bluuebunny/crossref_metadata_2025 huggingface dataset:
Random Amplified Polymorphic DNA (RAPD) Marker Variability between and within Gene Pools of Common Bean
Authors: Haley Scott D. , Miklas Phillip N. , Afanador Lucia , Kelly James D.
Published: January 2019

The objective of this study was to evaluate the degree of RAPD marker variability between and within commercially productive market classes representative of the Andean and Middle American gene pools of common bean (Phaseolus vulgaris L.). Six sets of near-isogenic lines were screened with oligonucleotide primers in the polymerase chain reaction-based RAPD assay. Simultaneous analyses with at least three sets of lines enabled us to score RAPD markers between the two major gene pools, races within the same gene pool, and different genotypes of the same race (within race). A “three-tiered” pattern of polymorphism was observed: between gene pools> between races> within races. The overall level of polymorphism between the Andean and Middle American gene pools was 83.4%. The overall level of polymorphism between races within the same gene pool was similar for Andean races (60.4%) and Middle American races (61.7%). The level of polymorphism between related commercial navy bean lines was 39.2% and between related commercial snap bean lines was 53.6 %. The inherent simplicity and efficiency of RAPD analyses, coupled with the number of polymorphisms detectable between related commercial genotypes, should facilitate the construction of RAPD-based genetic linkage maps in the context of populations representative of most bean breeding programs.
Fertilizer Nitrogen and Boron Uptake, Storage, and Allocation Vary during the Alternate-bearing Cycle in Pistachio Trees
Authors: Weinbaum S.A. , Picchioni G.A. , Muraoka T.T. , Ferguson L. , Brown P.H.
Published: January 2019

The effects of alternate bearing on recovery and loss of isotonically labeled fertilizer N and B and on the accumulation of carbohydrate and N reserves were assessed in mature `Kerman' pistachio (Pistacia vera L.) trees. Total recovery of labeled fertilizer N applied once (in late January) was ≈ 60% greater if applied to trees entering an “off' than an “on” year, with respect to fruiting. Eleven percent more labeled B was recovered in off- than on-year trees. Five times more N (1 vs. 0.2 kg N) was lost from the tree in fruit and senescent leaflets from on- than off-year trees. In dormant trees, 144% and 22% more starch and N reserves, respectively, were present after off than on years. Thus, on-year trees were characterized by a greater reproductive demand for N and carbohydrates, reduced accumulation of C and N (i.e., storage) reserves in perennial tree parts, and reduced recovery of January-applied labeled fertilizer N than off-year trees. As B is absorbed passively, the higher transpiration that may accompany the 43% larger leaf area per tree and the probability of increased root growth probably contributes to its increased uptake during off years. The enhanced labeled N recovery in early spring by trees entering their off year preceded fruit and seed development in on-year trees. The differential tree capacity for nutrient uptake in spring may have been conditioned the previous rather than the current year. The increased uptake of labeled N by trees entering an off year (i.e., emerging from an on year) was associated with lower levels of carbohydrate and N reserves than for on-year trees that had just completed an off year. Future experimentation should assess the comparative capacity for nutrient uptake by on-and off-year trees at other stages of phenology, e.g., during seed development and postharvest.
Comparative Flood Tolerance of Birch Rootstock
Authors: Ranney Thomas G. , Bir Richard E.
Published: January 2019

The potential for enhancing flood tolerance of birches by using better adapted rootstock was evaluated. Survival, growth, and physiological responses were compared among flooded and nonflooded container-grown Japanese birch (Betula platyphylla var. japonica Hara. `Whitespire') trees grafted onto each of four rootstock: paper birch (B. papyrifera Marsh), European birch (B.pendula Roth.), river birch (B. nigra L.), and `Whitespire' Japanese birch. Separate studies were conducted in Fall 1991 and Spring 1992. Results showed no consistent differences in net photosynthesis (Pn) or survival among nonflooded plants regardless of rootstock or season, nor, were any symptoms of graft incompatibility evident. Flooding the root system for as long as 44 days revealed considerable differences among the four rootstock, with similar trends for fall and spring. Plants on river birch rootstock typically had one of the highest P rates and stomatal conductance (g,) and, in certain cases, greater mean shoot growth rates and survival of plants subjected to prolonged flooding. Although plants with European birch rootstock had survival rates similar to those of plants with river birch rootstock, plants on European birch rootstock had lower Pn under prolonged flooding, fewer late-formed roots, lower root-tip density after flooding, more abscissed leaves, and greater inhibition of shoot growth of plants flooded the previous fall. Paper and Japanese birch rootstock were most sensitive to flooding and had the lowest survival rate after flooding. However, plants on paper birch rootstock were the only plants whose Pn did not increase significantly when flooding ended; they had the most abscissed leaves during spring flooding and the greatest inhibition of shoot growth in the spring after flooding the previous fall. The four rootstock ranked from most to least flood tolerant were river > European > Japanese > paper.
Additive Effects of Postharvest Calcium and Heat Treatment on Reducing Decay and Maintaining Quality in Apples
Authors: Conway William S. , Sams Carl E. , Wang Chien Yi , Abbott Judith A.
Published: January 2019

