bluuebunny/crossref_metadata_2025 huggingface dataset:
Abundance of cab RNA in Expanding Leaves of Peach cv Loring under Non-flowering Conditions
Authors: Bassett Carole L. , Callahan Ann M.
Published: February 2019

Leaf expansion in peach (Prunus persica) cv Loring was monitored by measuring the increase in blade length during the spring and early summer of 1994, a season in which no flowers were observed on the sampled trees. Expansion was correlated with time after vegetative budbreak and with leaf position on growing apical shoots. In preliminary studies, information from these measurements was used to identify the relative maturity of leaves during the growing season in order to define sampling times that would represent “old,” “mature,” and “young” leaves. Leaves in these categories were sampled and pooled on two different dates, and total RNA was isolated from each sample. The RNAs were examined by Northern blot analysis using a 32P-labeled cDNA clone encoding a peach cab (chlorophyll a/b binding protein) gene. Estimates of abundance based on the intensities of RNA bands hybridizing to the probe indicated that RNAs representing the cab gene family were most abundant in “mature” leaves. Further examination of abundance in pooled, individual leaves representing positions 1 through 19 (numbered acropetally) revealed a substantial decline in abundance in leaves from positions 1 through 5, which were already showing signs of senescence. These results are consistent with enhanced expression of the cab gene in the most photosynthetically active leaves.
Apple Shoot and Trunk Growth as Affected by Rootstock
Authors: Rom C.R.
Published: February 2019

Annual shoot and trunk xylem growth increment of `Starkspur Supreme' in the 1984 NC-140 uniform rootstock trial was studied of 10 selected rootstocks representing a range of tree sizes. Shoot growth was measured weekly from budbreak through harvest in each of four seasons. After 11 seasons of growth, whole trees were cut, placed in water containing diffuse fuschin dye for 30 to 60 min during mid-day. After that, a section of trunk (10 to 15 cm long) was excised at 25 cm above the graft union. Trunk xylem thickness and percent of water transport active xylem were measured. Shoot length during the study was related to both the duration and rate of growth; however, growth duration contributed more to variation among stocks. In all stocks, it appears that almost all xylem translocated water and that there was very little “plugged” or active xylem. There were no differences among stocks for the relative percentage of active xylem. Annual xylem increment width varied with stock. The vegetative growth of these trees will be discussed relative to the production efficiency of scions on these stocks.
Rootstock and Scion Interact to Affect Apple Tree Performance: A 5-year Summary of the 1990 NC-140 Trial
Authors: Autio Wesley R.
Published: February 2019

In 1990, a trial was established at 17 locations in the United States and Canada including the scions `Golden Delicious', `Jonagold', `Empire', and `Rome” and the rootstocks M.9 EMLA, B.9, Mark, O.3, and M.26 EMLA. In 1994, trees on M.26 EMLA were the largest and trees on B.9 and those on Mark were the smallest, regardless of scion. Trees on M.9 EMLA were intermediate. `Golden Delicious' and `Empire” trees on O.3 were larger than those on M.9 EMLA. `Jonagold' and `Rome' trees on O.3 were similar in size to those on M.9 EMLA. With all scions, B.9 and Mark resulted in the lowest cumulative yields. With `Jonagold', `Empire', or `Rome' as the scion, O.3, M.26 EMLA, and M.9 EMLA resulted in the greatest and similar yields. With `Golden Delicious' as the scion, however, trees on M.9 EMLA yielded only as much as those on B.9 or Mark. Trees on B.9 and those on Mark were the most yield-efficient, regardless of scion. `Golden Delicious' and `Rome' trees on O.3 were similar to those on B.9 and those on Mark, but `Jonagold' and `Empire' trees on O.3 were less efficient than those on B.9 or on Mark. Overall, M.26 EMLA resulted in the lowest efficiency; however, M.9 EMLA resulted in more efficient trees only with `Empire' as the scion. Participants include: J.L. Anderson (Utah), W.R. Autio (Mass.), J.A. Barden (Va.), G.R. Brown (Ky.), P.A. Domoto (Iowa), D.C. Ferree (Ohio), A. Gaus (Colo.), R.L. Granger (Quebec), R.A. Hayden (Ind.), F. Morrison (Kan.), C.A. Mullins (Tenn.), S.C. Myers (Ga.), R.L. Perry (Mich.), C.R. Rom (Ark.), J.R. Schupp (Maine), and L.D. Tukey (Pa.).
Effects of Temperature, Photoperiod, and Light Quality on Flowering in Several Herbaceous Perennial Species
Authors: Whitman Catherine , Heins Royal , Cameron Arthur , Carlson William
Published: February 2019

The influence of low temperatures on Campanula carpatica `Blue Clips' and Lavandula angustifolia `Munstead' flowering was determined; plants were stored at 5C for several weeks and forced under 9-h photoperiods with a 4-h night interruption (NI). C. carpatica, L. angustifolia, and Asclepias tuberosa were forced under NI at five temperatures (15–27C) and time to flower under each treatment was calculated. Flower number and size were reduced at highest temperatures. The effectiveness of cool-white fluorescent (CWF), high-pressure sodium (HPS), incandescent (I), and metal halide (MH) lights in inducing flowering in C. carpatica and Coreopsis lanceolata `Early Sunrise' was compared. Lighting was delivered as a 7-h daylength extension with PPF ranging from 0.05–2.0 μmol·m–2·s–1. Minimum irradiances above which all C. carpatica flowered were approximately 0.14, 0.12, 0.1, and 0.17 μmol·m–2·s–1, respectively. C. lanceolata under CWF displayed irregular flowering throughout the range of intensities used. Under HPS and MH, minimum irradiances for 100% flowering were 0.37 and 1.0 μmol·m–2·s–1, respectively, with sporadic flowering at lower intensities. Under I light, all C. lanceolata exposed to 0.12 μmol·m–2·s–1 or more flowered.
Water Relations and Growth of Catharanthus roseus `Cooler Peppermint' as Influenced by Moisture Stress Conditioning
Authors: Chapman Brent M. , Barrett James E. , Nell Terril A.
Published: February 2019

