bluuebunny/crossref_metadata_2025 huggingface dataset:
Stomatal and Cuticular Transpiration of Greenhouse Tomato Plants in Response to High Solution Electrical Conductivity and Low Soil Water Content
Authors: Xu Hui-lian , Gauthier Laurent , Gosselin André
Published: January 2019

`Capello' tomato plants (Lycopersicon esculentum Mill.) were grown in a greenhouse in peat-based substrate (70% sphagnum peat and 309'. perlite, by volume) and supplied with nutrient solutions of high (4.5 mS·cm-1) or low (2.3 mS·cm-1) electrical conductivity (EC) under high (95% ± 5%) or low (55% ± 8% of capillary capacity) soil water conditions. Three weeks after treatments started, stomatal transpiration (TRst) and cuticular transpiration (TRcu) rates were measured by three methods: 1) analyzing TRst and TRcu from a water retention curve obtained by drying excised leaves in air under a photosynthetic photon flux (PPF) of 400 μmol·m-1·s-1, 2) analyzing TRst and TRcu from a transpiration decline curve obtained by measuring transpiration rates after cutting the leaf from the stem of the dehydrated plant in the gas-exchange system, and 3) measuring transpiration rates under light and in dark respectively using the gas-exchange method. TRst and TRcu were decreased by high EC and/or low soil water content. For method 1, the transpiration decline curve shows two distinct phases: the initial steep slope that indicates TRst and the gently sloped section that indicates TRcu. Both slopes were lower for high EC and/or water-stressed plants compared to the control (low EC and high soil water content). The tangent lines of these two phases of the curve intersect at one point (t, w). The value oft that indicates the time for stomatal closure was longer and the value of w that indicates the critical tissue water level for stomatal closure was lower for high EC and/or water-stressed plants. In method 2, the initial rate of total transpiration was higher in high EC and/or water-stressed plants. Leaf wax content increased, especially under high EC stress. This suggests that increased deposition of wax prevents water loss from the cuticle. A delay in complete stomatal closure, complete closure at lower RWC, and reduced TRcu or an increase in wax deposit were adaptations to water and salinity stresses in tomato plants under our controlled environmental conditions.
Reduced Water Supply Induces Fall Acclimation of Evergreen Azaleas
Authors: Anisko Tomasz , Lindstrom Orville M.
Published: January 2019

The primary cause of losses in evergreen azaleas injured by early freeze is bark split on lower stems. Delayed acclimation in the fall is thought to permit this injury. We examined whether reduced water supply affects acclimation of Rhododendron L. `Coral Bell', `Hinodegiri', and `Red Ruffle'. Containerized plants were grown under four watering regimes and placed outdoors or in the greenhouse. The water content of the growing medium was maintained at either 0.3 to 0.4 or 0.5 to 0.6 m3·m-3 from 16 June to 30 Aug. 1993, when half of the plants under each of these regimes was switched to the other watering regime. Freeze tests were conducted on 30 Aug. and 9 (let. Injury to leaves, and lower, middle, and upper stems was evaluated visually. Acclimation of leaves and upper stems before the August test, in most cases, was not stimulated by reduced water content, while the response of lower and middle stems was cultivar- and location-specific. The lower water content treatment after 30 Aug. generally increased freeze tolerance of all plant parts regardless of the previous watering regime. The higher water content treatment after 30 Aug. either prevented or delayed acclimation. This study demonstrated that the reduced water supply provided a feasible means of promoting acclimation of evergreen azaleas in late summer.
Photoperiodic Response of Genetically Diverse Lettuce Accessions
Authors: Waycott William
Published: January 2019

A series of experiments was undertaken to study daylength-mediated control of transition to flowering in lettuce (Lactuca sativa L.), a quantitative long-day plant. Several genotypes (cultivars, landraces, and mutant lines) were grown at different photoperiods, sometimes in combination with different temperatures, and measured for number of days to either a) bolting initiation (a detectable increase in the rate of stem elongation) or b) anthesis of the first flower (a standard measure of maturity in lettuce). Experiments were conducted in controlled or partially controlled environments. Results of these studies indicate the following: a) high temperature alone is not sufficient to induce the bolting response, whereas photoperiod is; b) there is a range of genetic responses to various daylengths among lettuce genotypes; c) one of the genes known to control bolting initiation, gene Z', exhibited reverse dominance in conjunction with the Early Flowering genes, depending on the length of day. The latter observation implies the genetic role of T needs further investigation, as it does not appear to operate by simple dominance alone.
Identifying Critical Volatiles in the Flavor of Baked `Jewel' Sweetpotatoes [Ipomoea batatas (L.) Lam.]
Authors: Sun Jyh-Bin , Severson Ray F. , Schlotzhauer William S. , Kays Stanley J.
Published: January 2019

Thermal degradation of fractions from sweetpotato roots (`Jewel') was conducted with gas chromatographymass spectrometry to identify precursors of critical flavor volatiles. Upon heating (200 C), sweetpotato root material that was insoluble in methanol and methylene chloride produced similar volatile profiles to those from sweetpotatoes baked conventionally. Volatiles derived via thermal degradation of the nonpolar methylene chloride fraction and the polar methanol fraction did not display chromatographic profiles similar to those from conventionally baked sweetpotatoes. Initial reactions in the formation of critical volatiles appear to occur in the methanol and methylene chloride insoluble components. Maltol (3-hydroxy-2-methyl-4-pyrone) was found to be one of the critical components making up the characteristic aroma of baked sweetpotatoes. Integration of an analytical technique for the measurement of flavor into sweetpotato breeding programs could potentially facilitate the selection of improved and/or unique flavor types.
Source-Sink Relationship and Protea Postharvest Leaf Blackening
Authors: Dai Jingwei , Paull Robert E.
Published: January 2019

