bluuebunny/crossref_metadata_2025 huggingface dataset:
Inheritance of a Partial Chlorophyll Deficiency in Watermelon Activated by Low Temperatures at the Seedling Stage
Authors: Provvidenti R.
Published: February 2019

Seedlings of watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] are commonly affected by a partial chlorophyll deficiency that is activated by low temperatures (<20C), causing foliar symptoms and growth retardation. Cotyledons appear whitish-green, whereas the first leaves display a mosaic-like variegation consisting of scattered white flecks and patches. While this disorder is common in commercial watermelon cultivars, some land races from Zimbabwe appeared to be unaffected. From cross and backcross populations of the cold-sensitive cultivar New Hampshire Midget with the cold-resistant line PP261-1 (from PI 482261), the leaf variegation was determined to be conferred by a single recessive gene. The symbol slv (seedling leaf variegation) is assigned to this factor. The dominant allele at this same locus can be exploited for the development of new “cold-resistant” cultivars and F1 hybrids, thus providing economic gain due to earlier planting.
Inheritance of Tolerance to Verticillium albo-atrum in Raspberry
Authors: Fiola Joseph A. , Swartz Harry J.
Published: February 2019

Raspberry cultivars and hybrids were screened for reaction to Verticillium alboatrum Reinke and Berth to determine the mode of inheritance of resistance and to assist in the development of resistant germplasm. Greenhouse-grown seedlings of an incomplete partial diallel of two black, purple, and red raspberry Rubus subgenus Idaeobatus progeny were root-dipped in a mycelial slurry and stem-inoculated with a conidial suspension of V. albo-atrum. Fourteen weeks after the initial inoculation, disease symptoms were observed in the seedlings. Disease symptom severity and percentage of black raspberry parentage in the seedlings were correlated (P ≤ 0.01; r2 = 0.90). A similar significant (P ≤ 0.05; r2 = 0.66) linear trend was found with fungus reisolation percentages, although isolation of the fungus from symptomless plants indicates Verticillium tolerance among genotypes in Idaeobatus. These trends, coupled with large significant general combining ability (P ≤ 0.01), suggest primarily additive inheritance of resistance. However, considering noninoculated control scores, the possibility of escapes, and skewing of populations, one may hypothesize a gene-gene model for symptom expression, with partial dominance of resistance alleles.
Bell Pepper Seedling Growth and Yield following Pretransplant Nutritional Conditioning
Authors: Dufault Robert J. , Schultheis Jonathan R.
Published: February 2019

To reduce transplant shock of bell peppers (Capsicum annuum L.), we tested the effectiveness of pretransplant nutritional conditioning (PNC) as a promoter of earliness and yield. In Expt. 1, `Gatorbelle' bell pepper seedlings were fertilized with N from Ca(NO3)2 at 25, 75, or 225 mg·liter-1 and P from Ca(H2PO4)2 at 5, 15, or 45 mg·liter-1. Nitrogen interacted with P, affecting shoot fresh and dry weight, leaf area, root dry weight, seedling height, and leaf count. In Expt. 2, transplants conditioned with N from 50, 100, and 200 mg·liter-1 and P at 15, 30, and 60 mg·liter-1 were field-planted in Charleston, S.C., and Clinton, N.C. Nitrogen- and P-PNC did not greatly affect recovery from transplant shock. Although N- and P-PNC affected seedling growth in the greenhouse, earliness, total yield, and quality were similar in field studies among all PNC treatments at both locations. PNC with 50 mg N and 15 mg P/liter can be used with this variety and not have any long-term detrimental effects on yield and quality.
A Fourth Malate Dehydrogenase (MDH) Locus in Cucumber
Authors: Knerr Larry D. , Meglic Vladimir , Staub Jack E.
Published: February 2019

A new malate dehydrogenase (MDH) locus (Mdh) was identified in cucumber (Cucumis sativus L.) by using an extraction buffer containing sucrose and 2-mercaptoethanol. This fourth locus localizes on starch gels between the previously described Mdh-2 and Mdh-3 loci, necessitating the renaming of existing loci. Given previous MDH nomenclature in cucumber, this locus should be Mdh-3, and the former Mdh-3 is more correctly labeled Mdh-4. Mdh-x designates the interlocus heteromer formed between Mdh-2 and Mdh-4. Interpreting our data in terms of previous work, we hypothesize that Mdh-1 codes for a microbody isozyme; Mdh-2, Mdh-4, and Mdh-x code for cytosolic isozymes; and Mdh-3 codes for a mitochondrial isozyme.
Drying Interferes with Germination of Blackberry (Rubus sp.) Seeds in Vitro
Authors: Mian M.A.R. , Skirvin R.M. , Norton M.A. , Otterbacher A.G.
Published: February 2019

To study the causes of low germinability in dried blackberry seeds, seeds harvested from fresh `Thornless Evergreen' (TE) blackberry (Rubus laciniatus Willd.) were either air-dried (12, 24, 36, 48, 60, 72, 96, or 120 hours) or explanted directly onto growth-regulator-free medium after bleach disinfestation. Seeds were either cut in half before explanting or kept intact. None of the intact seeds germinated. Fewer of the halved seeds dried 12 hours or more germinated than control (fresh moist) seeds (42.7% and 54.5%, respectively). Germination decreased to <12% following >48 hours of air-drying. In a separate study, fresh seeds of TE and `Navaho' were either dried as described or held in sealed petri dishes on moist filter paper (moist treatment) for up to 60 hours. After 60 hours, germination of dried seeds of both cultivars had decreased significantly; there was no significant change in germination percentage for moist seeds. Since moist halved seeds germinated well and dried halved seeds did not, the inability of dried blackberry seeds to germinate is due to more factors than just the hard seedcoat typical of the genus.
In Vitro Flowering and Fruiting of Capsicum fruitescens L.
Authors: Tisserat Brent , Galletta Paul D.
Published: February 2019

