bluuebunny/crossref_metadata_2025 huggingface dataset:
Pepper Seedling Growth Response to Drought Stress and Exogenous Abscisic Acid
Authors: Leskovar Daniel I. , Cantliffe Daniel J.
Published: January 2019

ABA and drought stress were evaluated on growth morphology and dry weight of pepper (Capsicum annuum L.) seedlings subjected to continuous watering (CV) or alternate watering (AW) subflotation irrigation. When ABA (10-4m) was sprayed on to leaves 28, 32, or 37 days after seeding (DAS), leaf growth was limited relative to the controls. Root dry weight, basal root count, and diameter decreased in AW compared with CW-treated seedlings. ABA did not influence root growth of the transplants or subsequent total fruit yield. When ABA was applied to leaves at 20,23, or 29 DAS, there was a transient inhibition of leaf weight increase, but root growth was unaffected. Exogenous ABA may have a practical application as a substitute for drought stress to control transplant growth in the nursery. Chemical name used: abscisic acid (ABA).
Pecan Bud Growth and Freeze Damage are Influenced by Rootstock
Authors: Grauke L.J. , Pratt J.W.
Published: January 2019

Seven open-pollinated pecan [Carya illinoinensis (Wangenh.) K. Koch] stocks were grown in a nursery in blocks. Bud growth of ungrafted seedlings was influenced by rootstock, with growth being more advanced on `Curtis', `Elliott', `Apache', and `Sioux' seedlings than on `Moore', `Riverside', and `Burkett'. Bud growth of grafted trees was influenced by scion, with growth of `Candy' being most advanced, while `Cape Fear' trees were more advanced than `Stuart'. Growth of `Candy' grafted trees was affected by rootstock, with growth being more advanced on `Elliott' and `Curtis' seedling rootstock as compared to `Apache', Sioux', `Riverside', and `Burkett' seedling rootstock. Tree damage caused by a May freeze was directly related to bud growth and was influenced by scion and rootstock.
Controlled-release Potassium Fertilizers for Turfgrass
Authors: Snyder George H. , Cisar John L.
Published: January 2019

Field and laboratory studies were conducted to evaluate the K retention properties of several resin-coated (RC), sulfur-coated (SC), and plastic-coated (PC) K fertilizers. Substantial differences in K release were found among the controlled-release K materials, based both on the K content of `Tifgreen' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burt-Davvy] clippings and on direct measurement of K remaining in fertilizer granules in the field over time. One SC material appeared to release K too rapidly, and one RC material appeared to release K too slowly to be useful for providing extended plant-available K to turfgrass. The other sources appeared to have release characteristics that would be favorable for turfgrass maintenance. Because differences in K release were observed among the sources, a laboratory method for assessing K release would be useful. Toward this-end, models were developed relating K retention of sources in hot water (70C) to K retention under field conditions.
Modified-atmosphere Packaging of Blueberry Fruit: Effect of Temperature on Package O2 and CO2
Authors: Beaudry Randolph M. , Cameron Arthur C. , Shirazi Ahmad , Dostal-Lange Diana L.
Published: January 2019

Highbush blueberry (Vaccinium corymbosum L. `Bluecrop') fruit sealed in low-density polyethylene packages were incubated at 0, 5, 10, 15, 20, or 25C until O2 and CO2 levels in the package reached a steady state. A range of steady-state O2 partial pressures (1 to 18 kPa) was created by placing a range of fruit weights within packages having a constant surface area and film thickness. The steady-state O2 partial pressure in packages containing the same weight of fruit decreased as temperature increased, indicating the respiratory rate rose more rapidly (i.e., had a greater sensitivity to temperature) than O2 transmission through the film. Steady-state O2 and CO2 partial pressures were used to calculate rates of O2 uptake. CO2 Production. and the respiratory quotient (RO). The effects of temperature and 02 partial pressure on O2 uptake and CO2 production and the RQ were characte∼zed. The steady-state O, partial pressure at which the fruit began to exhibit anaerobic CO2 production (the RQ breakpoint) increased with increasing temperature, which implies that blueberry fruit can be stored at lower O2 partial pressures when stored at lower temperatures.
Cultivar-specific Apple Fruit Growth Rates in Vivo and Sink Activities in Vitro
Authors: Archbold Douglas D.
Published: January 2019

Absolute and relative fruit growth rates (AGR and RGR) of apple (Malus domestics Borkh.) were calculated from the fruit dry weights of several cultivars harvested periodically following June drop during 1988-90. AGRs were constant or varied slightly, and RGRs generally declined as the season progressed. Generally, both AGR and RGR values were higher for relatively large fruit of several cultivars with similar days to maturity, e.g., `McIntosh' vs. `Jonathan' and for summervs. fall-ripening cultivars, e.g., `Stayman' vs. others. An exception was observed in 1990, when `Golden Delicious' exhibited a higher AGR but lower RGR than `Rome Beauty', yet ripened 1 month earlier. `Golden Delicious' AGR and RGR values were lower for both fruit of a pair on a spur than the values for a single fruit on a spur, and the dominant fruit of the pair exhibited higher growth rates than the inferior fruit. Rates of sorbitol accumulation (SAR) by cortex disks incubated in 14C-labeled sorbitol solutions in vitro declined as the season progressed. Within a cultivar, SARS were not related to fruit size, nor were differences found between cortex disks from competing fruit on a spur, although SARS were higher for both competing fruit on a spur as compared to that of a single fruit per spur. Due to a positive correlation between RGR and SAR values, the SAR of cortex cells may be regulated in such a manner as to be a physiological constraint on fruit sink strength and growth rate.
Use of Molecular Markers to Locate Quantitative Trait Loci Linked to High Soluble Solids Content in a Hybrid of Lycopersicon cheesmanii
Authors: Garvey T. Casey , Hewitt John D.
Published: January 2019

