bluuebunny/crossref_metadata_2025 huggingface dataset:
Low Temperature Induced Azide-insensitive Oxygen Uptake in Grapefruit Flavedo Tissue
Authors: Purvis Albert C.
Published: August 2022

O2 uptake by tissues of grapefruit (Citrus paradisi Macf.) was measured using manometric Warburg techniques. The highest rate of uptake was by flavedo tissue and the lowest rate was by intact juice vesicles. O2 uptake by flavedo tissue increased exponentially when temperature increased, and the proportion of O2 uptake insensitive to azide (N3), an inhibitor of the cytochrome path, was greater at low temperatures than at high temperatures. Salicylhydroxamic acid (SHAM), an inhibitor of the alternative path, was only marginally inhibitory at all temperatures. Arrhenius-type plots of O2 uptake showed discontinuities at 12°C in the presence and absence of respiratory inhibitors. O2 uptake increased in flavedo tissue of grapefruit during the low temperature hardening of young trees. The increase was primarily in the N3-insensitive component. Low temperatures also induced N3-insensitivity in detached stored fruit, and induction was greater in chilling-resistant interior canopy fruit than in chilling-susceptible exterior fruit. Thus, N3-insensitive O2 uptake may be related to chilling resistance of sensitive fruit.
Strawberry Receptacle Growth and Endogenous IAA Content as Affected by Growth Regulator Application and Achene Removal
Authors: Archbold Douglas D. , Dennis F. G.
Published: August 2022

Parthenocarpy was induced in emasculated strawberry (Fragaria × ananassa Duch.) flowers with aqueous solutions of 10−3M NAA, GA3 or GA4+7 in 2% DMSO plus 0.1% Tween 80. All fruit except those treated with NAA stopped growing within 12 days of treatment. Repeat application with NAA or GA4+7 20 days after initial treatment stimulated continued growth of NAA-induced fruit, but had little or no effect on growth of GA4+7-induced fruit. The diameters of mature parthenocarpic fruit ranged from 70% to 90% of that of pollinated fruit. Achene removal 12 days after pollination greatly reduced subsequent growth of receptacle tissue, complete removal being more effective than partial removal. Following achene removal 16 days after pollination, treatment with aqueous solutions of NAA in 2% DMSO and 0.1% Tween 80 produced receptacles 75% the size of controls with intact achenes, but neither GA3 nor GA4+7 stimulated growth. Achene removal 24 days after pollination did not influence further receptacle enlargement. Concentration of free indoleacetic acid (IAA) in NAA-treated fruit was 5-times that in controls and 3-times that in GA4+7-treated fruit 6 days after treatment. By 14 days after treatment, the levels had declined in all treated fruit. Free IAA concentration in the receptacle tissue of intact fruit was nearly equal to or greater than that in achenes 14 days after pollination. The growth rates of receptacles were positively correlated with numbers of intact achenes and free IAA content of the receptacle. Chemical names used: naphthaleneacetic acid (NAA); gibberellins (GA3 or GA4+7); dimethylsulfoxide (DMSO)
Changes in Water Relations and Elastic Properties of Apple Fruit Cells during Growth and Development
Authors: Steudle E. , Wieneke J.
Published: August 2022

Water relations parameters of individual cells in the cortex of apple fruit (Malus domestica Borkh., ‘Cox's Orange Pippin’) were determined during 2 growing seasons between the end of June and the end of September. Apple and cell diameters doubled during this time. Cell turgor pressure (P) of sliced tissue incubated in a nutrient solution ranged between 6 and 12 bar (0.6 and 1.2 MPa). The elastic cell modulus (∈) increased with both cell turgor and cell volume. For high turgor pressures (P > 5 bar), the average values of ∈ ranged between 30 and 180 bar (3.0 and 18.0 MPa). The half-times (T1/2) for the water exchange of individual cells with their adjacent tissue increased during the seasons from 8–10 s to 20–25 s which was partly due to a decrease of the hydraulic conductivity of the cell membrane (Lp) during ripening. Lp decreased from about 3 to about 1 · 10−6cm · s−1 · bar−1 (from 3 to 1 · 10−7m · s−1 · MPa−1). The probe data allowed estimates of the diffusion coefficient for the propagation of a change in water potential, volume and turgor pressure across the tissue (Dc) · Dc ranged between 3 and 9 · 10−7 cm2 · s−1 (3 and 9 · 10−11m2 · s−1) and increased continuously during the season. The results indicate that the reduction in the elastic extensibility at the cell level (1/∈) does not correspond with the reduction of the firmness of the fruit as maturity is approached. On the contrary, the fruit become softer. Therefore, the physiological meaning of tissue Young's moduli as determined by other methods has to be questioned. The results are discussed with respect to the development of fruit disorders.
Seasonal Response of ‘Anjou’ Pear Trees to Different Irrigation Regimes. I. Soil Moisture, Water Relations, Tree and Fruit Growth
Authors: Brun Charles A. , Raese J. Thomas , Stahly Edward A.
Published: August 2022

Mature bearing pear [Pyrus communis L. ‘Beurre d’Anjou’ (‘Anjou’)] trees in an arid climate were irrigated weekly at 125% of pan evaporation (wet), biweekly at 100% of pan evaporation (normal), or irrigated only twice (dry) during the summer (1980, 1981), and were fertilized with and without 0.9 kg of supplemental N. Prior to final fruit harvest in 1981, depletion of available soil moisture (ASM) averaged 10%, 16.7%, and 89% for the wet, normal, and dry treatments, respectively. Mid-day leaf water potential (ψL) was correlated with the level of ASM only on bright days of high vapor pressure deficit. Stomatal conductance (κs) and transpirational flux density (F) of dry treatment leaves was lower than that of either wet or normal treatment leaves ψL exceeded −1.4 to −1.7 MPa. Resistance to vapor (water) transport (Rν) of fruit was independent of irrigation regime. Terminal buds had set on shoots from all 3 irrigation regimes at 58 days after full bloom (AFB) in 1981, but resumed growth on normal and wet treatment shoots at 87 days AFB. On 7 of 10 sampling dates during 1981, dry treatment fruit weighed less than normal or wet treatment fruit.
Annual Root Growth Pattern of Young Citrus Trees in Relation to Shoot Growth, Soil Temperature, and Soil Water Content
Authors: Bevington Kenneth B. , Castle William S.
Published: August 2022

