bluuebunny/crossref_metadata_2025 huggingface dataset:
A Methodology for Determining Suitable Heat-unit Requirements for Harvest of Highbush Blueberry
Authors: Carlson J.D. , Hancock J.F.
Published: January 2019

Fifteen years of Michigan harvest data for highbush blueberry (Vacciniun corymbosum L.) were used in conjunction with daily maximum and minimum temperatures to determine appropriate heat-unit models for first-picking dates of 13 cultivars. For each cultivar, an optimal heat-unit model was chosen after evaluating the performance of a standard method with 72 combinations of three variables: a) starting date for the heat-unit accumulations (SDATE), b) low-temperature threshold (TLOW), and c) high-temperature threshold (THIGH). The optimal model sought to include the most important criteria values with respect to model performance and to minimize the average square of the prediction error (days) and the range in that error. Compared with a strict calendar-day method of estimating harvest dates, the heat-unit models reduced the standard deviation of the prediction error from 22% to 69%, depending on cultivar.
NAA-induced Ethylene and ACC in `Delicious' Spur Tissues: Changes with Temperature and Time
Authors: Currv Eric A.
Published: January 2019

These studies with apple (Malus domestica Borkh.) spur tissues were conducted to investigate the mechanism whereby NAA may stimulate fruit abscission in the spring but acts to prevent fruit drop in the fall. NAA-induced ethylene evolution from `Delicious' spurs in vivo was similar to that evolved from excised leaf and fruit tissues that later were treated in the laboratory and incubated in darkness at 20C. The peak in ethylene production occurred 24 hours after treatment at 30C, 48 hours after treatment at 20C, and production was still increasing 72 hours after treatment at 10C. Leaf tissue showed the greatest induction of ethylene from NAA followed by fruit and petiolar tissues. Induction was greatest early in the season and declined steadily until about “June drop.” After this time, none of the tissues showed significant capacity for ethylene induction. Chemical names used: 2-(1 -naphthyl) acetic acid (NAA).
C02-enhanced Foliar Deformation of Tomato: Relationship to Foliar Starch Concentration
Authors: Tripp K.E. , Peet M.M. , Willits D.H. , Pharr D.M.
Published: January 2019

Two cultivars of greenhouse tomato (Lycopersicon esculentum Mill.) were grown with ambient or 1000 μl CO2/liter during Jan.-June 1987 and 1988. In both years, CO2-enrichment increased foliar deformation and foliar starch, but during the season, foliar starch levels decreased while deformation increased. `Laura' had more deformation, while `Michigan-Ohio' had higher foliar starch concentration. During an entire season, there was no significant relationship between foliar starch concentration and deformation severity. Foliar C exchange rates in the lower canopy were not affected by severity of deformation. Data from these experiments do not support the hypothesis that excess foliar starch is responsible for foliar deformation at elevated CO2.
Citrus Fruit Sector Chimeras as a Genetic Resource for Cultivar Improvement
Authors: Bowman Kim D. , Gmitter Frederick G. , Moore Gloria A. , Rouseff Russell L.
Published: January 2019

Citrus fruit with sector chimeras were collected in commercial packinghouses and from the field. Chimeric fruit from eight cultivars of sweet oranges [Citrus sinensis (L.) Osbeck], grapefruit (C. paradisi Macf.), tangelo (C. paradisi × C. reticulate Blanco), and tangors (C. reticulate × c. sinensis) were found at a frequency of 0.009% to 0.271%. Tetraploid plants obtained from one type of sector mutant (termed gigas) and albino plants obtained from another type of sector mutant confirmed that some genetic mutations observed in fruit rind can be recovered in nucellar seedlings. The gigas chimeras were identified as a source of citrus tetraploids. Several types of potentially useful sector mutants with altered rind color were observed, and plants were produced from some mutant sectors by developed seed or culture of aborted ovules. HPLC analysis of rind tissues from sectors of one chimeric fruit revealed substantial quantitative and qualitative differences in pigment composition. Propagation of plants from mutant sectors may yield cultivars with improved fruit color, altered maturation date, and reduced disease or mite susceptibility and may eventually lead to breeding of seedless triploid hybrids.
Variation in Double-stranded Ribonucleic Acid among Pepper Cultivars
Authors: Valverde Rodrigo A. , Fontenot James F.
Published: January 2019

Double-stranded ribonucleic acid (dsRNA) was found associated with 51 of 80 healthy pepper (Capsicum annuum L., C. frutescent L., C. chinense Jacq.) cultivars analyzed. In general, dsRNAs were consistent within particular cultivars. Twelve distinct dsRNA profiles that varied in the number and size of the dsRNA segments were obtained. All bell and pimento pepper cultivars analyzed had a similar dsRNA profile. Furthermore, all six cherry pepper cultivars tested were free of dsRNAs. However, an association between the dsRNA profile and the pepper group was not obtained with other cultivars. Selected dsRNAs were transmitted at a high rate through the seed of self-pollinated plants but were not transmitted through grafts to plants that lacked them.
Carbohydrate Depletion and Leaf Blackening in Protea neriljiolia
Authors: McConchie Robyn , Lang N. Suzanne , Gross Ken C.
Published: January 2019