The inflorescence of Protea neriifolia B. Br. was two-thirds of the total cut floral stem fresh weight and significantly influenced blackening of the attached 20 to 30 leaves. Floral stems harvested at five developmental stages were characterized for inflorescence diameter, fresh and dry weights, respiration, and nectar production. Inflorescence diameter and fresh and dry weights increased from stage 1 (very tight bud) to stage 5 (bracts reflexed). Respiration rate was high in stages 1 and 3. Nectar production began at stage 4 (open, cylindrical flower) and increased from 2.7 to 9.8 ml per flower with 15% to 23.5% total soluble solids as the flower opened. Postharvest inflorescence diameter, respiration rate, and nectar production increased and leaf blackening decreased when floral stems were placed in 5% (w/v) sucrose solution. Application of 14C-sucrose to a leaf subtending the inflorescence lead to >50% of the radioactivity being found in the nectar within 24 hours. These data indicate that leaf blackening in protea is the result of depletion of carbohydrate by the inflorescence, and that this depletion is primarily due to the sugar demand for nectar production.
The Dark Corona Character in Seedcoats of Common Bean Cosegregates with the Pink Flower Allele vlae
Authors: Bassett Mark J.
Published: January 2019

Crosses were made with two common bean (Phaseolus vulgaris L.) parents that have pink flowers (vlae/-) and mineral-brown seedcoats with dark corona, viz., vlae BC3 5-593 (derived from Lamprecht V0491) and F3 vlae dark corona (derived from Lamprecht M0048). The third parent v BC2 5-593 had white flowers (v/v) and mineral-brown seedcoats without dark corona (derived from Lamprecht M0056). The F2 progenies of the crosses v BC2 5-593 × vlae BC3 5-593 and F3vlae dark corona × v BC2 5-593 segregated for only two phenotypic classes: either pink flowers and seeds with dark corona or white flowers and seeds without dark corona. Thus, it was demonstrated that the dark corona character (Cor) is either tightly linked to vlae (<4 map units) or is a pleiotropic effect of vlae. Pleiotropy is more probable, but tight linkage cannot be ruled out. A linkage of 15 map units between Cor and R (currently, R is known to be tightly linked with C) reported by Lamprecht was not found by subsequent authors, and the linkage map of common bean should be revised accordingly, i.e., no linkage exists between V (Cor) and C.
Pollen Parent Effect on the Selective Abscission of `Mauritius' and `Floridian' Lychee Fruitlets
Authors: Degani C. , Stern R.A. , El-Batsri R. , Gazit S.
Published: January 2019

Fruit produced by adjacent blocks of `Mauritius' and `Floridian' lychee (Litchi chinensis Sonn.) were sampled at four different stages of development and the embryos were analyzed for pollen parentage by phosphoglucose isomerase (PGI; EC 5.3.1.9) isozyme system. Hybrid percentage increased significantly from ≈5 weeks after fruit set to maturity as follows: from 29.5% to 76.3% in `Mauritius' and from 74.2% to 92.5% in `Floridian'. These findings clearly indicate selective abscission of selfed fruitlets. In `Mauritius', yield was not related to the distance from the pollenizer block or hybrid percentage. In `Floridian', yield of trees adjacent to the `Mauritius' pollenizer was higher by 36% than that of trees at a distance of 24 m. The correlation between `Flordian' yield and hybrid percentage tended toward significance (r= 0.64, P = 0.08). In addition, in both cultivars, fruit and seed weights were affected by the pollen parent: outcrossed fruit were heavier and contained heavier seeds than selfed ones.
Inheritance of Phosphoglucoisomerase in Fountain Grass
Authors: Meyer M. Hockenberry , White Donald B.
Published: January 2019

Starch gel electrophoresis was used to screen 10 enzyme systems for variation in fountain grass, Pennisetum alopecuroides (L.) Spreng. plants exhibiting four different growth habits: dwarf(d), mound(m), prostrate(p), and upright (u). Only phosphoglucoisomerase (PGI; E.C. 5.3.1.9) was found to be polymorphic at one locus, PGI-2, and was expressed as two alleles, which appeared to be associated with growth habit. The dwarf form expressed one slow band (SS), the mound and prostrate forms exhibited one fast band (FF), and the upright form carried triple bands indicating a heterodimer (FS). Hybrids between FF and SS parents were detected as triple bands (FS). Three generations of progeny resulting from 16 crosses and selfs of these growth habits all followed the expected segregation ratios for typical Mendelian inheritance of this isozyme.
Diurnal Vitiations in Tension, Osmolarity, and the Composition of Nitrogen and Carbon Assimilates in Xylem Fluid of Prunus persica, Vitis Hybrid, and Pyrus communis
Authors: Andersen Peter C. , Brodbeck Brent V. , Mizell Russell F.
Published: January 2019