`Golden Delicious' apples (Malus domestics Borkh.) were treated with heat or CaCl2 solutions or a combination thereof to determine the effects of these treatments on decay and quality of fruit in storage. Heat treatment at 38C for 4 days, pressure infiltration with 2% or 4% solutions of CaCl2, or a combination of both, with heat following CaCl2 treatment affected decay and firmness during 6 months of storage at 0C. The heat treatment alone reduced decay caused by Botrytis cinerea (Pers.:Fr.) by ≈30%, while heat in combination with a 2% CaC12 solution reduced decay by ≈60 %. Calcium chloride solutions of 2% or 4% alone reduced decay by 40 % and 60 %, respectively. Heat treatments, either alone or in combination with CaC12 treatments, maintained firmness (80 N) best, followed by fruit infiltrated with 2% or 4% solutions of CaCl2 alone (70 N) and the nontreated controls (66 N). Instron Magness-Taylor and Instron compression test curves show that heat-treated fruit differed qualitatively and quantitatively from nonheated fruit. Heat treatment did not increase the amount of infiltrated Ca bound to the cell wall significantly, and a combination of heat treatment after CaCl2 infiltration increased surface injury over those fruit heated or infiltrated with CaCl2 solutions alone.
Determining Chilling Injury Induction in Green Peppers Using Nondestructive Pulse Amplitude Modulated (PAM) Fluorometry
Authors: Lurie Susan , Ronen Reuven , Meier Shimon
Published: January 2019

Storing `Maor' green bell peppers (Capsicum annuum L.) for 3 weeks at 2C resulted in the development of chilling injury (CI) evidenced as surface pitting. Fruit held at 8C did not develop any CI symptoms, but, after 3 weeks of storage, the fruit began to change color from green to red. PAM fluorometry was used to measure changes in photosynthetic competency in whole green bell peppers. Three photosynthetic characteristics could be measured by this method: quantum yield (Fm/Fe), photochemical quenching (Qp), and nonphotochemical quenching (Qnp). Fm/Fo decreased 90% during the first week of storage at 2C and remained low thereafter, while Qnp decreased after 2 weeks at 2C, just before the peppers began to develop CL Qp was similar at both storage temperatures. Potassium leakage as a CI measurement also increased in excised pepper discs after 2 weeks at 2C. The results indicate that PAM fluorometry can measure CI nondestructively before tissue damage is visible in green peppers.
Apple Fruit Removal and Limb Girdling Affect Fruit and Leaf Characteristics
Authors: Schechter Ido , Proctor J.T.A. , Elfving D.C.
Published: January 2019

Mature apple trees (Malus domestica Borkh.) were studied in 1989 and 1990 to explore the effect of crop load on fruit dry weight (DW), dry-matter concentration (DMC), specific leaf area (SLA), and leaf C exchange, using girdled (G) and nongirdled (NG) limbs. Fruit DW and DMC decreased with heavier fruit loads. Fruit on G limbs had higher fruit DW and DMC than on NG limbs. SLA on NG limbs was unaffected by crop load, but increased dramatically on G limbs with a crop load of less than one fruit per square centimeter limb cross-sectional area. These leaves also had a low photosynthetic rate, high stomatal resistance, and high internal CO2 concentration. The results do not support the concept of feedback inhibition of photosynthesis and demonstrate specific circumstances in which the capacity of sinks to use assimilates was saturated. Exceeding this limit by significantly reducing sink strength resulted in excessive carbohydrate accumulation in leaves. Nutrient levels in leaves on G, nonfruiting limbs were generally lower than for the other treatments.
Water Relations of Field-grown Quercus virginiana Mill. from Preharvest through Containerization and 1 Year into a Landscape
Authors: Beeson R.C.
Published: January 2019

Large (≈5 m high) Quercus virginiana Mill. (live oak) trees produced in 0.64-m-diameter in-ground fabric containers were root pruned or not root pruned inside containers before harvest. Harvested trees were grown in two sizes of polyethylene containers for 10 months, then transplanted into a landscape. Water potential (ψT) of small branches (<4 mm in diameter) was measured diurnally during containerization and for 1 year in the landscape. Root pruning had no influence on postharvest survival. Neither root pruning nor container size affected tree water status during containerization or in the landscape. All surviving trees recovered from transplant shock following harvest after 16 weeks in a container, independent of treatment. In the landscape, 35 weeks of daily irrigation were required before dusk ψT declined to within 0.1 MPa of predawn values, a result indicating alleviation of transplant shock. Trunk growth rate during containerization was highest in larger containers. However, in the landscape, root pruning and small containers were associated with higher trunk growth rate. Tree water status during containerization and in the landscape is discussed.
Peach Fruit Weight Is Influenced by Crop Density and Fruiting Shoot Length but not Position on the Shoot
Authors: Marini Richard P. , Sowers Donald L.
Published: January 2019

The relationship between peach [Prunus persica (L.) Batsch] fruit position and fruit weight (FW) was studied in experiments involving thinned vs. nonthinned fruiting shoots, shoots with and without axillary shoots, and trees with varying crop densities (CDs). FW was not consistently related to position on the shoot, and the influence of fruit position varied depending on the presence of axillary shoots on the fruiting shoot. FW was best related to fruiting shoot length and total shoot length per fruit (1-year-old plus current-season wood). Mean FW was also influenced by the number of fruit per shoot × CD interaction, a result indicating that FW depends on photosynthate from leaves in the immediate vicinity of the fruit as well as photosynthate from more distant parts of the tree.
Trunk Xylem Anatomy of Mature Healthy and Blighted Grapefruit Trees on Several Rootstocks
Authors: Vasconcellos Luiz A.B.C. , Castle William S.
Published: January 2019

