bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrology of Horticultural Substrates: III. Predicting Air and Water Content of Limited-volume Plug Cells
Authors: Milks Robert R. , Fonteno William C. , Larson Roy A.
Published: August 2022

Plants grown in small containers often show limited growth due to low levels of aeration and water holding capacity in the medium. These levels can be changed by management practices such as medium compaction, medium wetness at time of container filling, container height and volume, peat : vermiculite ratio, particle size, and the use of a wetting agent. A modified equilibrium capacity variable model was applied to an investigation of media-container interactions for short containers (<5 cm tall). Predicted volume percentages for total porosity (TP), container capacity (CC), air space (AS), unavailable water (UW), and available water (AW) were developed from measured moisture retention data and container geometry. AS increased with: 1) increased particle size, 2) increased media moisture at time of container filling, 3) decreased medium compaction, 4) increased wetting agent concentration, 5) decreased ratio of peat : vermiculite, and 6) increased container height. Increased percent AW resulted from smaller particle size, increased media moisture at time of container filling, decreased container compaction, decreased wetting agent concentration, increased ratio of peat : vermiculite and decreased container height.
Economic Analyses of Space Management Practices In High-density Pecan Groves
Authors: Witt Harvey J. , Allison John R. , Daniell Jeff W.
Published: August 2022

A growth equation and a yield relationship were calculated to estimate space requirements and yields of two pecan cultivars (Carya illinoensis (Wangenh.) C. Koch]. The resulting estimates were used with pruning cost estimates in a simulation model to determine the orchard space management practice that maximizes income over time. The income maximizing spacings were 10.7 × 10.7 m and 13.7 × 13.7 m for the precocious ‘Desirable’ and the non-precocious ‘Stuart’, respectively. Annual pruning after the canopy closed produced the highest income for both cultivars.
Herbicide Treatment of Container-grown ‘Gloria’ Azaleas and ‘Merritt Supreme’ Hydrangeas
Authors: Moore Barbara Auxier , Larson Roy A. , Skroch Walter A.
Published: August 2022

Dormant budded plants of ‘Gloria’ azaleas (Rhododendron obtusum, Planch) and ‘Merritt Supreme’ hydrangeas [Hydrangea macrophylla (Thunb.) Ser.], and vegetative summer stock of ‘Gloria’ azaleas, were treated with various rates of chlorimuron, imazaquin, oxyfluorfen, and chloramben. Chlorimuron minimally injured both greenhouse crop species, but 0.14 kg a.i./ha was necessary to provide >70% preemergence control of the broadleaf weed species in peat-based or bark-based soilless media. Large crabgrass [Digitaria sanquinalis (L.) Scop.], redroot pigweed (Amaranthus retroflexus L.), Pennsylvania bittercress (Cardamine pensylvanica Muhl. ex. Willd.), common chickweed [Stellaria media (L.) Vill.], yellow woodsorrel (Oxalis stricta L.), and creeping woodsorrel (Oxalis corniculata L.) were the weed species tested. Imazaquin provided excellent control of all weed species at 0.56 kg a.i./ha for 14 weeks, but was phytotoxic to vegetative azaleas in both growing media. No difference in damage was detected when applications were made immediately after repotting and pinching or after 1 month of growth. Oxyfluorfen provided excellent control of all weed species for 4 weeks at 2.2 kg a.i./ha and, on all species except chickweed, for 14 weeks at 4.5 kg a.i./ha with no phytotoxicity to azaleas or hydrangeas for media drench applications. Chloramben drench and foliar spray applications at 6.7 kg a.i./ha injured vegetative azaleas regardless of application time. Foliar and drench applications of chloramben at 3.4 kg a.i./ha produced slight to moderate injury on vegetative azaleas. More injury resulted when applications were delayed until 4 weeks after pinching. Chloramben was not toxic to either dormant-budded species. Chemical names used: 2-((4[4-chloro-6-methoxypyrimidine-2yl)amino carbonvl]amino sulfonyl))benzoic acid, ethyl ester (chlorimuron); 2-[4,5-dihydro-4-methyl-4-(1-methyl-ethyl)-5-oxo-1H-imidazol-2yl]-3-quinolinecarboxylic acid (imazaquin); (2-chIoro-l-(3-ethoxy-4-nitrophenoxy)-4-(trifIuoromethyl) benzene (oxyfluorfen); 3-amino-2,5-dichloro-benzoic acid (chloramben).
Harvest Method and Sulfur Dioxide Influence the Postharvest Quality of ‘Noble’ and ‘Stover’ Wine Grapes
Authors: Sims Charles A. , Johnson Richard P. , Bates Robert P. , Moore Linda F.
Published: August 2022

Hand- and machine-harvested ‘Stover’ (a white Euvitis hybrid) and ‘Noble’ (a red Vitis rotundofolia cultivar) grapes were either treated with 100 mg SO2/kg (applied as potassium metabisulfite, K2S2O5) or not treated and held at ambient temperature (≈25°C) for 0, 24, and 48 hr after harvest. Raw fruit and wine quality from each treatment were evaluated. ‘Noble’ grapes of all treatments held for 24 hr had developed signs of microbial spoilage, and the machine-harvested grapes held without SO2 had the most. However, only the machine-harvested ‘Stover’ grapes held without SO2 had began to deteriorate during 24 hr. Grapes of both cultivars had deteriorated after 48 hr, but SO2 limited the deterioration of both machine- and hand-harvested grapes. In general, machine-harvested grapes deteriorated to a greater extent than hand-harvested grapes. Wines made from ‘Noble’ grapes that had been held for 0 or 24 hr had similar quality, but machine-harvested ‘Stover’ grapes held for 0 to 24 hr without SO2 produced a poorer wine than the other treatments. Wines from machine-harvested grapes held for 48 hr had poorer quality than wines from hand-harvested grapes. Postharvest additions of SO2 improved the quality of wine from machine-harvested but not hand-harvested fruit held for 48 hr.
Wound Healing and Weight Loss of Sweet Potatoes Harvested at Several Soil Temperatures
Authors: Walter William M. , Hammett Larry K. , Giesbrecht Francis G.
Published: August 2022