An interspecific hybrid was made between an accession of Lycopersicon cheesmanii f. minor Riley (LA 1508) from the Galapagos Islands, Ecuador, and L. pennellii (Corr.) D'Arcy (LA 716). LA 1508 was used because of its high soluble solids content (SSC). It was crossed with LA 716 to test for linkage between isozymes and morphological markers and loci conditioning high SSC. For both accessions, chromosome numbers are equal and there are large differences between SSC and no barriers to crossing. Modified BC1 populations derived from the hybridization were assayed for isozyme markers using starch gel electrophoresis. Associations between marker loci and quantitative-trait loci (QTL) conditioning high SSC were determined using analysis of variance. Six isozymes located on five chromosomes and one morphological marker had significant associations with SSC, indicating linkage to QTL. Digenic epistatic interactions between pairs of independent markers did not appear to play an important role in the interactions between QTL that condition SSC.
Plot Technique Studies on Sweetpotato Yield Trials
Authors: Vallejo Roger L. , Mendoza Humberto A.
Published: January 2019

The objective of this research was to determine optimum plot size and number of replications to evaluate yield of sweetpotato (Ipomoea batatas Lam.) clones. The optimum plot size was estimated using the methods of maximum curvature and comparison of variances. The adequate number of replications was determined using the Hatheway method. Using the maximum curvature method, the estimated optimum plot size was 10 basic units (b.u. = six plants or 1.2 m2) for La Molina and San Ramon, and 5 b.u. for Tacna, Peru. Using the comparison of variances method, the optimum plot size was 15 b.u. for all locations tested. The adequate number of replications with a plot size of 15 b.u. was four.
Simulation Modeling of Temperatures in Root Container Media
Authors: Martin Chris A. , Ingram Dewayne L.
Published: January 2019

A three-dimensional computer model was developed to simulate numerically the thermal environment of a polyethylene container-root medium system. An energy balance was calculated at the exterior container wall and the root medium top surface. Thermal energy exchanges at the system's boundaries were a function of radiation, convection, evaporation, and conduction energy flaxes. A forward finite difference form of a transient heat. conduction equation was used to calculate rates of temperature changes as a result of thermal energy exchanges at the system's boundaries. The χ2“goodness-to-fit” test was used to validate computer-generated values to actual measured temperature data. Probabilities for the null hypothesis of no association ranged from P = 0.45 (Julian day 271), to P = 0.81 (Julian day 190), with P ≥ 0.70 on nine of 10 validation days in 1989. Relative to net radiation and convection, conduction and evaporation had little effect on thermal energy exchanges at the root medium top surface during sunlight hours. The rate of movement of thermal energy (thermal diffusivity) was slower and generally resulted in lower temperatures in a pine bark medium than in a pine bark medium supplemented with sand when volumetric water content (VMC) ranged from 0.25 to 0.45.
Solubility and Application Rate of Controlled-release Fertilizer Affect Growth and Nutrient Uptake in Containerized Woody Landscape Plants
Authors: Hicklenton Peter R. , Cairns Kenneth G.
Published: January 2019

Nutrient release from Nutricote Type 100 (100-day N release; 16N-4.4P-8.1K), and from a 1:3 mixture of Nutricote Type 40 (40-day N release; 16N-4.4P-8.1K) and Type 100 was affected by time and temperature. The Type 40/100 mixture released nutrients more rapidly over a 5 to 35C range in laboratory studies. Seasonal growth of containerized cotoneaster (Cotoneaster dammeri C.K. Schneid `Coral Beauty') and juniper (Juniperus horizontalis Moench. `Plumosa Compacta') increased with increasing application rates of either Nutricote Type 100 or a 1:3 mixture of Type 40/100 over the range 2-10 kg·m-3. Between 25 June and 27 July, cotoneaster grew more rapidly in media with Type 40/100 Nutricote, but by the end of the season (27 Sept.), fertilizer type showed no effect on plant dry weight. Shoot N was higher in cotoneaster plants grown with Type 40/100 Nutricote than with the Type 100 formulation during the first 2 months of growth, reflecting the more rapid release and uptake of N from the mixture. During the last month the situation was reversed, as nutrients from the Type 40/100 mixture were depleted. Potassium and P shoot concentrations were not affected by fertilizer type. Juniper growth and shoot concentrations of N, K, and P were not affected by fertilizer type at any time during the season. The results provided no evidence that seasonal growth could be enhanced in either cotoneaster (grows rapidly) or juniper (slower growing) by mixing rapid and more slowly releasing types of Nutricote.
Modification of Plant Architecture in `Crimson Giant' Easter Cactus with Benzyladenine
Authors: Boyle Thomas H.
Published: January 2019

Investigations were performed to determine the effects of timing of application and concentration of BA on the vegetative growth of Easter cactus [Rhipsalidopsis gaertneri (Regel) Moran `Crimson Giant']. BA was applied to rooted phylloclades at 27, 37, and/or 47 days after propagation (DAP) at 200 to 1000 mg·liter-1. At 80 DAP, the number and cumulative length of secondary (2°) phylloclades (those developing from the rooted phylloclade) of BA-treated plants exceeded those of the controls. Number and cumulative length of 2° phylloclades increased linearly with increasing BA concentration. At 316 DAP, there were no differences between BA-treated plants and controls in numbers of 2° and apical (terminal) phylloclades. BA also was applied to plants at either 95 or 187 DAP. Treatments included 10, 50, 100, and 200 mg BA/liter and an unsprayed control. Number of new phylloclades (those developing after treatments) and percentage of old phylloclades with new phylloclades increased linearly in response to increasing BA concentration. Relative to the controls, one application of BA at 50, 100, or 200 mg·liter-1 resulted in a ≈50% to 400% increase in total dry weight of new phylloclades accompanied by a ≈4% to 30% decrease in total dry weight of old phylloclades. Branching of mature plants, i.e., with three to five tiers of phylloclades, was significantly affected by timing of application and concentration of BA. BA may be useful for modifying plant architecture of Easter cactus to increase flowering and product marketability. Chemical name used: N- (phenylmethyl) -1H- purine-6-amine[benzyladenine (BA)].
Firmness Measurement of Stored `Delicious' Apples by Sensory Methods, Magness-Taylor, and Sonic Transmission
Authors: Abbott Judith A. , Affeldt Henry A. , Liljedahl Louis A.
Published: January 2019