The annual pattern of root growth of ‘Valencia’ orange [Citrus sinensis (L.) Osb.] trees on rough lemon (C. jambhiri Lush.) and Carrizo citrange [Poncirus trifoliata (L.) Raf. × C. sinensis] rootstocks was studied in relation to shoot growth, soil temperature, and water stress in Plexiglas-walled root observation chambers. The chambers were filled with a reconstituted profile of a fine sand soil and were installed below-ground at a field site in central Florida. The chambers periodically were raised above-ground to record root growth. Under nonlimiting soil water conditions, continuous root extension growth was evident from February to November. The overall seasonal trend in root growth was significantly correlated with soil temperature. The most intense root growth occurred when soil temperatures were above 27°C, and was limited at soil temperatures below 22°. Root growth was cyclic. During periods of shoot elongation, the number of growing roots and the rate of root elongation declined. Shoot growth was a major factor controlling the intensity of root growth when soil temperature and soil water content were nonlimiting. When the soil water content was decreased intentionally, root growth was checked at a soil matric potential of −0.05 MPa. After rewatering, there was a lag period of 2 days before root growth increased. Both number of growing roots and rate of root elongation were influenced by shoot growth, soil temperature, and soil water content; however, the growth response of the root system to these factors was mediated largely through the number of roots initiating growth. No rootstock differences were apparent in the pattern of root growth.
Growth, Carbohydrate, and Mineral Element Status of Shoot and Spur Leaves and Fruit of ‘Spartan’ Apple Trees Treated with Paclobutrazol
Authors: Steffens G. L. , Wang S. Y. , Faust M. , Byun J. K.
Published: August 2022

‘Spartan’ apple (Malus domestica Borkh.) trees were treated with paclobutrazol, a gibberellin biosynthesis inhibitor, in the spring of 1982 and again in 1983. In 1983, extension shoot and fruiting spur growth was reduced as were leaf number and area. Shoot and spur leaf chlorophyll levels were not affected. Treatment reduced fruit size and weight slightly, but firmness and soluble solids at harvest were unchanged. Sorbitol was signficantly higher in leaves from paclobutrazol-treated trees at all 4 sampling dates [78, 112, 134, and 163 days-after-full-bloom (DAFB)]. Paclobutrazol treatment had little effect on leaf fructose, glucose, and sucrose but increased starch. Treatment had no effect on apple flesh carbohydrate levels. Bud and wood carbohydrate levels in early 1984 differed at various sampling dates but overall carbohydrate metabolism during bud development appeared to be unaffected by treatment. Mineral element content of spur leaves was not affected by treatment, but shoot leaves showed significantly increased Ca levels 112 and 134 DAFB. Mineral content in apple flesh and skin was not changed by paclobutrazol treatment. Chemical name used: β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1-H-1,2,4-triazole-1-ethanol (paclobutrazol).
Chemical Treatments to Delay Bloom in Peach
Authors: Coston D. C. , Krewer G. W. , Elkner T. E. , Williamson J. G. , Sims E. T.
Published: August 2022

CGA-15281 applied in the fall delayed bloom in peach (Prunus persica L. Batsch) by 4–9 days without damage to the trees. The length of the delay was cultivar and concentration dependent. Fall ethephon applications (500 ppm) damaged trees severely, but delayed bloom 10–18 days, whereas 125 or 250 ppm ethephon caused little tree damage and delayed bloom 3–5 days. Bloom delay from application of ethylene-generating compounds resulted from both prolonging rest and slow bud development once rest was complete. Daminozide applied in January caused bloom delay in 1983 but not in 1984. Silver nitrate had little effect on bloom delay or blossom density at any time of application. Dimethipin and merphos applications in late summer caused defoliation and reduced blossom density, but did not affect date of bloom. Thidiazuron did not induce defoliation or delay in bloom, but greatly reduced blossom density. Chemical names used: (2-chloroethyl)methylbis(phenylmethoxy)silane (CGA-15281); (2-chloroethyl) phosphonic acid (ethephon); butanedioic acid mono (2,2-dimethylhydrazide (daminozide); 2,3-dihydro-5,6-dimethyl-1,4-dithiin 1,1,4,4-tetraoxide (dimethipin); N-phenyl-N′-1,2,3-thiadiazol-5-ylurea (thidiazuron); Tributyl phosphorotrithioite (merphos).
Remobilization of Nonstructural Carbohydrates from Vegetative Tissues to Fruits in Tomato
Authors: Hewitt J. D. , Marrush M.
Published: August 2022