Leaf blackening on cut flower Protea nerii[olia R. Br. stems was dramatically reduced under a 12-hour photosynthetic light period (120 μmol·m-2·s-1) at 25C for 15 days compared with stems kept in the dark. In the light, addition of 0.5% exogenous sugar to the vase solution resulted in a maximum of 2.5% leaf blackening, while stems with no exogenous sugar had a maximum of 16.5%. Continuous darkness resulted in 94% leaf blackening by day 7, irrespective of sugar treatment. Starch and sucrose concentrations were markedly lower in leaves on dark-held stems than in leaves on stems held in the light; thus, carbohydrate depletion could be the primary stress that initiates leaf blackening. In the light, rates of carbon exchange and assimilate export were similar, indicating that the amount of carbon fixed maybe regulated by sink demand. The pattern of carbon partitioning changed in light-held leaves of the 0% sugar treatment during rapid floral expansion and senescence. Inflorescence expansion appears to influence partitioning of photoassimilates and storage reserves into transport carbohydrates; under decreased sink demand, the assimilate export rate decreases and photoassimilates are partitioned into starch. The data suggest that sink strength of inflorescences held in darkness may be responsible for the depletion of leaf carbohydrates and. consequently, blackening.
Shading, Growth, and Dry-matter Partitioning of Cocoyam [Xanthosoma sagittifolium (L.) Schott]
Authors: Valenzuela Hector R. , O'Hair Stephen K. , Schaffer Bruce
Published: January 2019

Cocoyam was grown in 100%, 50%, or 30% daylight to determine the effect of light intensity on growth characteristics at various stages of plant development. Beginning ≈ 2 months after planting, growth was monitored at three or four monthly intervals. Plants grown in shade had more petiole and leaf lamina growth and extension, as well as increased top: corm plus cormel ratio (dry-weight basis), than plants grown in 100% daylight. Shade-grown plants had a higher leaf area index and specific leaf area than sun-grown plants. Sun-grown plants had a higher net assimilation rate and specific leaf density than shade-grown plants. Linear equations were developed to predict lamina area through measurements of leaf lamina width and length, petiole length, and lamina dry weight.
Evaluation of Controlled-release Fertilizers for Young Citrus Trees
Authors: Zekri Mongi , Koo Robert C.J.
Published: January 2019

Controlled-release sources of N and K were compared with soluble sources on young `Valencia' orange trees (Citrus sinensis [L.] Osb.). The effects of these fertilizers on leaf mineral concentration, soil chemical analysis, and tree growth were evaluated for 3 years. Soluble fertilizers were generally more readily available but had shorter residual effects on leaves and soil than controlled-release fertilizers. In the top 30 cm of soil, the plots treated with controlled-release N had 23% more total N than those treated with soluble N sources, while the plots fertilized with controlled-release K contained 56% more extractable K than those that received soluble K. Different effects on leaf and soil N between the two controlled-release N sources, sulfur-coated urea (SCU) and methylene urea (MU), were also found. With the use of controlled-release fertilizers, application frequency was reduced from a total of 15 to six applications with no adverse effects on tree growth, leaf mineral composition, or soil fertility during the first 3 years. Combining soluble and controlled-release fertilizers in a plant nutrition program offers an economical and effective strategy for citrus growers.
Calcium Accumulation, Calcium Distribution, and Biomass Partitioning in Collards
Authors: Johnson Jon R.
Published: January 2019

`Vates' collard (Brassica oleracea L. Acephala Group) was more susceptible to tipburn than `Blue Max' or “Heavi Crop' in field and nutrient solution culture experiments. The root system of Vates' was smaller than that of `Blue Max' in all experiments. Because of its smaller root system, `Vates' may be more susceptible to moisture stress than `Blue Max' when grown under high-temperature conditions on sandy soils, thus increasing susceptibility to tipburn. Root system size, however, did not influence Ca accumulation or Ca concentration in the plants. Calcium accumulation rate was higher for `Blue Max' and `Heavi Crop' than for Yates' during the 3rd through the 5th weeks of culture, in a nutrient solution that contained 5 mM Ca. Calcium efficiency ratio (CaER, milligrams of dry matter produced per milligram of Ca in tissue) for young leaves was higher for `Blue Max' and `Heavi Crop' than “for `Vates' when plants were grown with 1 mM Ca, which may partly explain the greater susceptibility of `Vates' to tipburn. `Heavi Crop' had a higher total plant CaER than `Blue Max' when grown with 5 mM Ca.
Nitrogen Supply Influences Carbohydrate Partitioning of Pepper Seedlings and Transplant Development
Authors: Aloni Beny , Pashkar Tamara , Karni Lea , Daie Jaleh
Published: January 2019

We investigated the effects of N nutrition on growth and carbohydrate partitioning of pepper (Capsicum annuum L., cv. Maor) seedlings in the greenhouse and on their subsequent recovery and development after transplanting. Seedlings received 0, 30, 100, or 200 mg N/liter for 14 days, after which they were transplanted and received 100 mg N/liter. Nitrogen levels below 100 mg·liter−1 inhibited shoot growth and leaf chlorophyll content; both were severely inhibited in the absence of supplemental N. Root growth had a negative relation with N supply; an enhanced root: shoot ratio was observed under low-N regimes. On a unit-leaf-area basis, CO2 fixation was not affected when N was present; however, it was greatly inhibited in the absence of N. Changes in the leaf starch and soluble sugar concentrations occurred as a function of N supply and leaf age. In the roots, low N led to lower sucrose and higher levels of hexose and starch. More sucrose was transported and accumulated into leaf veins of low-N tissue. Exogenously supplied 14C-labeled sucrose was rapidly converted into starch in the low-N tissue. Seedlings that received 100 mg N/liter had the highest post-transplant growth rate and flowered earlier. Carbohydrate status of young pepper seedlings influenced their post-transplant recovery. Optimal N supply is essential for full recovery and development of transplants.
Gas Permeability of Fruit Coating Waxes
Authors: Hagenmaier Robert D. , Shaw Philip E.
Published: January 2019