`Delicious' apples (Malus domestica Borkh.) from five major U.S. production areas were tested after ≈3 months of commercial storage. Soluble solids concentration (SSC), titratable acidity (TA), Magness-Taylor (MT) firmness, and sonic transmission spectra were compared with ripeness (maturity in trade terminology) scores assigned by six U.S. Dept. of Agriculture (USDA)-licensed apple inspectors according to USDA Grades and Standards inspection procedures. USDA ripeness categories are defined by textural and flavor terms. Inspectors in this test used visual, manual, oral, and auditory sensations to make their judgments, but firmness was the paramount characteristic judged. SSC and TA did not correlate with inspectors' scores, MT, or sonic measurements and thus are not satisfactory indices of ripeness for stored apples. Sonic resonance functions correlated significantly with mean inspectors' scores and with MT firmness. Inspectors' scores correlated slightly better with MT firmness than with sonic terms. MT is destructive and site-specific; in contrast, sonic measurements are nondestructive and representative of the entire fruit.
Isolation and Characterization of Rhizobia Effective with Maackia amurensis
Authors: Batzli Janet McCray , Graves William R. , van Berkum Peter
Published: January 2019

Our objectives were to test whether Maackia amurensis Rupr. & Maxim. nodulates and fixes N and to characterize the N-fixing bacteria effective with this host. Soil samples were collected near diverse legume trees at arboreta and public gardens in the United States, Canada, and China. Seedlings of M. amurensis were grown for 6 weeks in a low-N, sterile medium and inoculated with soil samples. At harvest, nodules were found on the lateral and upper portions of root systems. Bacteria were isolated from nodules and subculture. Roots of seedlings inoculated with all 11 of these isolates nodulated and freed N, confirming that the isolates were rhizobial bacteria. Growth of isolates in axenic culture generally was poor when single sources of C were provided. Generation times of the isolates ranged from 6 to 10 hours, and all isolates raised the pH of culture media. Isolates were highly resistant to several antibiotics, showed no 6-phosphogluconate dehydrogenase (6PGD) or β-galactosidase activity, and were highly sensitive to NaCl. These results provide the first evidence that M. amurensis has the capacity to form N-fixing symbioses with rhizobial bacteria and indicate that the bacteria are Bradyrhizobium sp.
Screening Tomato Seedlings for Multiple Disease Resistance
Authors: Erb W. Alan , Rowe Randall C.
Published: January 2019

Two procedures for screening tomato (Lycopersicon esculentum Mill.) seedlings for resistance to three pathogens were developed. In one scheme, seeds were sprayed with a spore suspension of Fusarium oxysporum f. sp. radicis-lycopersici Jarvis & Shoemaker (fusarium crown and root rot). Resistant seedlings were root-dipped 2.5 weeks later in a spore suspension of Verticillium dahliae Kleb. (verticillium wilt), and 1 week following the root dip, leaves were rubbed with tobacco mosaic virus. In the other scheme, 2-week-old seedlings were dipped in a spore suspension of F. oxysporum Schlecht f. sp. lycopersici (Sacc.) Snyd. & Hans. races 1 and 2 (fusarium wilt). Resistant seedlings were root-drenched 1.5 weeks later with a suspension of Meloidogyne incognita Kofoid & White (rootknot nematode), and 1 week following, the leaves were rubbed with tobacco mosaic virus. These procedures were effective for disease screening, and their use should reduce the time required for development of two multiple disease-resistant populations. Inbreds from each population could be crossed to produce hybrids resistant to five pathogens.
Postpollination Reproductive Biology of Rhododendron prinophyllum (Small) Millais
Authors: Padrutt Julie , Pellett Harold , Ascher Peter
Published: January 2019

Complete diallel matings were performed during two consecutive seasons in a full sibling population of Rhododendron prinophyllum, the pinkshell azalea. Examination of pollen tubes from collected and fixed styles revealed no differences in growth, rate of pollen tubes between selfs and outcrosses. Penetration of pollen tubes through the ovular micropyle region occurred 4 to 7 days after pollination, regardless of pollen source. Embryogenesis was studied in pistils collected from forced greenhouse plants of the same population. All ovules appeared to develop for a short period before senescing. Percent capsule set data from both years' diallel pollinations indicated that some active form of self-recognition and rejection was operating and that environmental stresses and resource allocation were also influential. Additional information gathered included ovule counts, seed count to capsule size correlations, and germination trials. These pointed to a reduction in reproductive success at each developmental stage. Self-incompatibility (SI), defined as inability to set seed following self-pollination, is clearly not applicable here. There are inherent difficulties in separating an active, late-acting self-recognition/rejection system from inbreeding depression, which is a passive accumulation of homozygous recessive lethal and sublethal genes.
Optimizing Embryogenic Callus and Embryo Growth of a Synthetic Seed System for Sweetpotato by Varying Media Nutrient Concentrations
Authors: Chée Raymond P. , Leskovar Daniel I. , Cantliffe Daniel J.
Published: January 2019