Soluble sugar and starch levels were measured in leaf, stem, and petiole tissues of 3 tomato (Lycopersicon esculentum Mill.) cultivars throughout plant development in order to 1) assess the contribution of reserve carbohydrates to final fruit yield and quality and 2) determine whether genotypic variation exists for this trait. In all 3 cultivars — ‘VF145B-7879’ (‘7879’), ‘UC82’ (‘82’), and ‘BL6807’ (‘6807’) — leaf tissue was found to accumulate high levels of both soluble sugars and starch. Stem and petiole tissues, although having high sugar content, accumulated little starch. An estimate of the proportion of fruit dry weight attributable to remobilization of nonstructural carbohydrate (NSC) from vine tissue was made by determining the dry weight of sugars and starch lost from vegetative tissue once the vine had ceased gaining weight and dividing by the final fruit dry weight. Values for ‘6807’ and ‘7879’ were 4.8% and 0.3%, respectively. No remobilization of NSC was apparent in ‘82’. The primary remobilized carbohydrate was leaf starch in both ‘6807’ and ‘7879’. Leaf and stem sugars were also remobilized in ‘6807’. The relatively high degree of remobilization in ‘6807’ was associated with early maturity and a high fruit/leaf ratio.
Reduction of Initial Plagiotropic Growth of Softwood Fraser Fir Cuttings
Authors: Wise Farrell C. , Blazich Frank A. , Hinesley L. Eric
Published: August 2022

Timing of severance, auxin treatment, and staking were evaluated for their effects on reducing abaxial-concave bending of softwood Fraser fir [Abies fraseri (Pursh) Poir.] stem cuttings. Cuttings collected 21 July 1983, were much less plagiotropic after a 135-day rooting period than those collected 3 weeks earlier. This upright habit was related to stronger internal support from increased amounts of xylem and lignified pith at severance. Staking also reduced abaxial-concave bending, but postseverance auxin treatment had no effect. Stakes apparently provided external support until stems became lignified. Nonstaked cuttings collected 30 June 1983 continued to exhibit greatest bending at the end of the 2nd growing season. Basal defoliation and wounding in preparation for rooting increased plagiotropic growth and reduced survival during rooting, but did not affect the percentage of rooting. Evaluation of xylem distribution indicated that abaxial-concave bending in the 2nd season was caused by greater production of compression wood and total xylem on adaxial than on abaxial sides of the original cutting segments.
Water Relations, Growth, and Yield in Two Snap Bean Cultivars Infected with Root Knot Nematode, Meloidogyne hapla (Chitwood)
Authors: Wilcox D. A. , Loria R.
Published: August 2022

Seedlings of snap bean (Phaseolus vulgaris L.) ‘Strike’ and ‘Kentucky Wonder’ were inoculated with 0, 6,000, 12,000, or 18,000 Meloidogyne hapla (Chitwood) larvae/pot. Leaf xylem potential, stomatal conductance, transpiration, root hydraulic conductivity, leaf area, and plant weight were measured 4 weeks after inoculation. In a 2nd experiment, inoculated plants were grown for 7 weeks to obtain yield data. Leaf area, xylem potential, and yield were significantly reduced by nematode infection. The 2 cultivars differed in their response to M. hapla. Yield was reduced more at high nematode populations in ‘Kentucky Wonder’ than in ‘Strike’. This differential response also occurred with xylem potential. There was a trend toward decreased hydraulic conductivity in infected ‘Kentucky Wonder’, but not ‘Strike’ roots. Cultivar tolerance in beans appears to be related to the effects of nematodes on plant water relations.
Changes in Cytoplasmic and Vacuolar pH in Harvested Lettuce Tissue as Influenced by CO2
Authors: Siriphanich Jingtair , Kader Adel A.
Published: August 2022

‘Climax’ lettuce (Lactuca sativa L.) exhibited more severe CO2 injury symptoms than ‘Salinas’ and ‘Winterhaven’ lettuce when exposed at 20°C to air for 1 day following treatment for 6 days at 0° with 15% CO2 in air. All 3 cultivars, however, had similar decreases as revealed by NMR analysis, of about 0.4 and 0.1 pH units in the cytoplasm and vacuole, respectively. This result indicates that variation in the buffering capacity was not related to differences in susceptibility to CO2 injury among these cultivars. Although CO2 reduced pH, it also reduced titratable acidity of lettuce tissue. This change resulted in a higher pH when the lettuce was moved to air. Exposure of lettuce at 0° to light reduced CO2 injury by about 50% relative to tissue kept in the dark. Lettuce tissue kept in air had a higher glucose-6-phosphate content than the CO2-treated lettuce. A hypothesis regarding alternate energy supply mechanisms for resistance of lettuce tissue to elevated CO2 injury is discussed.
Calcium Hydroxide Reduces Splitting of ‘Lambert’ Sweet Cherry
Authors: Callan Nancy W.
Published: August 2022

Preharvest applications of Ca(OH)2 reduced splitting of ‘Lambert’ sweet cherry (Prunus avium L.) in laboratory trials. Three sequential preharvest sprays of Ca(OH)2 consistently reduced splitting, while single sprays of Ca(OH)2 in combination with NAA, ethephon, or B were moderately effective. Ca(OH)2 was a more effective Ca source than CaCl2 for reduction of splitting. Ca applications did not affect fruit size, but 3 applications of Ca(OH)2 increased fruit soluble solids. Chemical names used: (2-chloroethyl)phosphonic acid (ethephon) and 1-naphthaleneacetic acid (NAA).
Soil Cultivation and Incorporation Effects on the Edaphic Properties of Turfgrass Thatch
Authors: Danneberger T.K. , Turgeon A.J.
Published: August 2022

Cultivation practices have been used to control thatch, principally by removal of organic constituents and by incorporation of soil to promote decomposition of the organic residues. The purpose of this study was to determine the influence of soil incorporation on the edaphic properties of turfgrass thatch. Field studies were performed on 2 creeping bentgrass (Agrostis palustris Huds.) and 2 Kentucky bluegrass (Poa pratensis L.) sites. Treatments included core cultivation and vertical mowing, separately and in combination; after 6 weeks, samples of the thatch and thatch like derivatives were taken for determining ash content, bulk density (BD), cation-exchange capacity (CEC), and pH. Soil incorporation into thatch reduced the percentage of ash content and CEC, but increased BD and CEC·BD — an expression of CEC on an undisturbed volume basis. The extent to which these changes occurred reflected the amount of soil incorporated by the number and type of cultivation methods employed.
A Reliable Actinometric Method for Characterizing the Light Regime in Plant Canopies
Authors: Avidan B. , Erez A.
Published: August 2022

