. Soluble sugars included sucrose (54% of total), fructose (31%), and glucose (15%). `Sam Houston' had lower SSC, a higher percentage of sucrose, lower levels of glucose and fructose, but the same relative sweetness values as the high-acid cultivars.
Postproduction Carbohydrate Levels in Pot Chrysanthemums
Authors: Trusty Susan E. , Miller William B.
Published: January 2019

Postproduction changes in carbohydrate types and quantities in the leaves, stems, and inflorescences of pot chyrsanthemums [Dendranthema × gramfiflorum (Ramat.) Kitamura `Favor'] placed in interior conditions were investigated. Fructans, sucrose, glucose, and fructose were present in all plant parts. In inflorescences and leaves, an additional unidentified substance was present. All plant parts decreased in dry weight during the postproduction evaluation. This decrease was accompanied by overall reductions in total soluble carbohydrates (TSC) and starch. The appearance of leaves and stems was acceptable throughout the experiment. Leaves lost significant amounts of TSC during the first 4 days postproduction (DPP), due primarily to a 76% decrease in sucrose concentration. After 4 DPP, leaf and stem TSC remained relatively unchanged. In inflorescences, petal expansion continued through 12 DPP. Visible signs of senescence, including loss of turgor, color changes, and inrolling of petal edges were observed at 20 DPP, and by 28 DPP, the plants were determined unacceptable for consumer use. Inflorescences increased in fresh weight, but not dry weight, during petal expansion, then each decreased. Inflorescence TSC fell from 146 mg.g-1 dry weight at O DPP to 11 mg.g-1 at 28 DPP. Reducing sugars accounted for 84% of the inflorescence TSC at 4 DPP, dropping to 48% at 28 DPP. Fructan concentration decreased through 16 DPP and then remained unchanged, while starch levels rose from 25 to 34 mg·g -1 dry weight through 12 DPP, then decreased. Fractans decreased in polymerization during petal expansion. This result suggests an alternate use of fructans and starch as pools of available reserve carbohydrate during petal expansion in chrysanthemum.
Morphological and Physiological Changes during Fruit Growth and Maturation of Seven Melon Cultivars
Authors: Miccolis Vito , Saltveit Mikal E.
Published: January 2019

External color, length, diameter, fresh weight, C02 production, internal C2HA concentration, flesh firmness, soluble solids concentration (SSC), flesh color, and seed cavity diameter were measured during fruit growth and maturation of seven melon cultivars (Cucumis melo L., Inodorus Group, Naud. cv. `Amarelo', `Golden Beauty Casaba', `Honey Dew', `Honey Loupe', `Juan Canary', `Paceco', and `Santa Claus Casaba') of known age. There was no increase in C02 production either during ripening (e.g., loss of firmness and increased SSC) or with increasing C2H4 levels in fruit from any of the seven cultivars. There was a significant decline in respiration only at the second sampling date, which ranged from 14 to 18 days after anthesis. Respiration measured 1 week later was substantially higher and was followed by a general decline. This post 14- to 18-day rise in respiration was not a climacteric since it occurred well in advance of other ripening characteristics, e.g., loss of firmness, increase in SSC, or rise in internal C2H4. The increase in internal C2H4. coincided with or followed attainment of full fruit size, while flesh softening and the rapid rise in SSC preceded the rise in internal C2H4, concentration. Respiration declined from 67 to 18 ml CO2/kg per hour by day 43 in all cultivars, except `Honey Dew' and `Honey Loupe'. Respiration in `Honey Loupe' remained above 23 ml CO2/kg per hour and showed a rise to 32 ml/kg per hour on day 53. Respiration in `Honey Dew' did not fall below 18 ml CO2/kg per hour until day 53. As with internal C2H4 levels, there was no correlation between changes in and any marked change in the other signs of ripening that were measured.
Breeding Tomatoes for Salt Tolerance: Field Evaluation of Lycopersicon Germplasm for Yield and Dry-matter Production
Authors: Saranga Y. , Zamir D. , Marani A. , Rudich J.
Published: January 2019

Salt tolerance of 59 cultigens of tomato (Lycopersicon esculentum Mill.), seven wild Lycopersicon accessions (acc.), and one interspecific hybrid was studied under arid field conditions. Evaluation of salt tolerance was based on relative total dry matter (RD) and relative total yield (RY), calculated as the ratio between performances of salinetreated and control plants. The tomato cultigens were irrigated with water having electrical conductivities (ECi) of 1.5 (control), 5, 10, or 15 dS·m−1. Considerable variation in salt tolerance was found among the cultigens, but at 15 dS·m−1 all showed reduced RD and RY (<0.6). The cultivar M82-1-8 (M82), one accession of L. cheesmanii (Lc), three accessions of L. pennellii (Lpen), three of L. peruvianum (Lper), and an interspecific F1 hybrid (M82 × Lpen acc. LA-716) were examined for RD at three salinity levels, ECi = 1.5, 10, and 20 dS·m−1, in three annual trials. The salt tolerance of Lpen and Lper were higher than those of M82 and Lc; the interspecific F1 was the most tolerant and was usually unaffected by even the highest salinity level. The results of this study indicate the existence of a genetic potential for high salt tolerance in wild Lycopersicon germplasm.
Regeneration of Plants from Peach Embryo Cells Infected with a Shooty Mutant Strain of Agrobacterium
Authors: Smigocki Ann C. , Hammerschlag Freddi A.
Published: January 2019