Diurnal variations in the chemical composition of xylem fluid have been established for many plant species exhibiting positive root pressure; similar patterns have not been well documented in transpiring plants. Diurnal changes in plant water status and xylem fluid chemistry were investigated for `Flordaking' peach [Prunus persica (L.) Batsch], `Suwannee' grape (Vitis hybrid), and `Flordahome' pear (Pyrus communis L.). Xylem tension was maximum at 1200 or 1600 hr and declined to <0.5 MPa before dawn. Xylem fluid osmolarity ranged from 10 to 27 mm and was not correlated with diurnal patterns of xylem tension. The combined concentration of amino acids and organic acids accounted for up to 70%, 45%, 55%, and 23% of total osmolarity for irrigated P. persica, nonirrigated P. persica, Vitis, and P. communis, respectively. The concentration of total organic compounds in xylem fluid was numerically greatest at 0800 or 0900 hr. For irrigated P. persica the osmolarity of xylem fluid was reduced by 45% from 0800 to 1200 hr, 1 h after irrigation, compared to only a 12% reduction from 0800 to 1200 hr for nonirrigated trees. Asparagine, aspartic acid, glutamine, and glutamic acid were mainly responsible for diurnal changes in the concentration of total amino acids and organic N for P. persica; the diurnal variation in organic N for Vitis was due to glutamine. Arginine, rather than the amides, was the primary source of organic N in xylem fluid of P. communis, and there was no consistent diurnal change in the concentration of amino acids or organic N. The predominant organic acids in all species examined were citric and malic acids. No consistent diurnal trend occurred in the concentration of organic acids or sugars in xylem fluid.
The Relationship between Carbohydrates and Flower Bud Hardiness among Three Forsythia Taxa
Authors: Flinn Cindy L. , Ashworth Edward N.
Published: January 2019

The accumulation of total soluble sugars (TSS) and starch and their relationship to flower bud hardiness were studied in three Forsythia taxa: Forsythia ×intermedia `Spectabilis', Forsythia ×intermedia `Lynwood', and F. suspensa. Taxon hardiness was based on the mean temperature at which low temperature exotherms (LTEs) occurred during thermal analysis. Ethanol-extracted soluble sugars were quantified with anthrone, and starch was enzymatically digested and quantified with Trinder reagent. Qualitative changes in sugar content were determined with high-performance liquid chromatography and co-chromatography of authentic standards. Quantitative and qualitative changes in sugar content, similar for the three taxa, were observed in conjunction with fluctuations in flower bud hardiness, although neither TSS nor starch were correlated with mean LTE temperature. TSS was higher in acclimated than nonacclimated buds. However, after deacclimation began, sugars continued to increase with mean LTE temperature. Buds lacked starch except for a brief period during deacclimation. Galactose, stachyose, raffinose, and an unidentified carbohydrate were positively correlated with hardiness (P = 0.005, 0.001, 0.005, and 0.001, respectively).
Identifying Pecan Cultivars by Isozymes and Inheritance of Leucine Aminopeptidase
Authors: Marquard Robert D. , Grauke Larry J. , Thompson Tommy E. , Janos Ruth S.
Published: January 2019

More than 170 pecan [Carya illinoensis (Wangenh.) K. Koch] cultivars were evaluated formalate dehydrogenase, phosphoglucose isomerase, phosphoglucomutase, leucine aminopeptidase (LAP), and diaphorase (DIA). Isozymes of LAP were observed in two regions after starch gel electrophoresis. The faster region of activity (Lap-1) was polymorphic and consistently expressed in leaves, wood, and roots. Controlled crosses suggest that Lap-1 is simply inherited and controlled by at least two alleles. DIA was well resolved and storable only from leaf material and produced a complex banding pattern. The ability to differentiate among cultivars by isozymes was good. The 177 cultivars sorted into 72 classes. Forty of the cultivars (23%) possessed a unique series of isozyme patterns. Most cultivars (124 of 177) shared common banding patterns with less than four other cultivars. From the inheritance models of four isozymes, some historical pedigrees can be questioned. Most notably,' Western Schley' could not have been parented by `San Saba' based on the inheritance of Mdh-1 and Lap-1.
Identification and Inheritance of Delayed First Pustule Appearance to Common leaf Rust in Sweet Corn
Authors: Gingera G.R. , Davis D.W. , Groth J.V.
Published: January 2019

Partial resistance effectively reduces common leafrust (Puccinia sorghi Schw.) epidemics in sweet corn (Zea mays L.). One measurable field component of partial resistance is delayed first pustule appearance (FPA), influenced by latent period and infection efficiency. This is the first report of delayed FPA against common rust in sweet corn. Our objectives were to determine 1) if differences in delayed FPA could be assessed in a field environment, 2) the relationship between delayed FPA and disease severity, and 3) the inheritance of delayed FPA. FPA was screened in a field environment during 1992 and 1993 using two susceptible U.S. station inbreds and 32 breeding lines selected for partial resistance to common rust. The range in mean delay in FPA on a genotype basis was 2.4 to 5.0 days in 1992 and 1.5 to 7.4 days in 1993. Although the rank correlation of genotypes between years was small (r = 0.27), several breeding lines had longer delayed FPA in both years while others produced shorter FPA delay in both years. Seven commercial sweet corn hybrids with a wide range of partial resistance did not differ (P ≤ 0.05) for delayed FPA. There was no correlation between disease severity and delayed FPA (r2 = 0.00 to 0.21) for breeding lines or commercial hybrids, indicating that selection for delayed FPA may be conducted independently of disease severity. In a generation mean analysis conducted in 1993 and 1994 for three high x low delayed FPA crosses, the genetic control of delayed FPA was primarily additive. Dominant genetic effects were found in two crosses and epistasis was not significant in any cross.
High Temperature and Low Moisture Reduce the Storage Requirement of Freshly Harvested True Potato Seeds
Authors: Pallais Noël
Published: January 2019

