bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluating Quality Attributes of Four Fresh Fig (Ficus carica L.) Cultivars Harvested at Two Maturity Stages
Authors: Crisosto Carlos H. , Bremer Vanessa , Ferguson Louise , Crisosto Gayle M.
Published: February 2019

The effect of two fruit maturity stages on the quality attributes of four fresh fig cultivars was examined, including consumer acceptance and antioxidant capacity. Fig quality attributes such as weight, soluble solids concentration (SSC), titratable acidity (TA), SSC:TA, firmness, antioxidant capacity, and consumer acceptance varied by cultivar. Fig cultivars harvested at the advanced maturity stage (“tree ripe”) had lower TA and firmness but higher weight, SSC, and SSC:TA than figs harvested at “commercial maturity.” Fig maturity did not affect antioxidant capacity, but tree ripe figs had higher consumer acceptance than commercial maturity figs. SSC was more highly correlated with consumer acceptance than TA or SSC:TA, but other factors may also be important in controlling this relationship. Cultivars with high SSC and firmness, at a maturity stage high enough to tolerate harvesting and postharvest handling, should be selected to develop the fresh fig industry. Because fig firmness is a concern, changes to packaging should be evaluated to protect the flavor of advanced maturity figs during postharvest handling.
Hardening and Dehardening of Peach Flower Buds
Authors: Szalay László , Timon Béla , Németh Szilvia , Papp János , Tóth Magdolna
Published: February 2019

At the northern borders of the peach-growing zone, low temperatures during winter are the critical factors for the survival of the trees and for the reliability of production. Our aim was to carry out detailed analysis of the hardening and dehardening processes of flower buds of three peach cultivars with contrasting frost tolerance and to evaluate the effects of environmental factors and of genotypic differences in two consecutive winters with very diverse weather conditions. Based on our results, the hardening process takes place in two phases in peach flower buds. In the first phase, gradual cooling is essential if the level of frost resistance characteristic of the genotype is to develop, but in the second phase, it is a prerequisite that the external temperature drop consistently below zero for reaching the maximum frost tolerance. The maximum level of frost resistance developed by peach flower buds was only maintained for a limited time and the differences between the cultivars gradually decreased as flowering time approached. At the time of leaf fall in the fall and before flowering, the difference between the mean frost tolerance values for flower buds of the extremely frost-tolerant and frost-sensitive cultivars was only 2 °C, whereas in midwinter, it was 5 to 5.5 °C.
Changes in Sugar Content and Sucrose Synthase Enzymes during Fruit Growth in Eggplant (Solanum melongena L.) Grown on Different Polyethylene Mulches
Authors: Boo Heeock , Kim Honggi , Lee Hyunhwa
Published: February 2019

This study clarified the role of the key enzymes [sucrose phosphate synthase (SPS), sucrose synthase (SS)] in the sucrose synthesis of eggplant (Solanum melongena L.) cultured on different polyethylene mulches. Sugar concentration in fruit and SPS and SS activities in leaf and fruit were measured during the different fruit development stages. Total sugar concentration was the highest on the reflective mulches throughout all the developmental stages of eggplant and followed by the white, the black, and transparent mulches. The concentrations of all three individual sugars (sucrose, glucose, and fructose) increased during fruit development on all four polyethylene mulches. Although no specific pattern in enzyme activities of leaf and fruit related to the sugar accumulation of eggplant fruit was observed, the reflective and white mulches triggered higher sucrose synthase enzyme activities than did the black and transparent mulches.
In Vitro Shoot Proliferation and Root Induction of Shoot Tip Explants from Mature Male Plants of Casuarina cunninghamiana Miq.
Authors: Shen Xiuli , Castle William S. , Gmitter Frederick G.
Published: February 2019

This study examined the effects of plant growth regulators, explant types, and their orientations on in vitro shoot proliferation of Casuarina cunninghamiana Miq. and also the subsequent rooting ability of shoots. Results showed that shoot proliferation occurred only in shoot tip explants cultured vertically on Murashige and Skoog (MS) medium supplemented with 2 or 4 μM thidiazuron (TDZ). Neither 6-benzylaminopurine alone nor in a combination with 1-naphthalene acetic acid (NAA) or gibberellic acid had any effect on shoot proliferation. TDZ at 4 μM resulted in the greatest percentage of axillary bud sprouting (70%) and mean number of sprouts per explant (2.3). Additionally, no shoot proliferation was observed from detipped or single-node explants or from horizontally placed shoot tip explants when cultured on the same TDZ-containing medium. The induced shoots produced adventitious roots on MS medium supplemented with 2.5, 5, or 10 μM indole-3-butyric acid (IBA), not with indole-3-acetic acid and NAA. Although the mean number of roots per explant was not significantly different between 2.5 and 5 μM IBA, the highest rooting percentage (68%) and mean length of roots per explant (0.7 cm) was achieved at 5 μM IBA. The current study provided preliminary information toward commercial in vitro propagation of Casuarina cunninghamiana male plants.
In Vitro Shoot Regeneration and Polyploid Induction of Rhododendron ‘Fragrantissimum Improved’
Authors: Hebert Cary J. , Touchell Darren H. , Ranney Thomas G. , LeBude Anthony V.
Published: February 2019