The permeability to O2, CO2, C2H4, and water vapor was determined for 19 commercial fruit wax coatings, four ingredients thereof, and one shrink-wrap film. For the commercial coatings, the O2permeability at 50% relative humidity and 30C ranged from 470 to 22,000 ml (STP) × mil/(m2 × day × atm) (1 mil = 0.0254 mm) with CO)2. permeability two to eight times as high. Permeability to noncondensable gases tended to be higher for coatings made from carnauba wax than for those made from shellac and rosin. Commercial fruit wax had sufficiently low noncondensable gas permeability to account for large reductions in the respiration rate of coated fruit. Wax coatings could be improved if permeability were controlled:
Sulfur Dioxide and Nitrogen Dioxide Meet Growth, Gas Exchange, and Water Relations of Potato Plants
Authors: Petitte Jane M. , Ormrod Douglas P.
Published: January 2019

The effects of SO2 and NO2, singly and in combination, on the growth and physiology of nontuberizing Solarium tuberosum L. `Russet Burbank' plants were studied in controlled conditions. Plants were exposed to 0.11 μl SO2 and/or 0.11 μl NO2/liter for 24 hours a day up to 10 days. Statistically significant effects were observed mainly in the SO2+ NO2 treatments compared with the control plants. Leaf area was reduced from day 2 onward, and root fresh and dry weights were reduced from day 4 onward. Significant reductions in leaf and stem dry weights occurred on day 6. Net CO2 exchange rates were reduced for SO2 exposed compared with control plants beginning on day 3, while water loss rates were increased with SO2 + NO2 beginning on day 3. The increases in water loss rate were possibly due to the development of cuticular injury observed as abaxial glazing on the upper and middle canopy leaves. Leaf osmotic potential (π) of plants with SO2 + NO2 became more negative within the first 24 hours of the exposure. This reduction was accompanied by an increase in reducing sugar concentration. Xylem water potential was reduced in the mature and expanding leaflets by day 2 of the SO2 + NO2 exposure. The most sensitive aspect of the action of SO2 + NO2 appeared to be the increase in reducing sugars that affected osmotic potential in the leaves. Considering the retardation of root growth, these data suggest that the pollutant gases may have interfered with partitioning of dry matter from the leaves to the roots.
Flowering, Ethylene Production, and Ion Leakage of Coffee in Response to Water Stress and Gibberellic Acid
Authors: Schuch Ursula K. , Fuchigami Leslie H. , Nagao Mike A.
Published: January 2019

The effects of water stress and GA, on breaking dormancy of flower buds of coffee (Coffea arabica L.) were investigated. In the first experiment, water was withheld until the trees reached leaf water potentials (WP) of -1.20, - 1.75, -2.65, or -3.50 MPa. Water potential, ethylene production, and ion leakage of flower buds and leaf disks were examined from release from water stress until anthesis. Trees that had experienced leaf WP of less than - 2.65 MPa, and flower bud WP of about - 4.0 MPa flowered within 9 days after irrigation. In flower buds where dormancy had been broken with water stress, ethylene production was low compared to dormant buds and flowers at anthesis. In the second experiment, O, 50, 100, or 200 mg GA3/liter was painted on branches of nonstressed trees. In experiment three, water was withheld until plants reached leaf WP of -0.6, -1.3, - 2.1, or - 3.0 MPa, then two branches per tree were painted with O, 50, and 100 mg GA3/liter. Gibberellic acid partially compensated for insufficient water stress to initiate flower opening. Ethylene evolution of flower buds was affected by water stress but not by GA3 treatment. Severe water stress treatments and GA, treatment (200 mg·liter-1) increased ethylene evolution of leaf disks. Ion leakage of flower buds and leaf disks was increased by severe water stress. Ion leakage of flower buds was highest at anthesis. After water stress, dormant and nondormant flower buds at the 4-mm stage could be distinguished based on their ethylene evolution. Chemical name used: gibberellic acid (GA3).
Six New Somatic Citrus Hybrids and Their Potential for Cultivar Improvement
Authors: Grosser Jude W. , Gmitter Frederick G. , Sesto Franca , Deng Xiu Xin , Chandler J.L.
Published: January 2019

Protoplasm culture following polyethylene glycol (PEG) -induced fusion resulted in the regeneration of somatic hybrid plants from the following six parental combinations: Citrus sinermis (L.) Osbeck cv. Hamlin + Severinia buxifolia (Poir.) Tenore (Chinese box-orange); C. reticulate Blanco cv. Cleopatra + Poncirus trifoliata (L.) Raf. cv. Flying Dragon; C. reticulate cv. Cleopatra + Swingle citrumelo (C. paradisi Macf. × P. trifoliata); C. sinensis cv. Hamlin + C. jambhiri cv. Rough lemon; C. sinensis cv. Valencia + C. jambhiri cv. Rough lemon; and C. paradisi cv. Thompson + `Murcott' tangor (purported hybrid of C. reticulate × C. sinensis). Diploid plants were regenerated from nonfused embryogenic culture-derived protoplasts of `Cleopatra' mandarin and `Hamlin' and `Valencia' sweet orange, and from nonfused leaf-derived protoplasts of Rough lemon and `Mnrcott'. Regenerated plants were classified according to leaf morphology, chromosome number, and isozyme analyses. All of the somatic hybrids reported herein are tetraploid (2n = 4x = 36), with the exception of the `Hamlin' + S. buxifolia hybrid, which was unexpectedly found to have a chromosome number of 2n = 27. These six new somatic hybrids have potential in citrus scion and rootstock improvement for commercial use.
Relationship between Corky Root Disease and Yield of Crisphead Lettuce
Authors: Datnoff L.E. , Nagata R.T.
Published: January 2019