Roots of three sweet potato [Ipomoea batatas (L.) Lam] cultivars, Centennial, Jewel, and Pope, were harvested at three soil temperature ranges, cured for 1 to 7 days at 30°C and 90% to 95% RH, and stored at 13° to 13.5° and 90% and 95% RH. Wound healing during curing was evaluated using a rapid color test and histochemical methods. The color test was a good indicator of the lignification phase of wound healing for ‘Centennial’ and ‘Jewel’, and a fair indicator for ‘Pope’. Wound healing rates for the cultivars were similar. Roots harvested from the warmest soils (22° to 25°) had higher color scores (most wound lignification) up to 3 days of curing. After 5 days, there were ≈2.7 layers of lignified cells and one layer of wound periderm. After 16 weeks of storage, roots harvested at soil temperatures of 10° to 12° and 22° to 25° had lost more weight and developed more rots than did roots harvested at 15° to 17°, despite the fact that wound healing progress was similar. Thus, factors other than wound healing strongly influence storage stability.
Pecan Production Responds to Root Carbohydrates and Rootstock
Authors: Wood Bruce W.
Published: August 2022

The problematic alternate-bearing characteristic of pecan [Carya illinoensis (Wangenh.) C. Koch] has prompted an investigation of the role of rootstock and carbohydrate concentrations in tree organs in relation to nut production. Six years of data on the influence of open-pollinated pecan rootstocks on in-shell nut production by 80- year-old trees of ‘Stuart’ of ‘Schley’ scion cultivars provide evidence that rootstocks may influence yield, yield efficiency, and alternate bearing and that yield is closely associated with January root starch concentrations. Several “superior” trees, possessing greater-than-average nut yields and less-than-average alternate-bearing intensity, were identified as candidates for improved pecan rootstocks, indicating a projected frequency of ≈5% for the occurrence of superior rootstocks.
Development Rate during Four Phases of Chrysanthemum Growth as Determined by Preceding and Prevailing Temperatures
Authors: Karlsson M. G. , Heins R. D. , Erwin J. E. , Berghage R. D.
Published: August 2022

Time required to complete four developmental phases in chrysanthemum ‘Bright Golden Anne’ (Dendranthema grandiflora Tzvelev.) was determined under greenhouse conditions at constant temperature setpoints of 10, 15, 20, 25, 30, or 20 day/16C night. The four developmental phases were: I—start of short days to visible bud (2-mm-diameter terminal flower bud), II—visible bud to disbud (10-mm-diameter terminal flower bud), III—disbud to color (flower bud showing first color), and IV—color to flower. Plants either remained at the same temperature during all four phases or were moved to one other constant temperature regime after phase I, II, or III. Fastest development during all phases occurred at 20 day/16C night or constant 20C. Temperature of previous phases had less of an effect on future phases as plant development progressed. Low temperature (10C) during phase I delayed development in phase II, and high temperature (30C) during phase I and II delayed development during phase III. The length of each phase could be predicted based on the temperature preceding and during the phase. Optimum temperatures for fastest development during the four phases were calculated as 21.3, 20.3, 23.1, and 19.1C, respectively.
Paclobutrazol, Gibberellin, and Cytokinin Effects on Growth, Development, and Histology of Apple Pedicels and Fruits
Authors: Privé Jean-Pierre , Elfving D. C. , Proctor J. T.A.
Published: August 2022

The effects of the plant growth regulators (PGR) gibberellins A4+7 (GA4+7; 25, 50, and 150 mg·liter−1), BA (25 mg·liter−1), and GA4+7 + BA (Promalin; 25 mg·liter−1) on pedicel growth and fruit development of ‘McIntosh’ and ‘Spartan’ apple (Malus domestica Borkh.) trees previously treated with foliar- or soil-applied paclobutrazol (PBZ) were examined. By full bloom, pedicels had completed the elongation growth phase regardless of treatment. Pedicel length was very sensitive to PBZ treatment since it was reduced logarithmically in response to dose. No differences in pedicel diameters were found. PBZ decreased fruit fresh weight, dry weight, and fruit length and diameter in both ‘McIntosh’ and ‘Spartan’ trees. The adverse effects of PBZ carryover on fruit-quality factors such as size and pedicel length were not overcome with GA4+7 (25 or 50 mg·liter−1), BA, or Promalin (25 mg·liter−1) applied when the king-bloom was in full bloom. Reversal of PBZ-induced pedicel length inhibition was only observed with GA4+7 (150 mg·liter−1) applied prior to the main period of pedicel elongation. BA alone had no effect on any fruit growth parameters. PBZ reduced pedicel and fruit cell length, while GA4+7 (150 mg·liter−1) applied at 2 weeks before full bloom increased pedicel cell length. Chemical names used: β-[(4-chIorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazol-1-ethanol (paclobutrazol); N-(phenylmethyl)-1H-purine-6-amine (BA); (1α,2β4aα,4bβ,10β)-2,4a,7-trihydroxy-1-methyl-8-methylenegibb-3-ene-l,10-dicarboxylic acid l,4a-lactone (GA4+7).
Carbohydrate Changes of Easter Lilies during Growth in Normal and Reduced Irradiance Environments
Authors: Miller William B. , Langhans Robert W.
Published: August 2022