Rhododendron L.‘Fragrantissimum Improved’ is an attractive cultivar with showy, fragrant flowers but has limited potential for breeding because it is a sterile wide hybrid. Protocols for in vitro regeneration and polyploid induction were developed for this cultivar as a means to potentially restore fertility and enhance ornamental traits. Combinations of thidiazuron (TDZ) at 0, 5, 10, 15, or 20 μM and 1-naphthaleneacetic acid (NAA) at 0, 2.5, 5, or 10 μM were used to induce shoot regeneration from leaves. Shoot regeneration was optimized (68% of leaf segments produced shoots) using 8.8 μM TDZ and 10 μM NAA. To induce polyploidy, regenerative callus was treated with 7.5, 15, 30, 60, or 90 μM of the mitotic inhibitor oryzalin for 1, 3, 5, 7, or 14 d in various combinations. Oryzalin significantly affected survival and shoot regenerative capacity. A percentage of homogenous, tetraploid shoots was recovered from treatments of 30 μM oryzalin for 1 (13%) or 3 (13%) days and 7.5 μM oryzalin for 7 (20%) or 14 (7%) days.
Micropropagation of Ilex glabra (L.) A. Gray
Authors: Sun Youping , Zhang Donglin , Smagula John
Published: February 2019

Nodal segments containing one axillary bud (1 to 1.5 cm) were disinfected using 10% bleach and were established on a Murashige and Skoog (MS) medium without hormones at 27 °C and with a 16-h photoperiod. The sprouted shoots (≈1.0 cm) were cultured on a MS medium supplemented with 6-benzylaminopurine (BAP), kinetin (KIN), or zeatin (ZT) at 2.3, 4.5, 9.1, or 18.2 μM. After 38 d, ZT and BAP significantly induced multiple shoot formation with multiplication rates of 4 to 6, whereas the multiplication rate of KIN was less than 2. Shoots cultured on ZT grew significantly taller than those on BAP and KIN. The height of the longest shoots treated with ZT was 4.6 cm, which was 1.6 to 2.2 times greater than those treated with BAP or KIN. To induce rooting, shoots (≈2 cm) were subcultured on one-fourth strength MS (1/4 MS) medium containing either 3-indolebutyric acid (IBA) or 1-naphthylacetic acid (NAA) at 2.6, 5.1, or 10.3 μM. Adventitious roots formed in vitro after 2 to 4 weeks. IBA at 10.3 μM produced the best rooting (100%) compared with other treatments after 38 d of culture. The average number of roots per shoot for IBA was ≈15, which was 1.6 to 3.1 times as many as that of other treatments. All rooted plantlets were then transplanted into a mix of peatmoss and perlite (1:1 v/v) and acclimatized in a mist system. Average plantlet survival was 73.6% after 35 d. After acclimatization, they were grown in a pot with Metro-mix under greenhouse conditions for 10 weeks where 95% of plants survived and grew up to 6.8 cm high. The micropropagation procedure, i.e., nodal segments containing one axillary bud proliferated on MS with 4.5 μM ZT followed by in vitro rooting on 1/4 MS plus 10.3 μM IBA, could be used for commercial mass production of new inkberry cultivars.
Foliar Sprays Containing Phosphorus (P) Have Minimal Impact on ‘Pinot noir’ Growth and P Status, Mycorrhizal Colonization, and Fruit Quality
Authors: Schreiner R. Paul
Published: February 2019

Grapevines grown in low-phosphorus (P) soils typical of western Oregon vineyards may benefit from additional P applied to the canopy using foliar sprays. Alternatively, vines may be negatively affected by foliar P sprays because lower root colonization by arbuscular mycorrhizal fungi (AMF) could reduce uptake of other nutrients or increase vine water stress. The impact of foliar P sprays on vine growth, vine nutrient and water status, AMF colonization, and fruit yield and quality was studied in two ‘Pinot noir’ vineyards with a history of low vine P status over 3 years. Three foliar spray treatments [phosphite, phosphate, water (control)] were applied to vines three times each season using a standard air-blast sprayer at a commercial vineyard. Two foliar spray treatments (phosphite, water) were applied using a hand sprayer at a smaller research vineyard. Phosphite sprays increased leaf blade and petiole P concentrations and reduced arbuscular colonization of roots at the research vineyard, but neither phosphate nor phosphite significantly affected these variables at the commercial vineyard. Foliar P sprays had no effect on vine growth, vine water relations (leaf water potential and stomatal conductance), yield, or fruit quality attributes at either site. These results indicate that there is little benefit to spraying the canopy of grapevines with P, even in vineyards with low P status.
Development of Microsatellite Markers from Crape Myrtle (Lagerstroemia L.)
Authors: Wang Xinwang , Dean Deborah , Wadl Phillip , Hadziabdic Denita , Scheffler Brian , Rinehart Timothy , Cabrera Raul , Trigiano Robert
Published: February 2019

Lagerstroemia L. (crape myrtle) is an economically important woody plant genus with several deciduous flowering ornamental species. A wide range of flower colors, long flowering periods, growth habits ranging from miniature to tree sizes, and exfoliating bark characteristics provide horticulturists and nursery growers with a great deal of interest in the breeding and genetics of this genus. We report microsatellite marker development from a GT-enriched genomic library of the interspecific hybrid ‘Natchez’ (L. indica L. × L. fauriei Koehne). Twelve of 43 novel microsatellite loci were characterized on a collection of 33 Lagerstroemia cultivars and accessions. Four to eight alleles per locus (mean = 5.6 alleles) were detected. Allelic richness ranged from 3.9 to 7.2 with a mean of 5.3. The level of polymorphism detected (average gene diversity of 0.68) indicates moderately high genetic diversity within the selections of crape myrtle cultivars and accessions. The examined markers also exhibited high cross-species transferability to L. fauriei, L. limii Merr., and L. subcostata Koehne.
Genetic Characterization and Dollar Spot Fungus Susceptibility in Accessions of Festuca rubra from Northern Spain
Authors: Oliveira Jose A. , Monteagudo Ana B. , Bughrara Suleiman S. , Martínez Jose L. , Salas Ana , Novo-Uzal Esther , Pomar Federico
Published: February 2019