Embryogenic callus growth of sweetpotato [Ipomoea batatas (L.) Lam.] was selectively enhanced by subculture on basal callus proliferation medium modified to contain 15 mm NH4NO3. Embryogenic callus production was doubled on basal callus proliferation medium modified to contain 60 mm K+, while nonembryogenic callus production was reduced 40%. Additions of up to 40 mm NaCl to basal callus proliferation medium did not affect callus proliferation. The development of embryos from calli subculture to embryo production basal medium was unaffected by the KCl or NaCl treatments of the callus proliferation phase. However, embryo production was increased by subculturing callus from callus proliferation medium containing 20 mm NH4+ to embryo production medium containing 10 mm NH4+ Our results demonstrate that changes in mineral nutrition, in addition to growth regulator differences between callus proliferation and embryo production media, are important factors in sweetpotato somatic embryogenesis.
Ripening Patterns within a Peach as Indicated by Force and Soluble Solids Concentration
Authors: Horton B.D.
Published: January 2019

Variability in maturity within a peach (Prunus persica, L. Batsch) fruit was estimated by measurements of force and the soluble solids concentration (SSC) at 16 coordinates around the peach at five maturity stages: 1) about one-half final swell (immature); 2) 85% final swell (green); 3) firm-ripe and similar to chip #3 of the Clemson Univ. system; 4) firm-ripe and similar to chip #5; and 5) tree-ripe. Firm-ripe 3 and 4 stages were firm enough to ship, but the tree-ripe stage was too soft. Firmness measured with a 4.7-mm-diameter penetrometer tip from two cultivars indicates a strong trend for the peach tip and cheeks to be firmer than tissue at other coordinates. Coordinates at the equator and around the stem end are generally firmer than coordinates at lat. 45°N, particularly in stages 3, 4, and 5. The SSC in juice from a cylinder of fruit adjacent to the puncture was higher at long. 90°E-W than at the sutures and higher at lat. 0° than at 70°S. Variance increased for force and decreased for SSC between maturity stages to the firm-ripe stage. The coordinate technique might be used to characterize and select cultivars that would be most suitable for once-over harvests.
NADP+-Malic Enzyme and Organic Acid Levels in Developing Tomato Fruits
Authors: Knee Michael , Finger Fernando L.
Published: January 2019

Tomato (Lycopersicon esculentum Mill., cv. Ohio 7814) fruits were harvested weekly following flowering to relate changes in NADP+-malic enzyme (NADP-ME) activity and major organic acids (malate and citrate) to fruit development. Specific activity of NADP-ME and fresh weight concentrations of the acids reached maximal levels at the mature-green stage. During ripening, a decline in malate concentration was followed by decreases in NADP-ME activity and citrate concentration. Activity of NADP-ME and organic acid concentrations were highest in the locular gel, but activity also occurred in tomato leaves, stems, and roots. The data do not exclude a role for NADP-ME in the metabolism of organic acids during fruit ripening. However, it is also possible that the enzyme is involved in cytoplasmic pH regulation.
Variation in Lipid Composition of Apples in Relation to Watercore
Authors: Wang Shiow Y. , Faust Miklos
Published: January 2019

The glycolipids, phospholipids, and sterols were determined in normal and watercore-affected apple (Malus domestica Borkh. cv. Delicious). Fruit with watercore contained higher amounts of glycolipids, phospholipids, and sterols. The ratios of unsaturated to saturated fatty acids and (18:3) to (18:1 + 18:2) were lower in watercore-affected tissue than in normal tissue. The ratio of free sterols to phospholipids was higher, whereas the ratio of phosphatidylcholine to phosphatidylethanolamine was lower in watercore-affected apple. Membrane lipids were altered in watercore-affected fruit.
Electrolyte Leakage and Evolution of Ethylene and Ethane from Pepper Leaf Disks Following Temperature Stress and Fatty Acid Infiltration
Authors: Nanaiah Geeta K. , Anderson Jeffrey A.
Published: January 2019

Electrolyte leakage (EL) and ethane: ethylene ratio (EER) responses of pepper (Capsicum annuum L. `Early Calwonder') leaf disks to temperature stresses were in close agreement. Midpoints of sigmoidal response curves following freezing stress were -4.6 and -4.4C for EL and EER, respectively, and 49.0 and 48.7C following high-temperature stress. Leaf disks exposed to temperatures below -4C in freezing experiments were induced to freeze while disks held at -4C and higher avoided freezing by supercooling. Evolution of ethane and EL were measured from disks infiltrated with a saturation series of 18-C fatty acids ranging from 0 to 3 double bonds. Only cis-9,12,15 linolenic acid (18:3 n-3) stimulated ethane production and EL. In a second fatty acid experiment with 18 and 20-C acids with a double bond 3 (n-3) or 6 (n-6) carbons from the nonpolar end of the molecule, n-3 fatty acids stimulated more ethane than n-6 acids with the same number of carbons. Trienoic 18-C fatty acids stimulated more ethane than trienoic 20-C acids. Both 18-C trienoic acids yielded significantly greater EL, while values from 20-C fatty acids were only slightly higher than those of controls. Propyl gallate, a free radical scavenger, reduced ethane production without decreasing EL or K+ leakage.
Aboveground Screening for Genotypic Differences in Cucumber Root Growth in the Greenhouse and Field
Authors: Grumet Rebecca , Barczak Mary , Tabaka Chris , Duvall Robert
Published: January 2019