Changes in carbohydrate types and quantities in the bulbs, stems, leaves, and buds of Easter lilies (Lilium longiflorum Thunb. ‘Nellie White’) forced under ambient or reduced irradiance conditions were investigated. Analysis by high-performance liquid chromatography (HPLC) revealed that sucrose is the dominant soluble carbohydrate in bulb tissues, with glucose, fructose, and mannose present at significantly lower concentrations. During growth of the flowering shoot, mother bulb reserves are preferentially used regardless of greenhouse irradiance. Beginning 40 days after planting, there was a steady decrease in mother bulb starch concentration until anthesis, 70 days later. Increased bulb sucrose, glucose, mannose, and fructose concentrations were correlated with the induction of starch breakdown and carbohydrate export. Under natural greenhouse irradiance conditions, daughter bulb carbohydrate reserves were not used, as starch and soluble carbohydrate concentrations remained constant. Irradiance reductions of 50% to 85% significantly reduced total carbohydrate concentration in leaves and floral buds and induced export from the daughter bulb, as evidenced by elevated levels of daughter bulb soluble carbohydrates and reductions in starch concentration. Dark-grown plants exhibited similar daughter bulb carbohydrate metabolism patterns as plants grown in full sun: starch was not hydrolyzed and soluble carbohydrates did not increase in concentration. Collectively, these results suggest 1) bulb export metabolism is characterized by elevated soluble carbohydrate concentrations, 2) there is a minimum irradiance requirement for carbohydrate export processes from the daughter bulb, and 3) reductions in greenhouse irradiance result in reduced carbohydrate levels in Easter lily leaves and flower buds.
Spectrophotometric Measurement of Leached Phenolic Compounds as an Indicator of Freeze Damage
Authors: Chalker-Scott L. , Fuchigami L. H. , Harber R. M.
Published: August 2022

Rhododendron leaf disks (Rhododendron L., cv. Jean Marie de Montague) release water-soluble phenolic compounds when subjected to lethal freezing stress. Following low-temperature exposure, the levels of phenolic compounds leached from the disks are assessed by spectrophotometric measurement (260 nm). The increase in phenolics is highly correlated with other viability tests—electrolyte leakage, visual browning, ethane production, and TTC reduction have r values of 0.99, 0.99, 0.95, and −0.88, respectively. Chemical names used: Trichloroacetic acid (TCA), polyvinylpolypyrrolidone (PVPP), 2,3,5-triphenyl tetrazolium chloride (TTC).
Inheritance of Potassium Efficiency, Sodium Substitution Capacity, and Sodium Accumulation in Tomatoes Grown Under Low-potassium Stress
Authors: Figdore Scott S. , Gabelman W. H. , Gerloff G. C.
Published: August 2022

One hundred tomato (Lycopersicon esculentum Mill.) strains were grown under low-K stress (0.071 mm K) in the absence and presence of added Na to identify strain differences in efficient K use, efficient substitution of Na for K, and upper leaf Na accumulation. Five strains, selected as representing extreme differences for K efficiency and Na substitution capacity, were used as parents to create a series of F1, F2, and backcross generations to study the inheritance of K efficiency, Na substitution, and upper leaf Na accumulation of tomatoes grown under low-K stress. Reciprocal differences in the F1 generation were relatively unimportant in the inheritance of K efficiency, Na substitution capacity, and Na accumulation. K efficiency in the absence of Na was a trait of low heritability, with highly significant additive, dominance, and additive × additive epistatic effects. Na substitution capacity was highly heritable, with highly significant additive and dominance effects. Na accumulation also was highly heritable, with highly significant additive effects. Moderately high correlations were observed between Na accumulation and Na substitution capacity within genetically segregating generations.
Combining Ability Analyses of Fruit Yield and Quality in Near-homozygous Lines Derived from Cucumber
Authors: Fredrick Linda R. , Staub Jack E.
Published: August 2022

Combining ability estimates for characters relating to yield and fruit quality were undertaken to determine if lines derived from Cucumis sativus var. hardwickii (R.) Alef. (hardwickii) could be used in the development of higher-yielding commercial cucumbers. General and specific combining ability estimates were obtained in a North Carolina Design II experiment for nine near-homozygous processing cucumber (Cucumis sativus L.) lines, five of which were derived from hardwickii germplasm. Lines were evaluated under two planting densities (29,000 and 58,000 plants/ha) for three harvests, and environments sampled were two planting times (2 weeks apart within the same year). Traits evaluated included fruit number per plant, primary lateral branch number, percentage of pistillate flowers, days to anthesis, fruit length, and fruit length : diameter (L:D) ratio. General combining ability (GCA) mean squares were significant at both planting densities for all traits when combined over planting times, except for fruit L:D ratio at the higher density. Specific combining ability mean squares were significant for days to anthesis. Of the lines evaluated, WI 2963 and 4H261 produced the greatest GCA female and male effects, respectively, for three harvest yield and primary lateral branch number, but the lowest effects for fruit size. Our results suggest that further selection within these high-performance hardwickii derivatives for fruit shape will produce lines that perform well at a high planting density when crossed with sativus lines having good general combining ability.
Morphogenic Responses to Propagule Trimming, Spectral Irradiance, and Photoperiod of Grapevine Shoots Recultured in Vitro
Authors: Chée R. , Pool R. M.
Published: August 2022