The objective of the present study was to characterize the diversity of 15 Festuca rubra accessions collected from northern Spain on the basis of amplified fragment length polymorphism (AFLP) and flow cytometry variation. Additionally, all accessions along with the cultivar Wilma (Festuca nigrescens ssp. nigrescens) were evaluated for susceptibility to one isolate of dollar spot fungus (Sclerotinia homoeocarpa F.T. Bennett) collected in Asturias. Five AFLP primer combinations of EcoRI and MseI produced 980 bands; 82.3% were polymorphic and used for analysis. The best combination of primers was EcoRI-AGC+MseI-CAG, because these displayed the highest degree of polymorphism. Jaccard's similarity coefficients between accessions varied from 0.30 to 0.63 and revealed low genetic similarity. Both the unweighted pair group method with arithmetic mean dendrogram and principal coordinate analysis distinguished two groups of accessions. Genetic variability in these accessions was not related to the geographic origin or to the agronomic data. Three accessions exhibited moderate resistance to dollar spot disease and may be valuable parent material for introducing this resistance in other susceptible cultivars.
An Extended Intervarietal Microsatellite Linkage Map of Cucumber, Cucumis sativus L.
Authors: Weng Yiqun , Johnson Shanna , Staub Jack E. , Huang Sanwen
Published: February 2019

A recombinant inbred line (RIL) population derived from two cultivated cucumber (Cucumis sativus var. sativus L., 2n = 2x = 14) lines, Gy7 (synonym G421) and H-19, was previously used to map yield and fruit quality components. However, the map consisted mainly of dominant markers (i.e., random amplified polymorphic DNAs or amplified fragment length polymorphisms) limiting its use in plant improvement and map-based gene cloning. We report here a moderately saturated genetic map derived from this RIL population that incorporates codominant microsatellite [simple sequence repeat (SSR)] markers and two architectural traits, little leaf (ll) and determinate (de), growth habit. Of 821 cucumber genomic SSR primer pairs evaluated for map construction, 140 (17.0%) were polymorphic between the mapping parents. In combination with 42 previously mapped sequence characterized amplified region (SCAR) and SSR makers, these polymorphic markers were used to construct a linkage map with 46 RILs and 176 mapped loci spanning ≈400 cM across seven linkage groups (LG). The numbers of loci mapped on LG 1 through 7 were 11, 6, 35, 18, 46, 45, and 15, respectively. The ll locus was flanked by SSR02355 and SSR03940 (4.2 and 3.6 cM from ll, respectively), and de was flanked by CSWCTT14b and SSR13251 (1.4 and 4.2 cM from the de, respectively). The SSR markers linked with the de and ll genes were mapped to Chromosome 6. No recombination suppression was detected among the mapped loci examined. This Gy7 × H-19 RIL-based genetic map shared 94 marker loci with a previously reported RIL-based linkage map derived from a wide cross between C. sativus var. sativus line Gy14 and C. sativus var. hardwickii Alef. R. PI 183967. Comparative mapping supported previous findings that genomic differences (likely chromosomal rearrangements) exist between Gy14 and PI 183967.
Hot Water Treatment Released Endodormancy but Reduced Number of Flowers in Potted Red Raspberry Plants
Authors: Rantanen Marja , Palonen Pauliina
Published: February 2019

Partially released dormancy causes poor and uneven bud break in temperate plant species like red raspberry (Rubus idaeus L.). Insufficient chilling may be a problem when raspberries are grown at southern latitudes and in year-round production. Dormancy may be released by sublethal stress in many species. We studied the effect of sublethal stress on endodormancy in red raspberry ‘Glen Ample’ and ‘Ottawa’. Canes growing in pots were treated with either hot water (45 °C, 1 h) or the dormancy-breaking chemical, hydrogen cyanamide (1.04%), after accumulation of 0, 240, 480, 720, 960, or 1200 h of chilling at 1 °C. Bud break, vegetative growth, and number of flowers were recorded during 12 weeks of greenhouse forcing after the treatments. Chilling increased bud break, growth, and dry weight of lateral shoots and number of flowers in both cultivars. During deepest endodormancy (0 and 240 h of chilling), treatment with either hot water or hydrogen cyanamide enhanced bud break and lateral shoot growth but could not completely replace chilling. In ‘Ottawa’, hydrogen cyanamide was more effective than hot water during deepest endodormancy, but hot water treatment broke dormancy effectively when 720 h of chilling had accumulated. For ‘Glen Ample’, hot water was as effective as hydrogen cyanamide in breaking endodormancy. Hot water treatment reduced the number of flowers in ‘Glen Ample’ during late endodormancy (720, 960, and 1200 h of chilling). The chilling requirement for ‘Ottawa’ was fulfilled between 720 and 960 h of chilling. However, in ‘Glen Ample’, 1200 h of chilling was not enough to fully release bud dormancy; bud break remained low and it was increased by dormancy-breaking treatments. Hot water treatment can be used to release endodormancy in raspberries, but treatment conditions need to be optimized to preserve crop potential. Chemical name used: hydrogen cyanamide (Dormex, Hi-Cane, Morgrapes).
Peel Color and Blemishes in ‘Granny Smith’ Apples in Relation to Canopy Light Environment
Authors: Fouché Jacques R. , Roberts Stephanie C. , Midgley Stephanie J.E. , Steyn Willem J.
Published: February 2019

