bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-temperature Storage of Rooted Chrysanthemum Cuttings: Relationship to Carbohydrate Status of Cultivars
Authors: Rajapakse Nihal C. , Miller William B. , Kelly John W.
Published: January 2019

Low-temperature storage potential of rooted cuttings of garden chrysanthemum [Dendranthema ×grandiflorum (Ramat.) Kitamura] cultivars and its relationship with carbohydrate reserves were evaluated. Storage of chrysanthemum cuttings at -1 and -3 °C resulted in freezing damage. Visual quality of rooted cuttings stored at 0 or 3 °C varied among cultivars. Quality of `Emily' and `Naomi' cuttings was reduced within a week by dark storage at 0 or 3 °C due to leaf necrosis, while `Anna' and `Debonair' cuttings could be held for 4 to 6 weeks without significant quality loss. In `Anna' and `Debonair', low-temperature storage reduced the number of days from planting to anthesis regardless of storage duration. However, flowers of plants grown from stored cuttings were smaller than those of nonstored cuttings. At the beginning of storage, `Emily' and `Naomi' had lower sucrose, glucose, and fructose (soluble sugars) content compared to `Anna' and `Debonair'. Regardless of temperature, leaf soluble sugar was significantly reduced by dark storage for 4 weeks. In stems, sucrose and glucose were reduced while fructose generally increased during low-temperature storage probably due to the breakdown of fructans. Depletion of soluble sugars and a fructan-containing substance during low-temperature dark storage was greater in `Emily' and `Naomi' than in `Anna' and `Debonair'. Low irradiance [about 10 μmol·m-2·s-1 photosynthetically active radiation (PAR) from cool-white fluorescent lamps] in storage greatly improved overall quality and delayed the development of leaf necrosis in `Naomi'. Cuttings stored under light were darker green and had a higher chlorophyll content. Leaf and stem dry weights increased in plants stored under medium and high (25 to 35 μmol·m-2·s-1 PAR) irradiance while no change in dry weight was observed under dark or low light. Results suggest that the low-temperature storage potential of chrysanthemum cultivars varies considerably, and provision of light is beneficial in delaying the development of leaf necrosis and maintaining quality of cultivars with short storage life at low temperatures.
Controlled-atmosphere Suppression of ACC Synthase and ACC Oxidase in `Golden Delicious' Apples during Long-term Cold Storage
Authors: Gorny James R. , Kader Adel A.
Published: January 2019

Preclimacteric `Golden Delicious' apples (Malus domestica Borkh.) were stored at 0 °C in: air; air + 5% CO2; 2% O2 + 98% N2; or 2% O2 + 5% CO2 + 93% N2, and sampled monthly for 4 months to investigate the mechanism(s) by which reduced O2 and/or elevated CO2 atmospheres inhibit C2H4 biosynthesis. Ethylene biosynthesis rates and in vitro ACS activity were closely correlated in all treatments, while in vitro ACO activity significantly increased over time regardless of the treatment. Only a small amount of C2H4 biosynthesis inhibition by lowered O2 and/or elevated CO2 atmospheres could be accounted for by suppressed induction of ACO activity. Western blot analysis demonstrated that apples held for 2 months in lowered O2 and/or elevated CO2 atmospheres had significantly reduced abundance of ACO protein, compared to fruit held in air. Northern blot analysis of ACS and ACO transcript abundance revealed that reduced O2 and/or elevated CO2 atmospheres delay induction and reduce the abundance of both transcripts. Reduced O2 and/or elevated CO2 atmospheres reduce C2H4 biosynthesis by delaying and suppressing expression of ACS at the transcriptional level and by reducing the abundance of active ACO protein. Chemical names used: 1-aminocyclopropane-1-carboxylic acid (ACC), ACC synthase (ACS), ACC oxidase (ACO), ethylene (C2H4), S-adenosylmethionine (AdoMet).
Susceptibility of Common and Tepary Beans to Agrobacterium spp. Strains and Improvement of Agrobacterium-mediated Transformation Using Microprojectile Bombardment
Authors: Brasileiro Ana Cristina M. , Aragão Francisco J. Lima , Rossi Sílvia , Dusi Diva Maria A. , Barros Leila M. Gomes , Rech Elíbio L.
Published: January 2019

To develop an efficient protocol for Agrobacterium-mediated transformation of common bean (Phaseolus vulgaris L.) and tepary bean (P. acutifolius A. Gray), we have tested the susceptibility of six genotypes to eight Agrobacterium tumefaciens and two A. rhizogenes strains. The virulence of the Agrobacterium strains was shown to be genotype dependent. In general, the tumors observed on common bean cultivars were larger than those observed on tepary bean cultivars. The A. tumefaciens AT8196 and Ach5 strains and the A. rhizogenes 8196 strain induced the best responses in all genotypes tested. Polymerase chain reaction (PCR) analysis confirmed the presence of T-DNA in tumors derived from inoculation with three A. tumefaciens strains in common beans. Apical meristems of P. vulgaris cv. Jalo were bombarded with tungsten microprojectiles and then inoculated with an A. tumefaciens wild-type strain (Ach5). One month later, the explants showed a high frequency of tumor formation (50% to 70%). Similarly, when bombarded meristems were inoculated with an A. tumefaciens disarmed strain (LBA4404/p35SGUSINT), 44% of them showed substantial sectors of GUS activity, suggesting the expression of introduced gene. The bombardment/Agrobacterium system appears to be a promising method to stably transform bean through the regeneration of plants directly from transformed apical meristems.
Nutrient Uptake Response of New Guinea Impatiens to Light, Temperature, and Nutrient Solution Concentration
Authors: Mankin Kyle R. , Fynn R. Peter
Published: January 2019