In an effort to improve grapevine micropropagation, shoot proliferation and rooting in response to explant preparation and incubation conditions were investigated. The explants were three- to four-node shoots (15 mm) of the Vitis hybrid ‘Remaily Seedless’ cultured in vitro. The factors considered were white light of diverse spectral irradiance distributions, blue light, red light, 10-hr light/14-hr dark and 16-hr light/8-hr dark photoperiods, and leaf and/or apex removal from the explant. In white light and short days, leaf and/or apex removal did not affect shoot production; however, more shoots of at least three nodes, the desired size for micropropagation, were produced when leaves were retained. Shoot production was significantly greater in blue than in red light. Differences in shoot production in white lights of various spectral irradiance distributions were attributed to differences in blue : red irradiance ratios. Shoot production was greater with ratios of 0.6 to 0.9 than with lower and higher ratios. A greater percentage of subcultured shoots rooted in long days and red light than in blue or white light. The number of roots produced per shoot, and total root length, were also greater in red light.
Root-zone Temperature Affects Water Status and Growth of Red Maple
Authors: Graves William R. , Dana Michael N. , Joly Robert J.
Published: August 2022

Red maple (Acer rubrum L.) plants were evaluated for their responses to 5 weeks of constant root-zone temperatures from 18 to 36C. Shoot lengths of plants grown with 18 to 30C root zones did not differ significantly from one another at any time during the study, and shoot dry weights of these plants were similar. However, after 21 days of exposure, shoot length of plants grown with roots at 36C was significantly less than that of plants with roots grown at 30C and below. Leaf area was greatest among plants with roots at 24C, and mean shoot and root dry weights of plants in the 36C treatment were 57% and 68% less, respectively, than those for plants with roots at 30C. Leaf diffusive resistance of plants grown at 36C was five times greater than for plants with root zones at 30C or below. Shoot water potential decreased with increasing temperature, but increased solute concentration in leaves of 36C-grown plants probably contributed to turgor maintenance.
Stimulation of “Hydrangea Distortion” Through Environmental Manipulations
Authors: Bailey Douglas A. , Hammer P. Allen
Published: August 2022

Plants of Hydrangea macrophylla Thunb. were grown in various environments to identify factors responsible for the appearance of malformed hydrangea leaves and to screen cultivars for tolerance to the foliar disorder. Ambient temperature, photosynthetic photon flux (PPF), and root system temperature were studied. Hydrangea leaf malformation is under thermal control and can be stimulated by ambient temperatures of 33/26C (light/dark), but these must be maintained to sustain the development of distorted foliage. Placement of plants with malformed leaves into a 26/22C (light/dark) environment resulted in subsequent development of typical leaves. A PPF of 506 μmol·s−1·m−2 resulted in a more rapid appearance of distorted leaves than a PPF of 224 μmol·s−1·m−2. Reducing the root system temperature below the ambient level of 32/28C to 20/18C (light/dark) reduced, but did not prevent, the development of malformed leaves. ‘Blau Donau’ and ‘Tricolor’ did not develop malformed foliage during 22 weeks of growth at 32/26C (light/dark). ‘Rose Supreme’, ‘Merritt's Supreme’, ‘Rosa Rita’, and ‘Dr. Bernard Steiniger’ had developed malformed leaves by week 8 of treatment. For ‘Rose Supreme’ and ‘Blau Donau’, leaves developing at the higher temperatures had shorter and narrower laminae, less fresh weight and surface area, and more dry weight per unit area than plants at the lower temperatures. Laminae developing at the higher temperatures were thicker due to an increase in adaxial palisade parenchyma tissue. Malformed ‘Rose Supreme’ leaves had fewer intercellular spaces than normal leaves and lacked an observable spongy parenchyma layer. However, laminae of ‘Blau Donau’ leaves developed a distinct, yet thinner, spongy parenchyma layer at the higher than at the lower temperatures; intercellular spaces were still prevalent in the spongy parenchyma layer at the higher temperatures.
Quality of Nectarines Stored in Insecticidal Low-O2 Atmospheres at 5 and 15C
Authors: Smilanick Joseph L. , Fouse David C.
Published: August 2022

The quality of several California-grown nectarine cultivars stored in 0.5% O2 (balance N2) at 5 and 15C for up to 12 days was investigated to determine their utility in control of insects. Treatment in 0.5% O2 for 3 days at 15C caused abnormal ripening, suppressed ethylene production, elevated ethanol and acetaldehyde contents, and increased internal browning. Treatment in 0.5% O2 for 6 days at 5C caused similar injuries, but these were less severe than those at 15C. Pre-softening in air or post-treatment storage for 2 weeks at 2.5C did not reduce the injuries induced by the 0.5% O2 treatment. Since these fruit were damaged after only 3 days’ treatment at 15C, the atmospheres used to control insects probably cannot be tolerated by nectarines. Increased alcohol content and reduced ethylene production were the most sensitive indicators of controlled atmosphere-induced changes.
Enzymes of Sugar and Acid Metabolism in Stored ‘Valencia’ Oranges
Authors: Echeverria Ed , Valich John
Published: August 2022

The activities of key enzymes of sugar and acid metabolism were measured in desalted protein extracts from ‘Valencia’ oranges [Citrus sinensis (L.) Osb.] at 0, 3, 6, and 9 weeks of storage at 15C to investigate the relationship between the activities of gluconeogenic and glycolitic enzymes with postharvest changes in sugars and organic acids. Fructose-1,6-bisphosphatase (regulatory enzyme of the gluconeogenic pathway) activity was present throughout storage. Activities of the enzymes of acid metabolism (malic enzyme, isocitrate dehydrogenase/aconitase, and alcohol dehydrogenase) either increased during the first 3 weeks (malic enzyme) or remained constant during storage. Activity of enzymes involved in sugar catabolism (hexokinase, sucrose synthase, UDPG pyrophosphorylase, and PPi-dependent phosphofructokinase) increased during storage. These enzymes are necessary for organic acid use and for the subsequent oxidization of sugars in harvested sweet oranges.
Tomato Plant Photosynthetic Activity as Related to Canopy Age and Tomato Development
Authors: McAvoy Richard J. , Janes Harry W.
Published: August 2022