Freshly harvested, true potato (Solarium tuberosum L.) seeds (TPS) will germinate at 15 ± 5C, but because of dormancy they must be stored for ≈18 months before they will germinate at >25C. Effects of seed moisture content (SMC) and temperature in storage on germination and seedling emergence were periodically tested during 18 months for seeds harvested from three positions on the mother plant. Seeds were stored with 37.,5%, and 7% SMC (on a dry weight basis) at 5 and 45C; sublets were removed monthly (1 to 7 months) from 45C and stored at 5C. Seed dormancy and viability were best preserved in storage at low SMC and low temperature, Seeds stored at 45C and 3 % SMC progressively lost dormancy and, after 4 months of storage, germination was up to 88% after 4 days at 127C. This rate of germination decreased with further storage. Up to 100% emergence occurred in 9 days in seeds stored for 18 months at 45C and 3% SMC. Seeds stored at 45C and 5% SMC lost dormancy in 2 months and <50% emergence occurred after 18 months. Seeds stored at 45C and 7% SMC deteriorated and became nonviable within 6 months of storage. The position of seed development did not significantly affect seed size or weight. However, seeds produced from the bottom third of the plant (lot A) were the most vigorous after dormancy was released with sufficient storage. This suggests that efforts should be made to produce TPS in the primary branches of the mother plant.
Identifying Crabapple Cultivars by Isozymes
Authors: Marquard Robert D. , Chan Charlotte R.
Published: January 2019

Forty-five crabapple (Malus spp.) cultivars were evaluated for 16 isozyme systems by starch gel electrophoresis. Of the 16 systems evaluated, 6 were useful in separating among cultivars. Enzyme systems used to distinguish among the cultivars included alcohol dehydrogenase, aspartate aminotransferase, malate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphoglucoisomerase, and shikimate dehydrogenase. Each enzyme system produced one well-resolved polymorphic region except for 6-phosphogluconate dehydrogenase, which produced two. Most crabapple selections could be identified when all six enzymes were evaluated. Alcohol dehydrogenase had the most diagnostic banding patterns useful for cultivar identification.
Randomly Amplified Polymorphic DNA Fingerprinting for Identifying Rabbiteye Blueberry (Vaccinium ashei Reade) Cultivars
Authors: Aruna Myneni , Austin Max E. , Ozias-Akins Peggy
Published: January 2019

Cultivars of the economically important rabbiteye blueberry (Vaccinium ashei Reade) were differentiated at the DNA level using the technique of randomly amplified polymorphic DNA. Single decanucleotide primers of arbitrary sequence were used to amplify genomic DNA by the polymerase chain reaction. All cultivars tested exhibited a unique set of collective amplified fragments of distinct molecular weight. A blind fingerprinting experiment resulted in identification of unknown samples without ambiguity. We also clarified the genetic identity of two wild selections of rabbiteye blueberry, `Ethel' and `Satilla', which have been maintained as two different selections, hut are considered by some blueberry breeders to be of the same genetic constitution. The technique also verified the probable identity of two cultivars in a commercial blueberry field by comparing their amplified DNA patterns with those of standard cultivars. No variation was observed between the amplification profiles of `Brightwell' and its presumed sport. A cultivar key based on 11 markers amplified by four primers is presented.
Sequence-specific Polymerase Chain-reaction Markers Derived from Randomly Amplified Polymorphic DNA Markers for Fingerprinting Grape (Vitis) Rootstocks
Authors: Xu Hong , Wilson Diane J. , Arulsekar S. , Bakalinsky Alan T.
Published: January 2019

Randomly amplified polymorphic DNA (RAPD) markers were generated for identifying grape (Vitis) rootstocks. Seventy-seven primers (10 bases long) were screened using CsCl-purified leaf DNA derived from several field samples of nine rootstocks sampled in successive years. Nine RAPD markers were detected from six primers and, in combination, distinguished all nine rootstocks tested. Because inconsistencies were encountered in performing the RAPD assay, sequence-specific primers were derived from cloned RAPD bands for use under more stringent amplification conditions. Southern hybridization analysis of the RAPD gels with cloned RAPD bands as probes revealed deficiencies of scoring RAPD bands based solely on ethidium bromide staining. In some cases, bands of the same size generated by the same primer in different rootstocks-normally scored as the same marker-failed to cross-hybridize, implying lack of homology between the bands. More commonly, bands scored as absent based on ethidium bromide staining were detected by hybridization. Six of the nine cloned RAPD bands were partially sequenced, and sequence-specific primer pairs were synthesized. Two primer pairs amplified a product the same size as the original RAPD band in all rootstocks, resulting in loss of polymorphism. Two other pairs of sequence-specific primers derived from the same marker failed to amplify the expected band consistently. Three of the most useful primer pairs amplified apparent length variants in some accessions and will have value as polymerase chain-reaction markers for fingerprinting.
Characterizing the Celery Genome with DNA-based Genetic Markers
Authors: Yang Xiaofeng , Quiros Carlos F.
Published: January 2019

To characterize the celery (Apium graveolens L. var. dulce, 2n = 2x = 22) genome, 126 celery cDNA clones and 340 random 10-mer primers were used to generate restriction fragment-length polymorphism (RFLP) and randomly amplified polymorphic DNA (RAPD) markers between two cultivated types. Different abundance classes of the genomic sequences represented by the cDNA clones and the RAPD markers were observed. Most of the cDNA clones were single-copy sequences, suggesting the true diploid nature of the celery genome. Nearly half of the 39 RAPD markers tested by Southern hybridization were multiple-copy sequences. Of the RAPD markers tested, 28% was single- and low-copy, and 26% was high-copy sequences. The polymorphism level of the cDNA clones was 23% when tested with four restriction enzymes (Eco RI, Eco RV, Hin dIII, and Hae III). A positive association was observed between RFLP level and the size of cDNA inserts or hybridized restriction fragments. Deletion, insertion, and base substitution were important in the formation of the RFLP markers. Eighty-two (23%) of the 340 primers tested yielded useful RAPD markers, but only 3.8% of the amplified products were polymorphic. Base substitution may be the most important mechanism for the RAPD markers in celery. The RAPD fragments revealed no RFLP markers when tested by Southern hybridization, implying that RAPD markers are an important complement to RFLP markers in genomic mapping in celery. Random methylation of cytosine was determined in 5S rDNA on Bam HI and Hin dIII cutting sites that produced ladder patterns characteristic of tandem repeats.
Randomly Amplified Polymorphic DNA in Bulb Onion and Its Use to Assess Inbred Integrity
Authors: Bradeen James M. , Havey Michael J.
Published: January 2019