A simple, aboveground method to study cucumber (Cucumis sativus L.) root growth was developed using a subsurface herbicide banding technique. Those plants with roots that grow deeper or faster reach the herbicide sooner and exhibit herbicide injury symptoms sooner. Greenhouse pot trials showed that 0.25 or 0.50 kg simazine/ha could be used to produce distinctive symptoms; time to symptom expression increased with the depth of the band from the soil surface. Root washing experiments verified that root length was associated with response time. In field trials, response time and severity of symptoms varied with herbicide concentration, depth, and distance from the seed row, thereby providing an indication of where the roots were in the soil. About 100 diverse cucumber genotypes were tested for differences in root growth rate in the greenhouse and in the field. Time to symptom expression was normally distributed among the genotypes; analysis of variance (ANOVA) indicated significant genotypic differences. This system can be used for cultural or physiological studies, or nondestructively for selection and breeding purposes. If the herbicide is placed sufficiently deep to prevent damage to the cotyledons, the plants are capable of flowering and producing fruit. Chemical name used: 6-chloro-N, N′-diethyl-1,3,5-triazine-2,4-diamine (simazine).
Foliar Applications of Potassium Silicate Reduce Severity of Powdery Mildew on Cucumber, Muskmelon, and Zucchini Squash
Authors: Menzies Jim , Bowen Pat , Ehret David , Glass Anthony D.M.
Published: January 2019

The effect of soluble potassium silicate applied to cucumber (Cucumis sativus L.), muskmelon (C. melo L.), and zucchini squash (Cucurbita pepo L.) on the severity of powdery mildew was examined. Application methods included amending nutrient solutions to a concentration of 1.7 mm Si and foliar sprays containing 1.7, 8.5, 17, and 34 mm Si. Untreated plants and plants sprayed with distilled water were used as controls. The leaves of all plants were inoculated with known concentrations of conidia of Sphaerotheca fuliginea (Schlecht.:Fr.) Poll. (cucumber and mu&melon) or Erysiphe cichoracearum DC.: Merat (zucchini squash) 1 day after the sprays were applied. Inoculated leaves on plants receiving the Si-amended nutrient solution or foliar sprays of ≥ 17.0 mm Si developed fewer powdery mildew colonies than those on control plants. Results of a separate experiment that included a potassium spray, indicated that the active ingredient of the potassium silicate sprays appears to be Si. Experiments to test the persistence of Si foliar sprays on cucumber demonstrated that a 17 mm Si spray applied 7 days before inoculation with S. fuliginea reduced mildew colony formation.
External and Internal Factors Influence Fruit Tolerance to Low-oxygen Atmospheres
Authors: Ke Dangyang , Kader Adel A.
Published: January 2019

Fruits of `Bing' cherry (Prunus avium L.), `Red Jim' nectarine (Prunuspersica L.), `Angeleno' plum (Prunus salicina, L.), `Yellow Newtown' and `Granny Smith' apples (Malus domestica Borkh.), and `20th Century' pear (Pyrus serotina L.) were treated with 0.25% or 0.02% O2 (balance N2) at 0, 5, or 10C to study the effects of these insecticidal low-O2 atmospheres on their postharvest physiology and quality attributes. Development of alcoholic off-flavor was associated with ethanol accumulation, which was the most common and important detrimental effect that limited fruit tolerance to low O2. Relatively higher storage temperature (T), higher respiration rate (R), and greater resistance to gas diffusion (r) enhanced while relatively higher O2 concentration (C) and higher soluble solids concentration (SSC) reduced off-flavor development. Using a SAS computer program to do multiple regression analysis with T, C, R, r, and SSC as variables, models were developed for prediction of fruit tolerance to insecticidal low-O, atmospheres. Comparison of fruit tolerances and published information on the times required to completely kill specific insects by O2 levels at or below 1% suggests that low-O2 atmospheres have a good potential for use as postharvest quarantine treatments for some fruits.
Genetic Analysis of Isoenzymes in Raspberry
Authors: Cousineau Johanne C. , Donnelly Danielle J.
Published: January 2019

The inheritance of five isoenzymes was studied in red and purple raspberry F1 progenies (Rubus idaeus L. and Rubus × neglectus Peck). Isocitrate dehydrogenase (IDH; EC 1.1.1.42) was a dimeric enzyme present in the cytosol and coded for by one locus (Idh-1). Three of the four crosses analyzed at this locus had deviations from expected ratios, possibly caused by its linkage to a recessive lethal gene. Malate dehydrogenase (MDH; EC 1.1.1.37), phosphoglucoisomerase (PGI; EC 5.3.1.9), and triose phosphate isomerase (TPI; EC 5.3.1.1) were dimeric enzymes with two loci. Each of these three enzymes was present in an organelle and in the cytosol for locus 1 and 2, respectively. Phosphoglucomutase (PGM; EC 2.7.5.1) was monomeric with two loci, Pgm-1 and Pgm-2, located in an organelle and the cytosol, respectively. Each allele at Pgm-1 resulted in the formation of two bands. Although most progenies analyzed supported Mendelian inheritance of polymorphic loci (except for Idh-1), there was a higher than expected number of aberrant segregation ratios observed (18.4%). Analysis of 85 pairs of jointly segregating loci revealed a possible linkage group consisting of Mdh-2, Tpi-2, and Pgm-1.
Use of Clonally Replicated Seedlings in Field Screening for Resistance to Peach Tree Short Life
Authors: Beckman T.G. , Okie W.R. , Nyczepir A.P.
Published: January 2019