The dark green apple cultivar, Granny Smith (GS), makes up 25% of the South African apple industry. However, production of GS is becoming unprofitable as a result of a high incidence of sunburn, red blush, and pale green fruit that decreases the proportion of Class 1 fruit that is suitable for export to more lucrative markets. This study was conducted to investigate the relationship between canopy position and external fruit quality with the ultimate aim to devise pruning and training strategies to maximize export yield. During early fruit development [26 days after full bloom (DAFB)], chlorophyll concentrations were the highest in fruit from higher light environments. Good green color at harvest relied on exposure of fruit to high irradiance at this stage because 50% shading between 14 and 56 DAFB significantly decreased dark green color at harvest. Exposed fruit from the northern side of east–west rows received the highest irradiance throughout the season [53% of full sun photosynthetic photon flux (PPF)] and had the highest fruit surface temperature (on average 5 °C above ambient). A high proportion of exposed fruit from either side of the row developed red blush. Only 22% to 39% of exposed fruit from the outer canopy did not develop sunburn or red blush. Partially shaded fruit from the southern side of east–west rows received ≈5% of full sunlight and had the highest chlorophyll concentrations and darkest green color at harvest. Deeply shaded inner canopy fruit received ≈2% of full sunlight, had low chlorophyll concentrations, and were lighter green in color. The 10% darkest green fruit received moderately high irradiance (25% to 45% of full sun PPF) during early fruit development (until ≈80 DAFB) but became progressively shaded (3% of full sun PPF) during the latter half of the season. Fruit that developed sunburn and the lightest green fruit were exposed to high (1300 μmol·m−2·s−1) and extremely low (50 μmol·m−2·s−1) light, respectively, throughout their development. In conclusion, maximum chlorophyll synthesis and dark green color require an open canopy during the first half of fruit development, whereas shading is necessary during the latter half of fruit development to avoid the occurrence of sunburn, red blush, and photothermal destruction of chlorophyll. GS may benefit significantly from the installation of shade netting if combined with rigorous pruning and vigor control.
Effect of Controlled Atmospheres with Low Oxygen Levels on Extended Storage of Guava Fruit (Psidium guajava L. ‘Pedro Sato’)
Authors: Teixeira Gustavo H.A. , Durigan José F.
Published: February 2019

The effects of controlled atmospheres (CAs) containing different levels of oxygen (air, 21, 15, 10, 5, and 1 kPa) were investigated during cold storage of ‘Pedro Sato’ guava at 12.5 °C for 28 days. Atmospheres with lower O2 concentrations (1 and 5 kPa) significantly reduced respiratory rates and delayed the ripening process. This was confirmed by maintenance of fruit green color, higher total soluble, and reducing sugar contents. The control fruits and those stored in elevated oxygen concentrations (21 kPa) presented a climacteric peak. However, the peak was not observed for fruit maintained in atmospheres containing 1, 5, 10, and 15 kPa O2. After transferring the fruits from CA to ambient storage, they ripened normally in just 2 d without presenting any low O2 injury symptoms, even from the lowest oxygen concentrations (1 and 5 kPa O2). This supports the use of low-oxygen atmospheres for extended storage of ‘Pedro Sato’ guava fruit.
Factors Affecting Establishment of Sweet Cherry on Gisela 6 Rootstock
Authors: Neilsen Gerry H. , Neilsen Denise , Kappel Frank , Toivonen Peter , Herbert Linda
Published: February 2019

Cristalina and Skeena sweet cherry cultivars (Prunus avium L.) on Gisela 6 (Prunus cerasus × Prunus canescens) rootstock were maintained for the first four growing seasons in a randomized, replicated split-split plot experimental design with two main plot irrigation frequency treatments, the two cultivars as subplots and three soil management subsubplot treatments. The same amount of irrigation water was applied through four drip emitters per tree at either high (I1, four times daily) or low frequency (I2, once every second day) beginning in the second year. Three different soil management treatments were established the year of planting and included: 1) NK fertigation with a herbicide strip (control), or additionally; 2) maintenance of a 10-cm thick bark mulch over the herbicide strip; and 3) annual fertigation of 20 g phosphorus (P) per tree per year immediately after bloom. I1 irrigation increased soil moisture (0- to 20-cm depth) throughout each growing season. The I1 irrigation resulted in higher leaf and fruit concentrations of the immobile nutrients P and potassium (K) and larger trunk cross-sectional area than I2 trees. I1 irrigation, in general, did not affect initial yield or fruit size. Fruit from I2 irrigation had higher soluble solids concentration (SSC), color, and total phenolic concentration at harvest in 2008 and lower titratable acidity (TA), firmness, and stem pull force suggesting an acceleration of fruit maturity. When compared with the control soil management treatment, P fertigation resulted in leaves and fruit with higher P concentrations, a higher 2008 crop yield, and a delay in 2008 crop maturity as indicated by lower harvest color and SSC and higher stem pull force. Mulch application, relative to control treatments, resulted in trees with higher vigor (but only with I1 irrigation) and leaf K concentration and had few effects on initial fruit yield or quality. There were important differences in cultivar responses to treatments. ‘Cristalina’ vigor was lower than ‘Skeena’ whose fruit had lower firmness and pedicel retention than ‘Cristalina’.
Growth, Biomass, and Nitrogen Use Efficiency of Containerized Fraser Fir (Abies fraseri) as Related to Irrigation and Nitrogen Fertilization
Authors: Nzokou Pascal , Cregg Bert M.
Published: February 2019