Nutrient uptake by New Guinea impatiens (Impatiens X hb.) `Equinox' was measured in a growth chamber under various combinations of light [photosynthetic photon flux (PPF)], air temperature, and nutrient solution concentration. Nitrate-N, P, K, Ca, and Mg ions were evaluated individually by measuring depletion of each nutrient from a constant-volume solution over 9 hours with constant environmental conditions. Individual nutrient uptake was not correlated to concurrent daily temperature environment, and only K and Mg showed a correlation with PPF. Uptake rates of N, P, K, Ca, and Mg increased significantly with increasing nutrient solution concentration. Estimated net assimilation rates of nutrients, based on measured shoot tissue concentrations of each nutrient and assuming that uptake occurred continuously at a rate proportional to canopy area, were correlated to average measured uptake rates for N, Ca, and Mg and were not correlated to average uptake rates for P and K. Although nutrient demand from plant growth may determine rates of nutrient uptake necessary over longer periods of time, short-term uptake was not related directly to daily fluctuations in environmental factors.
Effects of Short-term Water Stress, Hydrophilic Polymer Amendment, and Antitranspirant on Stomatal Status, Transpiration, Water loss, and Growth in `Better Boy' Tomato Plants
Authors: Gu Sanliang , Fuchigami Leslie H. , Guak Sung H. , Shin Charles
Published: January 2019

Seedling plugs of `Better Boy' tomato plants (Lycopersicon esculentum Mill.) were potted in 60% processed fiber: 40% perlite (by volume) media amended or nonamended with either crystalline or powdered hydrophilic polymer (2.4 kg·m-3), and treated with one of several concentrations (0%, 2.5%, 5%, 7.5%, and 10%) of antitranspirant GLK-8924, at the four true-leaf stage. Plants were either well-irrigated or subjected to short-term water stress, withholding water for 3 days, after antitranspirant GLK-8924 application. Leaf stomatal conductance, transpiration rate, whole-plant transpirational water loss, and growth were depressed by short-term water stress and antitranspirant GLK-8924. In contrast, hydrophilic polymer amendment increased plant growth, resulting in higher transpirational water loss. The depression of stomatal conductance and transpiration rate by short-term water stress was reversed completely in 2 days after rewatering while the reduction of plant growth rate diminished immediately. The effects of antitranspirant GLK-8924 were nearly proportional to its concentration and lasted 8 days on stomatal conductance and transpiration rate, 4 days on plant growth rate, and throughout the experimental period on plant height and transpirational water loss. Plant growth was reduced by antitranspirant GLK-8924 possibly by closing leaf stomata. In contrast, hydrophilic polymer amendment resulted in larger plants by factors other than influences attributed to stomatal status. Hydrophilic polymer amendment did not interact with antitranspirant GLK-8924 on all variables measured. The application of antitranspirant GLK-8924 was demonstrated to be useful for regulating plant water status, plant growth, and protecting plants from short-term water stress.
Whole-plant Net CO2 Exchange of Raspberry as Influenced by Air and Root-zone Temperature, CO2 Concentration, Irradiation, and Humidity
Authors: Percival David C. , Proctor J.T.A. , Tsujita M.J.
Published: January 2019

The influence of irradiance, CO2, and temperature on whole-plant net CO2 exchange rate (NCER) of Rubus idaeus L. `Heritage' micropropagated raspberries was examined. Within the set of environmental conditions examined, irradiation was the most important factor, accounting for 58% of the whole-plant irradiance/CO2 concentration/temperature NCER model variation, followed by CO2 concentration (28%) and temperature (2.5%). Net photosynthesis (Pn) required irradiance levels >600 μmol·m-2·s-1 PPF for saturation, greatly increased under CO2 enrichment (up to 1500 μL·L-1), and was optimum at a whole-plant temperature of 20 °C. Temperature effects were partitioned in an experiment using varying air and root-zone temperatures (15, 20, 25, 30, and 35 °C) under saturated light and ambient CO2 levels (350 μL·L-1). Air and root-zone temperature influenced Pn, with maximum rates occurring at an air × root-zone temperature of 17/25 °C. The contribution of air and root-zone temperature to the NCER model varied, with air and root-zone temperature contributing 75% and 24%, respectively, to the total model variation (R2 = 0.96). Shoot dark respiration increased with air and root-zone temperature, and root respiration rates depended on air and root-zone temperature and shoot assimilation rate. Humidity also influenced Pn with a saturated vapor pressure deficit threshold >0.25 kPa resulting in a Pn decrease. Quantifying the physiological response of raspberries to these environmental parameters provides further support to recent findings that cool shoot/warm root conditions are optimum for raspberry plant growth.
Modeling the Stem Elongation Response of Poinsettia to Chlormequat
Authors: Fisher P.R. , Heins R.D. , Lieth J.H.
Published: January 2019