Clonally replicated peach seedlings [Prunus persica (L.) Batsch] of Lovell, Nemaguard, and four F1 selections of Lovell × Nemared were tested for field survival on a peach tree short life site. Rootstock families differed in growth, survival, and longevity. Genetic variation was similar to environmental variation for most families. Based on seedling within rootstock family, estimated broad-sense heritabilities for survival and longevity were high. The use of clonally replicated seedlings allowed the selection of apparently superior individuals from both Lovell and the other more short-lived rootstock families in a single screening.
Shoot Organogenesis and Plant Regeneration from Cotyledons of Diploid, Triploid, and Tetraploid Watermelon
Authors: Compton Michael E. , Gray D.J.
Published: January 2019

Adventitious shoots were obtained from watermelon [Citrullus lanatus (Thunb.) Matsun. & Nakai] cotyledons incubated on a modified Murashige and Skoog medium containing BA. Initial experiments comparing the effects of BA (0, 5, 10, or 20 μm) and IA4 (0, 0.5, or 5 μm) demonstrated that BA was required for adventitious shoot formation but its concentration in the medium was not critical. The addition of IAA to medium with BA increased callus production and inhibited shoot formation. However, the percentage of responding explants in the best treatment was <30%. Therefore, the manner in which cotyledon explants were prepared and seedling age at the time of explantation was examined to improve the organogenic response. The percentage of explants with shoots was improved by using explants that consisted of cotyledon bases (43%) or cotyledons cut in half longitudinally (39%). A lower percentage (16%) of cotyledons cut longitudinally into four pieces produced shoots. Explants taken from the apical half of cotyledons failed to regenerate shoots. Shoot formation was improved further by using explants from young seedlings. The percentage of explants with shoots was >90% for `Minilee', 64% for S86NE, and 50% for `Jubilee II' when explants were prepared from 5-day-old seedlings. Explants from nongerminated embryos or seedlings germinated for 10, 15, or 20 days produced fewer shoots. The effect of several cytokinins on shoot organogenesis was then examined using the optimized protocol. The percentage of explants with shoots and the number of shoots per explant were about two to four times higher when 5 to 10 μm BA was used compared to the most effective kinetin (20 μm) or thidiazuron (0.1 μm) concentration. The percentage of explants with shoots and the number of shoots per explant were greater for diploid (57% and 2.2, respectively) than for triploid (22% and 0.6, respectively) or tetraploid (20% and 0.8, respectively) lines. Chemical names used: N -(phenylmethyl)-1 H -purin-6-amine (BA); 6-furfurylaminopurine (kinetin); N -phenyl-N' -1,2,3-thiadiazol-5-ylurea (thidiazuron); 1 H -indole3-acetic acid (IAA).
Shoot Organogenesis in Callus Induced from Pedicel Explants of Common Bean (Phaseolus vulgaris L.)
Authors: Mohamed Mohamed F. , Coyne Dermot P. , Read Paul E.
Published: January 2019

Plant regeneration has been achieved in two common bean lines from pedicel-derived callus that was separated from the explant and maintained through successive subcultures. Callus was induced either on B5 or MS medium containing 2% sucrose and enriched with 0.5 or 1.0 mg thidiaznron/liter alone or plus various concentrations of indoleacetic acid. The presence of 0.07 or 0.14 g ascorbic acid/liter in the maintenance media prolonged the maintenance time. Up to 40 shoot primordia were observed in 4-week-old cultures obtained from 40 to 50 mg callus tissues on shoot-induction medium containing 1-mg benzyladenine/liter. These shoot primordia developed two to five excisable shoots (>0.5 cm) on medium with 0.1-mg BA/liter. A histological study confirmed the organogenic nature of regeneration from the callus tissues. The R2 line from a selected variant plant showed stable expression of increased plant height and earlier maturity. Chemical names used: ascorbic acid, N- (phenylmethyl)-1H-pnrin-6-amine [benzyl-adenine, BA], 1H-indole-3-acetic acid (IAA), N- phenyl-N'-1,2,3-thiadiazol-5-ylurea [thidiazuron, TDZ].
Comparison of Plant Establishment Method, Transplant, or Direct Seeding on Growth and Yield of Bell Pepper
Authors: Leskovar Daniel I. , Cantliffe Daniel J.
Published: January 2019

Transplants produced with overhead or subirrigation and plants from direct seeding using primed or nontreated `Jupiter' bell pepper (Capsicum annuum L.) seeds were evaluated for growth and yield in the field for 3 years. Early in development, overhead-irrigated (01) transplants had more basal root elongation than subirrigated (SI) transplants; however, root growth differences caused by irrigation systems in the greenhouse were minimized during late ontogeny in the field. Basal, lateral, and taproot dry weights accounted for 81%, 15%, and 4% of the total for transplants and 25%, 57%, and 18% of the total for direct-seeded plants. Direct-seeded plants maintained a more-balanced root, stem, leaf, and fruit dry matter partitioning than transplants, which allocated more dry weight (per unit of root growth) to stems, leaves, and fruits. Over all seasons, transplants exhibited significantly higher and earlier yields than direct-seeded pepper plants, and total yields were similar between SI and OI transplants and between primed and nontreated seeds.
Modeling Temperature and Photoperiod Effects on Growth and Development of Dahlia
Authors: Brøndum Jens J. , Heins Royal D.
Published: January 2019