Growth and nutrient uptake of containerized fraser fir (Abies fraseri) seedlings in response to irrigation and fertilization was investigated for 2 years in a greenhouse experiment. Height and stem diameter growth increased 12% to 35% and 4% to 32%, respectively, with increased irrigation. There was an inverse relationship between irrigation and foliar nitrogen content and no irrigation effect on foliar phosphorus, potassium, magnesium, and manganese. Irrigation increased foliar calcium. Approximately 2.0% to 4.5% of applied nitrogen was lost through leaching. Increases in total biomass in high irrigation treatments were caused by higher root and stem biomass. Higher irrigation treatments increased nitrogen use efficiency (NUE) and assimilatory nitrogen use efficiency probably as a result of increase in carbon assimilation efficiency leading to increase in net primary productivity. There was no clear effect on the root weight ratio, but the index nitrogen availability per unit of foliage indicated a higher availability in plants receiving the lowest irrigation. This suggests that under water stress, the decrease in assimilation and NUE may be buffered by an increase in the plant's ability to provide nitrogen and other nutrients to various organs.
Salt Tolerance and Canopy Reflectance of Kentucky Bluegrass Cultivars
Authors: Poss James A. , Russell Walter B. , Bonos Stacy A. , Grieve Catherine M.
Published: February 2019

Six cultivars or selections of kentucky bluegrass (Poa pratensis L.) were grown outdoors from vegetative clones in a gravelly sand medium from Apr. to Sept. 2005 in Riverside, CA, at soil water salinities ranging from 2 to 22 dS·m−1. Cultivars Baron, Brilliant, Cabernet, Eagleton, Midnight, and the selection A01-856, a ‘Texas’ × kentucky bluegrass hybrid (P.· arachnifera × P. pratensis), were evaluated for salt tolerance based on relative and absolute cumulative biomass production, growth rates, leaf chloride concentration, and hyperspectral ground-based remote sensing (RS) canopy reflectance measurements. Remotely sensed indices were linearly correlated with absolute biomass production. Three variations of a Normalized Difference Vegetation Index (NDVIred, NDVIprotein, and NDVIinfra) decreased with increasing salinity-induced changes in grass canopies. An index based on the red-edge inflection point increased (became less negative) with increasing salinity. A Floating Water Band Index decreased with decreased leaf moisture content related to increasing salinity but did not discriminate between cultivars. Shoot spreading rate and NDVIinfra were both related to shoot chloride concentration differences among the kentucky bluegrass (Poa pratensis L) (KBG) cultivars or selections. In theory, non-destructive RS monitoring of above-ground turf development, including NDVIinfra, coupled with measurement of leaf chloride concentrations could be useful in turf salt tolerance breeding programs. Salt tolerance rankings among the KBG cultivars varied depending on the evaluation methods and selection criteria used. Based on absolute and relative biomass, growth rate, and RS, cultivars Baron, Brilliant, and Eagleton were rated as more salt-tolerant than ‘Cabernet’, ‘Midnight’, and AO1-856.
Ploidy Levels and Genome Sizes of Berberis L. and Mahonia Nutt. Species, Hybrids, and Cultivars
Authors: Rounsaville Todd J. , Ranney Thomas G.
Published: February 2019

An extensive survey of genome sizes and ploidy levels was conducted for a diverse collection of Berberis and Mahonia taxa (Berberidaceae). Propidium iodide flow cytometric analysis was conducted using Pisum sativum L. ‘Ctirad’ (2C DNA = 8.76 pg) as an internal standard to determine genome sizes. Mean 1CX genome sizes varied between the two Mahonia subgenera (Occidentales = 1.17 ± 0.02, Orientales = 1.27 ± 0.01), whereas those of Berberis subgenera were similar (Australes = 1.45 ± 0.03, Septentrionales = 1.47 ± 0.02) and each significantly larger than those of Mahonia. Traditional cytology was performed on representative species to calibrate genome sizes with ploidy levels. Polyploidy among both wild and cultivated taxa was found to be rare. Although the majority of species were determined to be diploid with 2n = 2x = 28, artificially induced autopolyploid Berberis thunbergii seedlings were confirmed to be tetraploid and an accession of Mahonia nervosa was confirmed to be hexaploid. Genome size and ploidy level reports for the majority of taxa sampled are presented for the first time and are intended to be of use to plant breeders, ecologists, and systematists.
Integrated and Organic Fruit Production Systems for ‘Liberty’ Apple in the Northeast United States: A Systems-based Evaluation
Authors: Peck Gregory M. , Merwin Ian A. , Brown Michael G. , Agnello Arthur M.
Published: February 2019

A systems-based approach was used to evaluate integrated (IFP) and organic fruit production (OFP) (during and after the transition period) in an established high-density commercial orchard of disease-resistant ‘Liberty’ apples (Malus ×domestica Borkh.). Agroecological and economic evaluations included: yields, tree growth, leaf nutrient levels, arthropod and cosmetic fruit damage, environmental impacts, variable costs of production, and potential crop value using both direct market and wholesale market prices. Cumulative yields (2004–2007) of both harvested and total (harvested + dropped) fruit were not different between the two systems. Tree size (trunk cross-sectional area) was not consistently different between the production systems. The IFP-grown apples had between 3% and 6% insect damage (within normal percentages for this region) and between 3% and 17% total damage (either internal or cosmetic). The OFP-grown apples had between 3% and 25% insect damage and 3% to 75% total damage, varying greatly from year to year. In 2006, superficial blemishes, caused by diseases and scarfskin, were extensive on OFP-grown fruit. Using the Environmental Impact Quotient, the potential negative environmental impacts were estimated to be six times greater in the OFP system, largely as a result of the use of lime sulfur and fish oil for thinning and the large quantity of kaolin clay used for pest control. Partial budgets of both systems estimated variable production expenses to be 9% greater for OFP. Sales value was estimated to be 6% greater for OFP than IFP using direct market prices (e.g., farm stand or farmers' market) and 11% greater for IFP than OFP using wholesale market prices. A 56% premium was used to calculate the OFP crop value in the third and fourth years (fruit could have been sold with an organic label after 36 months from the last organically prohibited material). Four years of evaluation suggested that IFP could be widely implemented in the northeastern United States, but the lack of market incentives might impede its adoption. Producing disease-resistant apples under an OFP system also showed potential for success, but a price premium would be needed to offset the reduced profitability incurred from arthropod pests, poor fruit finish, and small fruit size.
Distinct Respiration and Physiological Changes during Flower Development and Senescence in Two Freesia Cultivars
Authors: Shu Zhen , Shi Yimin , Qian Hongmei , Tao Yiwei , Tang Dongqin
Published: February 2019