Stem elongation response to a single foliar application of the growth retardant chlormequat chloride [(2-chloroethyl) trimethylammonium chloride] for poinsettia (Euphorbia pulcherrima Klotz.) was quantified. Growth retardant applications did not affect final leaf count or timing of visible bud, first bract color, or anthesis. There was a statistically significant effect of growth retardant concentration on stem elongation, with a range from 289 ± 15 mm (mean 95% confidence intervals) for the control plants to 236 ± 17 mm at 4000 ppm. The growth-retarding effect during the first day after the application was not significantly different between 500 and 4000 ppm, and concentration primarily affected the duration of growth-retarding activity. A dose response function was incorporated into a three-phase mathematical function of stem elongation of single-stem poinsettia to predict elongation of treated and untreated plants. The model was calibrated using a data set from plants receiving 0, 500, 1000, 1500, 2000, 3000, and 4000 ppm, with a resulting R2 of 0.99. Validation of the dose response model against an independent data set resulted in an r2 of 0.99, and predicted final stem length was within 12 mm of observed final length.
Vegetative Growth and Nitrogen/Carbon Partitioning in Blueberry as Influenced by Nitrogen Fertilization
Authors: Merhaut Donald J. , Darnell Rebecca L.
Published: January 2019

Nitrogen uptake and N and C partitioning were evaluated in `Sharpblue' southern highbush blueberries fertilized with different N forms. Plants were grown in acid-washed silica sand and fertilized with a modified Hoagland's solution supplemented with 5.0 mm N as NH4+ or NO3-. Nutrient solution pH was adjusted to 3.0 and 6.5 for the NO3- and NH4+-treated plants, respectively. After 12 months of growth, plants were dual labeled with 14CO2 and 10% enriched 15N-N as either NaNO3 or (NH4)2SO4 and harvested 12 hours after labeling. Fertilization with NO3--N increased leaf, stem, and root dry weights compared to NH4+ fertilization. Total 15N uptake did not differ between N fertilization treatments, thus whole plant and root 15N concentrations were greater in NH4+-fertilized vs. NO3--fertilized plants. Fertilization with NO3--N increased C partitioning to new shoots compared to NH4+-fertilized plants. However, C partitioning to other plant parts was not affected by N form. Although NO3- uptake in blueberry appears to be restricted relative to NH4+ uptake, this limitation does not inhibit vegetative growth. Additionally, there appears to be adequate available carbohydrate to support concurrent vegetative growth and N assimilation, regardless of N form.
Ethylene Does Not Promote Adventitious Root Initiation on Apple Microcuttings
Authors: Harbage James F. , Stimart Dennis P.
Published: January 2019

We investigated the role of ethylene on adventitious rooting of `Gala' (easy-to-root) and `Triple Red Delicious' (difficult-to-root) apple (Malus domestica Borkh.) microcuttings. Root count increased significantly as IBA level increased, with highest root counts on `Gala'. Ethylene evolution increased significantly with IBA level without significant differences between cultivars. Basal section removal of microcuttings in the area of root origin reduced root count without changing ethylene evolution. Ethylene treatment of proliferated shoots before microcutting excision failed to enhance rooting. IBA-induced ethylene evolution was eliminated nearly by AVG, but root count remained IBA dependent. ACC reversed IBA plus AVG rooting inhibition, but ACC alone failed to influence root count. Polar auxin transport inhibitors NPA and TIBA stimulated ethylene evolution without increasing root count. Adventitious rooting of apple microcuttings was not associated with ethylene. Chemical names used: 1-H-indole-3-butyric acid (IBA); aminoethoxyvinylglycine (AVG); 1-aminocyclopropane-1-carboxylic acid (ACC); 2,3,5-triiodobenzoic acid (TIBA); N-1-naphthylphthalamic acid (NPA).
Axillary Bud Development of Poinsettia `Eckespoint Lilo' and `Eckespoint Red Sails' (Euphorbia pulcherrima Willd.) Is Inhibited by High Temperatures
Authors: Faust James E. , Heins Royal D.
Published: January 2019

The effect of temperature on axillary bud and lateral shoot development of poinsettia (Euphorbia pulcherrima Willd.) `Eckespoint Lilo' and `Eckespoint Red Sails' was examined. Rooted `Eckespoint Lilo' cuttings were transplanted and placed into growth chambers maintained at 21, 24, 27, or 30 °C for 2 weeks before apex removal. The percentage of nodes developing lateral shoots after apex removal was 68%, 69%, 73%, or 76% at 21, 24, 27, or 30 °C, respectively. Cuttings were removed from the lateral shoots, rooted, and placed into a 21 °C greenhouse, and the apices were removed. The percentage of nodes developing into lateral shoots on cuttings taken from plants held at 21, 24, 27, and 30 °C were 74%, 65%, 66%, and 21%, respectively. Of the cuttings in the 30 °C treatment, 83% of the nodes not producing a lateral shoot had poorly developed axillary buds or no visible axillary bud development. Visual rating of axillary bud viability decreased from 100% to 0% when `Eckespoint Red Sails' plants were transferred from a 21 °C greenhouse to a greenhouse maintained at 27 °C night temperature and 30 °C for 3 hours followed by 33 °C for 10 hours and 30 °C for 3 hours during the 16-hour day. Transfer from the high-temperature greenhouse to a 21 °C greenhouse increased axillary bud viability from 0% to 95%. Axillary buds of leaves not yet unfolded were sensitive to high temperatures, whereas those of unfolded leaves (i.e., fully developed correlatively inhibited buds) were not. Sixteen consecutive days in the high-temperature treatment were required for axillary bud development of `Eckespoint Red Sails' to be inhibited.
Penetrometer Measurement of Apple and Kiwifruit Firmness: Operator and Instrument Differences
Authors: Harker F.R. , Maindonald J.H. , Jackson P.J.
Published: January 2019