Immature `Redhaven' peach [Prunus persica (L.) Batsch] embryos were infected with a shooty mutant strain of Agrobacterium tumefaciens, tms328::Tn5, which carries an octopine-type Ti plasmid with a functional cytokinin gene and a mutated auxin gene. Shoots were regenerated from embryo-derived callus that was initiated on MS medium lacking phytohormones. Shoots exhibited increased frequency of branching and were more difficult to root than the noninfected. Transcripts of the tms328::Tn5-cytokinin gene were detected using northern analyses of total plant RNA. Polymerase chain reaction of genomic DNA and cDNA resulted in amplification of DNA fragments specific for the cytokinin gene, as determined by restriction enzyme and Southern analyses. The concentrations of the cytokinins zeatin and zeatin riboside in the leaves of regenerated plants were on the average 51-fold higher than in leaves taken from nontransformed plants. None of the shoots or callus tissues were postive for octopine. The expression of the T-DNA encoded cytokinin gene promotes growth of peach cells in the absence of phytohormones, thus serving as a marker for transformation. In addition, this gene appears to promote morphogenesis without an auxin inductive step.
Tillage Reduces Yield and Crown, Fern, and Bud Growth in a Mature Asparagus Planting
Authors: Wilcox-Lee Darlene , Drost Daniel T.
Published: January 2019

Asparagus officinalis L. cv. Centennial established with transplants in 1983 was maintained with tillage or a no-till (NT) system to evaluate effects of tillage on yield and plant growth in a mature asparagus planting. Metribuzin or metribuzin + napropamide at 1.12 and 1.68 kg a.i./ha, respectively, were used for weed control in both tillage regimes. Marketable yields were assessed for 5 years. In 1989, in addition to yield data, destructive harvests of entire plants were made every 3 weeks from March to November to evaluate the effect of tillage on fern, crown, and bud growth, and carbohydrate status. Yields were reduced by tillage from 12% to 50% from 1985 to 1989. There were no herbicide effects nor was there an effect on yield due to an interaction between herbicides and tillage. All indices of growth measured for NT exceeded those in tilled plots, although seasonal patterns of growth were similar in both. Crown and fern weight, bud cluster, and bud and fern counts were higher by 178%, 175%, 152%, 161%, and 195%, respectively, in NT than in tilled plots. The metribuzin + napropamide combination did not reduce fern fresh weight or yield, but significantly reduced the number of bud clusters, buds, and ferns when compared to metribuzin alone. Chemical names used: 4-amino-(1,1-dimethylethyl)-3-(methylthio)-l (metribuzin); 2,4-triazin-5(4H) -one, N,N-diethyl-2-(naphthalenyloxy)-propanamide (napropamide).
Temperature and Photoperiod Effects on Fuchsia × hybrida Morphology
Authors: Erwin John E. , Heins Royal D. , Moe Roar
Published: January 2019

Fuchsia × hybrids `Dollar Princess' plants were grown under 35 day/night temperature (DT/NT) environments ranging from 10 to 30C over 2 years. Plants were grown under short days (SD) (9-hour 15-minute photoperiod) or long days (LD) (9-hour 15-minute photoperiod plus a 4-hour night interruption) within each environment. The influence of temperature on Fuchsia stem elongation and leaf expansion was best described by the relationship or difference (DIF) between DT and NT (DT - NT) rather than actual DT and NT between 10 and 25C. Both internode length and leaf area increased linearly as DIF increased from - 15 to + 15C with DT and NT between 10 and 25C. Internode length increased 0.129 and 0.071 cm/1C increase in DIF for LD- and SD-grown plants, respectively. Individual leaf area increased 0.52 and 0.40 cm2/1C increase in DIF for LD- and SD-grown plants, respectively. DT or NT above 24C reduced stem elongation and leaf expansion, regardless of DIF. The response of stem elongation and leaf expansion to DIF was greater on a percent basis when plants were grown under SD and LD, respectively. On an absolute basis, both internode length and leaf area were greater on LD-grown plants. Branching increased as average daily temperature decreased from 25 to 12C. Photoperiod did not affect branching.
Effects of Fungicides on Nitrogen Transformations in Soilless Potting Media
Authors: Elliott George C. , Lang Harvey J.
Published: January 2019