Catharanthus roseus `Cooler Peppermint' were grown under four different watering regimes [well-watered (WW), wilt plus 1 day (W+1), wilt plus 3 days (W+3), and wilt plus 1 day during the last 2 weeks only (L W+1)] and two different light levels [1100 and 750 μmol·m–2·s–1]. Stress treatments affected finished plant size and leaf area as well as stomatal conductance, water potential and time to wilt during two dry-down periods imposed at the end of an 8-week production cycle. W+3 plants were 50% smaller with 50% less leaf area compared to WW plants. During the second dry-down period, WW plants in high light wilted in 2 days vs 4 days for the W+3 plants. Similarly, WW plants in low light wilted in 3 days vs 6 days for the W+3 plants. The W+3 plants maintained significantly higher water potentials and greater stomatal conductances than the other treatments throughout both dry-down periods.
Comparison of Genetic Diversity in Core and Whole Germplasm Collections for Phaseolus vulgaris L.
Authors: Nienhuis J. , Skroch P. , Sass M. , Beebe S. , Tohme J. , Pedraza F.
Published: February 2019

The number of Phaseolus vulgaris germplasm accessions numbers more than 30,000. While the large numbers of accessions increase the probability of preserving genetic variability they simultaneously limit the efficient and routine utilization of this resource. From the approximately 4000 P. vulgaris accessions in the C.I.A.T. whole collection that were collected in Mexico, a core collection of 400 accessions was developed based on variation for agronomic performance, ecological adaptation, and seed characteristics. Random samples of 90 accessions each were drawn from the core and whole collections and evaluated for 224 polymorphic RAPD bands. Based on analysis of the RAPD data there were no significant differences in genetic diversity between the two samples. The correlation of marker frequency for the two samples was 0.984 confirming that the two samples represent the same population.
Application of RFLP Analysis for the Assessment of QTLs in Cucumber (Cucumis sativus L.)
Authors: Dijkhuizen A. , Staub J.
Published: February 2019

Cross progeny (F3 and BC) of a Cucumis sativus var. sativus (GY 14) × C. sativus var. hardwickii (PI 183967) mating were used in conjunction with RFLP analysis to identify regions of the genome influencing yield and fruit quality, and to test the consistency of QTLs over environments and generations. QTLs affecting earliness, sex expression (F), fruit yield, and fruit size were identified. The number and map location of these QTLs was consistent over environments (years and plant densities). Differences in number and map location of QTLs were found when F3 and BC families were compared. Some of these differences could be attributed to disparities in population size (102 and 59 for F3 and BC families, respectively), dominance, and the amount of genetic information available (F3 > BC). Two shared chromosomes regions were identified that conditioned days to anthesis, fruit number, and weight. One of these regions coincided with the QTL affecting number of barren nodes, while the other was near the F-locus. Three to five QTLs were found to control fruit length (L), diameter (D), and L/D ratio. Depending on the locus, QTLs affecting fruit size appeared to express themselves with various degrees of dominance according to the direction of dominance observed in either parent.
Imitation of Cold Stress in `Beautiful Arcade' Apple Root using Electrical Impedance Analysis
Authors: Prive Jean-Pierre , Zhang M.I.N.
Published: February 2019

2,3,5-triphenyltetrazolium chloride (TTC) staining and electrical impedance (?) analyses of apple roots (Malus domestica Borkh. `Beautiful Arcade') taken in late March from either the field or from 3C refrigerated storage (cold-stored). LT50 levels using TTC were much lower than those found using electrical impedance. No loss of viability in the roots was detectable using TTC staining until a freeze–thaw stress of –9C whereas? analysis detected changes in cell viability after a freeze–thaw stress of only –3C. With increasing cold stress, two parameters: extracellular electrical resistance (Ro) and time constant?, decreased linearly for cold-stored roots and exponentially for field roots. Impedance analysis also revealed that the values for both extracellular Ro and total tissue electrical resistance (R?) for the field roots were approximately 5 and 8 times lower, respectively, than in the cold-stored roots. It is believed that the smaller Ro and R? values obtained from the field roots were due to natural in-field freeze–thaw cycling prior to the controlled stress tests in the laboratory. Based on the analyses of winter hardiness using the two methods, the impedance technique? provided the physiological information not only about the hardiness level, but also about freeze–thaw history prior to the hardiness assessment.
Freeze Tolerance of `Braeburn' Apple Shoots
Authors: Ketchie D.O. , Kammereck R.
Published: February 2019