The actinometric method, based on photolysis of uranyl oxalate, was adapted for measuring integrated light irradiance in plant canopies. The unique characteristics of the new actinometers are their small size, the avoidance of pressure build-up in the measuring cell, the good correlation with quantum sensors, and their response to the cosine law. The proposed system is inexpensive and reliable, integrates light measurement over a relatively long period, and needs little additional instrumentation. Numerous measurement points scattered in plant canopies can be determined simultaneously by this method, thus improving assessment of the light regime in fields and orchards. This paper describes such measurements in a peach meadow orchard planted at 2 densities, where 27 actinometers were dispersed in each density treatment and replicate
Effect of Soil Moisture Tension and Soil Water Content on the Growth of Chrysanthemum in 3 Container Media
Authors: Karlovich P.T. , Fonteno W.C.
Published: August 2022

No differences in final height, top fresh weight, top dry weight, or flower number were observed in Chrysanthemum morifolium Ramat. ‘Spice’ grown in 16.5-cm azalea pots when allowed to dry to soil moisture tensions of 5, 10, 20, or 30 kPa between waterings. Differences did occur in these parameters among the 3 tested media. Differences also occurred across all 3 media based on the volume of water remaining in the pot prior to watering. Plants growing in media containing more than 500 ml water just prior to irrigation had increased growth compared to plants in media containing less than 500 ml water. Cubic regression models were used to describe the percentage of moisture in the pot at soil moisture tensions between 0 and 30 kPa. The model may be used to predict container capacity and air space for most container sizes.
Chilling Sensitivity of Tomato Fruit in Relation to Ripening and Senescence
Authors: Autio Wesley R. , Bramlage William J.
Published: August 2022

Postchilling ion leakage, respiration, and C2H4 biosynthesis were used to measure the degree of chilling injury to fruit of tomato (Lycopersicon esculentum Mill. ‘Heinz 1350’). Chilling sensitivity, as measured by ion leakage, first declined as the tomatoes began to ripen and then increased during the late stages of ripening. Both C2H4 biosynthesis and respiration rate were stimulated during the chilling response early in ripening. In the nonripening mutant, nor, chilling sensitivity did not show the early decline but showed the increase during senescence. Variation in chilling sensitivity during tomato ripening was biphasic, with a decline at the onset of ripening followed by a senescence-related increase. It is proposed that the latter may be due to an increase in membrane viscosity.
Kinetics of Sugar Transport in Isolated Vascular Bundles and Phloem Tissue of Celery
Authors: Jaleh Daie
Published: August 2022

Celery (Apium graveolens L.) is a favorable plant material for phloem loading studies, because vascular bundles and phloem tissue can be isolated from fleshy petioles with minimal manipulations. Uptake kinetics for sucrose loaded into phloem are different than uptake by phloem-free tissue. In isolated vascular bundles, uptake of phloem sugars (sucrose and mannitol) were biphasic kinetics, consisting of an active, saturating component operating at low sugar concentrations, and linear kinetics at higher sugar concentrations. Glucose uptake exhibited linear kinetics. However, when the glucose analog, 3-0-methyl glucose (unmetabolized) was used, biphasic kinetic profiles were obtained. Sucrose and mannitol uptake in isolated phloem tissue consisted of one saturating component showing Michaelis-Menten kinetics. In the homogenous storage parenchyma tissue, sucrose uptake kinetics were by diffusion and insensitive to carbonyl cyanide m-chlorophenyl hydrazone (identical to that of L-glucose). The data suggested the presence of different mechanisms for sucrose uptake across the sieve-tube companion cell complex and nonphloem cells. It is proposed that celery may be a useful system to obtain direct evidence on mechanism of solute loading. Chemical names used: carbonyl cyanide m-chlorophenyl hydrazone (CCCP).
Ice Nucleation and Supercooling in Freezesensitive Peach and Sweet Cherry Tissues
Authors: Andrews Preston K. , Proebsting Edward L. , Gross Dennis C.
Published: August 2022

Ice nucleation temperatures were measured in peach [Prunus persica (L.) Batsch ‘Redhaven’] and sweet cherry (Prunus avium L. ‘Bing’) flowers, fruits, and stems by differential thermal analysis and by controlled freezing in test tubes and of droplets. The mean nucleation temperatures of peach and sweet cherry flowers were –4° to – 6°C, while those of 0.5-cm stem segments were –6° to –7°. The highest ice nucleation activity in peach flowers appeared to be associated with the pedicels. A logarithmic function described the relationship between stem weight and ice nucleation temperature, with 1.5-g (16-cm) stem segments freezing as high as –3°. Apparently, stem tissue contained a lower concentration of ice nucleators active above –5° than did the floral tissue. Homogenization of the tissues reduced their ice nucleation activity. Structural integrity may be necessary for the manifestation of optimal activity. Ice nucleation-active (INA) Pseudomonas syringae bacteria were isolated from the surfaces of peach and sweet cherry floral tissues only occasionally and then at low populations. The absence of epiphytic INA bacteria from these tissues suggested that ice nucleation was promoted by intrinsic ice nucleators within the plant. These intrinsic ice nucleators appeared to be active at temperatures similar to INA bacteria. Although these nucleators may be less numerous than bacterial ice nuclei on heavily colonized plant surfaces, their presence nonetheless suggests that control of INA bacteria or inhibition of the ice nucleation activity of INA bacteria alone may be insufficient to prevent ice nucleation and freezing injury of freeze-sensitive flowers and fruits during spring frosts in the orchard.
Cold Hardiness in the Genus Rhododendron
Authors: Sakai A. , Fuchigami L. , Weiser C.J.
Published: August 2022