The effects of corky root (CR) disease, caused by Rhizomonas suberifaciens(van Bruggen, Jochimsen, and Brown) on fresh and marketable weights of lettuce (Lactuca sativa L.) were assessed during the 1988 and 1989 cropping seasons in several commercial lettuce fields. The resistant crisphead cultivars Raleigh and South Bay and the susceptible cultivars Ithaca and Shawnee produced similar yields in fields either planted in lettuce for the first time or in continuous lettuce production for three cropping cycles. Average yields of the resistant cultivars, from two fields cropped for six cycles naturally infested with CR, ranged from 875 to 1062 g/head fresh weight and 674 to 907 g/head marketable weight. The average yields of the susceptible cultivars in these infested fields ranged from 419.8 to 668.7 g/head fresh weight (37% to 52% yield loss) and 317.5 to 488.2 g/head marketable weight (46% to 53% yield loss). CR severity ratings were highly negatively correlated with root dry matter accumulation and whole and marketable head weights of-lettuce.
Foliar Absorption of Urea, Ammonium, and Nitrate by Perennial Ryegrass Turf
Authors: Bowman Daniel C. , Paul Jack L.
Published: January 2019

The absorption and assimilation of 15N-labeled urea, (NH4)2 S O4, and KNO applied to the foliage of perennial ryegrass (Lolium perenne L.) turf were examined under a controlled environment. Each source of N was dissolved in deionized water to a final concentration of 25 g N/liter and spray-applied at a rate of 5 g N/m2. Absorption of the fertilizer-N over 48 hours, as measured by 15N analysis of tissue digests, amounted to 35%, 39%, and 40% for the urea, (NH4)2 S O4, and KNO3, respectively. Absorption was also estimated by a washing procedure that measured the urea remaining on the foliage and by the increase in total N in the ryegrass tissue. There were no significant differences between the three methods for absorption of (NH4) 2SO4 and KNO3. The washing method, however, significantly overestimated absorption of urea. Partitioning of the absorbed N between tissues was similar at 48 hours for all three N sources, averaging 32% in new leaves, 52% in old leaves and shoot tissue, and 16% in the roots. Most of the absorbed urea- and NH4 -N was assimilated by 48 hours, whereas only half of the NO3 -N was reduced during that period.
Autumn-applied Growth Regulators Influence Leaf Retention, Bud Hardiness, Bud and Flower Size, and Endodormancy in Peach and Cherry
Authors: Seeley Schuyler D. , Damavandy Hossein , Anderson J. LaMar , Renquist Richard , Callan Nancy W.
Published: January 2019

Foliar applications of growth regulators (GR) in early autumn induced leaf retention (LR) on peach [Prunu,s persica (L.) Batsch.] and `Montmorency' tart cherry (Prunus cerasus L.) trees. In `Johnson Elberta' peach, the relative effectiveness of GRs on LR was NAA = Promalin (BA + GA4+7) > GA4+7 > GA3 > BA > control, and on leaf detachment pull force (PF) NAA > BA + GA4+7 > GA4+7 = GA3 > BA3 > BA > control. Relative GR-induced chlorophyll (CL) content in retained leaves was BA + GA4+7 > GA4+7 > GA3 > BA > control > NAA. Relative xanthophyll (XN) content of retained leaves was NAA > control > BA > GA3 = GA4+7 = BA + GA4+7. Treating only half of a peach tree with NAA did not affect LR on the untreated side. NAA decreased subsequent bud and flower size in peach. Bud hardiness was enhanced by NAA in `Johnson Elberta' peach but not in `Redhaven' peach or in `Montmorency' tart cherry. NAA increased hardening on both the leafy treated (foliated) and untreated (defoliated) sides of half-treated `Johnson Elberta' trees. Increased endodormancy duration, as measured by GA3 forcing of terminal leaf buds, was proportional to LR. Chemical names used: N-(phenylmethyl)- 1H-purin-6-amine (BA); (1a,2ß,4bß,10ß)-2,4a,7-trihydroxy-l-methyl-8-methylenegibb-3-ene-l,lO-dicarboxylic acid,l,4a-lactone (GA3, GA4+7); l-naphthaleneacetic acid (NAA).
Soil-applied Sulfur Affects Elemental Leaf Content and Growth of `Tifblue' Rabbiteye Blueberry
Authors: Spiers James M. , Braswell John H.
Published: January 2019

Two-year studies were conducted on 4- to 6-year-old rabbiteye blueberry (Vacciniun ashei Reade) plants grown on a high (6.6) pH soil and irrigated regularly with water containing moderate amounts of Na and Ca (32 and 15 ppm, respectively). In one study, various levels (0, 280, 560, and 1120 kg·ha-1) of elemental S were applied in a single annual application. In another study, a single level (1120 kg·ha-1) of S was applied annually in either one, two, or four applications. Applications of S at up to 1120 kg·ha-1 were not detrimental to plant vigor of rabbiteye blueberries. Soil pH decreased with successively higher levels of applied S. Leaf P, K, and Mn contents were higher and soil pH was lower with single compared with multiple applications of S. Soil K, Ca, Mg, and S levels were negatively correlated with plant growth. Amounts up to 1120 kg·ha-1 of applied elemental S were not sufficient to lower soil pH to a level desirable for rabbiteye blueberry production when the soil was irrigated 7 months·year-1 with water containing moderate amounts of Na.
Plant Growth and Cutting Production of Container-grown Pelargonium Stock Plants as Affected by N Concentration and N Form
Authors: Ganmore-Neumann Ruth , Hagiladi A.
Published: January 2019