Commercial bulb-onion (Allium cepa L.) growers often complain that hybrids they have grown successfully for a few years fail to perform at the expected level. Inbreds used to produce hybrid-onion seed rarely have been self-pollinated for more than two generations and retain a high level of heterozygosity. Over time, selection, drift, or contamination of inbreds may contribute to disappointing hybrid performance. We identified randomly amplified polymorphic DNA (RAPD) between two inbred onion lines, demonstrated their Mendelian inheritance, and tried to distinguish among and examine changes in independently maintained, publicly released inbred lines of onion. We observed poor agreement between data sets based on genetically characterized and uncharacterized RAPD markers. Our analyses used only genetically characterized RAPD markers and revealed that contamination, in addition to-drift and/or selection, likely contributed to differences among independently maintained, publicly released inbreds. However, RAPD markers were not able to distinguish confidently among four related inbreds. RAPD markers will be useful in Allium genetics and breeding, but identifying and characterizing reliable polymorphisms is critical.
Dormant Pruning and Fall Ethephon Application Influence Peach Pistil Hardiness
Authors: Durner Edward F.
Published: January 2019

Flower bud hardiness of ethephon-treated (100 mg·liter-1 in October), dormant pruned (in December) `Redhaven' peach (Prunus persica L. Batsch.) trees was studied from December through March using exotherm analysis. In early December, buds not treated with ethephon were 0.5C hardier than ethephon-treated buds. From mid-December through March, ethephon-treated buds were 0.5 to 2.1C hardier than nontreated buds. When a main effect of pruning was detected, buds from pruned trees were 0.8 to 2.8C less hardy than buds from nonpruned trees. On several dates, a significant interaction on flower bud hardiness between ethephon treatment and pruning was detected. For trees not treated with ethephon, buds from pruned trees were 1.8 to 2.2C less hardy than those from nonpruned trees. Pruning did not affect hardiness of buds from ethephon-treated trees. Ethephon delayed bloom to the 75% fully open stage by 9 days. Pruning accelerated bloom to the 75% fully open stage by 3 days compared to nonpruned trees. Flower bud dehardening under controlled conditions was also studied. As field chilling accumulated, flower buds dehardened more rapidly and to a greater extent when exposed to heat. Pruning accelerated and intensified dehardening. Ethephon reduced the pruning effect. The percentage of buds supercooling from any ethephon or pruning treatment did not change as chilling accumulated. In trees not treated with ethepbon, fewer buds supercooled as heat accumulated, and pruning intensified this effect. In pruned, ethephon-treated trees, fewer buds supercooled after exposure to heat. The number of buds supercooling in nonpruned trees did not change with heat accumulation. Flower bud rehardening after controlled dehardening was also evaluated. After dehardening in early February, there was no difference in the bud hardiness of pruned or nonpruned trees. Buds from ethepbon-treated trees were hardier than those from nontreated trees. With reacclimation, buds from pruned trees were not as hardy as those from nonpruned trees. The percentage of buds supercooling from ethephon-treated trees did not change with deacclimation or reacclimation treatments. After deacclimation in late February, buds from pruned trees were 2.2C less hardy than those from nonpruned trees. After reacclimation, buds from pruned, ethephon-treated trees rehardened 2.6C while buds from all other treatments remained at deacclimated hardiness levels or continued to deharden. Ethephon-treated pistils were shorter than nontreated pistils. Pistils from pruned trees were longer than those from nonpruned trees. Deacclimated pistils were longer than nondeacclimated pistils. Differences in hardiness among ethephon and pruning treatments were observed, but there was no relationship between pistil moisture and hardiness.
Low-temperature Exotherms and Cold Hardiness in Three Taxa of Deciduous Trees
Authors: Lindstrom Orville M. , Anisko Tomasz , Dirr Michael A.
Published: January 2019

Although differential thermal analysis has been routinely used to evaluate cold hardiness, the relationship of deep supercooling ability and plant survival are not well understood. In this study, we compared the seasonal profiles of changes in low-temperature exotherm (LTE) occurrence with visually determined cold hardiness of Acer rubrum L. `Armstrong', Fraxinus americana L. `Autumn Purple' and Zelkova serrata (Thunh.) Mak. `Village Green' growing in three locations representing plant cold hardiness zones 8b, 7b, and 5a. Between December and February, LTEs in Acer rubrum `Armstrong' and Fraxinus americana `Autumn Purple' occurred at temperatures around 10 to 25C lower than the lowest survival temperatures. The mean difference between LTEs and lowest survival temperature was not significant for Zelkova serrata `Village Green' from January to April and for Acer rubrum `Armstrong' and Fraxinus americana `Autumn Purple' in March. Data indicated that LTEs could be used as an estimate of lowest survival temperature in Zelkova serrata `Green Village' but not in Acer rubrum `Armstrong' and Fraxinus americana `Autumn Purple'. This study demonstrated that LTEs may not reliably estimate cold hardiness in all species that deep supercool. Factors other than freeze avoidance ability of xylem may limit stem survival at temperatures above the LTE.
White-mold Avoidance and Agronomic Attributes of Upright Common Beans Grown at Multiple Planting Densities in Narrow Rows
Authors: Saindon Gilles , Huang Henry C. , Kozub Gerry C.
Published: January 2019