Wood samples were taken from healthy and blighted citrus trees on several rootstocks to describe and compare the xylem anatomy of the healthy trees and to determine if blight altered xylogenesis. Horizontal trunk xylem cores, 6 cm long, were extracted from blighted 18-year-old commercial grapefruit (Citrus paradisi Macf.) trees on rough lemon (RL) (C. jambhiri Lush.), Cleopatra mandarin (CM) (C. reshni Hort. ex Tan.), and Carrizo citrange (CC) [C. sinensis (L). Osb. × Poncirus trifoliata (L.) Raf] and from healthy trees on those rootstocks and sour orange (SO) (C. aurantium L.). Cores were taken from the eastern and western sides of the scion and rootstock of each tree. The cores were divided into 2-cm pieces and cross-sections were prepared for analysis of vessel element (VE) number and diameter in 0.5-cm increments. A sample-size study showed that tree side was not a significant source of variation and that 10 replications were sufficient to detect differences of ≈12% from the overall mean. Among the healthy trees, VE densities and diameters were similar for the trees on CC or RL and larger than those for trees on SO or CM. VEs were generally smaller and at lower densities in the scion than the rootstock. Few VE occlusions were observed in the healthy trees. In the blighted trees, to a depth of 1 cm, VE density increased and diameter decreased compared to the healthy trees. The largest change occurred in the trees on RL and in the rootstock vs. scion trunk part. The frequency of VE amorphous plugs in blighted trees ranged from 1% to 30%. Similar changes in xylem anatomy were not found in trees with citrus tristeza virus or soilborne pests. Trunk water uptake and dye movement patterns in blighted trees were typical for trees with xylem dysfunction.
Orchard Groundcover Management Impacts on Soil Physical Properties
Authors: Merwin Ian A. , Stiles Warren C. , van Es Harold M.
Published: January 2019

This study was conducted to compare various orchard groundcover management systems (GMSs)—including a crownvetch “living mulch” (CNVCH), close-mowed (MWSOD) and chemically growth-regulated (GRSOD) sodgrasses, pre-emergence (NDPQT) and two widths of post-emergence (GLY1.5 and GLY2.5) herbicides, hay-straw mulch (STMCH), and monthly rototillage (tilled)—during the first 6 years in a newly established apple (Malus domestica Borkh.) planting. Mean soil water potential at 5 to 35 cm deep varied substantially among treatments each summer, and treatment × year interactions were observed. During most growing seasons from 1986 to 1991, soil water availability trends were STMCH > NDPQT > GLY2.5 > GLY1.5 > tilled > GRSOD > MWSOD > CNVCH. Soil organic matter content increased under STMCH, CNVCH, and MWSOD and decreased under NDPQT and tilled treatments. Water infiltration and saturated hydraulic conductivity after 4 years were lower under NDPQT and tilled, and soil under STMCH and GRSOD retained more water per unit volume at applied pressures approximating field water capacity. Mid-summer soil temperatures at 5 cm deep were highest (25 to 28C) in tilled and NDPQT plots, intermediate (22 to 24C) under GRSOD, and lowest (16 to 20C) under CNVCH and STMCH. These observations indicate that long-term soil fertility and orchard productivity may be diminished under pre-emergence herbicides and mechanical cultivation in comparison with certain other GMSs.
Physiological Changes of Broccoli during Early Postharvest Senescence and through the Preharvest-Postharvest Continuum
Authors: King Graeme A. , Morris Stephen C.
Published: January 2019

The postharvest senescence of broccoli (Brassica oleracea L. Italica group) was studied immediately after harvest until senescence was essentially completed at 20C. Changes in respiration, ethylene production, and color were determined for florets, branchlets, and heads of three cultivars of field-harvested `Green Beauty', `Dominator', and `Shogun' broccoli. Changes in respiration and ethylene production were also determined for 3 hours of preharvest and 24 hours of postharvest storage using broccoli grown in containers. Carbon dioxide produced from heads of container-grown broccoli and from heads, branchlets, and florets of field-harvested broccoli decreased markedly during the first 12 hours of postharvest storage before stabilizing. The respiratory quotient shifted toward a more oxidative metabolism in parallel with the respiratory decline. Ethylene production during storage showed no consistent relationship to yellowing. However, time until onset of yellowing was broadly related to the basal levels of ethylene production. The maximum storage life at 20C is ≈72 hours. Branchlets are useful model systems for investigating broccoli senescence.
Blueberry Flower-bud Hardiness Is Not Estimated by Differential Thermal Analysis
Authors: Flinn Cindy L. , Ashworth Edward N.
Published: January 2019

Differential thermal analysis (DTA) was used to study the freezing behavior of `Berkeley' blueberry (Vaccinium corymbosum L.) flower buds at cooling rates of 10, 5, and 2C/hour. Experiments were conducted at various stages of hardiness on excised and attached (5 cm of stem) buds. The presence and number of low-temperature exotherms (LTEs) in hardy buds generally increased when analyses were conducted using faster cooling rates with excised buds. The number of LTEs detected in individual buds did not correlate (r2 = 0.27) with the number of injured florets. The inability to detect LTEs in buds attached to stem segments and cooled at 2C/hour indicates that DTA cannot reliably estimate blueberry flower-bud hardiness in field plantings.
GLK-8903 Reduces Membrane Phospholipid Peroxidation and Alleviates Chilling Injury in Phaseolus vulgaris L.
Authors: Zhang Cheng-lie , Li Paul H. , Shin Charles C.
Published: January 2019

Twenty-day-old `Bush Blue Lake 47' common bean plants grown in a growth chamber at 25 days/22C night and a 12-hour photoperiod regime were foliar sprayed with 0.5% GLK-8903 including 0.05% Tween-20. After 24 hours of treatment, plants were chilled in a cold room (4C day/night, 12 hours of light). After 3 days of chilling, leaves of untreated controls were injured, as visually characterized by leaf wilting, whereas leaves of the GLK-8903-treated plants still retained turgor. During chilling, the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) decreased. GLK-8903 treatment had no effect on SOD and POD activities; however, the CAT activity was reduced significantly after GLK-8903 treatment either at 25 or at 4C. During chilling, the content of malondialdehyde, a decomposition product of phospholipid peroxidation, increased in treated plants and untreated controls, with increased content significantly lower in the former compared with the latter. The GLK-8903 per se and total lipid extracted from GLK-8903-treated plants were able to reduce the linoleic acid oxidation in vitro. The mechanism by which GLK-8903 alleviates chilling injury in bean plants is discussed.
Optimum Allocation of Objective Color Measurements for Evaluating Fresh Strawberries
Authors: Sacks Erik J. , Shaw Douglas V.
Published: January 2019