Tomato plants (Lycopersicon esculentum Mill. cv. Laura), pruned to a single-flower truss, were exposed to 90 μmol·s−1·m−2 supplemental photosynthetic lighting (0400 to 2200 hr) during the developmental period: a) anthesis to initial fruit set, b) anthesis to mature-green fruit, or c) anthesis to red-ripe fruit. The yield response was compared to plants receiving d) no supplemental photosynthetic lighting after incipient anthesis. The greatest increase in average fruit weight was produced with continued supplemental lighting during the developmental-period initial fruit set to the mature-green stage. Net photosynthetic activity, μmol CO2/min per dm2, was the greatest in the canopy during early anthesis and then steadily declined as the canopy aged. Net whole plant photosynthetic activity, μmol CO2/min per plant, increased steadily after the early anthesis stage of development to a peak rate during the rapid fruit development stage. Net whole plant photosynthetic activity then declined as the plant approached the mature-green and then finally the red-ripe stage of fruit development.
Seasonal Soil Waterlogging Influences Water Relations and Leaf Nutrient Content of Bearing Apple Trees
Authors: Olien William C.
Published: August 2022

Bearing ‘Macspur’/M.26 apple trees (Malus domestica Borkh.) were grown in plastic-lined basins under orchard conditions. Four treatments were imposed in each of 3 years consisting of controls and 6-week periods of soil waterlogging in the spring, summer, or fall. Stomatal conductance (gs), transpiration rate (E), leaf water content (LWC), and stem water potential (ψstem) were measured at the end of each waterlogging period. Stomatal conductance was significantly reduced by spring and summer waterlogging, but not by fall waterlogging. Reduction in g, and E generally increased over years. Stem water potential after spring and fall waterlogging averaged 8% less negative than controls in all 3 years, with no trend over the 3 years. In contrast, of summer-waterlogged trees was unaffected, 45% was more negative, and 31% less negative than controls in the first, second, and third year of treatment, respectively. Annual reductions in growth and yield due to the waterlogging treatments were related to decreased gs and to both negative and postive changes in ψstem. Leaf levels of N, P, K, and Cu measured in July were reduced only by summer waterlogging, with no trend in reponse over years.
Control of Pink Root Disease in Onion Using Solarization and Fumigation
Authors: Hartz T. K. , Bogle C. R. , Bender D. A. , Avila F. A.
Published: August 2022

Effects of solarization and fumigation on control of pink root disease of onion (Allium cepa L.) were determined in microplot studies in 1984. A 62-day solarization treatment significantly improved stand and productivity of ‘Granex 429’ onion while decreasing pink root expression. Metam-sodium fumigation gave equivalent improvement in stand and reduction in pink root expression, while causing an even greater onion growth response. Effects of these soil disinfestation techniques in onion seedbeds on subsequent field performance of onion transplants were examined in 1985–1986. Fumigation and solarization of individual soil beds virtually eliminated Pyrenochaeta terrestris infection of onion transplants. Seedbed treatment had no beneficial effect on yield, bulb diameter, or pink root expression at harvest when transplants were grown to maturity in an infested field. Chemical name used: sodium methyldithiocarbamate (anhydrous) (metam-sodium).
Green Ash Establishment Following Transplant
Authors: Arnold Michael A. , Struve Daniel K.
Published: August 2022

Bare-root 1-year-old green ash (Fraxinus pennsylvanica Marsh.) seedlings were transplanted into root observation boxes under greenhouse conditions to study timing of budbreak, root regeneration, and subsequent shoot growth during establishment. Green ash seedlings began shoot growth before root growth. Seven to 20 days after transplant, intact second- and third-order lateral roots (referred to here after as intact roots) began to elongate, followed 10 to 19 days later by initiation of long roots from callus at pruned root surfaces. Plants with earlier budbreak were larger and regenerated more roots faster than plants that broke bud later. During establishment, there was a strong correlation between shoot and intact root elongation and a low correlation between shoot and long root elongation. Root pruning after establishment resulted in bud set and/or cessation of shoot elongation within 3 to 6 days in 1985 and within 20 to 28 days in 1986. The days to bud set and cessation of shoot elongation were positively correlated with increased numbers of regenerated roots from pruned surfaces (long roots). Only long root elongation was significantly correlated with shoot growth after root pruning. Root pruning also induced reductions (12 days) in net photosynthesis, transpiration, and stomatal conductance, and increased stomatal resistance to water loss; however, all recovered after root regeneration.
Early Harvest of Almonds to Circumvent Late Infestation by Navel Orangeworm
Authors: Connell Joseph H. , Labavitch John M. , Sibbett G. Steven , Reil Wilbur O. , Barnett William H. , Heintz Chris
Published: August 2022

Third-generation navel orangeworm (Amyelois transitella) damage to almond (Prunus dulcis Mill.) kernels is a serious problem in the California almond industry. An early harvest is one means of reducing losses and increasing crop quality. A successful early harvest was accomplished 2 to 3 weeks before the normal harvest date, with no perceptible effect on kernel quality. Percent hullsplit was correlated with nut removal, providing a field guide to acceptable maturity. Within defined limits, yield, drying rate, and hullability of early harvested almonds were acceptable.
Hydration and Temperature Influence in Vitro Germination of Pecan Pollen
Authors: Yates I. E. , Sparks Darrell
Published: August 2022