Stock plants of Pelargonium zonale `Empress' were grown for 130 days on coarse tuff medium in a greenhouse. Four N concentrations (50, 100,200, and 400 mg N/liter) and three NO3-: NH4+: ratios (70:30, 60:40, and 40:60) were applied. The development of mother plants, production of cuttings, and the recovery of applied N were measured. Number of cuttings was not affected by any treatments except for the low N concentration. The proportion of absorbed N was higher than that of water in the plants treated with 50 or 100 mg N/liter, while those fertilized with 200 or 400 mg N/liter absorbed more water relative to N uptake. Nitrogen recovery efficiency decreased from 70% to 10% for the 50- to 400-mg N/liter treatments, respectively. Percentage of applied N lost by leaching (30% to 70%), and N that could not be accounted for (0.5% to 20%), increased with increasing N concentration and NH4+ percentage in the solution. The minimum concentration to be used in fertilization of Pelargonium mother plants is 100 mg N/liter. Optimal N supplied ranged between 100 and 200 mg N/liter.
Drought, Paclobutrazol, Abscisic Acid, and Gibberellic Acid as Alternatives to Daminozide in Tomato Transplant Production
Authors: Latimer Joyce G.
Published: January 2019

`Floradade' tomato (Lycopersicon esculentum Mill.) transplants treated with foliar sprays of paclobutrazol at 0, 14, 30, 60, or 90 ppm exhibited reductions in stem length, leaf area, and plant dry weight in a cubic response pattern. Gibberellic acid (GA) drenches, at 10, 100, or 250 ppm, increased stem length, leaf area, and plant dry weight. Daminozide (2500 or 5000 ppm) sprays reduced leaf area and dry weight, but 5000 ppm had no effect on stem length. Abscisic acid drenches, at 275, 660, or 1320 ppm, did not affect final plant size. In subsequent experiments to produce transplants for field evaluation, plants treated with paclobutrazol sprays at 90 (1987) and 14 or 60 ppm (1988) had smaller leaf area, stem length, and shoot dry weight than untreated plants. In 1987,90 ppm paclobutrazol reduced stem shear strength, while 2500 ppm daminozide increased stem strength relative to controls. In 1988, 2500 ppm daminozide increased transplant growth while 660 ppm abscisic acid had no effect. Paclobutrazol (14 ppm) and drought improved field establishment of transplants as measured by shoot dry weight gain after field planting. In 1988, total fruit yield was reduced by 60 ppm paclobutrazol and GA. Although fruit size was unaffected by treatments, fruit number was reduced by GA. Chemical names used: butanedioic acid mono (2,2-dimethylhydrazide) (daminozide); B-[(4-chlorophenyl)methyl]-α -(1,1-dimethylethyl) -N-1,2,4-triazole-1-ethanol (paclobutrazol).
Controlled Atmosphere Storage of `Redcoat' Strawberry Fruit
Authors: Smith Richard B.
Published: January 2019

Strawberries (Fragaria × ananassa Duch.) cv. Redcoat were stored at several temperatures and for various intervals in controlled atmospheres (CA) containing 0% to 18% CO2 and 15% to 21% 02. Bioyield point forces recorded on the CA-stored fresh fruit indicated that the addition of CO2 to the storage environment enhanced fruit firmness. Fruit kept under 15% CO2 for 18 hours was 48% firmer than untreated samples were initially. Response to increasing CO2 concentrations was linear. There was no response to changing 02 concentrations. Maximum enhancement of firmness was achieved at a fruit temperature of 0C; there was essentially no enhancement at 21C. In some instances, there was a moderate firmness enhancement as time in storage increased. Carbon dioxide acted to reduce the quantity of fruit lost due to rot. Fruit that was soft and bruised after harvest became drier and firmer in a CO2-enriched environment.
Substantial Errors in Estimates of Sap Flow Using the Heat Balance Technique on Woody Stems under Field Conditions
Authors: Shackel Kenneth A. , Johnson R. Scott , Medawar Charles K. , Phene Claude J.
Published: January 2019

The heat balance method was used to estimate transpirational sap flow through 60- to 75-mm-diameter stems (trunks) of 3-year-old peach [Prunus persica (L.) Batsch. cv. O'Henry] trees under field conditions. On rare occasions, heat balance estimates agreed well with independent lysimetric measurements, but on most occasions, heat balance estimates of sap flow were unrealistic in both direction and magnitude. In some cases, the errors in sap flow approached two orders of magnitude and were always the result of a calculation involving division by a very small and sometimes negative temperature differential between the stem surface temperature above and below the gauge heater. The occurrence of negative temperature differentials under positive transpiration conditions may be inconsistent with a fundamental assumption in the heat balance model, namely that temperature differentials are solely a consequence of the dissipation of energy supplied to the gauge heater. In the absence of heating power applied to the gauge, temperature differentials exceeding - 1C were correlated with the rate of change in stem temperature, indicating that ambient conditions themselves can impose a bias in gauge signals and, hence, influence gauge accuracy. Our results suggest that the effect of ambient conditions on gauge signals should be critically evaluated before considering heat balance estimates of sap flow as reliable under any given conditions.
Crop Load Affects Mineral Concentrations and Incidence of Bitter Pit in `Cox's Orange Pippin' Apple Fruit
Authors: Ferguson I.B. , Watkins C.B.
Published: January 2019

Apple fruit (Malus domestics Borkh. cv. Cox's Orange Pippin) were harvested in four orchards from trees growing under the same conditions but differing in crop load. Regardless of fruit size, apples from light-cropping trees had lower Ca and higher K concentrations and more bitter pit than did fruit from trees with heavy crop loads. The inverse relationship between Ca concentration in the fruit and the incidence of bitter pit also varied according to crop load and could affect the ability to predict incidence of bitter pit from Ca measurements. Differences in fruit maturity that would influence bitter pit incidence were not associated with crop load. The enhanced susceptibility to storage disorders, such as bitter pit, in fruit of all sizes from light-cropping trees suggests the need to handle fruit from such trees differently for postharvest storage.
Water Stress and Storage Environment Affect Pillowy Fruit Disorder in Cucumber
Authors: Thomas Ronald S. , Staub Jack E.
Published: January 2019