Cold hardiness of 101 Rhododendron genotypes was assessed. In hardy rhododendrons, the difference in hardiness between floral primordia and other tissues or organs was greater than in the less hardy species. All rhododendrons tested were divided into 4 hardiness divisions: very hardy, semihardy, hardy, and tender. In all hardiness divisions, the vegetative buds, leaves, and stem cortex were hardiest, whereas the floral primorida were least hardy, with a lowest survival temperature (LST) of −35°C or higher. The majority of the very hardy division of rhododendrons, such as R. brachycarpum D., R. catawbiense Michx., and R. maximum L., belong to the ponticum series. In general, rhododendrons from cold regions were hardier than those from warm regions. The hardiness of the floral primordia of rhododendrons growing near the timberline (3900 m alt.) of East Himalaya and the high altitudes of the northwestern Yunnan area were similar (−20° to −23°). These were less hardy than those found in the subalpine forests of Japan and eastern North America, probably due to moderate temperature and high humidity during the winter in eastern Himalaya and northwestern Yunnan.
Somatic Embryogenesis in Jojoba
Authors: Wang Yi-Chang , Janick Jules
Published: August 2022

Somatic embryogenesis was induced from callus derived from immature zygotic embryos (3–4 mm in length optimum) of jojoba (Simmondsia chinensis Link) cultured on semisolid basal medium supplemented with 4.5 µM (1 mg/liter) 2,4-D. Somatic embryo initiated from single cells on the periphery of callus passed through typical stages of embryogenesis. Embryogenic-competent calli maintained on a medium containing 0.2 mM (40 mg/liter) sodium bisulfite antioxidant and 4.5 or 9 µm (1 or 2 mg/liter) 2,4-D continued to proliferate somatic embryos, but embryos remained in an arrested state of development until 2,4-D was withdrawn. Chemical names used: 2,4-dichlorophenoxyacetic (2,4-D); N-(phenylmethyl)-lH/-purin-6-amine (BA).
Development of Seedless Grapefruit Cultivars through Budwood Irradiation
Authors: Hearn C.J.
Published: August 2022

Buds from a mature ‘Foster’ grapefruit (Citrus paradisi Macf.) tree were exposed to 3, 5, 7, 9, and 11 kilorad (kr) of gamma irradiation. The irradiated buds were grafted to rootstocks in the nursery and greenhouse. The LD50 was near 5 kr for buds grafted in the greenhouse and 9 kr for those in the nursery; however, no buds receiving more than 5 kr initiated growth. Grafted trees that grew were field grown until fruiting and seed per fruit was counted. Several nonjuvenile, commercially seedless clones were developed among small populations of plants, and in significantly less time than required through seed irradiation.
High-density Nursery System for Breeding Peach and Nectarine: A 10-year Analysis
Authors: Rodriguez-A. Jorge , Sherman Wayne B. , Lyrene Paul M.
Published: August 2022

A 10-year analysis of the high-density nursery (HDN) in the breeding of low-chilling peach and nectarine [Prunus persica (L.) Batsch] cultivars indicated selection was effective during the first cropping year for chilling requirement, fruit development period, size, color, shape and firmness but not for crop load, which needs to be evaluated at normal spacing over several years. The HDN system effectively has advanced the breeding program by promoting short generation time, reducing labor and space, and allowing for rating of some characters within 2 years from seed.
Factors Accounting for the Within-tree Variation of Fruit Quality in Sweet Cherries
Authors: Patten K.D. , Patterson M.E. , Proebsting E.L.
Published: August 2022

Sweet cherry (Prunus avium L.) flower and pistil weight at anthesis decreased at late bloom times. Fruit from early-opening flowers remained larger through harvest and developed higher soluble solids and color than fruit from flowers than opened later. Time of anthesis was delayed and fruit color and soluble solids decreased linearly as flower or fruit location progressed basipetally on one- and 2-year-old wood.
Influence of Tissue Culture and Leaf-bud Propagation on the Growth Habit of ‘Northblue’ Blueberry
Authors: Grout Jeanne M. , Read Paul E. , Wildung David K.
Published: August 2022

‘Northblue’ blueberry (Vaccinium corymbosum L.) plants propagated by tissue culture (TC) have a branching pattern and growth rate different from plants propagated by leaf-bud cuttings. Two to 3 times more basal branches were formed on tissue culture-derived plants by the time they were 27 to 34 weeks old. These basal branches were maintained on older plants in the field, where lateral branching was also twice as high. The growth rate of the young TC-derived plants was 3 times the rate of young leaf-bud, cutting-propagated (ST) plants. However, lateral branch length of older plants in the field was similar for both groups of plants, indicating a reduction in the growth rate of TC-derived plants from 34 to 82 weeks after propagation. Pruning and chilling methods reduced basal branch length and the number of lateral branches produced in the field, while enhancing the length of lateral branches and total buds per lateral branch. Although TC-derived blueberry plants had numbers of total flower buds and total buds per lateral branch similar to ST-derived plants, they produced more flower buds per plant. The enhanced branching framework of TC-derived plants, composed of rapidly forming basal and lateral branches, may increase photosynthesis at an early age and hasten fruit production.
Greenhouse Rose Production with Split Night Temperatures
Authors: Shanks James B. , McArdle Alice J. , Osnos Glenna D. , Mityga Henry G.
Published: August 2022