Components of variance were estimated for 10 strawberry (Fragaria ×ananassa) color traits to determine their relative importance and to design optimal sampling strategies. The color attributes of >2000 fruit from 47 genotypes from the Univ. of California Strawberry Improvement Program were evaluated over three harvest dates (HDs) in one growing season. Measurements were obtained for a moderate number of fruit from each genotype on each date, and two measurements were obtained for each trait on all fruit. Variances for HDs were nonsignificant or small (0% to 8% of the total variance). Genotype × date variances were highly significant but small (≤6% of the total) for all color traits except internal hue (14% of the total). For external color traits, the within-fruit variance was greater than the among-fruit variance (16% to 64% and 0% to 14% of the total, respectively). For internal color traits, the among-fruit variance was greater than the within-fruit variance (20% to 37% and 9% to 19% of the total, respectively). Obtaining two measurements per fruit for several fruit on one HD is an efficient strategy for characterizing a genotype's fruit color; seven to 22 fruit are needed to estimate a genotype's fruit color within 2 units (Commission Internationale de L'Eclairage L*a*b* or degrees) with 95% confidence.
Induction of Dormancy in Nondormant Seeds
Authors: Khan Anwar A.
Published: January 2019

A gibberellic acid (GA) biosynthesis inhibitor, tetcyclacis, induced dormancy in nondormant seeds of lettuce (Lactuca sativa L.), tomato (Lycopersicon esculentum Mill.), pepper (Capsicum annuum L.), carrot [Daucus carota var. sativus (Hoffn.)], onion (Allium cepa L.), celery (Apium graveolens L.), and impatiens (Impatiens novette), as most of the seeds failed to germinate after washing under conditions that permitted germination before dormancy induction. In lettuce seeds, tetcyclacis and paclobutrazol were more effective in inhibiting germination in light than in darkness. A 16- to 24-h soak treatment with tetcyclacis was sufficient to induce dormancy in nearly all seeds. Tetcyclacis failed to induce dormancy if applied after 6 h presoak in water. Dormancy induced by tetcyclacis was released by GA4+7 (a mixture of gibberellin A4 and A7), light, and moist-chilling treatments. When GA4+7 was applied with tetcyclacis, dormancy induction was prevented under both favorable, e.g., 25C, and unfavorable, e.g., 5C, or low water potential (Ψ), germination conditions. Unlike tetcyclacis, abscisic acid (ABA) failed to induce dormancy in lettuce seeds. Thermodormancy induction in lettuce seeds at 35C was prevented by fluridone. However, neither ABA nor tetcyclacis countered its effect. Dormancy was also induced in lettuce seeds by ancymidol, flurprimidol, or paclobutrazol. Dormancy induced by tetcyclacis in pepper, tomato, carrot, and onion seeds was released by GA4+7, but not by irradiation or moist-chilling. Chemical names used: 5-(4-chlorophenyl)-3, 4, 5, 9, 10-pentaazatetracyclo [5.4.102,6.08,11]-dodeca-3, 9-diene (tetcyclacis); 1-(4-chlorophenyl)-4, 4-dimethyl-2-(1H-1, 2, 4-triazole-1-yl)-3-pentanol (paclobutrazol); α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidine methanol (ancymidol); α-(1-methyl)-α-[4-(trifluoromethoxy) phenyl]-5-pyrimidine-methanol (flurprimidol); 1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4 (1H)-pyridinone (fluridone).
Oscillations of Whole-plant Transpiration in `Moonlight' Rose
Authors: Rose Mark A. , Beattie David J. , White John W.
Published: January 2019

Two distinct patterns of whole-plant transpiration (WPT) were observed in `Moonlight' rose (Rosa hybrida L.) using an automated system that integrated a greenhouse climate computer, a heat-balance sap-flow gauge, an electronic lysimeter, and an infrared leaf temperature sensor. One pattern consisted of a steady rate of transpiration in a stable greenhouse environment. The second pattern consisted of large oscillations in transpiration unrelated to any monitored microclimate rhythms. These oscillations had a sine-wave pattern with periods of 50 to 90 minutes and ranged from 2 to 69 g·h-1 in natural light and 3 to 40 g·h-1 under high-pressure sodium lamps at night. Leaf-air temperature difference (T1 - Ta) also oscillated and was inversely related to transpiration rate. Oscillatory transpiration has not been reported in roses. Plant scientists need to recognize the complex and dynamic nature of plant responses such as the oscillatory pattern of WPT monitored in Rosa hybrida when selecting monitoring and control strategies.
Nitrate Nitrogen Movement through the Soil Profile beneath a Containerized Greenhouse Crop Irrigated with Two Leaching Fractions and Two Wetting Agent Levels
Authors: McAvoy Richard J.
Published: January 2019