Differential thermal analysis (DTA) and tetrazolium triphenyl chloride (TTC) were done on shoots of 4-year-old `Braeburn' apple trees for 3 years. The trees acclimated slowly in autumn. If cold temperatures last long enough in winter, shoots will acclimate as low as –40C. Shoots are sensitive to warm temperatures and deacclimated rapidly. An attempt to run a controlled test on freeze resistance of `Braeburn' did not respond to DTA. Moisture samples indicated trees were freeze dried. Different sets of trees were rehydrated and showed an exotherm pattern. Exotherms could be seen after 3 days at 26C, 14 days at 10C, and 21 days at 4C. Another controlled freeze test was performed on 1-year-old `Braeburn' trees. Trees were acclimated outdoors. An exotherm pattern could be seen upon DTA analysis. After artificial freezing, DTA and TTC tests showed pith killed at –24C, primarily xylem at –28C, and all tissue at –35C. After freezing, trees were placed in a greenhouse and warmed over 2 months. Upon dissection, we found xylem produced before freezing was dead, but a large amount of new xylem was generated. Trees appeared to have normal leaf and shoot growth for about a month, but eventually wilted and died. Dissection of these showed the same results as the first set dissected. New xylem evidently was not enough to carry the growth of the trees.
Influence of Warming Temperatures on Shoot Dehardening of Container-grown Nursery Stock
Authors: Dwyer Jennifer L. , Peterson N. Curtis , Howell G. Stanley
Published: February 2019

Studies were conducted with Physocarpus, Weigela, Hibiscus, Euonymus, Forsythia, Spiraea, Lonicera, and Taxus to evaluate the effects of warming temperatures on shoot dehardening. Container-grown plants were stored pot-in-pot, allowing shoots to receive natural outdoor conditions until early March. Control plants remained at 0C (32F), while treatment plants were placed in a temperature-controlled chamber at 21C (70F) and given up to 8 days of warming. Controlled-temperature freezing was used to evaluate plant hardiness. Hardiness levels of Weigela, Spiraea, and Forsythia rapidly decreased after 1 day of warming and again after the 7th day. Hibiscus gradually decreased in hardiness until the 7th day. The influence of polyhouse storage, in which plants were stored pot-in-pot, on the dehardening of Weigela, Hibiscus, and Euonymus was compared to outdoor storage, where plants were stored pot-in-pot. The warming effects of the polyhouse decreased the cold hardiness of the species studied. Results of the warming effects will be presented.
Involvement of HSP Synthesis and Protease Inhibitors in Heat Shock-induced Cucumber Seedling Chilling Tolerance
Authors: Jennings Paul H. , Fitzpatrick Ann
Published: February 2019

Heat shock induction of chilling tolerance in cucumber seedlings is not blocked by inhibitors of protein synthesis. Treatment of germinating seeds with cycloheximide and actinomycin-D, prior to heat shock and chilling, does not block the heat shock induction of chilling tolerance, while the inhibitors alone promote chilling tolerance of seedling roots. To test whether the heat shock effect might be acting on proteases, two protease inhibitors (bestatin and PMSF) were tested for their ability to induce chilling tolerance. Although PMSF slowed germination, it still provided protection against chilling, but bestatin was much more effective.
Evidence for Genetic Variability in the Speed of Cold Acclimation among Tuber-bearing Wild Potato Species
Authors: Vega-Semorile Sandra E. , Bamberg John B. , Palta Jiwan P.
Published: February 2019

Frost damage to the foliage is a common problem where potatoes are grown, and results in significant reductions in tuber yield. Frost injury also limits the cultivation of high-yielding S. tuberosum cultivars in the mountain regions of Central and South America, where potato is a staple crop. Recent studies have shown that some wild potato species possess a high degree of non-acclimated frost tolerance (growing in normal conditions) as well as high cold acclimation capacity (able to increase frost tolerance upon exposure to cold). Natural frosts affecting potatoes are of two types: a) late spring or early fall frost, where the minimum temperature during the frost episode can be very low; b) frost during the growing season, where the minimum temperature during the frost episode is not as low. It is expected that potato species able to acclimate rapidly would survive better from the latter type of frosts, whereas species having higher acclimation capacity might have a great chance to survive better from the former type of frosts. The objective of this study was to find out if there is genetic variability for the speed of acclimation among different tuber-bearing wild potato species. The species used were: S. acaule, S. commersonii, S. megistacrolobum, S. multidissectum, S. polytrichon, S. sanctae-rosae, and S. toralapanum. Relative freezing tolerance of these species was measured during cold acclimation. Preliminary results suggest that there are differences in the speed of acclimation among these species. We found that these species can be divided into four groups: i) non-acclimators; ii) rapid acclimators, with low to medium acclimation capacity; iii) slow acclimators, with low to medium acclimation capacity; iv) slow acclimators, with high acclimation capacity. We plan to use this information in our breeding program aimed at improving the freezing tolerance of potatoes.
Efficiency of Nitrogen Assimilation in Tomato Seedlings as Affected by Nitrogen Regime and Photoperiod
Authors: Nicola Silvana , Basoccu Luigi , Leoni Salvino
Published: February 2019

Excessive nitrogen can be detrimental to transplant quality when supplied during the period of suboptimal photoperiod conditions. This investigation was made to determine the relationship between nitrogen and photoperiod on the growth rate of the transplants. The growth analysis included the determination of the net assimilation rate (NAR) and the nitrogen productivity (NP). `Camone' tomato (Lycopersicon esculentum Mill.) seedlings were grown in the greenhouse under two photoperiods 8 and 12 h) at a constant light intensity and fertilized with three different N concentrations (8, 15, and 30 mmol·liter–1) applied four times. Longer photoperiods enhanced plant growth by increasing the internode, LAR, SLA, and SWR. Root fresh weight, dry weight, stem dry matter, NAR, and RWR were minimal when 30 mmol·liter–1 N concentration was supplied, while LAR and SLA were at their maximum level. The interaction between N and photoperiod was significant. Increasing N supply during an 8-h photoperiod decreased growth. During a 12-h photoperiod, 15 mmol·liter–1 was the optimum N concentration for fresh growth and 8 mmol·liter–1 for shoot dry growth. The RGR had the lowest value, with 30 mmol·liter–1 N and 8-h photoperiod. PNC was highest when plants received 30 mmol·liter–1 N during an 8-h photoperiod, and when the plants received 15 and 30 mmol·liter–1 N during the 8-h photoperiod. LNC doubled in plants fertilized with 30 mmol·liter–1 N compared to those with 8 mmol·liter–1 when grown under a 12-h photoperiod. The NP was at the maximum in plants fertilized with 8 mmol·liter–1 N at the 12-h photoperiod. The lowest NP values occurred when plants were fertilized with 30 mmol·liter–1 N. When photoperiod is a limiting factor in growing seedlings, N supply must be limited to optimize the efficiency of its utilization by the plant.
Thermotolerance in Lettuce
Authors: Sung Yu , Cantliffe D.J. , Nagata R.T.
Published: February 2019