Effects of temperature and photoperiod on growth rates and morphological development of Dahlia pinnata Cav. `Royal Dahlietta Yellow' were determined by growing plants under 45 combinations of day and night temperatures (DT and NT, respectively, and photoperiod. DT and NT ranged from 10 to 30C and photoperiods from 10 to 24 hours·day-1. Photoperiod influenced vegetative development more than reproductive development as plants flowered in all photoperiods. Lateral shoot count and length decreased and tuberous root weight increased as photoperiod decreased from 16 to 10 hours. Temperature interacted with photoperiod to greatly increase tuberous root formation as temperature decreased from 25 to 15C. Increasing temperature from 20 to 30C increased the number of nodes below the first flower. Flower count and diameter decreased as average daily temperature increased. Nonlinear regression analysis was used to estimate the maximum rate and the minimum, optimum, and maximum temperatures for leaf-pair unfolding rate (0.29 leaf pair/day, 5.5, 24.6, and 34.9C, respectively), flower development rate from pinch to visible bud (0.07 flower/day, 2.4, 22.4, and 31.1C, respectively), and flower development rate from visible bud to flower (0.054 flowers/day, 5.2, 24.4, and 31.1C, respectively). The results collectively indicate a relatively narrow set of conditions for optimal `Royal Dahlietta Yellow' dahlia flowering, with optimal defined as fast-developing plants with many large flower buds and satisfactory plant height. These conditions were a 12- to 14-hour photoperiod and ≈ 20C.
Phosphorus, Zinc, and Boron Influence Yield Components in `Earliglow' Strawberry
Authors: May Geoffrey M. , Pritts Marvin P.
Published: January 2019

The main effects and interactions of soil-applied P, B, and Zn on yield and its components were examined in the field at two pH levels with `Earliglow' strawberries (Fragaria × ananassa Duch.). Applied nutrients had significant effects on several yield components, but responses depended on the levels of other nutrients or the soil pH At a soil pH of 5.5, yield responded linearly to B and quadratically to P. At pH 6.5, P interacted with B and Zn. Fruit count per inflorescence was the yield component most strongly associated with yield followed by individual fruit weight. However, these two yield components responded differently to soil-applied nutrients. Foliar nutrient levels generally did not increase with the amount of applied nutrient, but often an applied nutrient had a strong effect on the level of another nutrient. Leaf nutrient levels were often correlated with fruit levels, but foliar and fruit levels at harvest were not related to reproductive performance. Our study identifies some of the problems inherent in using foliar nutrient levels to predict a yield response and demonstrates how plant responses to single nutrients depend on soil chemistry and the presence of other nutrients.
Pesticide Effect on Acetylene Reduction and Modulation by Soybean and Lima Bean
Authors: Yueh Lih-Yuh , Hensley David L.
Published: January 2019

The influence of 12 pesticides on acetylene reduction (N2 fixation) and modulation of soybean (Glycine max L. Merrill cv. Williams 82) and lima bean (Phaseolus lunatus L. cv. Geneva) was evaluated. All pesticides except diazinon were found to be harmless to nitrogen fixation at 3× the manufacturer's recommended rate, Diazinon significantly decreased C2H2 reduction of soybean 2 days after application, but not after 7 days or at normal label rates, Acetylene reduction of excised nodules imbibed with diazinon indicated that the chemical may have affected nitrogenase function directly. Soybean nodule counts were significantly decreased by application of 3× rates of methomyl and trifluralin, whereas lima bean nodule counts were decreased only by trifluralin. Tritluralin also depressed soybean modulation at label rates, but had no effect on lima bean modulation. Methomyl was innocuous to soybean modulation at the recommended label rate. Both chemicals were nontoxic to Bradyrhizobium/Rhizobium sp. based on a disc inhibition study. Chemical names used: O,O -diethyl O -(2isopropyl-4-methyl-6-pyrimidinyl phosphorothiote (diazinon); S-Methul- N -((methylcarbamoyl)oxy)-thioacetimidate (methomyl); a,a,a -Trifluoro-2-6dinitro-N-N -dipropyl-p-toluidine (triflnralin).
Molecular Characteristics of Pectic Constituents in Relation to Firmness, Extractable Juice, and Woolliness in Nectarines
Authors: von Mollendorff L.J. , de Villiers O.T. , Jacobs G. , Westraad I.
Published: January 2019

`Flavortop' nectarines [Prunus persica (L.) Batsch] were either stored for 4 weeks at -0.5C or not subjected to cold storage before being ripened at 15C. The differences in extractable juice, woolliness, composition, and gelling characteristics of extracted pectins between the two treatments were determined during ripening. As ripening progressed, the extractable juice in both treatments decreased to low values after which it increased with further ripening. Woolliness only occurred in fruit that was cold stored. Nectarines became woolly from the 2nd day and peaked on the 6th day of ripening in fruit cold stored for 4 weeks. As fruit firmness decreased, the soluble pectin concentration increased to the same extent in both treatments at the expense of insoluble pectin. In cold-stored fruit, the viscosity of pectin increased gradually until the 6th day of ripening, while in noncold-stored fruit maximum viscosity was higher and occurred between the 4th and 6th day of ripening. From the 6th day, the viscosity decreased in both treatments to levels lower than the initial viscosity. The extractable juice was lowest when the viscosity of soluble pectins and percentage of woolly fruit were highest. Molecular mass distribution of soluble pectins decreased considerably during ripening at 15C.
Detection of Vascular Discontinuity in Bud Unions of `Jonagold' Apple on Mark Rootstock with Magnetic Resonance Imaging
Authors: Warmund Michele R. , Barritt Bruce H. , Brown John M. , Schaffer Karen L. , Jeong Byoung R.
Published: January 2019