Flesh firmness is a characteristic used to indicate fruit quality. Experimental design and data analysis are important when comparing devices that measure fruit firmness. We compared the Effegi penetrometer operated by hand, mounted in a drill press and then operated by hand, and mounted on a motorized drive and operated remotely; the hand-operated EPT pressure tester; the Instron with an Effegi probe; and a hand-operated prototype of the twist tester. Devices varied in operator differences and precision. Comparisons between devices were at the within-fruit level of variability and, therefore, more precise than comparisons where different device-operators used different fruit. We demonstrate statistical methods that are appropriate for making the comparisons of interest and discuss the possible cause of differences between operators and between devices. We also discuss how the mechanical properties of the devices may affect results and consider implications for their practical use. In this study, we found the precision of discrimination between soft and hard apples was best using the Instron in 1992, while the Instron and hand-held Effegi penetrometer were comparable in 1991. For kiwifruit, the hand-held Effegi penetrometer consistently gave the most precise measurements of softening in 1991, while the twist test was the most precise in 1992.
Interactions of European Red Mite and Crop Load on Maturity and Quality, Mineral Concentrations, and Economic Value of `Starkrimson Delicious' Apples
Authors: Francesconi A.H.D. , Watkins C.B. , Lakso A.N. , Nyrop J.P. , Barnard J. , Denning S.S.
Published: January 2019

Fruit maturity, quality, calcium concentration and economic value of `Starkrimson Delicious' (Malus domestica Borkh.) apples, under a range of crop levels and European red mite [Panonychus ulmi (Koch)] cumulative mite-days (CMD), were best explained by local surface regression models involving CMD and crop load. Fruit from trees with low CMD and a light crop (125 fruit/tree, about 20 t/ha) were the most mature at harvest. Those fruit had higher ethylene concentrations, starch pattern indices, soluble solids concentrations, and watercore incidence at harvest than fruit from trees with low CMD and a normal crop (300 fruit/tree, about 40 t/ha), or with high CMD at any crop level. Those fruit also had higher incidences of watercore and internal breakdown after 4 months of cold storage. Calcium concentrations in fruit increased as crop load and CMD increased. Whole-canopy net CO2 exchange rate per fruit related better to fruit quality and calcium concentrations than either crop load or CMD alone, but was always a much worse predictor than local surface regressions. Low CMD and normally cropped trees had the highest crop value; lightly cropped trees had an intermediate crop value; while high CMD and normally cropped trees had the lowest crop economic value. Crop load should be considered when defining action thresholds for mites, and harvest schedules for apples should reflect crop load and mite populations on apple trees.
The Inheritance of Resistance to the Southern Root-knot Nematode in `Carolina Hot' Cayenne Pepper
Authors: Fery Richard L. , Dukes Philip D.
Published: January 2019

Greenhouse experiments were conducted to determine the inheritance of the high level of southern root-knot nematode [Meloidogyne incognita (Kofoid & White) Chitwood] resistance exhibited by `Carolina Hot' cayenne pepper (Capsicum annuum L.) and to compare the genetic nature of this resistance to that exhibited by `Mississippi Nemaheart.' Evaluation of parental, F1, F2, and backcross generations of the cross `Mississippi Nemaheart' × `California Wonder' confirmed an earlier published report that the `Mississippi Nemaheart' resistance is conditioned by a single dominant gene. Evaluation of parental, F1, F2, and backcross generations of a cross between highly resistant and highly susceptible lines selected from a heterogeneous `Carolina Hot' population indicated that the resistance exhibited by `Carolina Hot' is conditioned by two genes, one dominant and one recessive. Evaluation of the parental and F2 populations of a cross between `Mississippi Nemaheart' and the highly resistant `Carolina Hot' line indicated that the dominant resistance gene in `Mississippi Nemaheart' is allelic to the dominant resistance gene in `Carolina Hot.' Comparison of the data that were collected on the parental lines in the latter cross demonstrated the superior nature of the resistance exhibited by `Carolina Hot.' The presence of the second resistance gene in `Carolina Hot' probably accounted for the higher level of resistance. The ease and reliability of evaluating plants for resistance to root-knot nematodes and the availability of a simply inherited source of resistance makes breeding for southern root-knot nematode resistance a viable objective in pepper breeding programs. This objective should be readily obtainable by the application of conventional plant breeding methodologies.
The Margo (mar) Seedcoat Color Gene Is a Synonym for the Joker (j) Locus in Common Bean
Authors: Bassett Mark J.
Published: January 2019

The inheritance of hilum ring color in common bean (Phaseolus vulgaris L.) was investigated using various genetic tester stocks developed by backcrossing recessive alleles into a recurrent parent stock 5-593 with seedcoat genotype P [C r] D J G B V Rk, viz., mar BC2 5-593, mar BC3 5-593, mar v BC2 5-593, mar d BC2 5-593, and mar d BC3 5-593. The current hypothesis is that the margo character is controlled by mar and hilum ring color is controlled by d but expresses only with mar. The V locus controls flower and seedcoat color. The allelism test crosses `Citroen' (P C d j g b vlae) × mar BC3 5-593 and `Citroen' × mar d BC3 5-593 demonstrated that mar is allelic with j and that the putative d in mar d BC3 5-593 is allelic with the d in `Citroen'. Thus, the former genetic tester stocks mar BC3 5-593 and mar d BC3 5-593 are reclassified as j BC3 5-593 and d j BC3 5-593, respectively, because mar is a synonym for j. Similarly, the former genetic tester stock mar v BC2 5-593 is reclassified as j v BC2 5-593. The interaction of j with d expresses as loss of color in the hilum ring. The development of the white-seeded genetic tester stock P cu d j BC3 5-593 was described in detail, where the all-recessive tester `Prakken 75' was used as the source of the recessive alleles. The previously reported work showing that the partly colored seedcoat gene t interacts with mar to control seedcoat pattern is now interpreted to mean that the joker (J) locus interacts with t to produce partly colored seedcoat patterns. The genetic loci D and V were found to segregate independently. The common gene for dull seedcoats (asper, asp) is discussed and contrasted with j.
Inheritance of the Partly Colored Seedcoat Pattern, Bipunctata, in Common Bean
Authors: Bassett Mark J.
Published: January 2019