Mean daily stomatal resistance was higher (58%; to 384%), photosynthesis values lower (11% to 49%), and crop water stress index values higher (92% to 95%) in stressed cucumber (Cucumis sativus L.) plants than in irrigated control plants in three experiments performed in 1987 and four in 1988. Pillowy fruit disorder (PFD) was more frequent (110% to 150%) and more severe (59% to 81%) in freshly harvested fruits from stress plots when compared to controls. No after-storage differences in PFD were detectable between water stress treatments. Mean PFD ratings of processed fruit following postharvest storage at 26.5C and either 60% or 75% relative humidity were significantly higher than ratings of fruit stored at either 10.5 or 15.5C and 85% relative humidity. The progressive development of pillowy and the observed enhancement of PFD symptoms following storage at higher storage temperatures indicated that postharvest changes can occur in fruit mesocarp tissue and that the development of PFD can be altered, to some extent, during storage. Negative correlations (- 0.18 to - 0.78) between fruit quality and PFD ratings suggested that these changes can affect processed product quality. Pillowed tissue of processed fruit was significantly softer (33% to 39%) than nonpillowed tissue.
Enhanced Emergence and Seedling Vigor in shrunken-2 Sweet Corn via Seed Disinfection and Solid Matrix Priming
Authors: Parera Carlos A. , Cantliffe Daniel J.
Published: January 2019

Presowing seed treatments were devised to improve emergence and crop uniformity of two sweet corn (Zea mays L.) cultivars [`Crisp N' Sweet 711' (CNS-711) and `How Sweet It Is' (HSII)] that carry shrunken-2 (sh2) mutant endosperm. The treatments included a fungicide combination, sodium hypochlorite (SH), solid matrix priming (SMP), and SMP combined with SH during treatment (SMPSH). Seed germination was tested in a laboratory cold test. Emergence percentage, emergence rate index (ERI), and seedling dry weight were calculated from field trials. CNS-711, in the cold test and field trials, had a higher germination rate, ERI, final emergence, and seedling dry weight than HSII. In both cultivars, SMPSH significantly improved germination in the cold test and final emergence and ERI in the field trials for HSII compared to nontreated seeds. There was no significant difference between the fungicide and SMPSH treatments regardless of cultivar. These results suggest that the combination of SMP and disinfection with SH can be an alternative seed treatment to fungicides to improve uniformity and stand establishment in sh2 sweet corns.
Advancement of `Riesling' Fruit Maturity by Paclobutrazol-induced Reduction of Lateral Shoot Growth
Authors: Reynolds A.G. , Wardle D.A. , Cottrell A.C. , Gaunce A.P.
Published: January 2019

Paclobutrazol (PB) was sprayed on hedged `Riesling' (Vitis vinifera L.) vines at one of five concentrations (0, 1000, 2000, 3000, or 4000 mg·liter-1) as single annual applications over 3 years (1987-89). Observations were made on growth, yield, and fruit composition during the years of application and 1 year thereafter (1990) to test carryover effects. PB had no effect on vine vigor, expressed as weight of cane prunings, during the three application years, but reduced vine vigor linearly with concentration in 1990. Yield was reduced by PB in the first 2 years of the trial, while in one season cluster weight and berries per cluster were also reduced. °Brix was increased by PB during all 3 years of application; titratable acidity was reduced and pH increased in the first year of application. PB sprays significantly reduced lateral shoot length, mean leaf size on both main and lateral shoots, and total leaf area on main and lateral shoots. Winter injury to buds, cordons, and trunks was also reduced with increasing PB level. Residues of PB in fruit in the first year of application ranged from 9 μg·kg-1 at the 0-m·gliter-1 level to 638 μg·kg-1 at the 4000-mg·liter-1 level. PB shows promise as a viticultural tool for advancement of fruit maturity, with possible additional benefits such as improved vine winter hardiness. Chemical name used β -[(4-chlorophenyl) methyl]-α -dimethylethyl)-1-H-1,2,4-triazole-l-ethanol (paclobutrazol, PB).
Postharvest Handling of Cut Gloriosa rothschildiana O'Brien (Liliaceae) Flowers
Authors: Jones Rodney B. , Truett Janyce K.
Published: January 2019

Postharvest treatments designed to enhance the vase life of cut Gloriosa rothschildiana flowers were tested. Vase life was significantly extended by the germicides 8-HQC (250 mg·liter-1), DICA (50 mg·liter-1), and Physan-20 (50 mg·liter-1). Germicides acted primarily by improving solution uptake. Sucrose, either as a continuous treatment (of 2% or 5% w/v), or as a 24-hour pulse (20%), significantly enhanced vase life, primarily by enhancing the development of immature buds and delaying senescence in open flowers. Flowers stored at 1C developed signs of chilling injury within 3 days, but chilling symptoms were not displayed in stems stored at 10C for 10 days. Flowers were not affected when exposed to 50 μl ethylene/liter for 24 hours. Transport and short-term storage in sealed, air-filled bags to protect the flowers from physical damage resulted in some atmosphere modification within the bags. Fungal growth occurred when flowers were kept in air-tilled bags for more than 6 days, resulting in a reduction in vase life. Chemical names used: 8-hydroxyquinoline citrate (8-HQC); sodium dichloroisocyanuric acid (DICA); n-alkyl dimethyl ethylbenzyl ammonium chloride (Phyrsan-20).
Isozymes in Ananas (Pineapple): Genetics and Usefulness in Taxonomy
Authors: DeWald M.G. , Moore G.A. , Sherman W.B.
Published: January 2019

Genetically characterized isozyme loci are useful for taxonomic studies. In an initial study a few Ananas genotypes were used to determine which enzyme systems would give well-resolved banding patterns on starch gels. The enzyme-staining systems that resulted in well-resolved banding patterns were used to survey more Ananas genotypes to identify and characterize isozyme polymorphism. Genetic studies were performed using seedling populations to determine the basis of variability observed among genotypes. Two peroxidase loci and three phosphoglucomutase loci were identified and characterized. Information from these studies, was used to formulate a system by which species and plant introductions could be identified and distinguished.
Characterization and Inheritance of Four Induced Leaf Mutants in Common Bean
Authors: Bassett Mark J.
Published: January 2019