In vitro germination of freshly collected pollen from pecan [Carya illinoensis (Wangenh.) C. Koch) was examined following exposure to relative humidities (RH) of ≈5%, 50%, and 97% and temperatures of 25, 35, and 45C in a factorial experiment. Maximum germination percentage occurred as RH increased and temperature decreased. Pecan pollen stored for nearly 2 years at −80C and −196C, but not −10C, retained germination capacity equal to freshly collected pollen if stored pollen was given a period of controlled rehydration before in vitro assay for pollen tube formation. Differences in germination of pollen stored at −10C and −196C were substantiated with the fluorochromatic test procedure as well as light microscopy. Pollen removed from storage at −196C and left at ambient laboratory conditions for 59 days retained the capacity for in vitro germination.
Gibberellins A4+7 Influence Fruit Set, Fruit Quality, and Return Bloom of Apples
Authors: Greene Duane W.
Published: August 2022

Several experiments were conducted to evaluate the influence of time, concentration, and number of GA4+7 applications on ‘McIntosh’, ‘Early McIntosh’, and ‘Empire’ apples (Malus domestica Borkh.). GA4+7 at 150 mg·liter−1 increased fruit set and inhibited flower bud formation on ‘McIntosh’ and ‘Early McIntosh’. Flower bud formation was inhibited on ‘McIntosh’ when GA4+7 was applied over a wide range of times from 6 days before full bloom to 34 to 35 days after full bloom. Applications made 45 and 60 days after full bloom had no effect. Following storage, ‘Empire’ fruit treated with GA4+7 were softer and had a higher incidence of senescent breakdown than controls. Postbloom sprays of GA4+7 increased fruit set on ‘Empire’ one year when applied from 0 to 150 mg·liter−1, while two applications of 50 mg·liter−1 on similar trees in another year caused thinning. GA4+7 sprays appeared to advance ripening of ‘Empire’ apples. Gibberellin sprays reduced seed number. GA4+7 inhibited flowering in ‘Empire’. Repeat applications 19 and 34 days after full bloom were only slightly more inhibitory to flowering than one application of 0, 50, 100, or 150 mg·liter−1 made 10 days after full bloom.
Residual Effects of Controlled Atmospheres on Postharvest Physiology and Quality of Strawberries
Authors: Li Chingying , Kader Adel A.
Published: August 2022

Low O2 (2.0%, 1.0%, or 0.5%) or elevated CO2 (10%, 15%, or 20%) concentrations and their combinations reduced respiration and ethylene production rates of ‘Selva’ strawberries (Fragaria × ananassa Duch.) stored at 2C. After transfer from the various controlled atmospheres (CA) to air, respiration and ethylene production rates increased, but were still significantly lower than those of the fruits kept continuously in air. Atmospheres of 1.0% O2 + 15% CO2 and 0.5% O2 + 20% CO2 led to the accumulation of ethanol, which was still present at concentrations >100 μl·liter−1 (ppm) in strawberry juice after their transfer to air for several days. Keeping strawberries in CA had residual effects on maintaining their flesh firmness and color, but had no significant effects on skin or juice color, titratable acidity, pH, soluble solids content, and ascorbic acid content. In general, as O2 concentration was decreased or as CO2 concentration was increased, the residual effects were more pronounced. The combinations of reduced O2 and elevated CO2 had more pronounced residual effects than either reduced O2 or elevated CO2 alone. Exposures to CA for 4 days had greater residual effects than exposure to CA for 1 to 3 days.
Ripening Characteristics of a Tomato Mutant, dark green
Authors: Tong Cindy B. S. , Gross Kenneth C.
Published: August 2022

Respiration, ethylene production, firmness, polygalacturonase activity, cell wall composition, and soluble uronide content were measured during ripening of two tomato (Lycopersicon esculentum Mill.) genotypes, ‘Manapal’ and dark green (dg). Respiration rates and cell wall uronide contents of the two genotypes were similar. Climacteric ethylene production rates of dg fruit were about half that of ‘Manapal’ fruit. Firmness and polygalacturonase activity of dg tomatoes were similar to that of ‘Manapal’ fruit until 55 days postpollination, when dg fruit were twice as firm as ‘Manapal’ fruit and exhibited greater polygalacturonase activity. Soluble uronide content did not differ between the two genotypes, except at 50 days postpollination, when that of dg fruit was 60% that of ‘Manapal’ fruit. Cell wall uronide content of dg fruit was 1.5 times greater than ‘Manapal’ fruit at 55 days postpollination. Although dg fruit contained larger, absolute amounts of cell wall noncellulosic neutral sugars than ‘Manapal’ fruit, net changes in sugar composition were similar throughout ripening. Also, ratios of cell wall arabinosyl or galactosyl residues to cell wall galacturonic acid were similar in both genotypes. These data suggest that firmness differences between dg and ‘Manapal’ fruit are not due to differing activities of polygalacturonase or changes in cell wall composition during ripening, but to other factors that may affect solubilization of cell wall uronides.
Ethylene Evolution and Polyamine Accumulation by Tomato Subjected to Interactive Stresses of Ammonium Toxicity and Potassium Deficiency
Authors: Corey Kenneth A. , Barker Allen V.
Published: August 2022