`Jonagold'/Mark apple (Malus domestica Borkh.) trees that were chip-budded in Washington and Illinois on 31 Aug. or 21 Sept. 1989 were sampled in Apr. 1990 to determine if magnetic resonance imaging (MRI) could be used to nondestructively examine vascular continuity or discontinuity between the rootstock and scion. Images could be placed into three categories based on signal intensity: 1) the rootstock, bud shield, and the bud or new scion growth had a high signal intensity; 2) the rootstock and the bud shield had a high signal intensity, but the scion had a low signal intensity; and 3) the rootstock had a high signal intensity, but the bud shield and scion had a low signal intensity. High signal intensity was associated with bound water in live tissue and the establishment of vascular continuity between the rootstock and scion. Azosulfamide staining and destructive sectioning confirmed that vascular continuity was established when the rootstock, bud shield, and scion had a high signal intensity in images, whereas budding failure occurred when the bud shield and/or the scion had a low signal intensity. Additional trees that had wilted or weak scion growth were collected from Illinois in June 1990. Parenchyma tissue was found in the scion adjacent to the bud shield that interrupted the vascular tissue. Poor scion growth on trees from the 21 Sept. budding in Washington may be attributed to insufficient growth of rootstock and/or scion tissues at the union in the fall.
Characterization of the Kentville Stock Clone Apple Rootstocks. I. Growth and Efficiency
Authors: Embree C.G. , Lesser B.H. , Crowe A.D.
Published: January 2019

The 30 apple (Malus domestica Borkh.) rootstock candidates selected for cold hardiness, known as the Kentville Stock Clone (KSC), with `McIntosh' and `Delicious' as scion cultivars, were compared at 11 years of age for tree size, weight, fruit yield, and crop efficiency under field conditions. Trunk cross-section area and tree weight were highly correlated. Tree size was similar for the two cultivars in most cases and ranged in size from semidwarf to very vigorous. Cumulative yield efficiencies varied by nearly two-fold and were not correlated with tree size. The most efficient rootstocks were KSC 28, KSC 7, and KSC 6 in the semidwarf, semivigorous, and vigorous size classifications, respectively.
Optical Properties of Plastic Mulches Affect the Field Temperature Regime
Authors: Ham Jay M. , Kluitenberg G.J. , Lamont W.J.
Published: January 2019

Research was conducted to determine the optical properties of eight plastic mulches and evaluate their effects on soil, mulch, and air temperatures in the field. Optical properties of the mulches were measured in the laboratory in the shortwave (0.3 to 1.1 μm) and longwave (2.5 to 25 μm) wavebands using a spectroradiometer and Fourier transform infrared spectrophotometer, respectively. Additionally, each mulch was installed on a fine sandy loam soil near Manhattan, Kan. Air and soil temperatures were measured 5 cm above and 10 cm below the surface, respectively. Measurements of longwave radiation emitted and reflected from the surface were used to approximate the apparent temperature of the surface. Shortwave transmittance of the mulches ranged from 0.01 to 0.84, and shortwave reflectance ranged from 0.01 to 0.48, with the greatest reflectance from white and aluminized mulches. Infrared transmittance ranged from 0.87 for a black photodegradable mulch to 0.09 for aluminized material. Air temperatures at 5 cm were similar for all mulch treatments, but were typically 3 to 5C higher than the air at 1.5 m during the day. Midday soil temperatures were highest beneath mulches with high shortwave absorptance (black plastics) or those with high shortwave transmittance coupled with low longwave transmittance. Apparent surface temperatures approached 70 to 80C during midday, with the highest temperatures occurring on mulches with high shortwave absorptance. For some mulches, both, shortwave and longwave optical properties of the plastic governed the level of radiative heating. Our results suggest that conduction of heat between the plastic and the soil surface also affects the extent of soil heating in a mulched field.
Production Method Affects Growth and Post-transplant Establishment of `East Palatka' Holly
Authors: Harris J. Roger , Gilman Edward F.
Published: January 2019

Growth and physiological responses before and after transplanting to a simulated landscape were studied for `East Palatka' holly (Ilex ×attenuata Ashe `East Palatka') grown in plastic containers (PC), in the ground in fabric containers (FC), or in the ground conventionally. At the end of a 15-month production period, trees grown in PC had more shoot dry weight and leaf area than trees grown in FC, and they had thinner trunks than field-grown trees. Root balls on harvested field-grown trees contained 55% and those grown in FC 65% of total-tree root surface area. Trees transplanted from FC had the lowest predawn leaf xylem potential and required more frequent post-transplant irrigation than trees grown in PC or in the ground. Carbon assimilation rate and stomata1 conductance in the first week after transplanting were highest for trees planted from PC. Dry weight of regenerated roots was similar for all production methods 4 months after transplanting from the nursery, but trees grown in PC had SO% more regenerated root length, and the roots extended further into the back-fill soil.
Application of Calcium to Soil and Cultivar Affect Elemental Concentration of Watermelon Leaf and Rind Tissue
Authors: Scott W. Dennis , McCraw B. Dean , Motes James E. , Smith Michael W.
Published: January 2019

Field experiments were conducted to quantify the effect of Ca supplied as gypsum in factorial combination with watermelon [Citrullus launatus (Thumb) Matsum and Nakai] cultivars Charleston Gray, Crimson Sweet, and Tri-X Seedless on yield and the elemental concentration of leaf and rind tissue. Also, the effect that ontogenetic changes and sectional differences had on the elemental concentration in rind tissue was investigated. The experiments were conducted at two locations in Oklahoma. Yield was not affected by Ca; however, mean melon weight was reduced at 1120 kg Ca/ha. Leaf Ca concentration increased linearly in response to Ca rate. `Tri-X Seedless' had lower leaf Ca and higher K concentrations than did `Charleston Gray' or `Crimson Sweet'. Fruit ontogeny (days from anthesis) and melon section (blossom or stem-end) interacted to affect elemental concentrations in the rind tissue. There was also a significant genotypic effect on elemental concentration in rind tissue. Increasing rates of Ca applied to soil reduced the incidence of-blossom-end rot (BER) in `Charleston Gray' melons. Calcium treatment did not affect flesh redness or soluble solids concentration (SSC) of watermelon.