The development of genetic tester stocks in common bean (Phaseolus vulgaris L.) for the partly colored seedcoat patterns `bipunctata BC3 5-593' (t z bip) and `virgarcus BC3 5-593' (t z) was described. The inheritance of the bipunctata pattern was studied in the F2 from the crosses `bipunctata BC1 5-593' × 5-593 and `bipunctata BC2 5-593' × 5-593. The data supported the hypothesis that a single recessive gene (bip) converts virgarcus (t z Bip) to bipunctata (t z bip). The inheritance of bipunctata was also studied in the F2 from the cross `bipunctata BC3 5-593' × `virgarcus BC3 5-593'. The data supported the hypothesis of complete dominance of Bip over bip in a t z genetic background highly related to the recurrent parent 5-593, where only the parental phenotypes appear in the F2.
Growth, Productivity, and Mineral Composition of Hydroponically Cultivated Greenhouse Tomatoes, with or without Nutrient Solution Recycling
Authors: Zekki H. , Gauthier L. , Gosselin A.
Published: January 2019

Tomato plants (Lycopersicon esculentum Mill. cv. Capello) were grown in the three most promising and used hydroponic cultivation systems using rockwool and peatmoss substrates and nutrient film technique (NFT), either with or without recovery and recycling of the drainage solutions. Prolonged recycling of nutrient solutions in NFT caused a reduction in fresh weight, dry weight, and yield compared to plants grown in NFT with regular renewal of the nutrient solution. There were no differences in growth, productivity, and leaf mineral composition between plants grown in rockwool and peatmoss systems, with or without recycling, and in the NFT system without recycling. These results suggest that recycling drainage solutions is an economically and environmentally sound horticultural practice that when used correctly does not cause a reduction in yield of tomatoes cultivated in rockwool or peatmoss. However, prolonged use of the same solution in the NFT cultivation system can negatively affect growth and yield. This is most likely due to an accumulation of sulfate ions in the fertigation solutions.
The Effect of Nitrogen Fertilizer Rates and Timing on Cranberry Yield and Fruit Quality
Authors: Davenport Joan R.
Published: January 2019

To examine the impact of N fertilizer rates and timing on cranberry (Vaccinium macrocarpon Ait.) yield and the fruit quality factors total anthocyanin, average berry weight, and field and storage rot, plots were established for 3 to 4 years. The cranberries received a total of 0, 22, or 44 kg N/ha over the growing season applied in three, four, or five applications, which varied by growth stage. There were eleven possible treatment combinations in Massachusetts on `Early Black' and `Howes' and in Wisconsin on `Stevens' and `Searles', and seven possible treatments in New Jersey on `Early Black' and in Washington on `McFarlin'. The results showed a nationwide response to N that suggests the experimental middle rate of 22 kg·ha-1 would result in high yields with moderate rot. However, the best timing for applying the fertilizer varied by both state and cultivar, where three late season applications were best on `Early Black' in New Jersey versus four early season applications on the same cultivar in Massachusetts, and applying N fertilizers across five applications was optimal for `Stevens' in Wisconsin.
Use of 1H-NMR to Determine Grape Bud Water State during the Photoperiodic Induction of Dormancy
Authors: Fennell Anne , Wake Carol , Molitor Paul
Published: January 2019

Nuclear magnetic resonance longitudinal (T1) and transverse (T2) times were used to monitor changes in bud water state during the photoperiodic induction of dormancy in grape (Vitis riparia Michx.). Short day (SD) treatments were used to promote a rapid onset of bud dormancy, and long day (LD) treatments were used to prevent the onset of dormancy. Water content (WC) and the state of bud water were monitored after 2, 4, and 6 weeks of LD or SD treatment in three bud developmental stages. There was no difference in WC in the SD and LD treatments after 2 weeks. WC decreased in LD and SD buds of all stages during the 6 weeks of treatments, but there was a greater decrease in WC in SD treatments. The state of bud water changed during the SD treatments, shown in changes in T1 and T2 relaxation times. The SD T1 relaxation times were shorter than the LD T1 values at all measurement times. The SD T2 times were shorter than the LD T2 values in the 4- and 6-week treatment only. Tissue age was an element in lowering the T1 and T2 times but not the primary factor. A comparison between the bud dormancy response in the SD and LD treatments and the relaxation times showed that the shorter relaxation times indicate a restriction of motional freedom. The short relaxation times of the SD treatment correlated with the onset of dormancy. When dormancy is fully induced, T2 times correlated better with dormancy than T1 times.
Absorption and Assimilation of Foliarly Applied Urea in Tomato
Authors: Nicoulaud Bernard A. L. , Bloom Arnold J.
Published: January 2019