Tomato plants (Lycopersicon esculentum Mill. ‘Heinz 1350’, yellow-green-5, and neglecta-1) were grown in sand culture with 15 mm or and with K+ varying from 0 to 8 mm. Other nutrients were provided at the concentrations of Hoagland's solution. The medium supplying was buffered with CaCO3 (pH 6.9) or was unbuffered (pH 3.4). Silver ions (0.01 μm) were incorporated in the nutrient solution in one experiment. Ammonium nutrition relative to nutrition elevated rates of ethylene evolution from all genotypes, but yg-5 and neg-1 showed resistance to toxicity and exhibited relatively low ethylene evolution. Ethylene evolution declined as K+ supply increased. Accelerated rates of ethylene evolution did not occur at tissue K+ concentrations >10 g·kg−1 of the dry weights of shoots with nutrition, but higher K+ levels were required with nutrition. Putrescine concentrations in leaves of ‘Heinz 1350’ supplied with were 2 to 5 times greater than in leaves of plants supplied with . Potassium deficiency increased putrescine accumulation regardless of N form. Spermidine concentrations in leaves of plants supplied with were lower than in those supplied with , whereas spermine concentrations were unaffected by treatments. ‘Heinz 1350’ grown in -based nutrient solutions with 0.01 μΜ Ag+ had low rates of ethylene evolution and developed few symptoms of toxicity. Quantities of ethylene and putrescine produced by tomato genotypes susceptible to the nutritional stresses were linked directly to the degree of stress imposed, and symptoms of toxicity were related to increased ethylene synthesis.
Light Stress Following a Frost Episode Influences the Frost Tolerance of a Wild Potato Species
Authors: Steffen Kenneth L. , Palta Jiwan P.
Published: August 2022

The effect of light stress following various levels of freezing stress on photosynthetic and respiratory functions in leaf tissue of Solanum acaule (Bitt.) was investigated under laboratory conditions. Terminal leaflets from plants grown at 18/16C (light/dark) and 400 μmol·s−1·m−2 photosynthetically active radiation (PAR) were slowly frozen in the dark to various minimum temperatures and then thawed on ice, also in the dark. Immediately after thawing, paired leaf disks were cut from a single terminal leaflet. Disks were then held at 1.0C for 3 hr, with one disk exposed to 800 μmol·s−1·m−2 PAR and the other disk of the pair was held in the dark. Our experimental approach allowed comparative studies on tissue from the same leaflet. Light during the post-thaw period, as compared to darkness, resulted in greater inhibition of photosynthetic processes, but had little effect on respiration. Our results demonstrate a) the importance of considering a light stress component during the assesment of relative frost tolerance in photosynthetic tissue and b) that chloroplast functions are much more sensitive than mitochondrial functions to a post-thaw light stress.
Interspecific Hybridization of Papaya with Other Carica Species
Authors: Manshardt Richard M. , Wenslaff Timothy F.
Published: August 2022

Interspecific hybridizations were attempted between papaya (Carica papaya L.) and six Carica taxa, including C. monoica Desf., C. parviflora (A. DC.) Solms, C. pubescens Lenne et Koch, C. quercifolia (St. Hil.) Hieron., stipulata Badillo, and C. × heilbornii Badillo nm. pentagona (Heilborn). Prezygotic barriers were minimal; pollen tubes of wild species freely penetrated into the seed cavity of papaya, and papaya pollen tubes were similarly unhindered in reciprocal pollinations on C. pubescens. Postzygotic barriers were formidable due to ovule abortion and endosperm failure. However, dissection of more than 150 C. papaya fruits 90 to 180 days after interspecific pollination yielded at least a few hybrid embryos of each species combination. All crosses in which C. papaya was the male parent failed, with the exception of C. pubescens × C. papaya, which succeeded only after young ovules were cultured 30 to 45 days after pollination. Multiple embryos were common in all successful crosses, and these were shown to be of zygotic origin by analyses of isocitrate dehydrogenase, malate dehydrogenase, and phosphoglucomutase isozymes in parental and hybrid tissues. Hybrids successfully recovered from in vitro cultures included C. papaya × C. pubescens and reciprocal, C. papaya × C. quercifolia, and C. papaya × C. stipulata.
Root-lesion Nematodes, Potassium Deficiency, and Prior Cover Crops as Factors in Apple Replant Disease
Authors: Merwin Ian A. , Stiles Warren C.
Published: August 2022

Growth chamber evaluations of soil from an orchard replant site showed severe stunting of ‘Northern Spy’ apple (Malus domestica Borkh.) seedlings grown in field soil (FS) compared with pasteurized soil (PS) from the same site. The FS : PS seedling dry weight ratio of 0.44 indicated a serious replant problem. Leaf nutrient content was generally higher in PS than FS seedlings. Multiple-regression analysis indicated that leaf K and root-lesion nematode (Pratylenchus penetrans Filipjev) primary inoculum accounted for 75% of the variation in FS seedling dry weight. Apple seedling dry weight in FS was 97% of that in PS following a marigold (Tagetes patula L. cv. Sparky) cover crop, and 75% following oats (Avena sativa L. cv. Saia). Root-lesion nematodes were nearly eliminated from the plots with marigold. Other cover crops and a weed-free fallow period were less effective in controlling apple replant disease and/or phytonematodes.
Estimation of Peach Tree Water Use Using Infrared Thermometry
Authors: Glenn D. M. , Worthington J. W. , Welker W. V. , McFarland M. J.
Published: August 2022

Infrared (IR) thermometry has not been extensively applied in deciduous tree fruit production to determine water use. The objectives of this study were to a) examine IR measurement techniques for evaluating canopy temperatures in peach [Prunus persica (L.) Batsch.] trees; b) evaluate a foliage-minus-air temperature- (Tc – Ta) based diffusion equation for vapor flux used to predict tree water use; and c) measure the Tc – Ta response of irrigated peach trees over a range of air vapor pressure deficits. The mean Tc – Ta for a tree was similar for readings made from the canopy sides (horizontal orientation of the IR thermometer) or canopy tops (vertical orientation). Peach tree water use from weighing lysimeters was predicted within 9.4% ± 3% using the diffusion equation for vapor flux. Tc – Ta for irrigated peach trees was related to the air vapor pressure deficit (VPD). Data are presented to show that stomatal response to VPD does alter the Tc – Ta nonstressed baseline for peach at VPD > 2 kPa.
Skin Permeability to Oxygen in Apples Stored in Controlled Atmosphere
Authors: Andrich G. , Fiorentini R. , Tuci A. , Galoppini C.
Published: August 2022