The reduction of the minimum temperature during the latter part of the dark period as a means of energy conservation was studied for 3 consecutive years with greenhouse roses. A warm temperature during the early part of the dark period was more promotive of growth than at subsequent or continuing portions of the dark period. The most rapid bloom development in the first and 3rd years’ trials was at the continuous warm night temperature of 17°C. During the 2nd year, the greatest production of blooms was also at the continuous minimum night temperature of 17°, but, in the 3rd year, a reduction in the minimum night temperature to 9° from 0100 to 0800 hr did not reduce production below that at a continuous 17° minimum. Split night temperatures did not affect the quality of cut roses when compared to a continuous minimum of 17°.
Defoliation, Flower Bud Cold Hardiness, and Bloom Date of Peach as Influenced by Pruning Treatments
Authors: Marini Richard P.
Published: August 2022

Mature ‘Sunqueen’ peach [Prunus persica (L.) Batsch] trees were dormant pruned, summer pruned, or summer topped for 4 consecutive years. Dormant-pruned trees defoliated slightly earlier than summer-pruned trees, but the onset and duration of terminal vegetative bud rest was not influenced by pruning treatment. Compared to dormant pruning, summer topping slightly reduced cold hardiness of flower buds on 2 of 4 test dates in 1982, but not in 1984. Bloom on vertical shoots in the upper canopy was advanced by summer pruning and by summer topping in both 1982 and 1983. Bloom development at other canopy positions was not influenced by pruning treatment.
Effects of Artificial Enclosure of Young Lettuce Leaves on Tipburn Incidence and Leaf Calcium Concentration
Authors: Barta Daniel J. , Tibbitts Theodore W.
Published: August 2022

The young developing leaves of 20-day-old lettuce plants (Lactuca sativa L. ‘Buttercrunch’) were enclosed by aluminized polyethylene sheaths to decrease transpiration and reduce Ca transport. The plants were grown in recirculating solution culture systems using a modified half-strength Hoagland’s solution under cool-white fluorescent lamps with a photosynthetic photon flux of 350 μmol·s−1·m−2 in a 16:8-hr (light:dark) period. Air temperature and humidity were 20°C and 65%, respectively. After 4 days of enclosure, 53% of the inner leaves (leaves one to 3 cm in length) were tipburned. After the same period, less than 1% of the inner leaves on control plants were tipburned. The concentration of Ca in enclosed inner leaves was 0.63 mg·g−1 dry weight, compared to 1.48 mg·g−1 dry weight in inner leaves that were not enclosed. The Ca concentration in transpiring outer leaves of all plants was 9.9 mg·g−1 dry weight. The Mg concentration in enclosed inner leaves was 2.25 mg·g−1 dry weight, compared to 2.34 mg·g−1 dry weight in inner leaves that were not enclosed. This research documents that enclosure of leaves at the growing point, as would occur with normal head development, is sufficient to create a limiting concentration of Ca in the enclosed tissue and encourage tipburn development.
Comparative Anatomy and Physiology of Microcultured, Seedling, and Greenhouse–grown Asian White Birch
Authors: Smith Mary Ann Lila , Palta Jiwan P. , McCown Brent H.
Published: August 2022

Anatomical and physiological comparisons were made between tissues of Betula platyphylla var. szechuanica (Schneid.) Rehd. (Asian white birch) obtained directly from microcultured shoots, from seedlings grown in a micro-culture-like environment, or from micropropagated plants grown in a greenhouse. The diminished stature of microcultured shoots resulted primarily from reduced cell division, although their leaves had reduced cell size as compared to shoots from greenhouse-grown plants. The area occupied by vascular tissue in midrib veins and petioles was significantly reduced in microcultured shoots as was the extent of the palisade layer, indicating that cell differentiation had also been altered. The photosynthetic capacity of leaves from microcultured shoots was less than half that of leaves from greenhouse-grown plants. However, this capacity was restored after non-in vitro rooting of the microcultured shoots. Unlike greenhouse-grown plants, photosynthetic rates of leaves from microcultured shoots were not influenced by decreasing light intensities from 1200 to 200 μmol·s−1·m−2 nor was the respiration rate strongly inhibited by cyanide. Seedlings from a high-humidity, microculture-like environment generally had characteristics intermediate between those of microcultured and greenhouse-grown tissues, indicating that the environment and not the juvenile state of the tissue was probably of overriding importance in influencing these trends.
Influence of Water Stress on Nitrogen Fixation in Cowpea
Authors: Walker David W. , Miller J. Creighton
Published: August 2022

Two greenhouse studies were conducted to investigate the relationship between water stress and N2 fixation among drought-resistant and susceptible cowpea [Vigna unguiculata (L.) Walp.] genotypes. In both experiments, seeds were planted in 7.6-liter black polyethylene pots containing composted sawdust medium and were inoculated with Rhizobium. Throughout the experiments, flowers were removed to maintain vegetative growth. Water stress treatments were imposed by withholding water, while the control plants were watered as needed. The treatments were applied 58 and 56 days after planting (DAP) in the first and 2nd experiments, respectively. In both experiments, leaf water potential (LWP), shoot fresh weight (SFW), shoot dry weight (SDW), root fresh weight (RFW), nodule fresh weight (NW), nodule number (NN), and plant specific activity (PSA) by both in situ and destructive acetylene reduction methods were measured. Repeated observations of in situ acetylene reduction were made 58, 63, and 71 DAP in the first experiment. All other variables were measured 77 to 78 DAP in the first experiment. Single observations of all variables, including in situ and destructive acetylene reduction were made 56, 67, and 81 DAP in the 2nd experiment. Results suggested that resistant genotypes are capable of maintaining LWP and biomass production (as measured by SDW and SFW) during water stress. In addition, the effect of water stress on N2 fixation was far greater than the influence of genotype when genotypes were selected for relative drought resistance. Path analysis revealed that LWP is correlated to N2 fixation in water-stressed plants, and improvement of plant water status via drought resistance should increase N2 fixation potential under drought conditions. Therefore, breeding for drought resistance in conjunction with N2 fixation may be more beneficial than breeding strictly for N2 fixation potential without regard for environmental adaptation. The in situ method of acetylene reduction was found to be useful for detecting physiological changes due to water stress and estimating its genotypic N2 fixation potential.
Stress Symptoms of Citrus Trees in Successive Stages of Decline Due to Blight
Authors: Albrigo L.G. , Syvertsen J.P. , Young R.H.
Published: August 2022