Flowering and fruit production were obtained from cultured shoot tips of `California Wonder', `Super Cayenne', and `Zippy' peppers grown in a liquid Murashige and Skoog (MS) medium without growth regulators. Thirty-day-old pepper shoot tips, derived from seedlings germinated sterilely, were cultured in a 6-liter polycarbonate container coupled to an automated plant culture system (APCS). Plants were given ten daily, 30-minute, compressed-air applications at 300 ml/minute. These shoots began flowering after an additional 60 to 90 days in culture and flowered continuously thereafter. About 5% to 10% of the flowers set fruit. Maximum fruit size obtained was ≈25% to 75% of the size of fruit produced on plants grown in vivo. In contrast, no flowering occurred from shoot tips grown in 25 × 150-mm culture tubes containing agar medium and subcultured every 8 weeks to fresh medium. Immature fruit excised from plantlets grown in the APCS were cultured separately on agar medium containing 0.0, 0.1, 0.3, or 1.0 mg BA/liter with and without 0.1 mg NAA/liter. Isolated fruit grew best on MS medium with BA only and poorest on medium without growth regulators. Chemical names used: N-(phenylmethyl)-1H-purine-6-amine (BA); 1-naphthaleneacetic acid (NAA).
Response in Green and White Asparagus to Supplemental Nitrogen and Harvest Date
Authors: Makus D.J.
Published: February 2019

`Jersey Giant' asparagus (Asparagus officinalis L.), grown in an Enders silt loam mineral soil, was given 80 kg supplemental N/ha either before or after the harvest season. Neither N application timing affected spear yield, objective color, or pigment concentration. Early supplemental N application decreased K concentration in white spears and Ca concentration in green spears. Green asparagus contained higher total-N, K, P, S, Ca, Mg, Fe, Zn, Al, Mn, and Cu concentrations but a lower soluble solids concentration (SSC) and NO3 than did white asparagus. As the cutting season progressed, spear SSC and S, Ca, NO3 (NO3 in white spears only), Zn, Mn, and Cu (Cu in white spears only) concentrations decreased, but spear K and Al (Al in white spears only) increased on a dry-weight basis. Fall residual soil NO3 levels were not affected by N application timing, but organic matter (percent) was lower in soil that received early supplemental N.
Control of San Jose Scale, Terrapin Scale, and European Red Mite on Dormant Fruit Trees with Soybean Oil
Authors: Pless C.D. , Deyton D.E. , Sams C.E.
Published: February 2019

Emulsions of degummed soybean (Glycine max L.) oil were compared to a petroleum oil emulsion for efficacy against winter populations of San Jose scale [Quadraspidiotus perniciosus (Comstock); Homoptera: Diaspididae] and European red mite [Panonychus ulmi (Koch); Acari: Tetranychidae] on dormant apple (Malus domestica Borkh.) trees and terrapin scale [Mesolecanium nigrofasciatum (Pergande); Homoptera: Coccidae] on dormant peach [Prunus persica (L.) Batsch.] trees. In laboratory tests, more than 94% of San Jose scale was killed on stems dipped for 1 second in 5.0% or 7.5% soybean oil or 5.0% petroleum oil. Mortality of terrapin scale exceeded 93% on peach stems dipped for 1 second in 7.5% soybean oil or 5.0% petroleum oil. No European red mite eggs survived on apple stems dipped for 1 second in 2.5%, 5.0%, or 7.5% soybean oil, or 5.0% petroleum oil. In field tests, >95% of San Jose scale died on apple trees sprayed with one application of 2.5% petroleum oil or 5.0% soybean oil; two applications of these treatments or 2.5% soybean oil killed all San Jose scales. One or two applications of 2.5% petroleum oil or 5.0% soybean oil killed 85% and 98%, respectively, of the terrapin scales on peach trees. Soybean oil shows promise as a substitute for petroleum oil for winter control of three very destructive fruit tree pests.
THE EFFECTS OF HEAT STRESS ON RETENTION AND ABSCISSION OF LIMA BEAN REPRODUCTIVE STRUCTURES IN THE FIELD
Authors: Wootten Tracy L , Frett John J. , Kee W. Edwin
Published: February 2019

In an effort to increase lima bean yields in Delaware, the documentation of lima bean plant development and the comparison of Delaware and California lima bean production was conducted. Delaware lima bean yields have averaged 1905 kg·ha-1 for the last 30 years. California averages 3923-4484 kg·ha-1. Cultivar M-15 is used by both states for production. Plant population density, plant fresh weight, and final yield was greater in California than in Delaware. Although plant populations were the same in 1992, yields remained higher in California than in Delaware. High night temperatures have an adverse affect on lima bean yields. Minimum temperatures from both states were compared. Minimum temperatures from the California planting were greater than the minimum temperatures for the late planting in Delaware.
POPULATION VARIATION IN LOW-TEMPERATURE TOLERANCE OF ACER SACCHARINUM
Authors: Cappiello Paul E. , Preece John E.
Published: February 2019

A single clone of Acer saccharinum was selected and propagated from each of 15 provenances across the plant native range. The clones were field grown in Carbondale, Ill., during the study period. Plants were sampled during Winter 1992-93 and 1993-94 and assayed for low-temperature tolerance. During both winters, plants exhibited greatest variation in tolerance around the November and April sampling dates. In midwinter, there was little variation observed and 13 of 15 clones were tolerant to at least -40C. The relationship among Acer saccharinum provenance and cold tolerance curves will be discussed.
PERFORMANCE OF `NELLIE WHITE' EASTER LILIES IN ROOT MEDIA CONTAINING COAL BOTTOM ASH
Authors: Bearce Bradford C. , Smuta Lenka
Published: February 2019