`Rose Grenadine' and `Buckaroo' garden chrysanthemums [Dendranthema ×grandiflorum (Ramat.) Kitamura] were produced in 15-cm pots in the greenhouse and fertilized with either 550 or 1000 ml of a 15 mol·m-3 N solution at each irrigation. The nutrient solution applied to half the pots contained a wetting agent (WA), and the remaining pots received no WA. Core samples were removed at 15-cm increments to a depth of 90 cm from the soil beneath the pots. The average leaching fraction (LF) from pots receiving a WA was 0.29 but was 0.26 from pots receiving no WA. However, WA did not affect the leachate NO3-N concentration or the total NO3-N deposited on the soil beneath; these were most influenced by LF. After week 2, NO3-N concentration in the upper 15 cm soil layer was 3.4 times higher with a high LF than with a low LF (30 and 8.8 g·m-3 respectively). At week 10, the NO3-N concentration in the 30 to 45 cm soil layer averaged 71.9 g·m-3 under the high LF and 35.5 g·m-3 under the low LF. Total N and NO3-N in the potting medium was higher in the low LF pots than the high LF pots, while NO3-N was higher in the medium of pots irrigated without WA than with WA. Final plant shoot mass was higher in pots irrigated to a high LF or without WA than in pots irrigated to a low LF or with WA.
Temperature Effects on Imbibition and Germination of Cucumber (Cucumis sativus) Seeds
Authors: Jennings Paul , Saltveit Mikal E.
Published: January 2019

Unlike horticulturally mature fruit of `Dasher II' and `Poinsett 76' cucumbers (Cucumis sativus L.), two cultivars that differ significantly in their level of chilling tolerance, imbibing and germinating seeds of these two cultivars responded similarly to chilling temperatures (e.g., increases in fresh weight, time to radicle emergence, and root growth). `Dasher II' and `Poinsett 76' seeds were imbibed and germinated at 10 to 30C, and seeds germinated at 25C for 24 h were chilled at 2.5C for various durations. In comparison, seeds from an aged lot of `Poinsett 76' seed (1989) responded very differently from the 1992 seed lots in all experiments. The chilling tolerance level of germinating `Poinsett 76' seed varied with the seedling age as measured by resumption of root growth. Our results suggest that some factor that confers chilling tolerance is gradually lost during the early stages of germination following imbibition.
Using Fruit-bearing Explants for Physiological Experiments
Authors: Costa Guglielmo , Biasi Rita , Vizzotto Giannina , Martin George C.
Published: January 2019

One- and three-node nectarine explants were compared with intact potted units of similar dimension. The explants and intact plants performed similarly as judged by rate of leaf photosynthesis, leaf and fruit respiration, and changes in fresh and dry weights. Water loss and transpiration were less in explants than intact plants after 24 h. Explants with fruit of nectarine, olive, and prune were used to evaluate uptake and distribution of 14C-labeled paclobutrazol (PBZ), daminozide, and sucrose in plant parts. These comparisons reveal that the explant system is useful for primary testing of hypotheses, screening of chemicals, and evaluating species response for later testing of selected parameters in the field. Three-node explants containing fruit are reliable for experiments lasting up to 4 days. Chemical names used: succinic acid 2,2 dimethylhydrazide [daminozide (SADH)]; β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol [paclobutrazol (PBZ)].
Levels of a Hydrojuglone Glucoside in Developing Pecan Leaves in Relation to Scab Susceptibility
Authors: Gueldner R.C. , Yates I.E. , Reilly C.C. , Wood B.W. , Smith M.T.
Published: January 2019

Polyphenols were analyzed in expanding buds and developing leaves of pecan [Carya illinoensis (Wangenh.) C. Koch] cultivars with varying responses to Cladosporium caryigenum (Ell. et Lang. Gottwald), the organism causing scab. Plant tissue extracts were examined by high-performance liquid chromatography using a water: methanol gradient to separate polyphenolic components on a C-18 reversed phase column. A diode-array detector was used to identify profile components by retention times and computer matching of ultraviolet spectra to standard compounds in a library. Concentrations of these polyphenols were compared throughout the growing season in leaves of pecan cultivars with low (`Elliott'), intermediate (`Stuart'), and high (`Wichita') susceptibility to scab; during susceptibility to infection by Cladosporium caryigenum from 16 cultivars; and in `Wichita' leaf discs with and without scab lesions. The major polyphenolic constituent of tissues for all cultivars was identified as hydrojuglone glucoside, which was detected in intact buds and leaves throughout the growing season. Hydrojuglone glucoside concentration increased concomitantly with leaf expansion and then declined slowly. Juglone was barely, if at all, detectable, regardless of leaf age. No correlation was found between cultivar susceptibility to pecan scab and the levels of either juglone or hydrojuglone glucoside in the healthy leaves of 16 cultivars. Leaf tissue with scab lesions had significantly higher juglone and hydrojuglone glucoside levels than leaf discs without scab lesions. Chemical names used: 4-8-dihydroxy-1-naphthyl b-d-glucopyranoside (hydrojuglone glucoside); 1,5-hydroxy-naphthoquinone (juglone).
Firmness Measurement of Freshly Harvested `Delicious' Apples by Sensory Methods, Sonic Transmission, Magness-Taylor, and Compression
Authors: Abbott Judith A.
Published: January 2019

A rapid nondestructive method for measuring apple texture using sonic vibrational characteristics of intact apples was tested on freshly harvested `Delicious' apples from major U.S. production areas. Sonic transmission spectra and Magness-Taylor (MT) firmness were measured on whole apples and compression measurements were made on excised tissue. Two experienced Agricultural Marketing Service apple inspectors assessed each apple and assigned a ripeness score according to U.S. Dept. of Agriculture grades and standards inspection procedures (based primarily on texture). Sonic functions correlated significantly with ripeness scores, MT firmness, and forces to rupture or crush the tissue in compression. Ripeness scores were more closely correlated with the destructive firmness measurements than with sonic functions. However, sonic measurement has the advantage of being nondestructive, whereas MT and tissue compression are inherently destructive. Further research is needed to modify the Instrumentation and Sensing Laboratory`s sonic technique to improve the prediction of apple firmness before it can be adapted for on-line sorting.
Development of Dark Skin Discoloration on Peach and Nectarine Fruit in Response to Exogenous Contaminations
Authors: Cheng Guiwen W. , Crisosto Carlos H.
Published: January 2019