Lettuce seeds differentially fail to germinate at temperatures above 21C according to genotype. Twenty-one lettuce lines were screened for their ability to germinate at temperatures from 24C to 36C. Four cultivars, `Dark Green Boston', `Valmaine', `Floricos 83', and `PI251245', were selected for this study because of their range of ability to germinate at temperatures above 24C. Seeds of the four cultivars were collected from mother plants grown in growth chambers at 20/10C(day/night temperature), 25/15C, 30/20C and 35/25C. Seeds were germinated on a thermogradient table from 24C to 36C under light (12 h). Seeds from `Floricos 83' produced above 30C had higher germination percentage at 33C and 36C than those produced below 30C temperatures. At 30C germination temperature seeds of `Valmaine' produced above 30C had 98% germination compared to 45% of those produced below 30C. `Dark Green Boston' seeds produced at 35C had higher germination percentage(70%) at 30C than those produced at other temperatures. Seeds collected from the mother plant grown above 30C day temperatures had greater germination than those grown below 30C.
Preventing Thermodormancy in Lettuce Seeds by Fluridone Treatment
Authors: Khan Anwar A
Published: February 2019

Fluridone (FL), a catotenoid biosynthesis inhibitory herbicide, prevented supraoptimal temperatures from inducing thermodormancy in seeds and permitted seedling emergence in several lettuce cultivars. A 48-h dark soak at 35C with 23 μM FL completely prevented the induction of thermodormancy in `Mesa 659' and `Emperor' lettuce seeds as more than 90% of the seeds germinated on transfer to water in darkness at 25C. Abscisic acid (100 μM) applied with FL did not prevent FL from acting. Dormancy was released completely in the naturally dormant `Garnet' and `Grand Rapids' lettuce seeds at 25C in darkness by 1 μM FL. FL applied following thermodormancy induction at 35C in `Mesa 659' lettuce seeds had little effect on releasing the induced dormancy. A 2-h presoak of `Mesa 659' lettuce seeds with 0.47 μM FL followed by washing, drying, and sowing in a peatlite mix at 25C/35C (12 h/12 h), permitted 80% seedling emergence. Higher concentrations resulted in the emergence of albino seedlings. Similar results were obtained with seeds of other lettuce cultivars (`Prizehead', `Emperor', `Ithaca', and `Empress'). A 6-h matriconditioning (MC) (A.A. Khan, Hort. Rev. 13:131–181, 92) of `Mesa 659' lettuce seeds in 7.5 μM FL enhanced the emergence to a greater extent than by MC alone at 25C/35C. The FL procedure in alleviating high-temperature stress in lettuce and other seeds is being tested further.
Molecular Phylogeny and DNA Amplification Fingerprinting of Petunia
Authors: Cerny Teresa A. , Starman Terri W.
Published: February 2019

Seed of five species of petunia and 10 cultivars of Petunia xhybrida were obtained from several sources and plants were fingerprinted using DNA amplification fingerprinting (DAF). Within some species, variable fingerprints were generated between individual plants from the same seed source and/or different sources. Consistencies were found among DAF profiles by bulking the leaf tissue from 10 different plants, but not five plants. Each of 10 octamer primers used during the study revealed polymorphic loci between the species and cultivars. Among the 201 bands produced, 146 (73%) loci were polymorphic and these could be used to distinguish between each of the species and cultivars. Scoring for presence and absence of the amplified bands was used to generate a phylogenetic tree and to calculate the pairwise distances between each of the taxa using parsimony (PAUP) analysis. The tree generated using DAF molecular markers separated P. axillaris from P. parodii (two white-flowered species), and distinguished between the violet-flowered species, P, inflata, P. integrifolia, and P. violacea.
Breeding for Drought Tolerance in New Guinea Impatiens
Authors: Strefeler Mark S. , Quen Robert
Published: February 2019

Six commercial cultivars (Anna, Aurore, Danhill, Danlight, Melanie, and Thelca), one drought-tolerant cultivar (Orangeade), nine breeding selections, and one check genotype of Impatiens hawkeri Bull were evaluated for differences in drought tolerance based on water loss and time to wilt. The six commercially available cultivars had significantly higher mean water loss than the breeding selections and `Orangeade'. These cultivars wilted in 5.11 days vs. 7.33 for `Orangeade' and 9.10 for the breeding selections. These results suggests that sufficient variability exists in New Guinea impatiens germplasm for the reduction of water loss to improve drought tolerance. Regression analysis revealed that total transpirational water loss 96 h after withholding water was an excellent predictor of the time to wilting (a simple measure of drought tolerance) after water was withheld (R2 = 0.95). Thus, a simple, efficient, and objective method for selection of drought-tolerant genotypes has been developed for New Guinea impatiens. A comparison of offspring to parental genotypes showed that, after only one cycle of selection, water loss was significantly reduced by more than 30%. These results suggest that there is sufficient genetic variability present for the development of more drought-tolerant cultivars.
Impact of Mites and Miticides on the Photosynthetic Biology of Strawberry and Red Raspberry Leaves
Authors: Cameron J. Scott , Chen Chuhe , Klauer Stephen F.
Published: February 2019