Dry seeds of common bean (Phaseolus vulgaris L.) were treated with 20 krad (1 rad = 0.01 Gy) of gamma rays to induce plant mutations to be used as genetic markers in mapping studies. Four leaf mutants are described and illustrated. Inheritance studies demonstrated that each is controlled by a single recessive gene. The proposed gene symbols are: cml for chlorotic moderately lanceolate leaf, lbd for leaf-bleaching dwarf, glb for glossy bronzing leaf, and 01 for overlapping leaflets. Linkage tests involving cml and nine previously reported marker mutants failed to detect any linkages.
Variation in Polyunsaturated Fatty Acids Composition of Persian Walnut
Authors: Greve L. Carl , McGranahan Gale , Hasey Janine , Snyder Ronald , Kelly Kathy , Goldhamer David , Labavitch John M.
Published: January 2019

The variation in polyunsaturated fatty acid content of walnut (Juglans regia L.) oils was determined by analysis of samples isolated from specimens growing in four germplasm collections [California (55 cultivars), Washington (64 seedlings), China (12 cultivars), and France (20 cultivars)]. In addition, the impact of within-state geographic differences on oil composition was examined by comparing samples from three California cultivars (`Ashley', `Hartley', and `Franquette') grown in three locations. Local environmental effects on oil composition of `Chico' were also examined by comparing 1) samples collected from shaded and sun-exposed locations of the same trees and 2) samples collected from trees subjected to three irrigation regimes. Polyunsaturated fatty acid content, as a percentage of total fatty acids, ranged from 47.2% in nuts from PI 142323 from France to 81.0% in `Ashley' from California. However, our data indicate that environment, genotype, nut maturity, and their interactions all contribute significantly to variation in the degree of unsaturation of walnut oil.
Effect of Spacing and Sucker Removal on Precocity of Hazelnut Seedlings
Authors: Mehlenbacher Shawn A. , Smith David C.
Published: January 2019

The effect of parentage, spacing, and sucker removal on precocity of hazelnut (Corylus avellana L.) seedlings was investigated. Wider spacing (1.2 vs. 0.6 m) within the row doubled the number of nuts per seedling in the 5th year but had no effect on nut count in the 3rd or 4th year, nor did it affect the percentage of seedlings bearing nuts in any of the three years. Differences among the four progenies were highly significant for number of clusters, number of nuts, and percentage of seedlings bearing nuts in all years and for number of years to first fruiting. The progeny `Barcelona' × OSU 55.097 had the most bearing seedlings in, the 3rd year but was outperformed by `Casina' × OSU 55.129 in the 4th and 5th years. Number of years to first fruiting varied from 4.3 for `Casina' × OSU 55.129 to 5.2 for `Tombul' × `Tonda di Giffoni'. Sucker removal increased both the percentage of seedlings bearing nuts and the number of nuts per seedlings, but the difference was not significant until the 5th year. Sucker removal reduced the length of the juvenile phase by 3 months. The use of precocious parents was more effective than sucker removal in shortening the juvenile period, while sucker removal and wide spacing within seedling rows increased the number of nuts produced by seedlings in the 5th year. Selection of seedlings for early initiation of bearing will shorten the breeding cycle, and the resulting new cultivars will be precocious when planted in commercial orchards.
Light Environment and Time of Harvest Affect `Delicious' Apple Fruit Quality Characteristics
Authors: Campbell Richard J. , Marini Richard P.
Published: January 2019

Photosynthetic photon flux density (PPFD), measured at various canopy positions throughout the growing season in 1989 and 1990, was used to explain variation in fruit characteristics of `Delicious' apples (Malus domestica Borkh.) harvested from these positions at 135, 145, 155, and 165 days after full bloom (DAFB). Hours above an average PPFD threshold of 250 μmol·m-2·s-1 (HR250) explained an average of only 2% more variation in fruit characteristics than other PPFD threshold levels or total cumulative photosynthetic photon density (PPD) in each year. Percent of red surface had a positive linear relationship with HR250 on all harvest dates in both years; intercepts increased on each successive harvest. The slopes and R2 were highest at 135 DAFB and decreased on each successive harvest. Intensity of red pigmentation and soluble solids concentration also increased linearly with HR250, with equivalent slopes and increasing intercepts on each successive harvest. Fruit weight, flesh firmness, length: diameter ratio, and starch index were not consistently affected by any measure of canopy light levels. Except for intensity of redness, relationships developed between fruit characteristics and cumulative late-season PPD during the final 10 weeks before harvest (CPPDLS) had trends similar to the models for HR250 for all harvests in both years. Models developed with instantaneous light measurements were similar to those developed with the more detailed cumulative light measurements.
Nitrogen Nutrition of Containerized Eastern Redcedar. I. Growth, Mineral Nutrient Concentrations, and Carbohydrate Status
Authors: Henry Paul H. , Blazich Frank A. , Hinesley L. Eric , Wright Robert D.
Published: January 2019