Fungicides were applied at label rates to two commercial soilless potting media in which Iris siberica L. crowns had been potted and were subsequently grown under greenhouse conditions. Effects of fungicides on urea hydrolysis were inconsistent and generally insignificant. Ammonium oxidation was inhibited to varying degrees by Truban, Benlate, Banol, and Subdue. In a subsequent experiment, the same fungicides were added to cropped samples of the same media in vitro, followed 12 hours later by a solution containing urea and ammonium. Urea hydrolysis was essentially unaffected by fungicide treatments. Subsequent oxidation of ammonium was inhibited by Truban and Banol only in one medium. Transient accumulation of nitrite was inhibited by Truban but stimulated by Benlate in both media. When added to pure cultures of Nitrosomonas europea and Nitrobacter agilis, Truban completely inhibited oxidation of ammonium and nitrite. Benlate partially inhibited oxidation of ammonium and nitrite, while Subdue and Banal partially inhibited oxidation of ammonium but not nitrite. Chemical names used: [Methyl 1-(butylcarbamoyl)-2-benzimidazolecarbamate] (benomyl); N- (2,6-dimethylphenyl) -N- (methoxyacetyl)alanine methyl ester (metalaxyl); [2-chloro-6-(trichloromethyl)pyridine (nitrapyrin); 5-Ethoxy-3-(trichloromethyl)-1,2,4-thiadiazole (ethazol); Propyl[3-(dimethylamino)propyl]carbamate monohydrochloride (propamocarb).
Root Hairs and Root Lengths in Nine Warm-season Turfgrass Genotypes
Authors: Green R.L. , Beard J.B. , Oprisko M.J.
Published: January 2019

Root hairs contributed variously to total root length, ranging from a low of 1% for `Emerald' zoysiagrass (Zoysia japonica Steud. x Z. tenuifolia Willd. ex Trin) and 5% for `Georgia Common' centipedegrass [Eremochloa ophiuroides (Munro.) Hack], to a high of 95% and 89% for `Texturf 10' and `FB 119' bermudagrasses [Cynodon dactylon (L.) Pers.], respectively. Genotypes ranking highest for root lengths with root hairs also ranked highest for root lengths without root hairs and for number of main roots per plant. In terms of root lengths with root hairs, first-order lateral roots contributed more to total root length than root lengths of either main roots or second-order lateral roots for all nine genotypes. Number and length of root hairs arising from either main or lateral roots were not significantly affected by their relative distance from the cap of the main root. `Texturf 10' and `FB 119' bermudagrasses ranked highest for root and root-hair extent.
Carbon Dioxide Enrichment of High-value Crops under Tunnel Culture
Authors: Hartz T.K. , Baameur A. , Holt D.B.
Published: January 2019

The feasibility of field-scale CO2 enrichment of vegetable crops grown under tunnel culture was studied with cucumber (Cucumis saivus L. cv. Dasher II), summer squash (Cucurbita pepo L. cv. Gold Bar), and tomato (Lycopersicon escukntum Mill. cv. Bingo) grown under polyethylene tunnels. The drip irrigation system was used to uniformly deliver a CO2-enriched air stream independent of irrigation. Carbon dioxide was maintained between 700 and 1000 μl·liter-1 during daylight hours. Enrichment began immediately after crop establishment and continued for ≈4 weeks. At the end of the treatment phase, enrichment had significantly increased plant dry weight in the 2 years of tests. This growth advantage continued through harvest, with enriched cucumber, squash, and tomato plots yielding 30%, 20%, and 32% more fruit, respectively, in 1989. In 1990, cucumber and squash yields were increased 20%, and 16%, respectively. As performed, the expense of CO2 enrichment represented less than a 10% increase in total preharvest costs. A similar test was conducted on fall-planted strawberries (Fragaria × ananassa Duch. cvs. Irvine and Chandler). Carbon dioxide enrichment under tunnel culture modestly increased `Irvine' yields but did not affect `Chandler'.
Sulfur Deficiency Influences Vegetative Growth, Chlorophyll and Element Concentrations, and Amino Acids of Pecan
Authors: Hu Hening , Sparks Darrell , Evans John J.
Published: January 2019

Greenhouse-grown pecan [Carya illinoensis (Wangenh.) C. Koch] seedlings were treated with S as SO4-2 (0 to 4 mm) to determine the effect of S on its vegetative growth, chlorophyll concentration, nutrition, and free and protein amino acid content. Sulfur deficiency symptoms occurred when leaf S was ≈1.5 mg·g-1 dry weight or less. Chlorophyll concentration and growth increased curvilinearly with leaf S and had not peaked when leaf S was 2.7 mg·g-1 dry weight. The N : S ratio in the leaf and leaf S were equally reliable indicators of the S status of the plant, but the optimum ratio was less than the value of 15 found in other plant species. Calcium and Mg decreased with S application, suggesting a direct SO4-2 or NH4+ effect. The concentration of all other elements determined was elevated, in one or more plant parts, when S deficiency symptoms were visible. The most conspicuous effect of S deficiency on N metabolism was a greatly expanded free amino acid pool, mainly arginine. The concentration of free amino acids decreased exponentially with leaf S. Conversely, protein amino acid was inhibited by S deficiency and increased with leaf S concentration or, perhaps more specifically, with methiouine.
Seasonal Partitioning of Leaf and Fruit Potassium and Fruit Dry Matter in French Prune Trees at Various Potassium Levels
Authors: Niederholzer F.J.A. , Carlson R.M. , Uriu K. , Willits N.H. , Pearson J.P.
Published: January 2019