Limited twospotted spider mite feeding significantly reduced the CO2 assimilation rate of red raspberry leaves and damaged the photosynthetic apparatus prior to visible damage to the leaf. The impact of miticides on the photosynthetic biology of raspberry and strawberry leaves was tested in growth chambers, greenhouses, and the field, with similar results across environments. In general, miticides appear to reduce the photosynthetic capacity of the leaves for 10 to 14 days, with reductions of ≈30% occurring within the first several days. Chlorophyll fluorescence and fourth-derivative spectroscopy of intact leaf lamina showed changes in the structure and function of the photosynthetic apparatus in response to chemical treatment. High temperature reduced physiological processes in strawberry plants grown at two diurnal regimes (30/24C, 21/15C); however, the relative degree of reduction in photosynthetic activity due to miticide application was similar for both. A preliminary screening of mite-resistant and -susceptible red raspberry genotypes after prolonged infestation suggested varying levels of physiological tolerance of mite damage, which are not well-correlated with visual appearance.
Effect of Fruiting on Net CO2 Assimilation Rates of Peach and Nectarine Trees
Authors: Derkacz Maria , Chong Calvin , Proctor John
Published: February 2019

Growth of peach fruits is characterized by a double-sigmoid curve; two periods of rapid enlargement (stages I and III) separated by a lag phase (stage II). Seasonal net CO2 assimilation rates (NAR) were compared in leaves from fruiting and non-fruiting (deblossomed) trees of `Harrow Diamond' (early), and `Vivid' (mid-summer) peach (Prunus persica L. Batsch.) and `Fantasia' (late) nectarine (P. persica) to determine 1) the influence of fruits on photosynthesis and 2) the relationship between NAR and fruit growth. Seasonal trends in NAR tended to be qualitatively similar among the three cultivars, despite genotypic and phenotypic differences. There was a distinct increase in NAR at the time of horticultural fruit maturity (stage III) of each cultivar. Shortly after harvest, NAR rates declined. The average seasonal NAR of fruiting `Harrow Diamond', `Vivid', and `Fantasia' trees was 9%, 11%, and 10% higher, respectively, than that of corresponding non-fruiting trees. Parallel data for total chlorophyll was 28%, 20%, and 19% higher, and specific leaf weight (SLW) was 3%, 5%, and 6% lower, respectively. A negative correlation between NAR and SLW may indicate a feedback inhibition of photosynthesis.
Carbon Partitioning in Primocane-fruiting Red Raspberry as Influenced by Groundcover and Supplementary Irrigation
Authors: Percival David C. , Proctor John T.A. , Sullivan J. Alan
Published: February 2019

Field experiments consisting of trickle irrigation (TI), IRT-76 plastic film (PF), and straw mulch were initiated to determine the influence of soil temperature and water status on carbon partitioning during the establishment of Rubus idaeus L. `Heritage' (1993, 1994), `Autumn Bliss' (1994), and `Summit' (1994) micropropagated raspberries. Environmental, vegetative, reproductive, and nutrition data were collected. Photosynthesis (Pn) measurements were recorded under field conditions using a Li-Cor LI-6200 portable photosynthesis system. Neither node number nor shoot: root ratio was influenced by TI, PF, or straw mulch. PF, however, increased root and shoot weight, total flowers produced, total berries harvested, and foliar N and P. Although differences existed among cultivars, field Pn measurements indicated that, regardless of groundcover treatment or cultivar examined, the maximum Pn rate occurred at a root-zone temperature of 25C. Hence, results from this study indicate that conditions in both the air and root zone physical environment regulate carbon assimilation and partitioning.
Simulating Biotic Stress with Terbacil on Apple
Authors: Flore J. A. , Disegna Edgardo
Published: February 2019

Terbacil an inhibitor of photosynthesis was applied to 10-year-old `Redchief' apple trees in the field carrying a heavy or light fruit crop, or to trees in pots. This simulated the effect of photosynthetic inhibition (PN-I) by either biotic or abiotic stress. Current as well as the next season's crop and physiology were determined. The magnitude and duration of photosynthetic inhibition was dose-dependent. A concentration of 63 mg·liter–1 was applied at 15-day intervals from bloom through harvest. Photosynthesis was in inhibited by 50% to 80% within 24 h of application, but recovered to control levels 10 to 14 days later. Terbacil at 15 and 30 DAFB induced fruit abscission, but not at later dates. The earlier the application the greater the effect on current seasons yield and fruit size. There was also a significant interaction with crop load. There were no significant effects on fruit soluble solids, fruit firmness, fruit density, or fruit color at harvest. Terbacil did not affect cold acclimation, deep winter hardiness, or deacclimation. Pn inhibition at 30, 60, 80, and 100 DAFB reduced return bloom.
Physiological Basis for the Interaction of Mite and Crop Load on `Starkrimson Red Delicious' Apple Trees
Authors: Francisconi Ana H.D. , Lakso Alan N. , Nyrop Jan , Denning Steve
Published: February 2019