Easter lilies (Lilium longiflorum Thunb. `Nellie White') were forced in root media composed of 1 peat: 1 vermiculite (v/v) mixed with coal bottom ash (CBA) at rates of 0%, 25%, 50%, 75%, or 100% CBA. Lilies in all levels of CBA were equal in mean per plant flower bud numbers, fresh and dry weights, and numbers of yellow or brown lower stem leaves. Lilies in 100% CBA were significantly lower in mean stem length than plants in 0% or 50% CBA. Plants in 100% CBA required more frequent irrigation than plants in all other media. Media pH and solution electrical conductivity increased with increase in percent CBA. Analysis of leaf tissue showed no difference in nutrient levels between plants in 0% or 100% CBA.
GENETIC RELATIONSHIP AMONG STRAINS OF XYLELLA FASTIDIOSA BASED ON RAPD-PCR DATA
Authors: Pooler Margaret , Hartung John S.
Published: February 2019

Xylella fastidiosa is a fastidious gram-negative, xylem-limited, leafhopper-transmitted bacterium that has proven to be the casual agent of many economically important diseases, including Pierce's disease of grapevine and citrus variegated chlorosis. Genetic relationships among 11 Xylella fastidiosa strains isolated from mulberry, almond, ragweed, grape, plum, elm, and citrus were determined using random amplified polymorphic DNA (RAPD). Twenty-two 10 base primers amplified a total of 77 discrete polymorphic bands. Phenetic analysis based on a similarity matrix corresponded well with previous reports on X. fastidiosa RFLP-based similarity relationships, indicating that RAPD-PCR amplification products can be used as a reliable indicator of genetic distance in X. fastidiosa. Cladistic analysis suggests the existence of five groups of X. fastidosa: the citrus group, the plum-elm group, the grape-ragweed group, the almond group, and the mulberry group.
Photoperiod, Irradiance, and Temperature Influence Flowering of Hamelia patens (Texas Firebush)
Authors: Armitage Allan M.
Published: February 2019

Hamelia patens Jacq. (Texas firebush) is a long-day plant for flower initiation and flower development; however, flower development is more sensitive to photoperiod than is flower initiation. The critical photoperiod for flower development at 25C is between 12 and 16 hours. Flowering was delayed under low light conditions, and plant dry weight was heavier and flowering time was earlier for plants grown at a constant 25 or 30C than at 20C. A greenhouse environment with a 16-hour photoperiod and moderately high temperature (25C) would be appropriate for production of H. patens.
TIMING APPLICATION OF HYDROGEN CYANAMIDE (DORMEX) TO PEACH TREES USING A MODIFIED CHILLING MODEL
Authors: Powell Arlie A. , Harker Karl
Published: February 2019

This multifaceted study was conducted over the past 6 years in Alabama to determine the efficacy of using hydrogen cyanamide to replace lack of chilling in peaches and to develop a working chilling model to allow proper timing of application. Several timings (0%, 25%, 50%, and 75% chilling accumulation) for each chilling level and rates (0%, 0.5%, 1.0%, and 2.0% v/v of 50% hydrogen cyanamide) were evaluated in commercial orchards using replicated studies. It was determined that for Dormex to be effective, 60% to 65% of chilling for the cultivar involved must be accumulated, accompanied by no bud activity beyond bud swell. Rates of 0.5% and 1% v/v of 50% work well with the latter preferred. A computer chilling model was developed to assist growers with proper timing of application.
FLOWER BUD HARDINESS OF SOUTHERN HIGHBUSH BLUEBERRY CULTIVARS
Authors: Clark John R. , Bourne Robert
Published: February 2019

The southern highbush blueberry (Vaccinium spp.) `Blueridge', `Cape Fear', `Cooper', `Georgiagem', `Gulf Coast', and `O'Neal'; the rabbiteye (V. ashei Reade) `Climax'; and the highbush (V. corymbosum L.) `Bluecrop' were evaluated for ovary damage following exposure of flower buds to 0 to 30C in a programmable freezer in Dec. 1993 and Jan. and Feb. 1994. The plants sampled were growing at the Univ. of Arkansas Fruit Substation, Clarksville. Damage was based on oxidative browning of the ovaries following an incubation period after removal from the freezer. With the exception of `Climax', a minimum temperature of –15C was required before bud damage was sufficient enough to differentiate among cultivars. All southern highbush cultivars and `Bluecrop' had superior hardiness compared to `Climax' at –15C in December, –20C in January, and –15C in February. Maximum hardiness of all cultivars was found in January. The hardier southern highbush cultivars were `Cape Fear' and `Blue Ridge'. Less hardy cultivars were `Gulf Coast, `Cooper', `Georgiagem', and `O'Neal', although the date of sampling affected the ranking of these clones for hardiness, especially for the February sample date. `Bluecrop' was not consistently hardier than the hardier southern highbush cultivars, except at the February sample date.
EVALUATION OF APPLE CULTIVARS FOR RESISTANCE TO FOUR BITTER ROT PATHOGENS
Authors: Shi Yan , Rom C.R.
Published: February 2019

Fifty apple cultivars and 30 Malus species were evaluated for resistance to four isolates of bitter rot pathogens, Colletotrichum gloeosporioides and C. acutatum, in controlled conditions. Fruit were wound-inoculated by placing 0.1 ml of inoculum (106 conidia/ml) into puncture wounds (2 mm in diameter), and intact fruit were inoculated by spraying with inoculum. Inoculated fruit were incubated at 25 to 28C for 2 weeks. `Golden Delicious' (susceptible) and `Red Delicious' (resistant) were used as controls. Diseases were quantified by measuring lesion diameter, and disease severity was objectively rated. Relative lesion diameter and severity rating were calculated as [X × 100/RD – 100] and (X – RD) × 100/7 (X = parameter of given cultivar or species, RD = parameter of `Red Delicious') to determine relative resistance. Conclusions were as follows: 1) different levels of resistance were identified in apple cultivars and Malus species and also were detected within `Golden Delicious' and `Red Delicious' types; 2) `Jonagold', `Oregon Spur II', `Spartan', `Melrose', `Red Cort', `Jonafree', `VPI-9', and `Red Delicious showed good relative resistant; 3) M. halliana, angustifolia, prunifolia, sylvestris, and fusca were more resistant than `Delicious'; 4) M. angustifolia was immune to two isolates of C. acutatum.
WATER QUALITY AS A POSSIBLE LIMITING FACTOR IN LOUISIANA MAYHAW PRODUCTION
Authors: Picchioni G.A. , Johnson C.E.
Published: February 2019