The putative yield advantage associated with growing upright beans (Phaseohs vulgaris L.) at high planting densities in narrow (0.23-m) rows might he compromised by a higher risk of white mold [Sclerotinia sclerotiorum (Lib.) de Bary] because of reduced air flow through the crop canopy. This four-yeai-study was undertaken to compare the white-mold avoidance and agronomic attributes of upright bean lines and to determine whether their yields can he increased by raising planting density. Four upright lines and a viny line as a control were established in narrow rows at planting densities ranging from 25 to 60 plants/m* in a field artificially infested with sclerotia of S. sclerotiorum. On average, the four upright lines had lower incidence of white mold and smaller disease severity indices than the control, `UI36', indicating that the development of white mold is reduced in dense, erect canopies. There were differences in disease response among the upright lines, with `ISB82865' and `UI906' being the least and most susceptible entries, respectively. Increases in planting densities resulted in higher yields and influenced the development of white mold hut had no effect on vine length, lodging, and maturity. However, the planting density effect on the disease response was not consistent among entries in 2 of the 4 years. The results of this study indicate that upright beans can he grown at high planting densities without greatly increasing the risk of a white-mold outbreak. The choice of the most appropriate planting density for upright beans depends largely on the cost of seed.
Soil Temperature and Tomato Growth Associated with Black Polyethylene and Hairy Vetch Mulches
Authors: Teasdale John R. , Abdul-Baki Aref A.
Published: January 2019

Temperature and root length at selected locations within a raised bed under black polyethylene, hairy vetch (Vicia villosa Roth) residue, or bare soil were measured and correlated with tomato (Lycopersicon esculentum Mill.) growth. Early in the season, before the tomato leaf canopy closed, soil temperature was influenced more by vertical depth in the bed than by horizontal position across the bed. Maximum soil temperatures under black polyethylene averaged 5.7 and 3.4C greater than those under hairy vetch at 5 and 15 cm deep, respectively. More hours at optimum temperatures for root growth (20 to 30C) during the first 4 weeks of the season probably accounted for greater early root and shoot growth and greater early yield of tomatoes grown with black polyethylene than hairy vetch residue or bare soil. After canopy closure, soil temperatures under tomato foliage within the row were reduced by an average of 5.2 and 2.2C at 5 and 15 cm deep, respectively, compared to those on the outer edge of the beds. Most tomato roots were in areas of the bed covered by the tomato canopy where temperatures in all treatments remained in the optimum 20 to 30C range almost continuously. Soil temperature, therefore, did not explain why tomato plants in the hairy vetch treatment had equal or higher total yields than the black polyethylene or unmulched treatments.
Economics of a Hairy Vetch Mulch System for Producing Fresh-market Tomatoes in the Mid-Atlantic Region
Authors: Kelly' Terry C. , Lu Yao-Chi , Abdul-Baki Aref A. , Teasdale John R.
Published: January 2019

Concern for the environment has focussed attention on the need for environmentally sound, yet economically profitable, farming practices. A hairy vetch (Vicia villosa L. Roth.) organic mulch system for fresh-market tomato (Lycopersicon esculentum Mill.) production provides environmental benefits by enhancing the soil and reducing the need for fertilizer and herbicide inputs and is more profitable than conventional practices. Tomato field trials over 3 years at the Beltsville (Md.) Agricultural Research Center compared the hairy vetch mulch system with black polyethylene mulch and bare ground (no mulch). Using partial budget analysis in a farm context, the hairy vetch mulch treatment was more profitable in all years under all market and yield adjustment scenarios. The vetch mulch system also was the preferred system for a risk-averse grower, according to a safety-first criterion. The combination of environmental benefits and the economic benefits to the grower make the hairy vetch mulch system an attractive alternative for producing fresh-market tomatoes in the Mid-Atlantic and parts of northeastern United States.
Constant-light Injury of Potato: Temporal and Spatial Patterns of Carbon Dioxide Assimilation, Starch Content, Chloroplast Integrity, and Necrotic Lesions
Authors: Cushman Kent E. , Tibbitts Theodore W. , Sharkey Thomas D. , Wise Robert R.
Published: January 2019

Expanding leaflets of young `Kennebec' potato plants (Solanum tuberosum L.) develop visible necrotic spotting after 8 to 9 days of constant light and constant temperature, but little is known about this disorder before the appearance of injury. Whole-leaf autoradiography and iodine staining of terminal leaflets (5 to 10 mm long at the beginning of the constant-light period) showed a normal pattern of CO2 assimilation and starch content over the entire leaflet surface after 5 days of constant light. However, small areas of tissue devoid of CO2 assimilation and starch content became apparent on day 6, and these areas expanded to encompass much of the leaflet's medial and basal regions by day 7. At this stage of leaf development, on day 7, leaflets had attained 50% of their final leaflet length and ceased importing photosynthates from other leaves. Electron micrographs of chloroplasts from the medial and basal regions of leaflets on day 7 revealed a loss of membrane integrity and a senescence-like appearance. At this time, and within these affected regions, scattered groups of necrotic palisade cells began to appear. These scattered groups soon expanded in size and distribution and became apparent as visible necrotic spots on the upper leaflet surface by day 8 or 9. Leaflets on plants grown under constant light hut alternating temperatures, an environment known to be noninjurious, did not exhibit visible spotting or tissue devoid of starch content. In addition, none of these injury symptoms developed in `Denali', a potato cultivar tolerant of constant light. Despite its occurrence in expanding leaf tissue, constant-light injury appears to be a senescence-like event that leads to the catastrophic loss of photosynthetic competence, starch content, and chloroplast membrane integrity, producing chlorosis and necrosis of leaves and eventually stunting the plant.
Glucosinolates in Broccoli Stored under Controlled Atmosphere
Authors: Hansen Merete , Møller Peter , Sørensen Hilmer , de Trejo Marita Cantwell
Published: January 2019