Most research on the effects of European red mite (ERM) [Panonychus umli(Koch)] on apples has shown highly variable results. Those variations were probably due to different genotypes, internal status of the tree (e.g., crop load), environment and timing and severity of mite stress. We propose that limitations in carbon availability for fruit growth is the primary mechanism of foliar feeder injury to apple trees. Heavy-cropping tress should be more sensitive to ERM stress than low-cropping trees and differences in responses of apple trees should be better-related to carbon supply/demand than to cumulative mite-days (CMD) along. Eighteen mature `Starkrimson Red Delicious'/M26 trees were hand-thinned to low (≈20 t·ha–1) and high (≈40 t·ha–1) crop loads and submitted to low (<400 CMD), medium (400–1000 CMD), and high (>1000 CMD) target levels of ERM. A range of crop loads and CMDs was obtained. Mite population, fruit growth, single-leaf photosynthesis, and whole-tree gas exchange were monitored through the season. ERM reduced leaf and whole-tree net CO2 exchange (Pn). Heavy-cropping trees showed fruit weight reduction earlier and more severely than low-cropping trees with high ERM injury. The main effect, variations in final fruit weight, was much better related to whole-tree Pn/tree than to CMD.
The Effect of Salinity on Growth and Physiology of `Hass' Avocado on Three Rootstocks
Authors: Mickelbart Michael V. , Arpaia Mary Lu
Published: February 2019

Salinity effects on `Hass' avocado was studied on three rootstocks, `Thomas' (TH), `Toro Canyon' (TC), and `Duke 7' (D7). Four levels of salinity (1.4, 3.0, 4.5, and 6.0 dS·m–1) were applied to 1-year-old trees grown in sand culture for 10 weeks. Increased salinity resulted in decreased trunk cross-sectional area and reduced shoot growth. Specific leaf area and dry weight decreased linearly with increased salinity. TH was significantly more affected than TC of D7. Leaf necrosis was also greatest in TH. Older leaves had the highest percentage of leaf necrosis, while younger leaves of TH exhibited symptoms only in the 6.0 dS·m–1 treatment. TH had the highest Cl leaf levels. TC maintained the lowest Na levels in the scion plant organs, indicating an ability to sequester Na in the rootstock. TC also had the lowest Na:K ratio in leaf tissue, indicating that TC can utilize K as an osmoticum. Predawn xylem potential decreased linearly with increased salinity in all rootstocks. Leaf osmotic potential decreased with increased salinity; however, leaf age moderated the response, indicating an adjustment to the stress. No rootstock differences were observed. Net CO2 assimilation (A) decreased with time only in trees exposed to 4.5 or 6.0 dS·m–1. Reduction in A due to increased salinity was less in younger leaves. No rootstock differences were noted. Chlorophyll per leaf area decreased with increased salinity to the greatest degree in TH.
High-speed Blown Air as a Source of Thigmic Stress: Effect of Physiology and Yield of Red Raspberry
Authors: Kostman Todd A. , Cameron J. Scott , Chen Chuhe , Klauer Stephen F.
Published: February 2019

The effect of mechanical stress from sources such as wind on the physiology of higher plants has been documented in many species. Some of these reported changes, such as decreased photosynthetic activity, are not well-documented and bear closer examination. Mechanical stress has been reported to decrease the productivity of some crop plants. In both field and greenhouse trials, high-speed blown air was used as a thigmic stress for the temporary, nonchemical suppression of primocane growth in red raspberry. Field trials with the cultivar Meeker in 1993–94 have shown that high-speed blown air can be used to adequately control primocane height for mechanical harvest, while increasing yield through greater numbers of fruit per cane. In both field and greenhouse experiments, photosynthetic activity or red raspberry leaves was not affected by 273 km/h of wind applied twice daily, 5 days per week. Anatomical analysis demonstrated changes in the cross-sectional anatomy of mechanically stressed canes. Stressed canes had increased callose deposition and greater numbers of secondary xylem cells.
Influence of Floricane Number on Primocane Growth, Cold Hardiness, and Yield Components in `Marion' (Rubus sp.) Blackberry
Authors: Cortell Jessica M. , Strik Bernadine C.
Published: February 2019

In Spring 1993 and 1994, treatments of 0, 4, 8, and 12 floricanes per plant were established in a mature `Marion' planting. Primocanes were measured weekly for the number and length of primocanes and primocane branches. Maximum hardiness of primocanes was determined in Jan. 1994 and 1995 by controlled freezing. Yield components were measured in both the current and following season. Additional plants were harvested in summer and winter for dry-weight partitioning. Plants with no floricanes had an increased number and length of primocanes and branches than plants with floricanes in 1993, with similar trends in 1994. Primocane growth on plants without floricanes showed a 65% increase in primocane dry weight in 1993. However, in 1994, there were no significant differences among treatments. Primocane branch dry weight generally increased with decreasing floricane number. The relationship between primocane growth and the following season's yield components will be presented.
Effects of “Colormotor” on Anthocyanin Accumulation, Fruit Coloration, and Superficial Scald Susceptibility of `Delicious' Apples
Authors: Ju Zhiguo , Liu Chenglian , Yuan Yongbing , Wang Yongzhan
Published: February 2019

“Colormotor” is a new product formulated mainly from seaweed extracts for promoting anthocyanin synthesis and improving fruit coloration in apples. The product was applied (150 ppm) 3 weeks before harvest in 2 years of experiments with `Delicious' apples. Colormotor treatment promoted anthocyanin accumulation by 2.5-fold and increased color index of fruit by 50% over controls. Only 23.5% of control fruit had full red color when harvested 140 DAFB, whereas 80% of the fruit sprayed with Colormotor had full red color. UDPG-o-3-glucosyltransferaw activity also was significantly greater in treated fruit. Treatment did not affect ethylene synthesis, fruit firmness, soluble solids, total sugars, or titratable acid incidence either at harvest or during prolonged storage. However, scald incidence after 20 weeks at 0C was significantly decreased by Colormotor treatment. The scald scores were 1.59 in control fruit and 0.67 in treated fruit, respectively, on a scale of 1 to 4.
Elevated CO2 and/or Low O2 Atmospheres Influence ACC Synthase and ACC Oxidase during Long-term Storage of `Golden Delicious' Apple Fruit
Authors: Gorny James R. , Kader Adel A.
Published: February 2019