In short-term experiments (10 days), urea applied foliarly as the sole N source promoted growth of `T-5' tomato (Lycopersicon esculentum Mill.) seedlings. The optimum urea concentration in the spray solution was 0.2% (w/w), and the best application frequency was once a day. Higher urea concentrations suppressed growth, producing severe leaf damage. The growth observed with foliar urea was less than that observed when inorganic N was supplied to the nutrient solution. Tomato seedlings absorbed 75% of the foliar applied urea within 12 hours and 99% within 24 hours after application. Urea concentrations in the plant tissues increased rapidly after foliar application. The maximum concentration was obtained in shoots at 12 hours and in roots at 24 hours after application. After that, concentration in the tissue declined to its original value within 48 hours. Tissue ammonium concentrations also increased after foliar application of urea. Shoot and root ammonium concentrations reached a maximum after 12 hours and stayed constant for the remainder of the 48-hour observation period. In the long-term experiment (5 weeks), the growth obtained with daily foliar applications of urea as the sole N source was only 10% of that when mineral N was available in the nutrient solution. Ammonium concentrations in the tissues of urea-treated plants were higher than those of plants treated with mineral N in the nutrient solution. Although urea concentrations were initially higher in plants treated with mineral N, after 2 weeks urea concentrations declined in these plants and increased in the shoots of plants receiving foliar applications of urea. These results indicate 1) that urea applied foliarly can supply at least part of the N required to sustain growth; 2) that urea is absorbed and assimilated fast enough to alleviate N deprivation; and 3) that failure to promote rapid growth with foliar urea is probably due to phytotoxicity and not to N deprivation.
Carbohydrate Contribution to Fruit Development in Two Phenologically Distinct Rabbiteye Blueberry Cultivars
Authors: Darnell Rebecca L. , Birkhold Keith B.
Published: January 2019

Rabbiteye blueberry (Vaccinium ashei Reade) cultivars differ in timing of floral and vegetative budbreak and in final fruit size. For example, `Bonita' exhibits concomitant floral and vegetative budbreak and has relatively large fruit size, while floral budbreak precedes vegetative budbreak in `Climax' and fruit size is smaller. Mobilization of carbohydrate before and during fruit development in `Bonita' and `Climax' rabbiteye blueberries was examined to determine if differences in carbohydrate availability between these two cultivars were correlated with differences in fruit size. Root dry mass (DM) of both cultivars decreased from dormancy (31 days before anthesis) through fruit development. Sugar concentrations in roots and stems of both cultivars decreased significantly between dormancy and anthesis, then remained relatively steady throughout fruit development. Starch concentrations in roots and stems of `Bonita' decreased significantly between dormancy and anthesis. The extent of total starch depletion in `Climax' was similar; however, the decrease was more gradual, extending from dormancy to 28 days after anthesis (DAA); at which time, vegetative budbreak in `Climax' occurred. Thus, although total reserve carbohydrate pool sizes were similar between the two cultivars, remobilization patterns were different, resulting in increased starch mobilization in `Bonita' compared to `Climax' in the period leading up to anthesis. Concentration of 14C from reserve carbon sources was similar in flowers of both cultivars at anthesis. These values declined throughout fruit development as a result of dilution of the labeled carbon by unlabeled carbon from current photosynthesis. There was a sharper decline in 14C concentration of `Bonita' fruit compared to `Climax' fruit between anthesis and 51 DAA. This, coupled with differences in timing of vegetative budbreak between the two cultivars, suggests that `Bonita' fruit were accessing current (unlabeled) assimilate earlier (i.e., before 51 DAA) than `Climax' fruit. Smaller fruit size in `Climax' compared to `Bonita' may be a consequence of a decrease in reserve carbohydrate mobilization to `Climax' flower buds before anthesis relative to `Bonita', as well as a delay or reduction in the availability of current carbohydrates to developing `Climax' fruit between anthesis and 51 DAA.
Sugar Composition of Pectin and Hemicellulose Extracts of Peach Fruit during Softening over Two Harvest Seasons
Authors: Hegde Supreetha , Maness Niels O.
Published: January 2019

Changes in cell wall polysaccharides associated with peach fruit softening were characterized over two harvest seasons. Enzymically inactive cell walls were prepared from mesocarp tissues of peach fruit harvested at three stages of softening. Pectin-associated and hemicellulose-associated polysaccharides were extracted from the cell walls sequentially, and glycosyl residue compositions were determined by GLC. Pectin extracts from both years were richest in galacturonosyl, arabinosyl, and rhamnosyl residues. Hemicellulose extracted with 1 m potassium hydroxide contained a high mole percentage of xylosyl, glucosyl, and fucosyl residues. Hemicellulose extracted with 4 m potassium hydroxide contained a substantial amount of pectin-associated sugar residues in addition to hemicellulose-associated sugar residues. During softening in both years, sugar compositions for cell walls, aqueous phenol-soluble polysaccharides, and imidazole extracts reflected a decrease in galacturonosyl residues and a concomitant increase in arabinosyl residues on a mole percent basis. The degree of change for galacturonosyl residues in these fractions depended on season, with greater variation exhibited from fruit at earlier stages of softening. With the notable exception of the seasonal variation exhibited for galacturonosyl residues in cell walls, the relative stability of other glycosyl compositional changes over seasons indicates conserved changes for pectins and hemicelluloses occur during peach fruit softening.
Fertilizer Diffusion in Container Medium
Authors: Kelly Shaun F. , Green James L. , Selker John S.
Published: January 2019