Content of total and individual glucosinolates were determined in, `Marathon' broccoli florets (Brassica olerucea L. var. italica stored 7 days at 10C under air, 0.5% O2, 0.5% O2 + 20% CO2 or 20% CO2 atmosphere, followed by transfer to air for 2 days. `Marathon' broccoli contained glucoraphanin, glucobrassicin, neoglucobrassicin, glucoiberin, 4-methoxyglucobrassicin, progoitrin, glucoalyssin, and gluconasturtiin. The methylssulfinylalkylglucosinolates (glucoiberin and glucoraphanin) and the indol-3-ylmethylglucosinolates (glucobrassicin, neoglucobrassicin and 4-methoxyglucobrassicin) accounted for 78% and 20% of the total content, respectively, in freshly harvested broccoli. CA treatment and storage time had no significant effect on the relative content of these two groups of glucosinolates. Freshly harvested broccoli contained 47 μmol glucosinolate/g dry weight. The total glucosinolate content increased 42% and 21% during 7 days storage under air and 0.5% O2 + 20% CO2, respectively, as compared to freshly harvested broccoli, and decreased 15% in broccoli stored under 20% CO2. Treatment with 20% CO2 in the absence of 0, resulted in visible CO, injury and water soaking of the tissue. Aeration had no significant effect on total glucosinolate content but reduced the glucobrassicin content 35% in broccoli stored 7 days under 0.5% O2 + 20% CO2 or 20% CO2 atmosphere. In contrast, the 4-methoxyglucobrassicin content increased during storage under low O2 atmosphere and increased further after transfer to air.
Selecting Lemon Protoplasts for Insensitivity to Phoma tracheiphila Toxin and Regenerating Tolerant Plants
Authors: Deng Z.N. , Gentile A. , Domina F. , Nicolosi E. , Tribulato E.
Published: January 2019

Protoplasts isolated from an embryogenic callus line of `Femminello siracusano' lemon [Citrus limon (L.) Burm. f.] were incubated with 0.5 μm toxin of Phoma tracheiphila (Petri) Kanc. et Ghik., the pathogen of the mal secco disease, which seriously damages most commercial lemon cultivars. Two toxin-tolerant cell lines were obtained, and plants were regenerated from each line. The selected protoclones were tested for their tolerance by exposing callus and protoplasts to the toxin and detecting chitinase (a pathogenesis-related protein) among the intra- and extracellular proteins extracted from leaves of regenerated plants and suspension culture, respectively. The tolerance of the protoclones in these tests was equivalent to the tolerant lemon cultivar Monachello, and they were substantially more tolerant than their mother cultivar Femminello siracusano.
Differential Effect of Population Density on Shape and Size of Cylindrical Red Beet (Beta vulgaris L.) Genotypes
Authors: Goldman I.L.
Published: January 2019

The effects of population density on shape and size of cylindrical red beet genotypes were evaluated in a field experiment during 1994 and 1995. Two F1 hybrids and two open-pollinated genotypes were planted in replicated trials consisting of three population densities. Yield, harvest weight, percent harvestable beets per plot, length, middle width, top width, bottom width, length × width, length to width ratio, and a shape index (SI) were measured on a sample of beet plants from each plot. The density × genotype interaction was nonsignificant for all 10 traits. Averaged over genotypes, significant differences among densities were found for harvest weight, percent harvestable beets per plot, length, middle width, and length × width. In general, greater harvest weights, a higher percentage of harvestable beets, and greater length, middle width, and length × width values were found at low density. Averaged over densities, significant differences among genotypes were measured for all 10 traits. The open-pollinated genotypes Cyndor and Cylindra exhibited lower yield, lower harvest weight, greater SI, and a higher percentage of harvestable beets than their hybrid counterparts. These data demonstrate that population density has a differential and significant effect on the shape and size of cylindrical beet genotypes.
A Reevaluation of Tree Model, Inflorescence Morphology, and Sex Ratio in Lychee (Litchi Chinensis Sonn.)
Authors: Robbertse Hannes , Fivaz Jaco , Menzel Chris
Published: January 2019

The architecture of the lychee tree and the structure of the inflorescence are described according to the terminology of Hallè et al. and Weberling. The lychee tree has rhythmic modular growth and the inflorescence is a heterocladic pleiothyrsoid. Additional paracladia may develop from a second serial bud below the first-order paracladia. Male and female flowers are borne at variable positions on the dichasia. The relation between the position and gender of the flowers on the partial inflorescences (dichasia) varied with cultivar and time.
Transformation of Plum with the Papaya Ringspot Virus Coat Protein Gene and Reaction of Transgenic Plants to Plum Pox Virus
Authors: Scorza Ralph , Levy Laurene , Damsteegt Vern , Yepes Luz Marcel , Cordts John , Hadidi Ahmed , Slightom Jerry , Gonsalves Dennis
Published: January 2019