The objective of this study was to compare and contrast the mode of action by which elevated carbon dioxide and/or reduced oxygen atmospheres inhibit ethylene biosynthesis. `Golden Delicious' apple fruit were placed at 0C in one of the following four atmospheres: 1) air; 2) air + 5% CO2; 3) 2% O2 + 98% N2; or 4) 2% O2 + 5% CO2 + 93% N2 and then sampled monthly for 4 months. Ethylene biosynthesis rates and in vitro ACC synthase activities were closely correlated in all treatments. In vitro ACC synthase activity and ethylene biosynthesis rates were lowest in fruit treated with 5% CO2 + 2% O2, while air-treated fruit had the highest ethylene biosynthesis rate and in vitro ACC synthase activity. Fruit treated with air + 5% CO2, or 2% O2 + 98% N2, had intermediate ethylene and in vitro ACC synthase activities. In vitro ACC oxidase was significantly different among treatments, but not as closely correlated with the ethylene biosynthesis rate as in vitro ACC synthase activity. Western blot analysis of the ACC oxidase protein was performed to determine if activity differences among treatments were correlated with the amount of enzyme present in vivo. ACC synthase and ACC oxidase mRNA transcript of abundance was determined via Northern blot analysis. Results will be discussed regarding how ethylene biosynthesis is inhibited at the molecular level by elevated CO2 and/or reduced O2.
Unique and Quick in Vitro Procedure to Detect Grapevine Virus Diseases
Authors: Shlamovitz N. , Spiegel-Roy P. , Tanne E.
Published: February 2019

In many cases the diagnosis of a viral disease in perennial woody plants requires indexing by grafting on indicator plants. In the case of grapevine leafroll and corky-bark diseases, indexing requires 2 to 3 years for symptom recording. Both diseases are found in all grapevine-growing countries. It would therefore be advantageous to develop a sensitive, quick, and reliable diagnostic technique. Explant shoots infected with corky-bark were micrografted onto healthy indicator rootstocks and maintained in vitro. Typical corky-bark symptoms appeared on the indicator within 8 to 12 weeks. Osmotic stress, in vitro, induced by sorbitol, enhanced leafroll symptoms. Explants expressed symptoms after 2 to 3 months of growth on these media. The advantages of these techniques are: Rapid indexing, saving of space and labor, could be performed year-round. Further experiments are underway for adaptation of the micrografting to leafroll disease and the stress method for corky-bark disease.
Progress in the Characterization of Cold-hardy Grapes using Simple Sequence Repeat DNAs (SSRs)
Authors: Lamboy Warren , Alpha Christopher , Szewc-McFadden Amy , Bleik Sharon
Published: February 2019

The cold-hardy Vitis (grape) collection at the USDA/ARS Plant Genetic Resources Unit in Geneva, N.Y., comprises ≈1300 accessions. While much of the collection has been evaluated for morphological and viticultural traits, little of it has been well-characterized genetically. Lack of genetic information hampers the identification of accessions, the determination of genetic relationships among them, the evaluation of potential new accessions, and the construction of a core subset of the collection. Because simple sequence repeat DNA polymorphisms (SSRs or microsatellites) have already been proven to be useful genetic markers in Vitis vinifera (non-cold-hardy wine, raisin, and table grapes), our research focuses on the use of the markers both for the identification (“fingerprinting”) of species, hybrids, subspecies, cultivars (varieties), and accessions of cold-hardy Vitis, and for the determination of genetic relationships between these taxa. Our latest research results in this area will be presented.
Aluminum Uptake and Root Cation Exchange Capacity (CEC) in Mycorrhizal and Non-mycorrhizal Blueberry (Vaccinium carymbosum L.) Plants
Authors: Yang Wei Qiang , Goulart Barbara L.
Published: February 2019

Aluminum (Al) uptake and root cation exchange capacity (CEC) of mycorrhizal (M) and non-mycorrhizal (NM) blueberry plants (Vaccinium corymbosum L.) were studied. Mycorrhizal roots took up more Al than non-mycorrhizal roots over a 48-h period. Different patterns of Al uptake occurred between M and NM roots. The M roots contained more Al at hour 1, followed by a deep decrease at hour 3, and then increased gradually. However, Al uptake in NM roots increased with time. Foliar Al analysis indicated that Al concentration increased with time in both M and NM plants, but a significant increase of foliar Al concentration during the first 3-h period was not observed in M plants. The results suggested that the rate of Al transport and the redistribution of foliar Al were different in M and NM plants. The higher Al concentration in M roots may be due to the higher CEC in M roots and vice versa. Further, the CEC of M roots was decreased by the respiration inhibitor (CN-) treatment while the CEC of NM roots was not, suggesting that CEC in M roots is related to respiration.
Effect of Boron and Calcium on in Vitro and in Vivo Lowbush Blueberry Pollen Germination
Authors: Chen Youzhi , Smagula John M.
Published: February 2019