Dark skin discoloration development on peach and nectarine cultivars was investigated in response to exogenous pH and metallic ions. The influence of skin abrasion and washing in combination with exogenous contaminants was studied in a factorial design experiment by using skin discs. Only abraded skin discs with and without washing developed discoloration after being exposed to high pH and different metallic ion concentrations. Among the metallic ion contaminants studied (Fe, Al, Cu, Sn, Zn, and Na), iron was the most effective in causing dark skin discoloration at physiological pH (3.5). Iron concentrations ≥10 ppm induced dark discoloration on abraded fruit skin. Dark discoloration development produced by exposing the skin tissue to pH levels >6 was reversible, whereas the dark discoloration induced by iron and aluminum remained stable.
Carbon Partitioning and Translocation in Primocane-fruiting Red Raspberries (Rubus idaeus L.)
Authors: Privé Jean-Pierre , Sullivan J.A. , Proctor J.T.A.
Published: January 2019

Leaf removal, cane girdling, and 14C translocation patterns were used to study source-sink relationships of primocane-fruiting (PF) red raspberries. Although the leaves in the reproductive zone were most important for vegetative and reproductive development, compensatory effects between the cane leaves were evident. When 14C translocation was studied in the reproductive portion of the cane, the lateral closest to the 14C-treated leaf was the major sink for carbohydrate from that leaf, independent of leaf position or reproductive development. Thereafter, partitioning to leaves and/or flowers or fruits above the 14C-treated leaf was related to leaf phyllotaxy 75% of the time.
Dehydration Rate after Solid Matrix Priming Alters Seed Performance of Shrunken-2 Corn
Authors: Parera Carlos A. , Cantliffe Daniel J.
Published: January 2019

In a test to overcome poor seed germination and seedling vigor of sweet corn (Zea mays L.) seeds carrying the shrunken-2 (sh2) mutant endosperm, primed seeds of two sh2 sweet corn cultivars—Crisp N'Sweet 711 (CNS-711) and How Sweet It Is (HSII)—were redried at 15, 20, 30, or 40C and 25% relative humidity after solid matrix priming (SMP). The dehydration rate was significantly lower in `CNS-711' than `HSII' at all temperatures. In both cultivars, the drying temperature after SMP was critical for seed performance. Primed seeds with a higher dehydration rate (dried at 30 or 40C) had better seed vigor, greater field emergence and seedling vigor, lower leachate conductivity and imbibition rate, and a higher respiration rate and glutamic acid decarboxylase activity than primed seeds redried at the lower temperatures or control seeds. Increased incidence of pathogen growth was observed on seeds dried at 15 and 20C relative to those dried at 30 or 40C, probably as a consequence of greater leakage from the seeds at a lower redrying temperatures. Lack of tolerance to dehydration at 15 and 20C was another factor adversely affecting the seeds redried at low temperature. A more rapid dehydration rate at a higher temperature after priming sh2 sweet corn improved many of the physiological characteristics used to measure seed quality and the subsequent emergence and vigor of the seedlings under field conditions.
Growth and Drought Tolerance of Viburnum plicatum var. tomentosum `Mariesii' in Pine Bark-amended Soil
Authors: Wood Carleton B. , Smalley Timothy J. , Rieger Mark , Radcliffe David E.
Published: January 2019

Container-grown Viburnum plicatum Thunb. var. tomentosum (Thunb.) Miq. `Mariesii' were planted in unamended planting holes, tilled plots, and tilled plots amended with aged pine bark. A 36-day drought was initiated 108 days after planting. Amending induced N deficiencies, reduced shoot growth, and increased root growth. Plants harvested from tilled and planting-hole plots at drought initiation had 63% and 68% more dry weight, respectively, than plants from amended plots. Between 8 and 19 days after drought (DAD) initiation, plants from tilled plots maintained higher relative leaf water content (RLWC) than plants from planting holes. Plants in amended plots maintained higher RLWC than both other treatments between 7 and 33 DAD. Amended and tilled treatments had higher relative leaf expansion rates (RLERs) than the planting-hole treatment 8, 11, 13, and 15 DAD. As the drought lengthened, plants in amended plots maintained higher RLERs than plants in tilled plots. While plants in pine bark-amended plots were more drought tolerant than those in tilled plots, it is unclear if increased drought tolerance was caused by the improved rooting environment or N deficiency.
Critical Zinc+2 Activities for Sour Orange Determined with Chelator-buffered Nutrient Solutions
Authors: Swietlik Dariusz , Zhang Linsen
Published: January 2019