Ground water salinity is a major concern for crop diversification in Louisiana where mayhaw (Crataegus opaca) is being considered as a new fruit crop. Its saline resistance is unknown; thus, we evaluated it in greenhouse conditions. One-year-old seedlings were irrigated with tap water, 10 mm NaCl (+ 2 mm CaC12), and 25 mm NaCl (+ 5 mm CaC12) for 9 weeks. Leaf and stem dry matter accumulation were reduced by an average of 80% and 60% below controls, respectively, in seedlings irrigated with 25 mm NaCl. The fresh weight: dry weight ratios of stems and roots also were reduced by 25 mm NaCl (15% and 28% below controls, respectively). Notably smaller leaf growth suppression occurred when 25 mm NaCl was supplemented with 5 mm CaC12 compared to 25 mm NaCl in the absence of CaC12. The fact that CaC12 partially reversed the leaf growth inhibition may indicate that Ca fertilization could be of benefit for mayhaw orchards relying on saline ground water.
EFFECT OF GIBBERELLIC ACID ON BLUEBERRIES GROWN UNDER NONSTRESS CONDITIONS
Authors: Magee James B.
Published: February 2019

Rabbiteye blueberry (Vaccinium ashei) cultivars `Climax', `Premier', and Tifblue' were treated with gibberellic acid when 50% to 75% of the flowers of each were at stage 5 and again 10 days later. No known pollination stresses occurred during flowering, and the growing conditions were near optimum. First harvest yields from the gibberellic-acid-treated plants of each cultivar were significantly lower than the yields from nontreated controls. Gibberellic acid treatment essentially delayed commercial quantity production by an estimated 5 to 7 days for each cultivar; for the early ripening cultivars `Premier' and `Climax', this delay could mean lower yields of more profitable early berries in the Mississippi–Louisiana growing areas. Harvest-season total yields from treated plants were lower than the yields from nontreated plants of each cultivar. Using gibberellic acid as a routine cultural practice may not be necessary for small-scale growers when pollination stresses, such as frost damage to flowers, do not occur.
EXTENT OF GENOTYPIC VARIATION AMONG SWEETPOTATOES PRODUCED THROUGH NODAL AND ADVENTITIOUS SPROUTS
Authors: Villordon Arthur O. , La Bonte Don R.
Published: February 2019

Our research compared the extent of genomic variability between plants originating from adventitious sprouts and nodal cultures. Plant materials, derived from a single sprout and originating from a storage root each of `Jewel,' `Sumor,' and L87-95, were clonally propagated for seven generations nodally and through adventitious sprouts. PCR-based analysis using 15 random primers identified 58 scorable molecular markers, 37 (63.79%) of which were shared by all three genotypes represented by 60 samples (10 nodal and 10 adventitiously derived plants/genotype). Of 29 putatively polymorphic markers, 24 (82.75%) were putative polymorphisms across the entire data set. The remaining four (13.79%) represented putatively fixed genotypic differences that were monomorphic within genotypes. A multidimensional scaling analysis differentiated seven (23.33%) adventitiously derived phenotypic marker variants, compared to four (13.33%) among nodal materials. Our results support previous findings that, relative to nonmeristematic tissues, meristematic regions strictly control cell division and DNA synthesis that exclude DNA duplication and other irregularities.
Root-medium Nutrient Levels and Irrigation Requirements of Poinsettias Grown in Five Root Media
Authors: Argo William R. , Biernbaum John A.
Published: February 2019

`V-14 Glory' poinsettias (Euphorbia pulcherrima Willd. ex Klotzsch) were grown in five root media using top watering with 20% leaching for 112 days. Root media with a high water-holding capacity required fewer irrigations and fertilizer applications than those with a lower water-holding capacity. However, similar amounts of water were applied and leached with both types of root media over the entire experiment. The reduction in the number of fertilizations was compensated for by an increase in the amount (volume) of fertilizer applied at any one irrigation. The greatest differences in root-media nutrient concentrations were found between the top 2.5 cm (top layer) and the remaining root medium within the same pot (root zone). After 58 days, when fertilization with water-soluble fertilizer (28.6N–0P–8.5K mol·m–3) was stopped, nutrient concentrations in the top layer were 3 to 6 times greater than those in the root zone for all five root media tested. For the final 42 days of the experiment after fertilization was stopped, nutrient concentrations in the root zone remained at acceptable levels in all root media. The nutrients contained in the top layer may have provided a source of nutrients for the root zone once fertilization was stopped.
Susceptibility of Strawberry Cultivars and Advanced Selections to Leaf Spot Caused by Mycosphaerella fragariae
Authors: Delhomez Nathalie , Carisse Odile , Lareau Michel , Khanizadeh Shahrokh
Published: February 2019

Seventeen strawberry (Fragaria ×ananassa Duchesne) cultivars and six selections were tested under greenhouse conditions for susceptibility to leaf spot induced by Mycosphaerella fragariae (Tul.) Lindau. The level of susceptibility was evaluated based on maximum disease severity and area under the disease progress curve (AUDPC). The 23 genotypes were ranked based on AUDPC and grouped according to their susceptibility. Cluster analysis for AUDPC gave four groups corresponding to low, moderate, high, and very high susceptibility to leaf spot. `Annapolis', `Chambly', `Glooscap', `Redcoat', and `Veestar' consistently showed a low level of susceptibility. The selections SJ89700-1 and SJ8518-11 and `Tribute' showed a very high level of susceptibility, and the remaining cultivars were grouped as either moderately or highly susceptible.
Micropropagation of Three Pyrus Rootstocks
Authors: Yeo Dennis Y. , Reed Barbara M.
Published: February 2019