The skin permeability to O2-diffusion and the mass transfer equilibrium constant for ‘Super Golden Delicious’ spur and ‘Red Stark’ (Malus domestica Borkh.) have been studied using a kinetic approach. A direct proportionality between the O2-exchange initial rate and the environmental PO2 is shown by a linear regression line passing near the origin of the axes. This confirms the suitability of the adopted mass-transfer equations and allows the calculation of the two involved constants: the equilibrium mass-transfer constant and the kinetic constant, which represents a suitable measure of permeability of the apple skin. As apple-skin permeability to O2 increases with fruit ripening, to reach a maximum near the commercial harvesting time, this parameter could be used as a ripening index.
Fruit Characteristics of ‘Red Delicious’ Apple Strains during Maturation and Storage
Authors: Ingle Morris , D’Souza Mervyn C.
Published: August 2022

Firmness, soluble solids concentration (SSC), starch index, and internal ethylene concentration were measured in the ‘Starkrimson’, ‘Oregon Spur’, ‘Redchief, ‘Royal Red’, and ‘Topred’ strains of ‘Red Delicious’ apple (Malus domestica Borkh) between 130 and 150 days after full bloom (DAFB). Firmness was significantly correlated with DAFB, although there were increases and decreases between 130 and 144 DAFB. SSC increased and was correlated with DAFB. The starch index increased linearly most of the time. There were differences in starch index between the 1983 and 1984 seasons, but no consistent differences among strains. Internal ethylene concentration began to change later than the other characteristics, but was correlated with DAFB in 90% of the comparisons. Fruit attributes that were significantly correlated in 80% or more of the comparisons were firmness with starch index, SSC with starch index, and starch index with internal ethylene. Firmness was correlated with starch index in 90% of the comparisons, SSC in 85%, and internal ethylene in 60%. Superficial scald was consistently correlated only with DAFB. Changes in firmness during storage were not correlated with any of the characteristics measured.
Permeability Characteristics of Isolated ‘Golden Delicious’ Apple Fruit Cuticles with Regard to Calcium
Authors: Chamel A. R
Published: August 2022

The penetration of Ca through apple (Malus domestica Borkh) fruit cuticles was investigated using isolated cuticles. Permeability coefficients (P) and diffusion coefficients (D) were determined from self-diffusion measurements (0.1 mm CaC12) in a permeability apparatus. It was demonstrated that the apple fruit cuticles carry fixed charges with an isoelectric point of 2.1 and that Ca can penetrate into fruit directly across the fruit cuticle. Intraspecific variability was high, which is typical of cuticular permeability (P = 1.852 × 10−6 cm·s−1, sd = 1.29; D = 13.830 × 10−11 cm2·s−1, sd = 7.72, at pH 8). The permeability coefficient increased with increasing pH; this result was confirmed with isolated tomato fruit cuticles that revealed a lower permeability (P = 0.253 × 10−6 cm·s−1; sd = 0.12; D = 3.502 × 10−11 cm2·s−1, sd = 1.12, at pH 8). The permeability increased to a value about four times greater after the extraction of soluble cuticular lipids. There appears to be a direct relationship between cuticular sorption and penetration.
Rootstock and Scion Influence Growth, Productivity, Survival, and Short Life-related Performance of Peach Trees
Authors: Yadava U.L. , Doud S.L.
Published: August 2022

Fifty-nine available combinations of 16 peach [Prunus persica (L.) Batsch] seedling rootstocks and four cultivars were evaluated for survival, growth, productivity, and peach tree short life (PTSL) performance of scions for 10 years (1975–1984). Rootstock influenced tree survival, cold and bacterial canker damages, root suckering, bloom date, degree of budbreak, and fruit yield. However, rootstock had little effect on bud density, fruit maturity and size, and time of autumn defoliation, and no influence on trunk circumference and bark gummosis. Cultivars differed in all characteristics except tree survival and canker damage. Tree survival was negatively correlated with budbreak, bloom date, cambial browning, Pseudomonas canker, suckering, and defoliation. Lovell rootstock had the best overall PTSL-related performance, while Siberian C had the worst. ‘Derby’ was the most desirable and ‘Hamlet’ the least of the four cultivars evaluated.
Translocation of Triazole Growth Retardants in Plant Tissues
Authors: Reed A.N. , Curry E.A. , Williams M.W.
Published: August 2022

Translocation patterns of the triazole plant growth retardants paclobutrazol, triapenthenol, and BAS111 were found to be similar when applied as a trunk paint, soil drench, or in hydroponic systems. Chemical degradation studies indicate that the greatest percentage of parent compound is translocated to roots and mature leaves following soil drench and hydroponic treatments. Generally, residue levels of BAS111 were significantly lower than those of paclobutrazol and triapenthenol. Data from trunk paint applications indicate triapenthenol and BAS111, even at concentrations 5 times greater than paclobutrazol, are not as effective in controlling shoot growth. Significant negative correlations were found between shoot growth and foliar residue levels of paclobutrazol and triapenthenol 13 weeks after trunk paint application. Chemical names used: (2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-pentan-3-ol (paclobutrazol); (E)-(RS)-1-cyclohexyl-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)-pent-1-en-3-ol (triapenthenol); 1-phenoxy-5,5-dimethyl-3-(1,2,4-triazol-1-yl)-hexan-5-ol] (BAS111); trimethylonylpolyethoxyethanol (WK surfactant).