Ten clones of lowbush blueberry (Vaccinium angustifolium) having low leaf boron (B) concentrations (<20 ppm) were selected to receive fall foliar B (400 ppm), Ca (4000 ppm), B (400 ppm) + Ca (4000 ppm), or water (control). B concentration was raised in stem and bud tissue 3 months after application, but Ca concentration was unaffected. Two randomly selected 5-inch sod plugs from treatment plots within each clone were transported to cold storage at 2.7C for 1000 h to satisfy flower bud dormancy, then to a growth chamber at 24C to blossom. Pollen from plants receiving B had lower in vitro germination rates on 5% agar with 12% lactose after 20 h compared to control and Ca treatments. For in vivo germination, 10 blossoms were randomly selected on sod plugs of each treatment plot to receive 15 control-treatment pollen grains, which were allowed to germinate for 3 days. With the aid of fluorescence microscopy, a higher pollen germination percentage was observed in blossoms of plants receiving B, Ca, and B + Ca. B and Ca may have more influence on the ability of the stigma to stimulate pollen germination than on the germinability of pollen grains themselves.
Influence of Rootstock on Bloomtime Petiole Analyses of Selected Grape Cultivars
Authors: Wolpert J. , Weber E. , Duncan R. , Hirschfelt D. , Anderson M.
Published: February 2019

Petioles were gathered at bloomtime in four trials, one each of `Chardonnay and `Zinfadel' and two of `Cabernet Sauvignon' over 2 years, 1993 and 1994. In each trial, scions were grafted onto 12 to 14 rootstocks. Petioles were analyzed for NO3-nitrogen, NH4-N, K, P, and Mg. NO3-N levels differed among rootstocks by as much as 16-fold (126 to 2064 μg·g–1), NH4-N by as much as 4-fold (253 to 1-28 μg·g–1), K, P, and Mg by about 3-fold (9.7 to 30.6 mg·g–1, 1.8 to 6.3 mg·g–1, and 2.9 to 7.5 mg·g–1, respectively). `Freedom' had the highest levels of NO3-N. `Salt Creek' had moderate levels of NO3-N, but had the highest levels of NH4-N. The rootstock 420A Mgt was consistently low in NO3-N, NH4-N, and K. Freedom was among the highest in K content. The rootstock 44-53 Malègue' had high levels of K and low Mg. Implications for vineyard fertilization programs will be discussed.
Bruising Susceptibility of Green Bell Pepper Fruit Varies with N Level and Planting Time
Authors: Kaaya A.N , Brecht J.K. , Locascio S.J. , Sargent S.A. , Alligood M.
Published: February 2019

Green `Jupiter' bell peppers (Capsicum annuum L.) were grown in the spring and fall seasons of 1994 on polyethylene mulch with drip irrigation. Seedlings were planted on three dates in each season, either 2 weeks (spring) or 1 week (fall) apart, with N applied at rates of 0, 100, 200, or 400 kg·ha–1. Primary fruit were harvested upon reaching full size (diameter) and the bioyield-point (which reflects bruising susceptibility) measured at the fruit shoulder with an Instron machine; pericarp thickness was measured adjacent to the area where bioyield-point was measured. Dry weight of the fruit tissue was measured in the fall only. Bioyield force decreased with increasing N rate and increased with later planting time in the fall, but did not change with N rate and decreased only slightly with planting time in the spring. Pericarp thickness increased with N rate in both spring and fall, but increased with planting time in the spring while decreasing in the fall. Dry matter increased with planting time, but decreased with N rate in the fall peppers. These results indicate that bioyield force is not controlled by pericarp thickness, but rather may be more closely related to cell size or cell wall thickness, as suggested by dry weight differences.
Tomato Locule Cell Wall Polysaccharides: Changes during Maturation and Ripening
Authors: Cheng Guiwen W. , Huber Donald J.
Published: February 2019

Softening and liquefaction of `Solar Set' locules was studied by examining cell wall polysaccharides during fruit developmental stages (FDS) of immature green, mature green and breaker. Ethanol insoluble solids (EIS) were sequentially extracted by H2O, CDTA, and Na2CO3 solutions. The chromatograms of gel filtration among the same-solution extracts of EISs from three FDS were similar. Gradient DEAE also yielded similar patterns among FDS in each extraction solvent, even though the patterns of Na2CO3 extracts differed from those of H2O and CDTA extracts. The mole ratio of total polyuronides decreased for Gal, Ara, and Xyl at later FDS in both EIS and in all extracted polymers. Gal had the highest mole percentage of total neutral sugars, followed by Ara, Xyl, and Rha. While the mole percentage of neutral sugars for Gal, Rha, Ara, and Xyl were relatively similar among FDS in H2O extracts, those in CDTA and Na2CO3 extracts either increased or decreased, depending on individual neutral sugar. SDS-PAGE showed increased density in locule-tissue proteins, especially one with a molecular weight of less than 20 kDa, during later FDS. Results indicate that pectin depolymerization was limited and major neutral sugars commonly composing side chains showed a net decrease.
Instrumental and Sensory Analysis of Tomato Flavor
Authors: Baldwin E.A. , Scott J.W. , Malundo T.M. , Shewfelt R.L.
Published: February 2019

Sugars, acids, and flavor volatiles are components of flavor that have been measured instrumentally, revealing differences among tomato cultigens. For objective measurements to be useful, however, they need to relate to sensory data. In this study, objective and sensory analyses of tomato flavor were compared. Seven tomato cultigens were ranked for sweetness, sourness, and flavor and rated for overall acceptability by a panel of 32 experienced judges. Sucrose equivalents (SE), measured by HPLC, but not soluble solids correlated with sweetness at P = 0.10. In addition, SE highly correlated with flavor (P = 0.03), while titratable acidity (TA) negatively correlated with overall acceptability (P = 0.03). Regression analysis indicated that 2+3-methylbutanol, cis-3-hexenal, and 6-methyl-5-hepten-2-one significantly contributed to flavor at a 5% level of significance. It is apparent from this study that sucrose equivalents are more meaningful than soluble solids for measurement of sweetness, and that certain flavor volatiles play a role in tomato flavor.