Nutritional and H2O stress symptoms of 1) healthy citrus trees, 2) predecline trees (those with elevated bark Zn but no visible wilt or dieback symptoms), and 3) trees in early decline due to citrus blight were compared. All early decline trees had elevated Zn and reduced H2O uptake in the trunk; N accumulation in trunk wood, bark, and leaf tissues; and increased xylem vessel plugging and correspondingly reduced H2O conductivity compared to healthy trees. The early decline trees did not have reduced feeder root densities, and wood pH was elevated in this stage for only one of 2 locations. Generally, predecline trees had none of the drought-related or decline symptoms associated with blight and only expressed the Zn symptoms — elevated bark Zn followed by elevated wood Zn. Three or 4 of 8 predecline stage blight trees have subsequently reached the stage of blight where trunk H2O uptake is significantly reduced. Xylem plugging and drought stress followed trunk Zn accumulation. Other previously reported blight symptoms occurred only after H2O stress, leaf wilt, and canopy dieback; thus, these results support the contention that Zn accumulation in the trunk bark (active phloem tissues) is the earliest known symptom of blight.
The Influence of Nitrate:Ammonium Ratios on Growth, Fruit Development, and Element Concentration in ‘Floradel’ Tomato Plants
Authors: Hartman Paul L. , Mills Harry A. , Jones J. Benton
Published: August 2022

Tomato (Lycopersicon esculentum Mill. ‘Floradel’) plants were grown under greenhouse conditions in a modified Hoagland’s solution to determine the influence of NO3:NH4 ratio (100:0, 75:25, 50:50, 25:75) on vegetative growth, fruit development, and tissue levels of N, P, K, Ca, and Mg at 3 stages of maturity. Vegetative growth prior to fruit set was increased significantly by adding 25% of the N as NH4, although higher NH4 ratios reduced vegetative growth. During flower and fruit development, the number of fruit formed with each flower cluster was not influenced by the NO3:NO4 ratio, although fruit weights were reduced significantly when NH4 supplied any part of the N form. With each increment of NH4 in the N ratio, tissue P increased whereas K, Ca, and Mg decreased. Kjeldahl N (less NO3-N) in the vegetative tissue at all harvests increased with each increment of NH4 in the N ratio. It is concluded that the use of Kjeldahl N as an indicator of the N status of the plant without consideration of the effect of N form on the percentage of N as well as the uptake and distribution of other essential elements could be misleading and potentially a misuse of this diagnostic tool.
Effect of a Hydrophilic Polymer Seed Coating on the Imbibition, Respiration, and Germination of Sweet Corn at Four Matric Potentials
Authors: Baxter Lawford , Waters Luther
Published: August 2022

A laboratory experiment was conducted to determine the effect of the hydrophilic polymer Waterlock B100 on the imbibition, respiration, and germination of seeds of the sweet corn (Zea mays L. var. saccharum) hybrid ‘Mevak’ at soil water matric potentials of -0.01, -0.40, -1.0, and - 1.5 MPa. Coated seeds had a higher final percentage of imbibition, higher rates of respiration, and germination at -0.01 and -0.40 MPa than uncoated seeds, but as the water potential decreased, the seed coating had a deleterious effect on the physiological processes leading to germination.
Effect of BA + GA4+7, BA, and Daminozide on Growth and Lateral Shoot Development in Peach
Authors: Elkner Timothy E. , Coston D.C.
Published: August 2022

The effects of BA alone or in combination with GA4+7 and with either daminozide or a surfactant on growth and lateral development of peach [Prunus persica (L.) cv. Redhaven] were evaluated at 4 stages of terminal growth. BA + GA4+7 at 500 ppm or 1000 ppm daminozide was the most effective treatment for inducing lateral development when applied at terminal growth of 15-20 cm or 31-36 cm. BA + GA4+7 increased both tree height and average internode length for all treatments. BA with either surfactant or daminozide was not effective in inducing lateral shoot formation and caused shorter internodes and retarded tree growth in all treatment combinations except 250 ppm + 1000 ppm daminozide. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine (BA) and (1α,2β,4aα,4bβ,10β)-2,4a,7-trihydroxy-l-methyl-8-methylenegibb-3-ene-l,10-dicarboxylic acid 1,4a-lactone (GA4+7).
Influence of 12 Ground Cover Systems on Young ‘Smoothee Golden Delicious’ Apple Trees: I. Growth
Authors: Shribbs J.M. , Skroch W.A.
Published: August 2022

Two-year-old ‘Smoothee Golden Delicious’ apples (Malus domestica Borkh.) on seedling rootstock were planted in Spring 1981. Twelve different ground cover systems were then established. After one growing season, trees in mulch, bare ground, red sorrel (Rumex acetosella L.), and nimblewill (Mulenbergia schreberii J. F. Gmel.) treatments had greater shoot length than trees in legume, tall broadleaf, Kentucky bluegrass (Poa pratensis L.), orchardgrass (Dactylis glomerata L.), and ‘KY31’ tall fescue (Festuca arundinacea L.) treatments. In the 4th year, the trunk diameter of trees in straw mulch plots were greater than all other treatments. Tree growth in bare ground and cultivation treatments was not different over the 4 years and was as great or greater than in treatments with living ground covers. Trees in tall broadleaf, Kentucky bluegrass, orchardgrass, and tall fescue treatments were smaller than in all other treatments. Nimblewill, a native species to North Carolina mountains, has potential for replacing Kentucky bluegrass, orchardgrass, and tall fescue in orchard soil management systems.
Use of Ethephon and NAA for Inducing Early Shuck Dehiscence of Pecan
Authors: Wood Bruce W.
Published: August 2022