A study was undertaken to determine the seasonal dynamics of leaf and fruit K content and the influence of tree K status and fruit growth on leaf and fruit K accumulation rates in French prune (Prunus domestics L. cv. d'Agen). Mature trees in a commercial orchard were treated with various rates of K2 SO4. (O to ≈20 kg/tree) in the fall. Fruit dry weight yield per tree at harvest and fruit K content were higher for high-K trees, but fruit percent K (by dry weight) was ≈1.0% for all trees. Leaf scorch and subsequent abscission severely reduced the canopy of K-deficient trees. Significant positive linear relationships between leaf and fruit K accumulation rates existed for the periods of 28 Apr.-28 May (May) and 28 May-7 July (June). A significant negative linear relationship existed between these two criteria from 7 July-3 Aug. (July). May (0.237 mg K per fruit-day) and July (0.267 mg K per fruit-day) mean fruit K accumulation rates were similar, but both were significantly higher (P = 0.001) than those for June (0.140 mg K per fruit-day). Mean leaf K accumulation rates for May (- 0.007 mg K per leaf-day) and July (-0.010 mg K per leaf-day) were similar, but both were significantly (P = 0.001) less than for June (0.005 mg K per leaf-day). Potassium per fruit accumulation was highest in trees with highest K status. Periods of net leaf K efflux and influx did not precisely correlate with fruit growth stages measured by fruit dry weight. The period of lowest fruit K accumulation (28 May-7 July) coincided with the period of maximum dry matter accumulation by the kernel. After 7 July, all increases in fruit dry weight and K content were due to mesocarp growth.
Carbon Dioxide and Ethylene Production by Harvested Grape Berries in Response to Acetaldehyde and Ethanol
Authors: Pesis Edna , Marinansky Rosa
Published: January 2019

Application of acetaldehyde (AA) at 90 to 360 mm to intact grape berries (Vitis vinifera L. cv. Sultanina and Vitis vinifera L. cv. 103) caused an increase in CO2 production rate and a reduction in ethylene evolution rate. The increase in CO2 production rate was accompanied by a decrease in juice acidity without any change in the total soluble solids content. Addition of ACC to berry halves dramatically increased ethylene production, which was inhibited by AA. Ethanol, applied at the same concentrations as AA, neither caused a reduction in ethylene evolution nor inhibited the conversion of ACC to ethylene. Chemical name used: 1-aminocyclopropane-1-carboxylic acid (ACC).
Chilling Injury in Peaches: A Cytochemical and Ultrastructural Cell Wall Study
Authors: Luza J.G. , van Gorsel R. , Polito V.S. , Kader A.A.
Published: January 2019

Fruits of mid- (`O'Henry'), late (`Airtime'), and extra-late-season (`Autumn Gem') peach [Prunus persica (L.) Batsch] cultivars were examined for changes in cell wall structure and cytochemistry that accompany the onset of mealiness and leatheriness of the mesocarp due to chilling injury. The peaches were stored at 10C for up to 18 days or at SC for up to 29 days. Plastic-embedded sections were stained by the Schiff's-periodic acid reaction, Calcofluor white MR2, and Coriphosphine to demonstrate total insoluble carbohydrates, ß-1,4 glucans, and pectins, respectively. Mealiness was characterized by separation of mesocarp parenchyma cells leading to increased intercellular spaces and accumulation of pectic substances in the intercellular matrix. Little structural change was apparent in the cellulosic component of the cell walls of these fruits. In leathery peaches, the mesocarp parenchyma cells collapsed, intercellular space continued to increase, and pectin-positive staining in the intercellular matrix increased greatly. In addition, the component of the cell walls that stained positively for ß-1,4 glucans became thickened relative to freshly harvested or mealy fruit. At the ultrastructural level, dissolution of the middle lamella, cell separation, irregular thickening of the primary wall, and plasmolysis of the mesocarp parenchyma cells were seen as internal breakdown progressed.
Sensitivity of Tomatoes at Mature-green and Breaker Ripeness Stages to Internal Bruising
Authors: Sargent Steven A. , Brecht Jeffrey K. , Zoellner Judith J.
Published: January 2019

Internal bruising (IB) caused by handling impacts results in disruption of normal ripening in tomato (Lycopersicon esculentum Mill.) locular gel. It was selected as an injury indicator to investigate the effect of drop height (O, 10, 20, 30 cm) onto an unpadded surface and number of impacts (one or two) for three tomato cultivars. For mature-green (MG) tomatoes, significant incidence of IB (5% to 45%) was found in all cultivars for single drops on opposite sides of fruits from 20 cm; two drops on the same location from 20 cm caused 20% to 30% IB. Breaker-stage (BR) tomatoes were more sensitive to impacts than MG. Single drops from 10 cm on opposite sides of BR fruits caused 15% to 73% IB, depending on cultivar. Two drops on a single location from 10 cm caused 50% to 68% IB. `Sunny' was less susceptible to IB than `Solar Set' or `Cobia' (formerly NVH-4459).
Carbon and Nitrogen Economy of Developing Rabbiteye Blueberry Fruit
Authors: Birkhold Keith T. , Koch Karen E. , Darnell Rebecca L.
Published: January 2019