Transgenic plum plants expressing the papaya ringspot virus (PRV) coat protein (CP) were produced by Agrobacterium-mediated transformation of hypocotyl slices. Hypocotyl slices were cocultivated with Agrobacterium tumefaciens strain C58/Z707 containing the plasmid pGA482GG/CPPRV-4. This plasmid carries the PRVCP gene construct and chimeric NPTII and GUS genes. Shoots were regenerated on Murashige and Skoog salts, vitamins, 2% sucrose, 2.5 μm indolebutyric acid, 7.5 μm thidiazuron, and appropriate antibiotics for selection. Integration of the foreign genes was verified through kanamycin resistance, GUS assays, polymerase chain reaction (PCR), and Southern blot analyses. Four transgenic clones were identified. Three were vegetatively propagated and graft-inoculated with plum pox virus (PPV)-infected budwood in a quarantine, containment greenhouse. PPV infection was evaluated over a 2- to 4-year period through visual symptoms, enzyme-linked immunosorbent assay, and reverse transcriptase PCR assays. While most plants showed signs of infection and systemic spread of PPV within l-6 months, one plant appeared to delay the spread of virus and the appearance of disease symptoms. Virus spread was limited to basal portions of this plant up to 19 months postinoculation, but, after 32 months symptoms were evident and virus was detected throughout the plant. Our results suggest that heterologous protection with PRVCP, while having the potential to delay PPV symptoms and spread throughout plum plants, may not provide an adequate level of long-term resistance.
Lettuce Response to Composted Broiler Litter as a Potting Substrate Component
Authors: Flynn R.P. , Wood C.W. , Guertal E.A.
Published: January 2019

A glasshouse study was conducted to evaluate the suitability of composted broiler chicken (Gallus gallus) litter as a potting substrate using lettuce (Lactuca sativa L.). Broiler litters containing wood shavings or peanut bulls as bedding materials were composted with either shredded pine bark or peanut hulls. Composted materials were then combined with a commercially available potting substrate. Greatest fresh weight yield was obtained when peanut bull compost was mixed with commercial potting substrate at a ratio of 3:1. Fresh weight was less with pine bark compost than with peanut hull compost. However, there were no differences in lettuce dry weight among composts except for pine bark composted with wood-shaving broiler litter. The pH of this material was below the lettuce tolerance level for mixes at or above 50% compost. There was no evidence of lettuce physiological disorders resulting from excessive nutrient concentration. Most elements analyzed (N, P, K, Ca, Mg, Fe, Mn, Cu, Zn, and Al) were within or slightly above sufficiency ranges for Boston-type leaf lettuce. It appears that composting broiler litter for use as a potting substrate or component would be one suitable alternative to land application in the southern United States. We recommend, however, that the pH of substrates be adjusted to suit desired crop requirements.
Leaf Nutrition and Soil Nutrients Are Affected by Irrigation Frequency and Method for NP-Fertigated `Gala' Apple
Authors: Neilsen G.H. , Parchomchuk P. , Neilsen D. , Berard R. , Hague E.J.
Published: January 2019

`Gala' apple (Malus domestica Borkh) on M.26 rootstock was subjected, in the first five growing seasons, to NP-fertigation and a factorial combination of treatments involving method and frequency of irrigation. Two types of emitters (drip or microjet) were used to apply the same quantity of water at high (daily), intermediate (about weekly) and low (about bi-weekly) irrigation frequencies. Although initial tree vigor and yield were higher for drip-fertigated trees, by the end of the study microjet fertigation produced larger trees of similar yield. These microjet fertigated trees had higher leaf P, K and Cu but lower leaf N, Mg, and Mn than drip-fertigated trees. Soil pH and extractable Mg and K concentrations were higher and extractable-P concentrations lower directly beneath microjet-emitters as a result of the larger fertigated soil volume relative to drip-emitters. High frequency irrigation improved tree growth but had less effect on leaf nutrient concentrations or soil chemical changes than lower frequency irrigation. Leaf N concentration was most affected by irrigation frequency, tending to decrease with daily irrigation.
Response of Forsythia ×intermedia `Spectabilis' to Uniconazole. II. Leaf and Stem Anatomy, Chlorophyll, and Photosynthesis
Authors: Thetford Mack , Warren' Stuart L. , Blazich Frank A. , Thomas Judith F.
Published: January 2019

Uniconazole was applied as a foliar spray at 0, 90, 130, 170, or 210 ppm to rooted stem cuttings of `Spectabilis' forsythia (Forsythia xintermedia Zab.) potted in calcined clay. Uniconazole resulted in higher total leaf chlorophyll (chlorophyll + chlorophyll,) concentration and a decreased ratio of chlorophyll a: b. Stomata1 density of the most recently matured leaves increased linearly with increasing uniconazole concentration 40, 60, and 100 days after treatment (DAT). The number of stomata per leaf (stomata1 index) increased linearly with increasing concentration of uniconazole throughout the initial 100 DAT. Uniconazole suppressed stomata1 length at all sampling dates and the level of suppression increased with increasing concentration of uniconazole from 20 to 100 DAT. Stomata1 width was suppressed by uniconazole at 40 DAT. Leaves developed after uniconazole application had higher levels of net photosynthesis when measured 55, 77, and 365 DAT. Stomata1 conductance for uniconazole-treated plants was higher compared to nontreated control (0 mg·liter-1) plants when measured 49, 55, 77, and 365 DAT. Initiation of secondary xylem for stem tissues of uniconazole-treated plants was suppressed and expansion of xylem vessel length and width was less. Secondary phloem tissues of stems from uniconazole-treated plants contained larger numbers of phloem fibers having smaller cross sectional areas than phloem fibers of controls. Chemical name used: (E)-1-(p-Chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-01 (uniconazole).