Explants of three rootstock selections Pyrus calleryana Dcne `Oregon Pear Rootstock (OPR) 157', P. betulifolia Bunge `OPR 260', and P. communis L. `Old Home' × `Farmingdale 230' (`OH × F 230') were initiated from forced branches of field-grown trees. `OPR 260' and `OH × F 230' shoots cultured on Cheng medium with IBA proliferated better than those on NAA. NAA and IBA at concentrations >0.5 μm inhibited shoot multiplication. Overall, the best micropropagation medium for `OPR 260' and `OH × F 230' was Cheng medium with 8 μm BA and 0.5 μm IBA. Shoot multiplication of `OPR 157' was best on 8 μm BA and better on low NAA (0.5 μm) or no auxin than on IBA. `OH × F 230' rooted easily (>80%) with all IBA and NAA treatments. The best rooting treatment (42.9%) for `OPR 260' was 10 μm IBA in darkness for 1 week; for `OPR 157' (23.9%), it was a 15-second dip in 10 mm NAA. Only rooted plantlets survived 4 weeks of greenhouse acclimatization. Chemical names used: N6-benzyladenine (BA); indole-3-butyric acid (IBA); napthaleneacetic acid (NAA).
Production Factors Affecting the Longevity and Quality of Flowering Plants
Authors: Nell Terril A.
Published: February 2019

The quality and longevity of flowering potted plants and cut flowers are affected by the cultivar grown and cultural practices used during production. Preharvest factors may account for 70% of the life of flowering plants. Longevity is directly related to the cultivar grown. In potted chrysanthemums, longevity has been increased by 100% by carefully selecting a long-lasting variety. Cultural factors, such as fertilization practices, may increase longevity by 40% to 50%. Chrysanthemums grown without fertilizer during the final 3 weeks of production lasted 10 to 14 days longer than plants receiving fertilizer for the entire crop. Flower and plant quality is influenced by cultivar and cultural practices. Poinsettia bract edge burn, a marginal burn or spotting on the bracts, appears to be caused by a calcium deficiency that may be triggered by use of cool day temperatures or warm night temperatures and use of cultivars sensitive to this disorder. Light compensation point and carbohydrate status of the plant at flowering have not been related to differences observed in flower longevity and quality.
The Effects of Different Concentrations of Gibberellic Acid (GA3) and Kinetin on in Vitro Tuberization of Potato (Solanum tuberosum L.)
Authors: Kefi Servet , Read Paul E. , Pavlista Alexander , Kachman Stephen D.
Published: February 2019

To determine the influence of gibberellic acid (GA3) and 6-furfuryl aminopurine (kinetin) concentrations alone and in combinations on in vitro tuberization of potato, nine treatments consisting of combinations of gibberellic acid and kinetin at three levels of concentration (0, 2, and 5 mg·liter–1) were included in Murashige and Skoog medium supplemented with 6% sucrose. Four single nodes of in vitro plantlets from Solanum tuberosum L. cultivar Atlantic were placed into each magenta box. All magenta boxes were arranged in a randomized complete box design with five replications and cultured under a short photoperiod condition (8 h light/16 h dark). Gibberellic acid strongly inhibited tuberization when used alone or with kinetin, whereas kinetin induced tuberization at both 2 and 5 mg·liter–1. Although tuberization was initiated in the absence of kinetin because of the high concentration of sucrose and short photoperiod, the presence of kinetin accelerated the in vitro tuberization process of potato.
A Modified Nodal Cutting Bioassay for Assessing Salinity Tolerance in Potato (Solanum sp.)
Authors: Zhang Y. , Donnelly D.
Published: February 2019

The potato (Solanum tuberosum L.) is considered moderately sensitive to salinity stress. Yields can be adversely affected by salinity at EC levels of 2 to 3 dS·m–1. In vitro screening and selection for salinity tolerance may be faster and more reliable than traditional field assessment. A modified nodal cutting bioassay was developed based on that of Morpurgo (1991) and used to rank the salinity tolerance of several potato cultivars, wild Solanum species, and their hybrids. Nodal cuttings were cultured in Murashige and Skoog (1962) basal medium which included NaCl at 0, 40, 80, and 120 mM. After 4 weeks at 25C and 16/8 h day/night period, vegetative growth parameters were assessed. Hybrids derived from S. chacoense outperformed hybrids of other wild species, their wild parents, and S. tuberosum cultivars. `Russet Burbank' and `Kennebec' were more salinity-tolerant than the three other cultivars tested.
The Effectiveness of a Workshop Model in Conveying Information on Xeriscaping
Authors: McKenney Cynthia , Terry Robert
Published: February 2019

Workshops are one of the primary tools utilized to convey information to audiences with diverse backgrounds. Frequently, the results obtained are of mixed success or unmeasurable. In this project, the Environmental Protection Agency sponsored the development of a model workshop to promote the concept of water conservation through xeriscaping. Two workshops were conducted in Spring 1994. Slide presentations, audience discussion sessions, tours of an existing xeriscape, and the administration of pre- and post-workshop surveys were included in the model. Statistical analysis comparing the surveys determined the effectiveness of the model. The results indicated both the perception and the general knowledge about water conservation were significantly improved. Promotion by newspaper was the most-effective method of reaching the audience, while TV spots were the least effective method used. The model was successful in reaching a new audience which was characterized as being 45 years old, having less than 1 year of gardening experience, and possessing some college education.
Changes in Broccoli Head Quality during Spring, Summer, and Fall, in Coastal South Carolina
Authors: Dufault Robert J. , Farnham Mark
Published: February 2019