Field observations indicate that conjunctive use of ethephon (Ethrel) and NAA (Fruitone-N) can induce early pecan [Carya illinoensis (Wangenh.) C. Koch] shuck (involucre) dehiscence, while greatly reducing undesirable leaflet abscission. Comparisons of the efficacy of 2,4-D and NAA in preventing undesirable leaflet abscission revealed that the comparative molar protective activity of 2,4-D greatly exceeds that of NAA, providing leaflets absolute protection against ethephon-induced abscission, but it was functionally inferior to NAA due to the induction of leaflet necrosis. Single ethephon treatments accelerated shuck dehiscence 3 to 6 weeks for several cultivars. Treatment of ‘Stuart’ and ‘Moneymaker’ pecan fruit and foliage, several weeks prior to the completion of natural shuck dehiscence, with a NAA-ethephon mixture accelerated shuck dehiscence by 5 and 3 weeks, respectively, without severe leaflet abscission or loss of nut quality. These data indicate possible development of harvest-aid technology for early harvesting of pecan without severe leaflet abscission. Chemical names used: (2-chloroethyl)phosphonic acid (ethephon); (2,4-dichlorophenoxy)acetic acid (2,4-D); and 1-naphthaleneacetic acid (NAA).
The Effect of Temperature and Bud Type on Rest Completion and the GDH°C Requirement for Budbreak in ‘Redhaven’ Peach
Authors: Scalabrelli G. , Couvillon G.A.
Published: August 2022

Dormant ‘Redhaven’ peach [Prunus persica (L.) Batsch.] cuttings with flower, lateral vegetative, and terminal vegetative buds were exposed to either 7.2°, 3°, or 2°C for 600, 1340 or 2040 hr. Terminal vegetative (TV) buds had the shortest chilling requirement and showed less differential response to the various temperature levels than the other bud types. ‘Redhaven’ lateral vegetative (LV) and flower buds (FL) had similar chilling requirements. In general, 7.2° was more effective in releasing buds from rest than 3° or 2°. Prolonged chilling (2040 hr) decreased the growing degree hours (GDH°C) required for vegetative bud opening regardless of temperature. However, the GDH°C required for flower bud opening was decreased only by prolonged chilling at 7.2°C.
Effect of Storage on Quality and Sugars in Muskmelon
Authors: Cohen R.A. , Hicks J.R.
Published: August 2022

Melons (Cucumis melo) of 3 cultivars (‘Gold Star’, ‘Saticoy’, and ‘Superstar’) were stored at 5° or 12.5°C for 2, 5, or 9 days and at 20° for 2 and 5 days. ‘Gold Star’ and ‘Superstar’ deteriorated less in storage than ‘Saticoy’. In general, levels of fructose and glucose decreased with an increase in storage time and temperature. The fructose : glucose ratio increased with storage. No change was detected in soluble solids content (SSC) or in sucrose concentration. Sensory evaluations of stored (7 days at 5° or 12.5°) vs. freshly harvested melons showed no difference in texture, flavor, off-flavor, sweetness, or overall acceptability. SSC and sucrose content correlated well with the latter 4 attributes only in ‘Gold Star’ melons.
Seasonal Changes in the Carbohydrate Concentration in Pecan Shoots and Their Relationship to Flowering
Authors: Smith Michael W. , McNew Ronald W. , Ager P.L. , Cotten B.C.
Published: August 2022

Vegetative and fruiting shoots were tagged in Oct. 1982 and 1983 on ‘Squirrel’, ‘Stuart’, and ‘Cape Fear’ pecan trees [Carya illinoensis (Wangenh) C. Koch], and flowering was determined the following years. One-year-old shoots were sampled from vegetative and fruiting shoots of each cultivar on 14 Oct. 1982, 9 Feb., 11 Apr., 14 Oct., and 24 Nov. 1983, and 6 Jan. and 17 Apr. 1984 and analyzed for reducing and nonreducing sugars and starch concentrations. Fruiting reduced return bloom of ‘Cape Fear’ in 1983 and 1984, and ‘Stuart’ in 1983. Sugar and starch concentrations varied inversely. Sugar concentrations were increased in November, January, and February, and starch concentrations were greatest during October and April. The total carbohydrate concentration in fruiting shoots of each cultivar was greater or equal to that of vegetative shoots in all but one instance. The degree of return fruiting was positively associated with cultivars with early fruit ripening dates.
Gas Exchange and Flooding Stress of Highbush and Rabbiteye Blueberries
Authors: Davies Frederick S. , Flore James A.
Published: August 2022

Highbush (Vaccinium corymbosum L. ‘Bluecrop’) and rabbiteye (V. ashei Reade ‘Woodard’) blueberry plants were flooded in the greenhouse to determine how transpiration, stomatal conductance to water and CO2, residual conductance, and C assimilation are affected during flooding and recovery. Carbon assimilation was measured using a portable CO2 analyzer and stomatal conductance using a steady-state porometer. Stomatal conductance and transpiration decreased significantly after 4 to 5 days of flooding, and responses were similar for highbush and rabbiteye blueberries. Carbon assimilation decreased for both species within 9 days and became negative in 11 to 19 days due to decreased photosynthesis, stomatal conductance to CO2, and high leaf temperatures, which increased respiration. Recovery after 24 days of flooding to preflood stomatal conductance values required 18 days for ‘Woodard’ and more than 18 days for ‘Bluecrop’. In laboratory experiments flooded plants were less responsive to changes in ambient CO2 and vapor pressure deficits than unflooded plants, and flooding durations of greater than 9 days significantly decreased residual conductance of the leaves.