Carbon dioxide exchange, dry weight, C, and N content of `Bonita' and `Climax' blueberry (Vaccinium ashei Reade) fruit were measured from anthesis through fruit ripening to quantify developmental changes in amounts of imported C and N required for fruit development. Net photosynthesis occurred in fruit of both rabbiteye cultivars from petal fall through color break. During this time, fruit net photosynthesis declined from 16 μmol CO2/g fresh weight (FW) per hour for `Bonita' and 22 μmol CO2/g FW per hour for `Climax' to 0.2 μmol CO2/g FW per hour for both. Dark respiration for both cultivars declined following petal fall from 16 μmol CO2/g FW per hour to 3 μmol CO2/g FW per hour before increasing at fruit ripening to 9 μmol CO2/g FW per hour. Fruit C content was constant at 0.43 mg C/mg dry weight (DW) throughout development, while N content declined from 0.05 mg N/mg DW at petal fall to 0.01 mg N/mg DW at ripeness. DW accumulation and respiration accounted for 63% and 37%, respectively, of the total C requirement for fruit development. Fruit photosynthesis was estimated to contribute 15% of the total C required for fruit development in both cultivars; however, fruit photosynthesis supplied 50% of the C required during the first 10 days after bloom and 85% during the 5 days after petal fall. This large, early contribution of C from fruit photosynthesis may aid in the establishment of fruit until the current season's vegetative growth can supplement plant carbohydrate reserves in providing C for fruit development.
Molecular Analysis and Cloning of Malus Ribosomal DNA
Authors: Simon C.J. , Weeden N.F.
Published: January 2019

The ribosomal genes of the two crab apple (Malus) genotypes White Angel' and `Robusta 5' were characterized to determine the extent of between- and within-genotype heterogeneity. Initial investigations with a cloned sequence of soybean rDNA failed to detect some Malus intergenic spacer region fragments. An alternative probing method that used electrophoretically purified Malus rDNA was developed. Double-digests of total genomic DNA with combinations of 13 restriction endonucleases identified the positions of 35 restriction sites. Restriction site polymorphism was observed both between and within the crab apple genotypes. Ribosomal DNA from White Angel' was cloned in phage and plasmid vectors and mapped with 11 enzymes. The region of the spacer causing length heterogeneity was identified. These clones should be useful as genetic markers and for examining population dynamics and systematic of Malus and closely related taxa.
Gene Transfer Using Electric Discharge Particle Bombardment and Recovery of Transformed Cranberry Plants
Authors: Serres Rodney , Stang Elden , McCabe Dennis , Russell David , Mahr Daniel , McCown Brent
Published: January 2019

Genetic transformation of the American cranberry, Vaccinium macrocarpon Ait., was accomplished using electric discharge particle acceleration. Plasmid DNA containing the genes GUS (β-glucuronidase), NPTII (neomycin phosphotransferase II), and BT (Bacillus thuringiensis subsp. kurstaki crystal protein) was introduced into stem sections, derived from in vitro cultures, that had been induced to form adventitious buds. The stage of development of these adventitious buds was critical for efficient initial expression. After exposure to electric discharge particle acceleration, stem sections were cultured on a solid-phase bud-inducing medium containing 300 mg kanamycin/liter. In addition, a thin overlay of 300 mg kanamycin/liter in water was added to inhibit growth of nontransformed cells. Within 7 weeks, green shoots emerged amidst kanamycin-inhibited tissue. No escape (nontransformed) shoots were recovered, and 90% of the transformed shoots were shown through PCR and Southern blot analysis to contain all three introduced genes. GUS expression varied markedly among various transformed plants. Preliminary bioassays for efficacy of the BT gene against the feeding of an economically important lepidopteran cranberry pest have shown no consistently effective control. Potential problems with the expression of the BT and GUS genes are discussed
External Morphological Characteristics for Periods during Pecan Microspore and Pollen Differentiation
Authors: Yates I.E. , Sparks Darrell
Published: January 2019

Catkin external morphological characteristics of a protogynous (`Stuart') and a protandrous (`Desirable') cultivar of pecan [Carya illinoensis (Wangenh.) C. Koch] were related temporally to the differentiation of microspore and pollen grains. Reproductive cell development was divided into seven periods based on evaluations of number, location, and intensity of staining of the nucleus and/or nucleolus; and vacuolization and staining intensity of the cytoplasm. Catkins with anthers and bracteoles enclosed by bracts did not have reproductive cells that were matured to free microspore. Free microspore developed only after bracteoles became externally visible. The Period 1 nucleus was at the periphery of the cell and a large central vacuole was present; at Period 2, the nucleus was at the center and vacuolation had been reduced. As the angle between the bract and catkin rachis increased to 45°, vacnolation was reduced as the nucleus enlarged and moved to a central location in the microspore (Periods 3 and 4). The majority of the pollen grains were binucleate, and the generative nucleus became elliptical (Periods 5 and 6) by the time anthers became externally visible. Acetocarmine staining intensity of cellular components masked the presence of the generative nucleus (Period 7) just before anther dehiscence. Staining reaction for protein was positive from Period 1; starch from Period 3; lipids and polyphenols from Period 5. The mature pollen grain was abundant in stored reserves of starch and lipids and had a wall with a thicker exine than intine as demonstrated by acetolysis.
Tree Size, Yield, Fruit Quality, and Leaf Mineral Nutrient Concentration of `Fairchild' Mandarin on Six Rootstock
Authors: Fallahi Esmaeil , Rodney D. Ross
Published: January 2019