The objectives of this study were 1) to identify high-quality broccoli cultivars for field production in spring, summer, and fall seasons; and 2) to illustrate dynamic changes in head quality of promising cultivars for a particular growing season compared to head quality over all seasons evaluated. Twenty-four hybrid cultivars were grown in spring, summer, and fall growing seasons 1993 to 1995 included `Arcadia', `Baccus', `Bonanza', `Citation', `Claudia', `Early Dawn', `Embassy', `Emerald City', `Everest', `Exselsior', `Galaxy', `Galleon', `Goliath', `Green Comet', `Green Duke', `Leprechaun', `Packman', `Paragon', `Skiff', `Southern Comet', `Sprinter', `Sultan', `Symphony', and `Viking'. Head density, color, leafiness, and shape, bead size, and consumer use were documented. `Symphony' performed best in Spring 1993 and 1994, and only `Paragon' tolerated heat in Summer 1993 and 1994. Fall climate in coastal South Carolina is most conducive to high-quality production versus spring and summer seasons, with the following cultivars producing superior heads in both years: `Symphony', `Embassy', `Galleon', `Galaxy', `Sultan', and `Emerald City'. Quality defects for each cultivar in each inappropriate growing season will be illustrated.
Nitrogen Partitioning in the Hazelnut Tree
Authors: Olsen Jeff , Righetti Timothy , Sanchez Enrique
Published: February 2019

Isotopically labeled 15N was applied to `Barcelona' hazelnut trees planted in 1982. The trees were given the following treatments: 120 g N applied to the ground in spring (SG), 120 g N applied to the ground after harvest (PHG), 40 g N applied foliarly after harvest (PHF). The percent of nitrogen from the labeled fertilizer was measured in all of the tree tissues. The uptake of 15N in the leaves was measured monthly for two seasons. The utilization of stored nitrogen reserves was quantified for each treatment. There was a 28% rate of recovery for the applied N. The hazelnut tree showed a strong reliance on stored N reserves in all of the tissues. The fruiting structures were a strong sink for N in the year of application, and for reserve N. Dry matter (DM) partitioning showed that the nuts accounted for 9.1% of the total DW of 11-year-old trees. The SG showed 10.63% of N from 15N in the buds, and 7.40% in the nuts. The PHG treatment was absorbed into the tree, and used the next season in amounts similar to the SG treatments. The PHF was absorbed and used in smaller amounts consistent with the reduced amount of N applied to the foliage.
Response to Iron-deficiency Stress of Pear Genotypes
Authors: Tagliavini M. , Rombolà A.D. , Marangoni B.
Published: February 2019

Pear rootstocks differ in tolerance to calcareous and alkaline soils. Roots of Fe-efficient dicots react to Fe-deficiency stress by strongly enhancing the Fe3+-reductase system, termed turbo-reductase, and by lowering the rhizosphere pH. In this study, we tested whether such adaptation mechanisms characterize pear and quince genotypes. Two trials were performed using micropropagated plants of three quince rootstocks (BA29, CTS212, and MC), three Pyrus communis rootstocks (OH × F51 and two selections obtained at Bologna Univ.: A28 and B21) and of two pear cultivars (Abbé Fétel and Bartlett, own-rooted). In the first trial, plants were grown in a nutrient solution with [Fe(+)] and without iron [Fe(–)] for 50 days. Their root iron-reducing capacity (IRC) was determined colorimetrically, using ferrozine and Fe-EDTA, and Fe uptake of Fe(+) plants was estimated. In the second trial, the rhizosphere pH of plants grown in an alkaline soil (pH in water = 8.3) was measured by a microelectrode. With the only exception of pears OH × F51 and A28, whose IRC was similar in Fe(+) and Fe(–) plants, the Fe-deficiency stress caused a significant decrease of the IRC. Among the Fe(–) plants, the two pear OH × F51 and A28 had higher IRC than the quince rootstocks and the cultivar Abbé F. When plants were pretreated with Fe, IRC was highest in the P. communis rootstocks (more than 50 nmol Fe2+/g fresh weight per h), intermediate in the own-rooted cultivars, and lowest in the quinces (<15 nmol Fe2+/g fresh weight per h). Fe uptake proved to be linearly and positively correlated with root Fe-reducing capacity (r = 0.91***). Rhizosphere pH, averaged over the first 2 cm from root tips, was highest in quince MC (7.2), intermediate in the other two quinces and in the cultivar Abbé F. (6.2–6.6) and lowest in the pear rootstocks and in the cultivar Bartlett (5.2–5.5). The results indicate that roots of pear and quinces do not increase their ability to reduce the iron under Fe-deficiency stress. The genotypical differential tolerance to iron chlorosis likely reflects differences in the standard reductase system and in the capacity of lowering the pH at soil/root interface. The determination of the root IRC appears very promising as a screening technique for selecting efficient Fe-uptake rootstocks.
Copper Sprays—Effects on Apple Fruit Typiness and Market Color Grades
Authors: Peryea Frank J. , Burrows Rhoda L.
Published: February 2019

Late dormant copper (Cu) sprays and mid-summer foliar Cu sprays are being promoted within the Washington apple industry as a means to enhance fruit typiness and red skin color, respectively. While there appears to be theoretical bases for these practices, they have not been tested for horticultural significance. Differential late dormant spray treatments of Cu hydroxide (the Cu source most commonly recommended by agricultural consultants) were imposed in two `Delicious' orchards. Flower cluster Cu was positively related to Cu rate, but the sprays had no effect on leaf Cu or on six fruit typiness variables. Differential mid-summer spray treatments of water, Cu sulfate, and Cu oxysulfate solutions were imposed in three `Delicious' orchards and one `Fuji' orchard. The Cu sprays increased leaf Cu, but had no effect on market color grade measured using a commercial color sorter. The results appear to reflect Cu physicochemistry and timing of application. These preliminary results call into question the utility of the Cu sprays for improving apple fruit quality characteristics when trees show no visual signs of Cu deficiency. They do suggest some alternative ways to manage Cu nutrition in deciduous tree fruit orchards.
Shoot Micropropagation in Vitis as a Source of Leaf-derived Embryogenic Cultures
Authors: Meyerson M. , Benton C.M. , Gray D.J.
Published: February 2019