Two cultivars of Freesia hybrida, ‘Shangnong Jinhuanghou’ and ‘Shangnong Hongtaige’, were used to study the respiration rate and physiological responses during flower development and senescence. Phenotypically, the vase life of ‘Shangnong Hongtaige’ was significantly shorter than that of ‘Shangnong Jinhuanghou’. At the whole flower level, both cultivars displayed similar change patterns on respiration rate. However, the change patterns in tepals, stamens, and pistils showed some differences in the two cultivars. A respiratory climacteric existed in most organs in both cultivars except for the stamen of ‘Shangnong Jinhuanghou’. During flower development and senescence, the levels of soluble proteins and soluble sugars were very high at early stages, followed by a dramatic decrease, and the lowest levels occurred in wilted tepals in both cultivars. Superoxide dismutase (SOD) activities increased slightly at early developmental stages followed by a constant decrease in two cultivars, and SOD activities in ‘Shangnong Jinhuanghou’ were significantly higher than those in ‘Shangnong Hongtaige’. Peroxidase activities showed a constant increase before tepals started wilting followed by a decrease in wilted tepals in both cultivars. In both cultivars, electrolytic leakage and malondialdehyde (MDA) content in tepals increased with the progression of development and senescence. MDA content in ‘Shangnong Hongtaige’ was much higher than that in ‘Shangnong Jinhuanghou’. These results indicated that the respiratory climacteric, the decrease of antioxidant enzyme activities, the peroxidation of membrane lipid, and the loss of soluble compounds could be considered as indicators of flower senescence in Freesia.
Residual Effects of Ethylene on Tulip Growth and Flowering
Authors: Cerveny Christopher B. , Miller William B.
Published: February 2019

Ethylene effects were investigated on two tulip (Tulipa gesneriana L.) cultivars, Markant and Carreria. Pre-cooled bulbs were treated with ethylene (flow-through) for 1 week at 0, 0.1, 1.0, or 10 μL·L−1 (± 10%) in a modified hydroponic system. After ethylene exposure, plants were either destructively harvested for root measurements or forced in a greenhouse for flower measurements. Ethylene exposure at concentrations as low as 1 μL·L−1 during the first week of growth reduced shoot and root elongation and subsequently increased flower bud abortion. At 10 μL·L−1, root growth was essentially eliminated. In a second experiment, bulbs were treated overnight with 1-methylcyclopropene (1-MCP) before a 7-day exposure to 1 μL·L−1 ethylene. 1-MCP pretreatment eliminated the harmful effects of ethylene on root and shoot growth. This study illustrates the effects of ethylene exposure during hydroponic tulip production and demonstrates a potential benefit to treating bulbs with 1-MCP before planting.
Glucosinolate Enhancement in Cabbage Induced by Jasmonic Acid Application
Authors: Fritz Vincent A. , Justen Veronica L. , Bode Ann M. , Schuster Todd , Wang Min
Published: February 2019

Glucosinolates (GSL) are bioactive compounds found in cruciferous vegetables that have been shown to have chemopreventive benefits for human health. The objective of this study was to determine whether foliar application of jasmonic acid (JA) increases glucosinolate accumulation and yield in cabbage (Brassica oleracea L. Capitata group). Field studies were conducted in 2004 and 2005 with a green (‘Quisto’) and red (‘Ruby Perfection’) cabbage cultivar. Foliar JA application rates were 0.1 mm, 0.2 mm, and split application of 0.2 mm JA with surfactant, surfactant control, and water control. Yield of both cabbage cultivars was not changed by JA application in both years of the study. In both years, ‘Ruby Perfection’ had significantly higher glucosinolate concentrations than ‘Quisto’ with sinigrin being the predominant glucosinolate in both varieties. JA application consistently increased sinigrin, gluconapin, and glucoiberin concentrations across cultivars and years of the study. JA application also increased progoitrin and total GSL concentrations, but the effect was inconsistent between years and cultivars. In most cases, a split application of 0.2mm JA resulted in the highest GSL accumulation. GSL accumulation was significantly higher in 2005 than 2004 for both cultivars. Climatic data suggest that annual differences in temperature may have influenced the variability in glucosinolate concentration in cabbage.
Bell Pepper (Capsicum annum L.) Grown on Plastic Film Mulches: Effects on Crop Microenvironment, Physiological Attributes, and Fruit Yield
Authors: Díaz-Pérez Juan Carlos
Published: February 2019