The influence of six rootstock on growth, yield, fruit quality, and leaf mineral nutrient concentration of `Fairchild' mandarin [`Clementine' mandarin (Citrus reticulata Blanco) × `Orlando' tangelo (C. paradisi Macf. × C. reticulata)] is reported for the arid climate of southwestern Arizona. Trees on macrophylla (Alemow) (C. macrophylla Wester) were precocious and produced high yield 4 years after planting. Six-year cumulative yields of trees on Volkamer lemon (C. limon Burro f.), Carrizo citrange [C. sinensis (L.) Osbeck × Poncirus trifoliata (L.) Raf.], Taiwanica (C. taiwanica Tan. & shin.), and rough lemon (C. jambhiri Lush.) were similar and higher than those of trees on macrophylla and Batangas mandarin (C. reticulata). `Fairchild' mandarin tree canopies were large with Volkamer lemon and Taiwanica; intermediate with Carrizo citrange, rough lemon, and Batangas mandarin; and small with macrophylla rootstock. Fruit from trees on Carrizo citrange had the highest soluble solids concentration (SSC), while those on Volkamer lemon and rough lemon had the lowest SSC and total acids. `Fairchild' trees on macrophylla had higher levels of leaf N, Mn, and Fe but lower Ca, while trees on Batangas mandarin and Carrizo citrange had higher leaf K than those on the other rootstock. Trees on Volkamer lemon had higher leaf Zn than those on Carrizo citrange, Taiwanica, rough lemon, and Batangas mandarin rootstock. Considering yield, growth, fruit quality, and/or leaf nutrient concentration, Volkamer lemon, Carrizo citrange, Taiwanica, and rough lemon are suitable for `Fairchild' mandarin in the arid regions of southwestern Arizona. Trees on macrophylla could be advantageous for short-term planting, but would not be satisfactory for long-term planting because of gradual decline in growth and yields. Batangas mandarin is not recommended for `Fairchild' mandarin due to poor production.
Auxin Application Duration and Concentration Govern Rooting of Hibiscus Stem Cuttings
Authors: Carpenter W.J. , Cornell J.A.
Published: January 2019

The interactions among IBA concentrations and durations of treatment and propagation medium temperatures on the rooting of stem cuttings were compared for cultivars of Hibiscus rosa-sinensk L. Cultivar rooting was rapid with extensive root development for `Pink Versicolor', average for `Jim Hendry', and slow with few roots per cutting for `Silver Anniversary'. The IBA concentration and duration of treatment that cuttings required to reach maximum rooting declined with increase in medium temperature (from 18 to 34C). `Pink Versicolor' stem cuttings receiving 4- to 6-minute basal dips required 8000 ppm IBA with the medium at 18C, 6000 ppm at 26C, and 2500 ppm at 34C, to achieve 100% rooting of the cuttings. `Pink Versicolor' stem cuttings had the most roots at 10,000 ppm IBA, with 10-min stem dips best at 18C, 4 to 8 min at 26C, and 7 to 8 min at 34C. Maximum dry weights per root were achieved at 6000 ppm IBA, with longer basal stem dip durations needed at 18C than 26 or 34C. Lower IBA levels were required for 100% rooting of `Pink Versicolor' than for `Jim Hendry', with highest levels needed for `Silver Anniversary'. The results indicated that the benefits in rooting achieved from higher IBA levels greatly exceeded those that could be achieved by increased medium temperature. Chemical name used: indole-3-butyric acid (IBA).
Responses of Papaya to Short-term Insecticidal Oxygen Atmosphere
Authors: Yahia Elhadi M. , Rivera Marisela , Hernandez Omar
Published: January 2019

Papaya (Carica papaya L., cv. Sunrise) fruits were exposed to a continuous flow of an atmosphere containing <0.4% 02 (the balance being N2) for 0 to 5 days at 20C. Decay was a major problem, and some fruit had developed off-flavors after 3 days in low O2 plus 3 days in air at 20C. The intolerance of the fruit to low O2 correlates with an increase in the activity of pyruvate decarboxylase and lactate dehydrogenase but not with the activity of alcohol dehydrogenase. Insecticidal O2 (< 0.4%) atmospheres can be used as a quarantine insect control treatment in papaya for periods <3 days at 20C without the risk of significant fruit injury.
Time of Root Pruning Influences Vegetative Growth, Fruit Size, Biennial Bearing, and Yield of `Jonathan' Apple
Authors: Ferree David C.
Published: January 2019