The process of fertilizer diffusion was examined using KBr and NaBr salts placed at the top of columns filled with a container medium at an initial water content of 4.0, 2.5, or 1.0 g·g-1 (mass of water/mass of medium). Columns were sealed to create a protected diffusion zone (PDZ) shielding the system from water infiltration and evaporation. Bromide and water distributions were determined after 5, 10, 25, and 120 days. Using a Fickian diffusion model, effective diffusion coefficients calculated for Br- in the medium at 2.5 g·g-1 ranged from 2.7 to 4.6 × 10-6 cm2·s-1, which is 3 to 9 times less than the diffusion coefficient in water alone. Diffusion rates increased with increasing medium water content. Differences in the hygroscopicity and solubility of KBr and NaBr affected the distribution of water and diffusion rates in the columns. Redistribution of water was driven to a significant degree by vapor-phase transport, caused by large gradients in osmotic potential, and was most apparent at low water content. At high water content, water redistribution was affected by solution density gradients in the system. This significantly complicates the mathematical modeling of the system, which renders a simple Fickian diffusion model of limited predictive value in high and low water content media.
Drought Response of Young Apple Trees on Three Rootstocks: Growth and Development
Authors: Fernandez R. Thomas , Perry Ronald L. , Flore James A.
Published: January 2019

`Imperial Gala' apple (Malus domestica Borkh.) trees, trained to two shoots, on M.9 EMLA, MM.111, and Mark rootstocks were subjected to two drought-stress and recovery periods in a rainshelter. Leaf growth rate, leaf area, leaf emergence, shoot length, and trunk cross-sectional area were measured during each stress and recovery period. Leaf growth rate was reduced during both stress periods but most consistently during the second drought stress. Length of the less-vigorous shoot was reduced most consistently due to drought stress but did not recover upon irrigation. Leaf emergence and trunk cross-sectional area increment were inconsistent in response to stress. Tree growth was reduced by drought stress to the greatest extent for trees on Mark, with MM.111 intermediate and M.9 EMLA least affected. At termination, the plants were separated into roots, current-season shoot growth, previous-season shoot growth, and rootstock, and dry weights were measured. Dry weights confirmed the growth measurements taken during the experiment with a 16%, 27%, and 34% reduction in total plant dry weight for drought-stressed trees on M.9 EMLA, MM.111, and Mark, respectively, compared to corresponding controls. It was concluded that Mark was the most sensitive of the three rootstocks followed by MM.111; M.9 EMLA was the most drought resistant.
Producing Nitrate-free Endive Heads: Effect of Nitrogen Form on Growth, Yield, and Ion Composition of Endive
Authors: Santamaria Pietro , Elia Antonio
Published: January 2019

In a growth chamber, endive (Cichorium endivia L. var. crispum Hegi) plants were grown using a solution culture method to evaluate the influence of four ammonium : nitrate (NH4-N : NO3-N) percentage ratios (100:0, 70:30, 30:70, and 0:100) on growth (leaf area, dry mass, crop growth rate, relative growth rate, and net assimilation rate), yield characteristics (head and root fresh mass and root length), quality (dry matter, nitrogen, and nitrate), and inorganic ion content. No symptoms of NH4+ toxicity were detected in endive plants 8 weeks after beginning nutrient treatments. Moreover, by feeding N in mixed form, the growth indices increased compared to indices from feeding with any of the two N forms alone. Ammonium-fed plants produced nitrate-free heads with a fresh mass (171 g) similar to nitrate-fed plants. Compared to the other treatments, the heads of NH4+-fed plants were darker green and more succulent. Mixed N improved yield but caused a remarkable accumulation of nitrate in heads. Following an increase in NO3-N from 30% to 70% in the nutrient solution, head fresh mass rose from 196 to 231 g and NO3- concentration more than doubled (from 2.4 to 6.1 g·kg-1 fresh mass). With 100% of NO3-N, NO3- concentration was 5.5 g·kg-1 fresh mass. With higher NO3-N percentages in the nutrient solution, the difference in the concentration of inorganic cations and anions increased, but K+ concentration was also high in ammonium-fed plants (on average 77 g·kg-1 dry mass). Head total N accumulation was increased by the presence of NH4+ in the nutrient solution and decreased with 100% NO3-N. From the commercial viewpoint, the produce obtained from 100% NH4-N was good, with the value-added factor of the absence of nitrate. This may be an extremely remarkable factor because of the commercial limits on the allowable nitrate content in leafy vegetables already enforced by many European countries and those the European Union is going to adopt in a directive.
Modeling the Sylleptic Branching on One-year-old Trunks of Apple Cultivars
Authors: Costes E. , Guédon Y.
Published: January 2019

The structure of 1-year-old trunks resulting from sylleptic branching are compared among apple (Malus domestica Borkh) cultivars with diverse branching and fruiting habits. The 1-year-old trunks developing from a graft are described as a succession of metamers whose structure refers to location, distribution, and length of sylleptic axillary shoots. We used a stochastic process called hidden semi-Markov chain to capture the embedded structure resulting from mixing of different types of axillary shoots developing along the trunks. The models, corresponding to the different cultivars, are composed of a first transient nonbranched state, a succession of transient states that cover the median sylleptic branching zone, and a final absorbing nonbranched state. They are interpreted with regard to complexity, extent, and branching distribution of the median sylleptic zone. Main results deal with the balance between long and short sylleptic shoots and the distribution of long sylleptic shoots along the trunks. Results suggest that sylleptic branching could be used as an early characteristic to evaluate the later branching behavior of cultivars.
Chloroplast DNA Restriction Fragment Variation among Strawberry (Fragaria spp.) Taxa
Authors: Harrison Richard E. , Luby James J. , Furnier Glenn R.
Published: January 2019