Chelator-buffered nutrient solutions were used to study the effect of different levels of Zn activity in the rhizosphere on growth and nutritive responses of various tissues of sour orange seedlings. The seedlings were grown for 3 months in a growth chamber in a hydroponic culture containing from 5 to 69 μm and 5 to 101 μm total Zn in Expts. 1 and 2, respectively. Zn+2 activities were calculated with a computerized chemical equilibrium model (Geochem-PC), and buffered by inclusion of a chelator, diethylenetriamine pentaacetate (DTPA), at 74 and 44 μm in excess of the sum of Fe, Mn, Zn, Cu, Ni, and Co in Expts. 1 and 2, respectively. The use of DTPA-buffered solutions proved successful in imposing varying degrees of Zn deficiency. The deficiency was confirmed by leaf symptomatology, leaf chemical analyses, i.e., <16 mg·kg-1 Zn, and responses to foliar sprays and application of Zn to the roots. Growth parameters varied in their sensitivity to Zn deficiency, i.e., root dry weight < leaf number and white root growth < stem dry weight < leaf dry weight < shoot elongation and leaf area. The critical activities, expressed as pZn = -log(Zn+2), were ≈10.2±0.2 for root dry weight, 10.1±0.2 for leaf number and white root growth, 10.0±0.2 for stem dry weight, 9.9±0.2 for leaf dry weight, and 9.8±0.2 for shoot growth and leaf area. Increases in growth were observed in response to Zn applications even in the absence of visible Zn-deficiency symptoms. Seedlings containing >23 mg·kg-1 Zn in leaves did not respond to further additions of Zn to the nutrient solution. Zinc foliar sprays were less effective than Zn applications to the roots in alleviating severe Zn deficiency because foliar-absorbed Zn was not translocated from the top to the roots and thus could not correct Zn deficiency in the roots.
Modeling Inflorescence Development of the African Violet (Saintpaulia ionantha Wendl.)
Authors: Faust James E. , Heins Royal D.
Published: January 2019

The effects of temperature and daily-integrated photosynthetic photon flux (PPFDI) on African violet (Saintpaulia ionantha Wendl.) flower initiation and development were quantified to provide the basis for an inflorescence development model. The percentage of leaf axils in which an inflorescence initiated and continued development increased as the PPFDI increased from 1 to 4 mol·m-2·day-1, while the rate of inflorescence development was a function of the average daily temperature (ADT). The appearance of a visible flower bud (VB) in a leaf axil was related to the growth of the subtending leaf blade. A polynomial model based on ADT and PPFDI was used to describe leaf blade length at visible bud (LBLVB). A nonlinear model was used to describe the influence of ADT on leaf expansion rate (LER). Inflorescence appearance in the leaf axil was predicted by measuring LBL and estimating the time for the leaf blade to develop to the length required for VB. A phasic-development scale was developed to quantify inflorescence development. Days required for an inflorescence to develop from VB to first open flower was described as a function of ADT and either inflorescence height or inflorescence development stage (IDS). Days from leaf emergence to first open flower for the inflorescence initiated in that leaf axil decreased from 86 to 55 as ADT increased from 18 to 26C.
Diffusivity of Carbon Dioxide through the Skin and Flesh of `Russet Burbank' Potato Tubers
Authors: Abdul-Baki Aref A. , Solomos Theophanes
Published: January 2019

The diffusion coefficient of CO2 in `Russet Burbank' potato (Solanum tuberosum L.) tubers was determined under steady-state conditions at 10 and 27C. The data showed that the skin is the main barrier to gas diffusion, with an average diffusion coefficient of 6.57 × 10-7 and 7.61 × 10-7 cm·s-1 at 10 and 27C, respectively. The flesh also presents an appreciable barrier to gas diffusion. The average diffusion coefficient of CO2 in the flesh was 2.00 × 10-4 and 2.24 × 10-4 cm·s-1 at 10 and 27C, respectively. Under regular storage conditions, the tuber is well aerated and the concentration of O2 at the center of the tuber is sufficient to maintain aerobic respiration.
Shrunken2 Sweet Corn Yield and the Chemical Components of Quality
Authors: Wong Adamson D. , Juvik John A. , Breeden David C. , Swiader John M.
Published: January 2019

Extensive variability was found among 24 currently available commercial sh2 hybrids of sweet corn (Zea mays L.) for yield and yield components, and for the chemical components of eating quality. The primary source of variation was explained by genotypic differences, with the environmental effects due to planting locations having a minor influence. Kernel sugar concentrations, however, had a highly significant level of genotype by environment interaction. The extensive genotypic variability among the sh2 hybrids indicated that allelic variation at other loci is profoundly influencing sucrose and total sugar levels in freshly harvested sweet corn. In each case, the kernel chemical components of quality decreased from 20 to 29 days after pollination (DAP). Mean performance of sh2 hybrids for yield, yield components, and kernel quality parameters was in all cases equal or better than the hybrids homozygous for the su1 endosperm mutation. In addition, there were no strong negative relationships between yield and some of the important chemical components of kernel quality, suggesting that it may be feasible to develop superior sh2 hybrids with acceptable yield potential and improved eating quality targeted for the different sweet corn markets.
Phasic Temperature Change Patterns Affect Growth and Tuberization in Potatoes
Authors: Cao Weixing , Tibbitts Theodore W.
Published: January 2019

This study determined the responses of potato (Solanum tuberosum L., cv. Norland) plants to various patterns of air temperature changes over different growth periods (phasic temperature changes). In each of two experiments under controlled environments, eight treatments of temperature changes were carried out in two growth rooms maintained at 17 and 22C and a constant vapor pressure deficit of 0.60 kPa and 14-hour photoperiod. Plants were grown for 63 days after transplanting of tissue culture plantlets in 20-liter pots containing peat-vermiculite mix. Temperature changes were imposed on days 21 and 42, which were essentially at the beginning of tuber initiation and tuber enlargement, respectively, for this cultivar. Plants were moved between two temperature rooms to obtain eight temperature change patterns: 17-17-17, 17-17-22, 17-22-17, 22-17-17, 17-22-22, 22-17-22, 22-22-17, and 22-22-22C over three 21-day growth periods. At harvest on day 63, total plant dry weight was higher for the treatments beginning with 22C than for those beginning with 17C, with highest biomass obtained at 22-22-17 and 22-17-17C. Shoot dry weight increased with temperature increases from 17-17-17 to 22-22-22C during the three growth periods. Tuber dry weight was highest with 22-17-17C, and lowest with 17-17-22 and 17-22-22C. With 22-17-17C, both dry weights of stolons and roots were lowest. Total tuber number and number of small tubers (<2.5 cm) were highest with 17-17-17 and 17-17-22C, and lowest with 17-22-22 and 22-22-22C, whereas number of medium tubers (2.5-5.0 cm) was highest with 22-17-22C, and number of large tubers (>5.0 cm) was highest with 22-17-17C. This study indicates that tuber development of potatoes is optimized with a phasic pattern of high temperature during early growth and low temperature during later growth.
Characterization of Blossom-end Morphology Genes in Tomato and Their Usefulness in Breeding for Smooth Blossom-end Scars
Authors: Barten J.H.M. , Scott J.W. , Gardner R.G.
Published: January 2019