`Jonathan'/M.26 apple (Malus domestics Borkh.) trees were root-pruned annually on two sides, 60 cm from the trunk, to a depth of 40 cm for 6 years while dormant, at bloom, or in mid-June. Root pruning reduced terminal shoot growth by ≈30% in 1985-89 with no influence in 1990. Cumulative yield was reduced by root pruning at bloom (14%) or mid-June (20%), and cumulative yield efficiency [kg·cm-2 trunk cross-sectional area) was reduced by root pruning with no difference among pruning times except in 1 year, where abundant moisture throughout the season appeared to negate the effect. The intensity of biennial bearing was reduced by root pruning with no relationships to time of pruning. Root pruning resulted in a decrease in large fruit and an increase in small fruit in 3 of the 6 years. A covariant analysis with yield showed that root pruning reduced average fruit size. Root-pruned trees produced firmer fruit with an increased soluble solids concentration and had less preharvest drop than nonpruned trees. Under severe drought conditions in 1988, root pruning reduced net photosynthesis and transpiration; supplemental water (57 liters·week-1) increased transpiration and fruit size at harvest.
Temperature Effects on Growth of Impatiens Plug Seedlings in Controlled Environments
Authors: Dreesen David R. , Langhans Robert W.
Published: January 2019

The objective of this study was to determine the dry weight, height, and leaf area growth responses of impatiens (Impatiens walerana Hook. f.) plug seedlings to air temperatures ranging from 18 to 29C. The conditions maintained in the controlled-environment growth rooms (CEGR) were ambient C02 levels, 24-h lighting, and photosynthetic photon flux (PPF) ranging from ≈215; to 335 μmol·m-2·s-1. Mean daily temperatures of the plug medium ranged from 19.6 to 27.7C. At the higher PPF level, shoot dry weight decreased at plug medium temperatures (PMT) > 25C; at lower PPF levels (<300 μmol·m-2·s-1), shoot dry weight continued to increase with PMT > 25C. The mean relative growth rate (MRGR) of shoot dry weight was positively correlated with PMT during the initial growth period (up to 14 days from sowing) and was negatively correlated thereafter. The maximum MRGR was predicted to occur at 11.7 days from sowing for a PMT of 19.6C, at 10.8 days for a PMT of 21.6C, and at 9.7 days for a PMT of 23.6C. Linear regression coefficients of shoot height as a function of PMT were substantially higher for seedlings grown at lower PPF than those for seedlings from the highest PPF level. Seedling leaf area consistently increased with increasing temperature. Net assimilation rate (NAR) decreased with increasing seedling age NAR increased with increasing PPF. A decrease in NAR was apparent at 29C relative to values at the lower temperatures. Leaf area ratio (LAR) declined with increasing seedling age and PPF; a quadratic relationship of LAR as a function of PMT indicates a minimum LAR at 22.5C. The seedlings grown at 29C were excessively tall, had thin succulent leaves, and were judged unacceptable for shipping and transplanting. Maximum quality indices (i.e., dry weight per height) were found at PMT of 24.3 to 25.OC for 10- to 14-day-old seedlings and at PMT of 23.0 to 24.OC for 16- to 20-day-old seedlings.
Pyrrolnitrin, Captan + Benomyl, and High CO2 Enhance Raspberry Shelf Life at 0 or 18C
Authors: Goulart Barbara L. , Hammer Philip E. , Evensen Kathleen B. , Janisiewicz Wojciech , Takeda Fumiomi
Published: January 2019

The effects of preharvest applications of pyrrolnitrin (a biologically derived fungicide) on postharvest longevity of `Bristol' black raspberry (Rubus occidentals L.) and `Heritage' red raspberry [R. idaeus L. var. strigosus (Michx.) Maxim] were evaluated at two storage temperatures. Preharvest fungicide treatments were 200 mg pyrrolnitrin/liter, a standard fungicide treatment (captan + benomyl or iprodione) or a distilled water control applied 1 day before first harvest. Black raspberries were stored at 18 or 0 ± lC in air or 20% CO2. Red raspberries were stored at the same temperatures in air only. Pyrrolnitrin-treated berries often had less gray mold (Botrytis cinerea Pers. ex Fr.) in storage than the control but more than berries treated with the standard fungicides. Storage in a modified atmosphere of 20% CO2 greatly improved postharvest quality of black raspberries at both storage temperatures by reducing gray mold development. The combination of standard fungicide or pyrrolnitrin, high CO2, and low temperature resulted in more than 2 weeks of storage with less than 5% disease on black raspberries; however, discoloration limited marketability after≈ 8 days under these conditions. Chemical names used: 3-chloro-4-(2'-nitro-3'-chlorophenyl) -pyrrole (pyrrolnitrin); N-trichloromethylthio-4-cyclohexene-l12-dicarboximide (captan); methyl 1-(butylcarbamoyl) -2-benzimidazolecarbamate) (benomyl); 3-(3,5 -dichlorophenyl) -N-(l-methylethyl -2,4-dioxo-l-imi-dazolidinecarboxamide (Rovral, iprodione).
Allelopathic Potential of Celery Residues on Lettuce
Authors: Shilling Dorm G. , Dusky Joan A. , Mossier Mark A. , Bewick Thomas A.
Published: January 2019