Micropropagation of Vitis bourquiniana Lenoir `Black Spanish', V. champini Planchon `Dog Ridge', Vitis hybrids (`Blanc du Bois', `Himrod', and `Niagara Seedless'), V. rotundifolia Michx. (`Carlos' and `Dixie'), and V. vinifera L. (`Autumn Seedless', `Cabernet Sauvignon', `Carignane', `French Colombard', `Ruby Cabernet', and `Tokay') was accomplished. Shoot tips taken from micropropagated plants in long-term culture were inoculated onto solidified C2D medium containing 5 μM benzyladenine. Culture times consisting of either one or two 4-week cycles were compared for effect on shoot number. A range of response among cultivars tested was noted. The best-responding variety was V. champini `Dog Ridge', with 5.8 shoots per apex. All other varieties were less prolific. When shoot micropropagation from nodal explants and apices was compared, so significant difference was noted. In vitro micropropagation offers rapid clonal production of grape and is a source of sterile leaf explant material for embryogenic cultures, which, in turn, are useful target for genetic transformation.
Evaluation of Non-climacteric Senescence of Gladiolus sp. Flowers
Authors: Pemberton G.H. , Nell Terril A. , Barrett James E.
Published: February 2019

Senescence of gladiolus flowers, like many geophytes, does not involve a climacteric burst of ethylene. Eleven gladiolus cultivars were screened and all were non-climacteric (NC) for both respiration and ethylene production. Average ethylene levels for individual flowers were 0.5 μl C2H4/kg per h or less. As in other NC flowers, protein synthesis may be linked to senescence. Our goal was to identify specific proteins that were involved in the senescence process that could be used as indicators of postharvest longevity. SDS-PAGE protein profiles of cut gladiolus flowers were determined from a tight bud stage to senescence. Both increases and decreases were observed in major polypeptides that may be connected to postharvest flower longevity. Total protein content of gladiolus flower petals decreased by ≈70% during the profile period. This could explain the relatively short postharvest life of 3 to 5 days for individual gladiolus flowers. Total protein profiles were probed with an ACC synthase antibody to establish the relationship of this enzyme in NC senescence.
The Effect of Timing and Duration of Supplemental Irradiance on Flower Initiation of Plug-grown Geraniums
Authors: Kaczperski Mark P. , Heins Royal D.
Published: February 2019

Plug-grown Pelargonium × hortorum `Pinto Red' seedlings were grown under natural daylight (average of 4.7 mol/day) or with supplemental irradiance from high-pressure sodium lamps. Seedlings were grown under 8-, 16-, or 24-h photoperiods with supplemental irradiances of 2.5, 3.75, or 5.0 mol/day at each photoperiod. Supplemental irradiance was provided for 7, 14, 21, and 28 days beginning 7, 14, 21, 28, and 35 days after sowing. Seedlings were transplanted 63 days after sowing to 8-cm containers (121 plants/m2) and grown to flower. Leaf number at time of transplant was not affected by photoperiod, but increased as daily irradiance and weeks of supplemental irradiance increased. Seedlings were more responsive to supplemental irradiance applications beginning 28 and 35 days than at 7 to 21 days after sowing. Ninety-two percent of seedlings receiving 28 days of 5.0 mol/day supplemental irradiance under a 24-h photoperiod starting 35 days after sowing had initiated flower buds at time of transplant; 75% of those receiving 3.75 mol/day were initiated. Plants receiving less than 3 weeks of supplemental irradiance or with an irradiance period beginning less than 28 days after sowing had not initiated flowers at transplant.
Statistical Design and Analysis of Producer/Consumer Evaluations to Assess Plant Quality
Authors: Stroup Walter W. , Adams Stacy A. , Paparozzi Ellen T.
Published: February 2019

An experiment was performed to investigate the effect of various nitrogen sulfer combinations on the quality of poinsettias. After various physiological measurements were taken, commercial growers, retailers, and consumers were asked to evaluate the salability of the plants. In order to avoid evaluator fatigue, only a limited number of plants could be evaluated. This presented both experimental design and data analysis problems. In view of these constraints, and in order to obtain meaningful results, an unreplicated 7 x 8 factorial design was used. Data were analyzed using the method of half-normal plots in conjunction with a modification of the analysis of variance procedure. Rationale and alternative designs will be presented, as well as the step-by-step procedure for using this method as contrasted with the standard ANOVA technique.
A Three-phase Model of Poinsettia Shoot Elongation using Flower Initiation Date as a Parameter
Authors: Fisher P.R. , Lieth J.H. , Heins R.D.
Published: February 2019

Stem elongation of commercially produced flowering poinsettia (Euphorbia pulcherrima L.) is often sigmoid. However, sigmoid mathematical functions traditionally used for representing plant growth fail to adequately describe poinsettia stem elongation when a shoot has a long vegetative growth period. A model was developed that explicitly described three phases of poinsettia stem elongation: 1) the initial lag phase, where stem length increases approximately exponentially; 2) a period when elongation is linear; and 3) a plateau phase, where elongation rate declines to zero and stem length reaches an asymptotic maximum length. The timing of the plateau phase was linked to flower initiation date. Fit of the resulting model to data from single stem `Freedom' poinsettia grown with different periods between transplant and flower initiation had an R2 of 0.99. Model parameters had clear biological meaning, and the poinsettia model has horticultural application for simulation and graphical tracking of crop height.
Optimization of Nitrogen Fertilization of Subirrigated Container-grown Chrysanthemum using a Simulation Model
Authors: Yelanich Mark V. , Biernbaum John A.
Published: February 2019