Restriction fragment-length polymorphisms (RFLPs) of chloroplast DNA (cpDNA) were used to study phylogenetic relationships among twenty-six Fragaria taxa and two closely related species, Potentilla fruticosa L. and Duchesnea indica (Andrews) Focke. Sixteen restriction enzymes and probes of the entire Nicotiana tabacum L. chloroplast genome revealed a very low level of variation among the Fragaria taxa, limiting phylogenetic resolution. However, Fragaria appears to be more closely related to Potentilla than Duchesnea. The diploid taxa, F. iinumae Makino, F. nilgerrensis Schlect. and F. vesca L. were the most divergent Fragaria taxa and F. iinumae appears to be the most ancestral taxon. Little variation was revealed within the economically important octoploid group of taxa, which gave rise to the cultivated strawberry, and no progenitor taxa to the octoploid group could be identified. The lack of variation in the chloroplast genome suggests that these Fragaria species may be of relatively recent evolutionary origin.
Variability in Sorbitol : Sucrose Ratio in Mature Leaves of Different Prunus Species
Authors: Moing Annick , Langlois Nathalie , Svanella Laurence , Zanetto Anne , Gaudillère Jean-Pierre
Published: January 2019

Sorbitol is a sugar alcohol, present with sucrose in Rosaceae trees, which seems to have a role in plant response to environmental stress. The aim of this study was to investigate variability in sorbitol : sucrose ratio in source leaves of 53 species or hybrids of Prunus. The studied taxa, representing three subgenera and 11 sections of the Prunus genus, were chosen from the Prunus collection at the Institut National de la Recherche Agronomique, Bordeaux, France. Young mature leaves were sampled on three dates in spring and summer and were analyzed for neutral soluble sugars using high-performance liquid chromatography. There were differences in sorbitol : sucrose ratio according to sampling date and according to taxon. Sorbitol content increased and sucrose content decreased from May to July, leading to an increase in sorbitol : sucrose ratio. For each date, there was a high variability within botanical sections for sorbitol : sucrose ratio. The highest variability between species for sorbitol : sucrose ratio was in July, with P. cocomilia having the lowest ratio (1.15, w/w) and P. fremontii having the highest ratio (5.59, w/w). When species were pooled according to their geographical zone of origin, species originating from Japan showed the lowest sorbitol : sucrose ratio for all sampling dates. In July, species originating from Japan, Europe, and central to western North America had sorbitol : sucrose ratio significantly lower than that of species originating from Europe to western Asia, China to eastern Asia, and central to eastern North America. These results indicate that variability in sorbitol : sucrose ratio exists in the Prunus germplasm and seems to be related to the geographical origin of the species. Moreover, variability in sorbitol to sucrose ratio is high in the germplasm of different Prunus taxa.
Somaclonal Variation among ex vitro `Thornless Evergreen' Trailing Blackberries: The Morphological Status of Selected Clones after Seven Years of Field Growth
Authors: Norton M.A. , Skirvin R.M.
Published: January 2019

Chimeral `Thornless Evergreen' (CTE), (Rubus laciniatus Willd.) somaclones selected in 1983 and field planted in 1985 were reexamined in 1992 for various vegetative and reproductive characteristics. Two major types of thornless (prickle-free) plants, intermediate-sized (`UI 6-6' = `Everthornless') and dwarf (`UI 6-4'), originally selected from a chimeral thornless parent plant, were compared with thorny plants. The intermediate and dwarf somaclones have maintained their distinctive habits over 7 years' growth in the field, indicating that their growth habits are stable and not a transient effect of tissue culture. Although the thornless somaclones remained thornless, the degree and type of prickle-like structures varies considerably, indicating that the thornless gene (Ste) does not entirely suppress the production of prickles, but apparently alters their development. Increasing suppression was directly related to increasing dwarfism, suggesting a link between thornlessness and internode length.
Expansion and Osmotic Adjustment of Strawberry Fruit during Water Stress
Authors: Pomper Kirk W. , Breen Patrick J.
Published: January 2019

Expansion of green-white and red fruit in control (watered) and water-stressed greenhouse-grown strawberry (Fragaria ×ananassa Duch. `Brighton') plants was monitored with pressure transducers. Expansion of green-white fruit in control plants was rapid, showing little diurnal variation; whereas in water-stressed plants, fruit expansion occurred only during dark periods and shrinkage during the day. Red fruit were mature and failed to show net expansion. The apoplastic water potential (ψaw), measured with in situ psychrometers in control plants was always higher in leaves than in green-white fruit. In stressed plants, ψaw of leaves was higher than that of green-white fruit only in the dark, corresponding to the period when these fruit expanded. To determine the ability of fruit to osmotically adjust, fruit were removed from control and water-stressed plants, and hydrated for 12 hours; then, solute potential at full turgor (ψs100) was measured. Water-stressed green-white fruit showed osmotic adjustment with a ψs100 that was 0.28 MPa lower than that of control fruit. Mature leaves of water-stressed plants showed a similar level of osmotic adjustment, whereas water stress did not have a significant effect on the ψs100 of red fruit. Fruit also were severed to permit rapid dehydration, and fruit solute potential (ψs) was plotted against relative water content [RWC = (fresh mass - dry mass ÷ fully turgid mass - dry mass) × 100]. Water-stressed, green-white fruit had a lower ψs for a given RWC than control fruit, further confirming the occurrence of osmotic adjustment in the stressed fruit tissue. The lack of a linear relationship between turgor pressure and RWC prevented the calculation of cell elasticity or volumetric elastic modulus. Osmotic adjustment resulted in about a 2.5-fold increase in glucose and sucrose levels in water-stressed green-white fruit. Although green-white fruit on water-stressed plants showed osmotic adjustment, it was not sufficient to maintain fruit expansion during the day.