Poor emergence of commercially grown lettuce has been observed when planted immediately after the removal of a celery crop. Greenhouse experiments were conducted to evaluate the possible allelopathic effects of celery residue on the emergence and growth of lettuce. The influence of amount and type of celery tissue, growth medium and fertility, incubation time in soil, and amendment of growth medium containing celery residue with activated charcoal was evaluated with respect to the allelopathic potential of celery. Celery root tissue was 1.8 and 1.6 times more toxic to lettuce seedling growth than was celery petiole or lamina tissue, respectively. Lettuce shoot growth was inhibited to a greater extent when grown in sand amended with celery residue rather than either amended vermiculite or potting soil. Incubation of celery root residue in soil for 4 weeks increased phytotoxicity at 1% (v/v) and decreased it at 4% (v/v). Increasing the fertility of pure sand with varying amounts of Hoagland's solution did not reverse the allelopathic effects of celery residue. The addition of activated carbon to the medium increased the growth of lettuce exposed to celery residues. Celery residues possess allelopathic potential to developing lettuce seedlings. Celery tissue type and concentration, soil type, incubation of celery root residue in soil, and addition of activated carbon to the growing medium influenced the magnitude of the observed phytotoxicity.
Enhanced Strawberry Seed Germination through in Vitro Culture of Cut Achenes
Authors: Miller A. Raymond , Scheereus Joseph C. , Erb Patricia S. , Chandler Craig K.
Published: January 2019

A tissue culture protocol was developed that increased the germination percentage and decreased the lag time to germination for strawberry (Fragaria x ananassa Duch.) achenes. This technique involved cutting surface-sterilized achenes across the embryo axis then placing the shoot apex/radicle-containing sections on semisolid Murashige and Skoog medium lacking hormones. Cut achenes began germinating 5 days after culture and achieved maximum germination (97% to 100%) in less than 2 weeks, compared to whole achenes, which began to germinate 7 to 10 days after sowing and required more than 7 weeks for maximum germination (<50%). Enhanced germination of cut achenes was a general phenomenon since achenes from 231 hybrid crosses responded similarly. Following placement on culture medium, cut achenes could be stored up to 8 weeks at 4C then removed to 27C, where germination and seedling development occurred at percentages and rates comparable to freshly cut achenes. Achenes did not require stratification before cutting to exhibit increased germination. Nearly 100% of the achenes from freshly harvested red-ripe, pink and white strawberries germinated after cutting and culture, although cut achenes from white and pink berries germinated more slowly than those from red-ripe berries. Achenes from green berries, whether whole or cut, did not germinate. This method of “embryo rescue” could be used to generate more seedlings from poorly germinating hybrid crosses, would considerably decrease the time from sowing to seedling production compared to traditional means, and would produce seedlings of uniform age for subsequent field evaluation.
Pollen Tube Growth in Carya and Temporal Influence of Pollen Deposition on Fertilization Success in Pecan
Authors: Marquard Robert D.
Published: January 2019

In vivo pollen tube growth of pecan [Carya illinoinensis (Wangenh.) K. Koch] was estimated to be ≈ 150 μm·hour-1 from 3 to 8 hours postpollination. Pollen tubes averaged 47, 194, 405, and 946 μm after 2, 3, 4, and 8 hours postpollination, respectively. Pollen tube growth was strongly influenced by temperature, and in vitro studies demonstrated pollen germination and tube growth were optimal at 27C for `Cape Fear' pecan. In in vivo studies, tubes of cross-pollen did not grow significantly faster than tubes of self-pollen. Pollen tubes of water hickory [C. aquatica (Michx. f.) Nutt.] grew significantly faster than those of C. illinoinensis. Bitternut [C. cordiformis (Wangenh.) K. Koch] and mockernut hickory (C. tomentosa Nutt.) pollen tubes grew significantly slower on pecan stigmas than did pecan pollen. Pollen arriving first on the stigma has a decided advantage for fertilization success of pecan. The fertilization success rate of pecan pollen arriving 24 hours after first pollen arrival was <3%.
Evaluation of Penicillium janthinellum as a Biological Control of Phytophthora Root Rot of Azalea
Authors: Ownley B.H. , Benson D.M.
Published: January 2019

Wheat bran inoculum of Penicillium janthinellum (Biourge) [1% w/w added to pine bark (PB) container medium] suppressed “`root rot of azalea (Rhododendron obtusum Planch.) caused by Phytophthora cinnamomi Rands in greenhouse experiments. Shoot fresh weight was increased by 31% to 91% and mortality reduced by 30% to 50% for azaleas planted in natural (nonsterile) PB amended with P. janthinellum compared with the infested control. The population densities of P. janthinellum exceeded 105 to 106 cfu/g dry PB within 7 days and remained stable over time. Penicillium janthinellum, a natural colonizer of PB container media, shows potential as a biological control of phytophthora root rot of azalea.