Plastic mulches are widely used for the production of vegetables. There are numerous studies on the use of plastic mulches for peppers, although relatively few have focused on the microenvironmental and physiological impacts of plastic mulches on bell pepper. The objectives were to determine the effects of plastic film mulches on root zone temperature (RZT), soil water status, incidence of thrips and Tomato spotted wilt (TSW), plant growth, gas exchange, accumulation of mineral nutrients, and fruit yield in bell pepper. The study was conducted in Tifton, GA, in the Fall of 2002 and the Spring of 2003 using eight colored plastic mulches. Plastic mulch color influenced the microenvironmental, physiological, and yield responses of bell pepper plants. Plastic film mulches differed in their soil-warming ability with RZTs in both spring and fall being highest in black mulches and lowest in silver mulches. The percentage of photosynthetically active radiation (PAR) reflected from the mulches was highest in silver mulches and lowest in black mulches. The mean RZT under the plastic mulch decreased with increasing percentages of reflected PAR. The number of thrips per flower and the incidence of TSW in mature plants were not significantly different among plastic mulch treatments. The number of thrips per flower had no relationship with the percentage of reflected PAR or with RZT. Plastic mulch treatments had no significant effect on soil water status. Neither soil water content nor soil water potential had a relationship with RZT. In the fall season, during the first 28 days after transplanting, plant growth attributes were among the highest in silver mulches and the lowest in black mulches. Gas exchange and accumulation of mineral nutrients in the leaves and the fruit were not significantly affected by plastic mulches. Both marketable and total yields were higher on silver mulches and lowest on black mulch in the fall, whereas they were in general higher on silver with a black strip mulch and lowest on white and silver1 mulches in the spring. The reduced plant growth and fruit yields in black mulches during the fall were probably the result of the increased RZTs, and thus higher heat accumulation, that resulted in higher plant heat stress conditions compared with silver and white mulches. Fruit yield decreased with mean seasonal RZTs above 27.5 °C. The optimal range of RZT for bell pepper fruit yield was computed to be 25 to 27.5 °C or less.
Ranking Cultivated Blueberry for Mummy Berry Blight and Fruit Infection Incidence Using Resampling and Principal Components Analysis
Authors: Ehlenfeldt Mark K. , Polashock James J. , Stretch Allan W. , Kramer Matthew
Published: February 2019

Mummy berry disease of blueberry has two distinct phases: a blighting phase that infects emerging shoots and leaves early in the spring and a flower infection phase that ultimately leads to infected (mummified) fruit. Cultivated blueberry (Vaccinium spp.) genotypes that are resistant to one phase are not necessarily resistant to the other phase. The resistance of cultivated blueberry (Vaccinium spp.) genotypes to each phase of the disease is different. A large number of cultivars were screened for resistance to each phase. Cultivar standards (cultivars with well-documented responses to the disease) were used in the screening to evaluate long-term variation and aid comparisons across years. Using nine standards for the blight phase, 125 cultivars were tested and ranked for relative resistance using a ranking system based on resampling and principal component analysis. Similarly, using six standards for the flower/fruit infection stage, 110 blueberry cultivars were tested and ranked for relative resistance. Cultivar rankings show that lowbush cultivars and other types possessing high percentages of lowbush germplasm are generally more resistant to both phases of the disease. Among highbush cultivars, Bluejay is reliably resistant to both phases. Documentation of resistance to each phase will allow selection of cultivars for planting in affected areas and will facilitate the development of breeding strategies to produce cultivars with superior resistance.
Blossom Thinning in Apple and Peach with an Essential Oil
Authors: Miller Stephen S. , Tworkoski Thomas
Published: February 2019

A series of experiments was conducted with apple (Malus ×domestica) and peach [Prunus persica (L.) Batsch] from 2003 to 2008 to evaluate the flower thinning efficacy of eugenol and a eugenol-based essential oil. Flower thinning effects by hand defoliation and alternative chemical agents were compared with eugenol in different years. Eugenol or the eugenol-based contact herbicide Matran 2 EC (or Matratec AG) produced noticeable phytotoxicity to floral parts and exposed leaf tissue within 15 min to 1 h after application and injury was proportional to rate. At the highest rates (8% and 10%), eugenol resulted in complete burning of all exposed tissue except bark tissue, in which there were no visible signs of injury. Within 3 to 4 weeks of application, phytotoxicity was difficult to observe even at the higher rates of eugenol. In companion experiments, hand defoliation of young leaves at bloom resulted in abscission of young fruitlets in apple, but not in peach, indicating that eugenol may cause thinning by multiple mechanisms. Ammonium thiosulfate (ATS) [49 L·ha−1 or 6.0% (v/v)] provided thinning in peach and showed little or no phytotoxicity, but the response was inconsistent. ATS was also inconsistent in thinning apple. The thinning response from monocarbamidedihydrogen sulphate (MCDS; Wilthin) at 3.2% (v/v) was inconsistent in peach. At the rate used, MCDS caused some phytotoxicity on peach. Applications of 1% to 2% eugenol appear promising, but good blossom coverage is critical for thinning. Furthermore, eugenol formulations need improvement to ensure uniform coverage for more predictable thinning.
Sustainable Production Practices Adopted by Greenhouse and Nursery Plant Growers
Authors: Dennis Jennifer H. , Lopez Roberto G. , Behe Bridget K. , Hall Charles R. , Yue Chengyan , Campbell Benjamin L.
Published: February 2019

Given recent consumer and market interest in more sustainable products and business practices, researchers conducted a nationwide survey of greenhouse and nursery crop growers to determine the current state of the industry in terms of sustainability. Growers were asked about the importance of sustainability, their views of state environmental regulations, sustainable practices in place and ones they would like to implement in the next 1 to 3 years, and interest in sustainable certification. None of the grower respondents in this survey were certified sustainable, but at least one fourth (25.8%) were interested in certification. More than half of the respondents currently recycle plastic pots, use controlled-release fertilizers, and composted plant waste. However, only 12% of growers want to use biodegradable plant containers or implement water conservation measures into their production system within the next 1 to 3 years. Grower respondents felt the biggest obstacle toward implementation was the sustainable production practice would not be compatible with their existing system of production.
Regeneration of Dracaena surculosa Through Indirect Shoot Organogenesis
Authors: Liu Juanxu , Deng Min , Henny Richard J. , Chen Jianjun , Xie Jiahua
Published: February 2019