Containerized seedlings of eastern redcedar (Juniperus virginiana L.) were fertilized weekly for 175 days with a solution containing 50 ppm P, 150 ppm K, and either 0, 5, 10, 20, 40, 80, 160, 320, or 640 ppm N. Plant height, stem diameter, and shoot and root dry weights increased asymptotically with applied N; 640 ppm N diminished response. Growth after 175 (height, stem diameter) and 180 (shoot and root dry weights) days was optimal (90% of maximum) at N concentrations of 115, 155, 230, and 105 ppm, respectively, 1.5% foliar N optimized height growth. Foliar concentrations of N, P, and K increased in treated plants over the duration of the experiment, while Ca, Mg, and Mn decreased or remained constant. Starch concentration of fertilized plants decreased sharply after initiation of the experiment, but controls showed little change during the first 120 days. Sucrose concentration remained constant over the summer but increased sharply in late fall. At 180 days, foliar concentrations of starch, sucrose, hexose, N, P, K, and B increased asymptotically with applied N; concentrations of Ca, Mg, and Mn decreased.
Nitrogen Nutrition of Containerized Eastern Redcedar. II. Influence of Stock Plant Fertility on Adventitious Rooting of Stem Cuttings
Authors: Henry Paul H. , Blazich Frank A. , Hinesley L. Eric
Published: January 2019

Hardwood stem cuttings of eastern redcedar (Juniperus virginiana L.), taken from containerized stock plants fertilized weekly with 0, 5, 10, 20, 40, 80, 160, 320, or 640 ppm N, were treated with 7500 ppm IBA and placed under intermittent mist for 12 weeks. Foliar starch and sucrose concentrations within cuttings at time of excision were significantly correlated with percent rooting and root length, respectively. Of the mineral nutrients analyzed (N, P, K, Ca, Mg, Mn, and B), only B and K were significantly correlated with rooting response. A threshold N level (20 ppm), applied weekly, maximized rooting; higher concentrations decreased response. Although N fertilization of stock plants affected adventitious rooting, there were no significant correlations between foliar N levels and measures of rooting response. Chemical name used: 1 H- indole-3-butyric acid (IBA).
Use of One Cycle of Recurrent Selection per Year for Increasing Resistance to Aphanomyces Root Rot in Peas
Authors: Lewis Mark E. , Gritton Earl T.
Published: January 2019

The effectiveness of one cycle (C) per year of phenotypic recurrent selection was evaluated for improving tolerance of peas (Pisum sativum L.) to aphanomyces root rot (Aphanomyces euteiches Drech.). Each cycle included field-screening a population of F2 lines (summer), diallel intermating among lines selected from the field (fall greenhouse), and one generation of selfing F1 plants (spring greenhouse) to produce F2 lines for the next cycle. The schedule is repeated for each cycle. A blocks-within-replicates design was employed in the field screening of C1 and C2 to improve within-block homogeneity. Selection intensities were 12.4%, 11.1%, and 10.6% for C0, C1, and C2, respectively. Using the performance of a tolerant control line, Mn 108, as a basis of comparison, the realized gain in dry seed yield and survival was 32% and 68% from C0 to C1 and 22% and 115% from C1 to C2, respectively.
Genome Size and DNA Polymorphism in Theobroma cacao
Authors: Figueira Antonio , Janick Jules , Goldsbrough Peter
Published: January 2019

The size of the haploid genome of Theobroma cacao L. (cacao), estimated using laser flow cytometry, was 0.43 pg. An improved DNA extraction procedure was developed based on isolation of a crude nuclei preparation from leaf tissue that effectively eliminated contamination of the DNA by polysaccharides and produced DNA that was, on average, longer than 50 kb. DNA yields ranged from 2 to 10 μg·g-1 fresh weight of leaf tissue. DNA blot hybridization experiments with a flax (Linum usitatissimum L.) ribosomal DNA probe revealed restriction fragment length polymorphisms between three cacao genotypes. Differences between the DNA of these genotypes were also detected by polymerase chain reaction amplification of polymorphic DNA fragments, using random oligonucleotide primers.
Photosynthesis, Growth, and Yield Response of `Casselman' Plum to Various Ozone Partial Pressures during Orchard Establishment
Authors: Retzlaff W.A. , Williams L.E. , DeJong T.M.
Published: January 2019

Nursery stock of plum (Prunus salicina Lindel., `Casselman') was planted 1 Apr. 1988 in an experimental orchard at the Kearney Agricultural Center, Univ. of California, near Fresno. The trees were enclosed in open-top fumigation chambers on 1 May 1989 and exposed to three atmospheric ozone partial pressures (charcoal-filtered air, ambient air, and ambient air + ozone) from 8 May to 15 Nov. 1989 and from 9 Apr. to 9 Nov. 1990. Trees grown outside of chambers were used to assess chamber effects on tree performance. The mean 12-hour (0800-2000 hr Pacific Daylight Time) ozone partial pressures during the 2-year experimental period in the charcoal-filtered, ambient, ambient + ozone, and nonchamber treatments were 0.044, 0.059, 0.111, and 0.064 μPa·Pa-1 in 1989 and 0.038, 0.050, 0.090, and 0.050 pPa·Pa-1 in 1990, respectively. Leaf net CO2 assimilation rate of `Casselman' plum decreased with increasing atmospheric ozone partial pressure from the charcoal-filtered to ambient + ozone treatment. There was no difference in plum leaf net CO2 assimilation rate between the ambient chamber and nonchamber plots. Trees in the ambient + ozone treatment had greater leaf fall earlier in the growing season than those of the other treatments. Cross-sectional area growth of the trunk decreased with increasing atmospheric ozone partial pressures from the charcoal-filtered to ambient + ozone treatment. Yield of plum trees in 1990 was 8.8, 6.3, 5.5, and 5.5 kg/tree in the charcoal-filtered, ambient, ambient + ozone, and nonchamber treatments, respectively. Average fruit weight (grams/fruit) was not affected by atmospheric ozone partial pressure. Fruit count per tree decreased as atmospheric ozone partial pressure increased from the charcoal-filtered to ambient + ozone treatment. Decreases in leaf gas exchange and loss of leaf surface area were probable contributors to decreases in trunk cross-sectional area growth and yield of young `Casselman' plum trees during orchard establishment.