A model constructed to describe nitrogen dynamics in the root zone of subirrigated container-grown chrysanthemum was used to develop and test nitrogen fertilization strategies. The model predicts the nitrogen concentration in the root zone by numerical integration of the rates of nitrogen applied, plant nitrogen uptake, and nitrogen movement to the medium top layer. The three strategies tested were constant liquid N fertilization, proportional derivative control (PD) based upon weekly saturated medium extraction (SME) tests, or PD control based upon daily SME tests. The optimal concentration of N to apply using a single fertilization concentration was 14 mol·m–3, but resulted in greater quantities of N being applied than if PD controller strategies were used. The PD controllers were better able to maintain the predicted SME concentration within 7 to 14 mol·m–3 optimal range and reduce the overall sample variability over time. Applying 14 mol·m–3 N at every irrigation was found to be an adequate fertilization strategy over a wide range of environmental conditions because N was applied in excess of what was needed by the plant.
`QAS-13': A New Promising Cold-hardy Scab-resistant Apple Selection
Authors: Granger Raymond L. , Groleau Y. , Fortin C. , Rousselle Gilles L. , Spangelo L.P.S.
Published: February 2019

`QAS-13' is an advanced apple selection that has a proven performance and is in the process of becoming a new cultivar that carries the Vf gene for resistance to apple scab (Venturia inaequalis Cke. Wint.) derived from `Malus floribunda 821'. It combines field immunity to scab and cold tolerance under Quebec climate and soil conditions. The Ott.521 (Melba x 11-51) x `Spartan' cross was made in Ottawa in 1968. The fruits are very attractive and exhibit a smooth and shiny finish somewhat similar to that of `Spartan'. Their glossy, medium- to dark-red color is slightly striped over a greenish-yellow background and covers up to 85% of the fruit surface. Their picking season coincides with that of `Spartan', which is ≈1 week before that of `Red Delicious'. They are round-oblate to oblate in shape with an average diameter of 70 to 75 mm and weigh ≈140 g/fruit. The skin is smooth, thin, and moderately tough, with widely spaced conspicuous beige lenticels. Both the stem and calyx cavities are fairly deep. The stem resembles that of `McIntosh'. the `QAS-13' apples keep better than `McIntosh' apples both in CA and air storages. Taste panelists have consistently ranked the `QAS-13' apples above `McIntosh' apples both at harvest and after storage. The `QAS-13' trees are less vigorous than those of `McIntosh', but more productive. However, they have exhibited a slight susceptibility to frog eye leaf spot (Botryosphaeria obtusa) similar to that of `McIntosh'.
Phytotoxicity and Plant Growth Regulation Associated with Insecticidal Dipping of Rooted Poinsettia Cuttings
Authors: Bell Michelle L. , Baker James R. , Bailey Douglas A.
Published: February 2019

Potential phytotoxicity and plant growth-regulating activity of insecticidal dips for poinsettias was investigated by dipping, then growing unpinched, rooted cuttings of `Red Sails', `Freedom', and `V-14 Glory' in the following insecticidal emulsions for five durations: 2% insecticidal soap (Safer's), 2% horticultural oil (Sunspray Ultrafine), fluvalinate (Mavrik Aquaflow), oxythioquinox (Joust), kinoprene (EnstarII), azadirachtin (Margosan-O), fenoxycarb (Precision), and an oil-carrier formulation of Beauveria bassiana (Naturalis-L). Dips in soap, oxythioquinox, Naturalis-L, and oil were phytotoxic to all three cultivars. Also, kinoprene and fenoxycarb were phytotoxic to `Red Sails'. At dip durations of 10 s and greater, soap, Naturalis-L, and oil were phytotoxic. Oxythioquinox was phytotoxic at durations of 1 min, 15 min, and 1 h. Only fluvalinate was not phytotoxic as a 4-h dip. After 2 weeks, plants dipped in oxythioquinox, Naturalis-L, and oil were stunted. By week 4, differential cultivar effects were seen: six dips (all but fluvalinate and azadirachtin) stunted growth of `Red Sails', whereas only Naturalis-L and oil retarded growth of `V-14 Glory'. Six weeks after treatment, growth of all cultivars was stunted by oxythioquinox, Naturalis-L, and oil, but was not retarded by fluvalinate or azadirachtin. Dip duration significantly affected growth by weeks 4 and 6, when all durations of Naturalis-L and oil reduced growth. Additionally, 4-h dips of oxythioquinox and kinoprene stunted plants after 4 weeks, and 1- and 4-h dips of oxythioquinox, kinoprene, and fenoxycarb adversely affected growth after 6 weeks.
Effect of Concentration and Time of Accel Application on Cropping of Selected Cultivars
Authors: Hull Jerome , Bukovac Martin J. , Black Brent L.
Published: February 2019

The effect of Accel concentration and time of application on fruit size and yield was studied using `Delicious' (Redchief), `Empire', `Jonathan', and `Gala'. High-volume sprays of Accel were applied at 25 to 150 mg·liter–1 to `Delicious' and `Empire' at king fruit diameter (KFD) of 5 to 20 mm. `Jonathan' and `Gala' were treated at KFD of 5 to 20 mm with 10 to 40 g/A. The effect of spray volume (500 to 2000 liters·ha–1) and surfactant (Regulaid) was studied using `Jonathan'. Response was indexed by yield and fruit size distribution at harvest. Although yield in `Delicious' was reduced with all concentrations of Accel, the percentage of fruits in the larger-size classes (3”+) was not significantly increased. In contrast, with `Empire', Accel reduced fruit load similar to hand-thinning (HT) and percentage of large fruit equaled or exceeded that of the HT treatment. Increasing concentration of Accel was related to an increase in fruit size; early application (5 mm KFD) was more effective than late (10, 20 mm KFD) application. There was no significant effect of spray volume or Regulaid. Increasing Accel rate (10 to 20 g/A) resulted in significant yield reduction and increase (4% to 9%) in mean fruit weight in `Gala'.