This study established a method of regenerating Dracaena surculosa Lindl. ‘Florida Beauty’ through indirect shoot organogenesis. Bud, leaf, and stem explants were cultured on a Murashige and Skoog basal medium supplemented with N6-(2-isopentyl) adenine (2iP) at 12.3 and 24.6 μM with 3-indoleacetic acid (IAA) at 0, 1.1, and 2.3 μM, respectively, and 2iP at 36.9, 49.2, 61.5, and 73.8 μM with IAA at 1.1 and 2.3 μM, respectively. Calluses were induced from leaf explants but failed to produce adventitious shoots. Calluses were also induced from stem and bud explants cultured on the basal medium containing 12.3 μM 2iP and 2.3 μM IAA, 24.6 μM 2iP or higher with either 1.1 or 2.3 μM IAA. The highest callus induction frequency was 63.2% from stem explants and 69.6% from bud explants when they were cultured on the basal medium supplemented with 49.2 μM 2iP and 2.3 μM IAA. The highest shoot formation frequency was 65.7% from stem-derived callus cultured on the basal medium containing 61.5 μM 2iP and 1.1 μM IAA and 88% from bud-derived callus cultured with 49.2 μM 2iP and 1.1 μM IAA. The highest number of shoots per piece of stem- and bud-derived calluses was 3.8 and 6.7, respectively. Adventitious shoots developed better root systems in the basal medium supplemented with 2.0 μM IAA. Plantlets after transplantation into a soilless substrate grew vigorously in a shaded greenhouse under a maximum photosynthetic photon flux density of 300 μmol·m−2·s−1. Neither disease incidence nor somaclonal variants were observed in the regenerated population. This established method could be used for efficient micropropagation of D. surculosa, and the availability of tissue-cultured liners could reduce the dependency on imported cuttings, which often bring new or invasive pests into the United States.
Salinity and Soil Type Effects on Emergence and Growth of Pepper Seedlings
Authors: Niu Genhua , Rodriguez Denise S. , Cabrera Rosa , Jifon John , Leskovar Daniel , Crosby Kevin
Published: February 2019

High soil salinity often results in poor stand establishment, reduced plant growth, and reduced yield of many horticultural crops such as peppers (Capsicum annuum). We investigated the effects of soil salinity and soil type on seedling emergence and growth of four commercial peppers (‘NuMex Joe E. Parker’, ‘NuMex Nematador’, ‘NuMex Primavera’, and ‘Jupiter’) in greenhouse experiments. Seeds were sown in either a loamy sand or a silt loam soil in pots and irrigated with saline solutions at electrical conductivity of 0.9 (tap water), 3.0, or 6.0 dS·m−1 (Expt. 1) or at 0.0 [reverse osmosis (RO) water], 0.9, or 1.5 dS·m−1 (Expt. 2). No seedling emergence was observed in treatments irrigated with 3.0 or 6.0 dS·m−1 solutions. The salinity at the top soil layer increased linearly with time when subirrigated with tap and saline solutions in both soil types, whereas no substantial increase in soil salinity was found when subirrigated with RO water or overhead irrigation with tap water. Salt accumulation at the top soil layer was greater in loamy sand than in silt loam. Seedling emergence percent subirrigated with RO water ranged from 70% to 80% in loamy sand and 45% to 70% in silt loam, depending on pepper cultivars. When subirrigated with tap water and saline solutions, the emergence percent ranged from 0% to 60%, depending on pepper and soil types. In Expt. 3, seedlings were germinated in commercial potting mix and grown in 1.8-L pots containing commercial potting mix. Saline solution treatments of 1.4 (control, nutrient solution), 2.1, 2.9, 3.5, or 4.2 dS·m−1 were initiated when seedlings had 11 to 13 leaves. Five weeks after initiating saline water irrigation, the reduction in shoot dry weight was greater in ‘Jupiter’ and ‘NuMex Primavera’ as compared with ‘NuMex Joe E. Parker’ and ‘NuMex Nematador’, but the differences were small.
A Vitis vinifera Cluster's Wing-related Structural Characteristics and Their Associations with Yield and Berry Composition
Authors: Tarter Michael E. , Poni Stefano
Published: February 2019

The hypotheses considered in this article concern the basic question, besides bearing a wing, in what ways do wing-bearing and non-wing-bearing clusters differ? Vines sampled at midseason were again selected at harvest. Each weight of a Vitis vinifera cluster sampled at midseason was multiplied by the number of clusters on the vine from which the cluster had been selected. Correlation coefficients between this quantity and the sampled vine's yield at harvest differed significantly in the sense that coefficients determined solely from the subset of sampled clusters on which a wing (a lateral arm originating from the peduncle and separate from the main body of the cluster) was present were found to be larger than coefficients determined from all sampled clusters. To shed light on distinguishing characteristics of clusters that bore wings, the weights of clusters that had been sampled at midseason were studied. Despite being weighed after the removal of their wings, clusters that had wings were found to be significantly heavier than clusters (sampled at the same midseason date) that had never had wings. Box and whisker plots were constructed to assess this finding as well to study the relationships between a Vitis vinifera rachis' (a cluster's principal axis) weight, length, and diameter and wing absence or presence. For each of the five vineyard blocks that we studied, the median rachis midseason diameters of wing-bearing clusters exceeded the median rachis diameters of non-wing-bearing clusters. Concerning ‘Cabernet Sauvignon’ Vitis vinifera clusters that had wings, it was also found that the late-season differences between the median soluble solids concentrations (°Brix) of wing-borne berries and the median °Brix of non-wing-borne berries were inappreciable.