Pointed blossom-end morphology may be used to reduce blossom-end scar size in large-fruited, fresh-market tomatoes (Lycopersicon esculentum Mill.). The usefulness of this characteristic has been limited due to persistence of pointedness on mature fruit, resulting in postharvest bruising, and to close association of pointedness with leaf curl, which may increase foliar disease problems. The inheritance of pointedness in three breeding lines (NC 140, Fla 890559-24, and Fla 894413-1) and four accessions with previously described blossom-end morphology genes [LA 2-5 with persistent style (pst), LA 986 with beaky (bk), LA 1787 with beaky-2 (Bk-2), and LA 2353 with nipple tip (n)] was investigated. In F1 s and F2s of crosses with wild types, some pointedness was observed in heterozygotes, but the level of expression was generally close to wild type expression, except for LA 986. Consequently, Bk-2 in LA 1787 was renamed bk-2. F1 complementation tests were difficult to interpret. Wild types segregated in F2s of all complementation crosses, except for LA 986 × LA 2-5, a result indicating the presence of the same gene in these two accessions. Three new nipple-tip genes were named; n-2 in NC 140, n-3 in Fla 890559-24, and n-4 in Fla 894413-1. None of the seven accessions tested had significant leaf curl. Early identification of mutant plants by the shape of the stylar base in flowers at anthesis was reliable only for bk. Various blossom-end morphology genes may be backcrossed into otherwise desirable breeding lines, and complementing parents may be intercrossed to obtain optimal smoothness in the hybrid without undesirable pointed mature hybrid fruit.
Genetic Analysis of 11 Polymorphic Isozyme Loci in Chestnut Species and Characterization of Chestnut Cultivars by Multi-locus Allozyme Genotypes
Authors: Huang Hongwen , Dane Fenny , Norton Joseph D.
Published: January 2019

Allozyme polymorphism in chestnut (Castanea) species was investigated using isoelectric focusing in thin-layer polyacrylamide slab gels. Genetic analysis of the progenies of intraspecific crosses and interspecific F2s and backcrosses (BC1s) allowed the verification of 11 polymorphic isozyme loci from 11 enzyme systems. The following loci were defined: Acp, Adh, Est-1, Est-2, Est-5, Me, Prx-1, Prx-2, Prx-3, Skd-3, and Skd-4. All polymorphic loci behaved as single-locus Mendelian genes. Skd showed unique species specificity. Skd-1 and Skd-2 were unique to the American chestnut (C. dentata Borkh.) and the European chestnut (C. sativa Mill.), whereas Skd-3 and Skd-4 were unique to the Chinese chestnut (C. mollissima Bl.) and the Japanese chestnut (C. crenata Sieb.). Linkage analysis revealed linkage for three pairs of loci: Skd-3/Skd-4, Est-1/Est-2, and Est-5/Prx-1. The single-tree progeny method was used successfully for isozyme genetic analysis. Forty-seven chestnut cultivars in six chestnut species were characterized using 12 isozyme loci and can be unambiguously identified by 12 multi-locus genotypes. The interspecific and geographic relationships among species were also discussed.
Ethylene-, Light-, and Prechill-enhanced Germination of Echinacea angustifolia Seeds
Authors: Feghahati S.M. Javad , Reese R. Neil
Published: January 2019

Echinacea angustifolia DC., the common coneflower of the western Great Plains, is difficult to propagate by achenes due to inherent seed dormancy. The effects of light and prechilling on seed germination were examined, alone and combined with scarification (mechanical, acid) and ethylene (ethephon) treatments. The results showed that a 2-week prechill treatment combined with ethephon and continuous light, followed by a 2-week germination period in light (16 hours per day) at 25C, could induce >95% seed germination in E. angustifolia. This was a significantly higher percentage of germination over a shorter period of time than any other method examined or previously described. This treatment also synchronized germination, with most viable seeds germinating in <1 week after being placed at 25C in the light. Chemical name used: 2-chloroethylphosphonic acid (ethephon).
Sugar Content, Compartmentation, and Efflux in Strawberry Tissue
Authors: John Ofosu-Anim , Yamaki Shohei
Published: January 2019

Using the compartmental analysis method, the distribution of sucrose, glucose, and fructose and their efflux from the free space, cytoplasm, and vacuole were determined in Nyoho strawberries (Fragaria ×ananassa Duch.) picked 25 or 35 days after pollination (DAP). At both stages, >70% of total sugar accumulated in the vacuole. Concentration of sugar in the free space increased from 167 mm in fruit at 25 DAP to 217 mm at 35 DAP, whereas that within the cell (cytoplasm + vacuole) increased from 233 to 352 mm. Permeability of the plasma membrane to sucrose, glucose, and fructose was higher than that of the tonoplast and, except for that of fructose, the permeability of the plasma membrane to sugars increased with fruit maturation. ABA at 10-5m compared to 10-4m restricted the release of all sugars from fruit discs and was due mainly to reduced efflux across the plasma membrane rather than the tonoplast. Thus ABA may stimulate the accumulation of sugars in fruit flesh by restricting their efflux. Chemical name used: abscisic acid (ABA).