bluuebunny/crossref_metadata_2025 huggingface dataset:
Combined Effects of Growth Cycle and Different Levels of Aeration in Nutrient Solution on Productivity, Quality, and Shelf Life of Watercress (Nasturtium officinale R. Br.) Plants
Authors: Niñirola Diana , Fernández Juan A. , Conesa Encarnación , Martínez Juan A. , Egea-Gilabert Catalina
Published: February 2019

The objective of this research was to study the effects of growing cycle (spring vs. winter) and nutrient solution aeration [no aeration (NA), low aeration (LA) or high aeration (HA)] on yield, quality, and on shelf life as a fresh-cut product of watercress grown in a floating system. The growing cycles lasted 25 days in spring and 39 days in winter. In the spring cycle, the plants had significantly higher yield and antioxidant capacity and lower specific leaf area, total root length, root diameter, length of 0 to 0.5 mm diameter root, and oxalate content than in the winter cycle. The absence of aeration increased the antioxidant capacity and vitamin C content in both cycles. Several adventitious roots developed exogenously from the watercress stem at the nodes as a morphological adaptation to oxygen depletion, particularly in NA conditions. The nitrate, oxalate, Ca2+, K+ contents, and microbial populations were affected by both the cycle and the aeration conditions. Hue angle of the leaves was affected by both the cycle and storage time, and chromaticity and lightness were affected by the three factors (cycle, aeration, and storage time). The global quality was significantly higher (7.8 over 9 points hedonic scale) in the spring cycle than in winter, the score reflecting their marketable value (7.0 over 9 points). The mild dehydration problems observed in the winter cycle that led to a slightly lower overall product quality that could be the result of the development of thinner leaves and also the differences in the respiration rates compared with the spring cycle. In general, the spring cycle led to higher productivity, antioxidant capacity, and Ca2+ and K+ contents and lower oxalate content. Aeration slightly affected the quality of the final product, the plants grown in non-aerated conditions being richer in vitamin C and antioxidants and with lower nitrate content.
Mean Daily Temperature Regulates Plant Quality Attributes of Annual Ornamental Plants
Authors: Vaid Tasneem M. , Runkle Erik S. , Frantz Jonathan M.
Published: February 2019

In protected environments, temperature is often regulated to produce ornamental crops for specific market dates. Temperature primarily controls plant developmental rate and thus production time, but it can also interact with light quantity to affect crop quality attributes such as flower number, branching, and biomass accumulation. We quantified how mean daily temperature (MDT) between 14 and 26 °C influenced quality characteristics of 15 common bedding plant crops. American marigold (Tagetes erecta), cup flower (Nierembergia caerulea), diascia (Diascia barberae), flowering tobacco (Nicotiana alata), geranium (Pelargonium ×hortorum), globe amaranth (Gomphrena globosa), heliotrope (Heliotropium arborescens), nemesia (Nemesia foetans), New Guinea impatiens (Impatiens hawkeri), osteospermum (Osteospermum ecklonis), pot marigold (Calendula officinalis), snapdragon (Antirrhinum majus), stock (Matthiola incana), and torenia (Torenia fournieri) were grown under two mean daily light integrals (9.0 and 18.0 mol·m−2·d−1) in five environmentally controlled greenhouse compartments with a 16-h photoperiod. As MDT increased from 14 to 26 °C, flower or inflorescence number decreased for nearly all crops. In six crops, flower or inflorescence size decreased as MDT increased, whereas in five crops, there was an initial increase in flower size with an increase in MDT and then a subsequent decrease at MDT greater than 20 °C. In 10 of the crops, shoot weight at flowering decreased linearly or quadratically with an increase in MDT. Branch number was inversely related with MDT in eight crops and was positively correlated with an increase in flower number. We conclude that in a majority of the crops studied, plant quality decreased as the MDT increased, which can at least partially be attributed to earlier flowering at the higher MDTs. Therefore, there is often a tradeoff between faster crop timing and higher plant quality, especially for plants with a low estimated base temperature (Tmin) for development.
Grow Tubes Reduce Root and Crown Growth but Not Early Production during Establishment of Highbush Blueberry
Authors: Strik Bernadine C. , Buller Gil , Tarara Julie M.
Published: February 2019

Grow tubes are sometimes used in blueberry (Vaccinium corymbosum L.) to establish plantings or replace dead plants in older fields. Two experiments were conducted at a commercial farm to evaluate the effect of various grow tubes used during planting establishment of highbush blueberry cultivars. The treatments in the first experiment were cultivar (‘Aurora’, ‘Elliott’, ‘Liberty’) and grow tube treatment (no tube, control; opaque cardboard tube in the first growing season; and opaque plastic tube in the first season or first through the second season). The treatments in the second experiment were cultivar (‘Aurora’, ‘Elliott’, ‘Liberty’, ‘Ozarkblue’) and grow tube treatment (control; translucent plastic; opaque plastic; and wire mesh tube over plants in the first growing season). The presence of a grow tube from spring to fall of the first growing season decreased crown dry weight (DW) by an average of 37% to 50% and root DW by 30% (all except translucent plastic in Expt. 2) and increased the aboveground:belowground DW ratio relative to the control by an average of 34% to 67%, depending on the experiment. Plants grown in tubes were taller, had a narrower canopy, and had fewer whips, likely a response to low light levels inside the tubes; the fewest whips were found in the opaque plastic or cardboard tubes and the most in the translucent plastic tube with an intermediate response in the wire mesh tube. Removal of grow tubes during the summer led to plant damage from sudden sun exposure. The opaque grow tubes (present in Year 1) reduced yield/plant in Year 2 for ‘Elliott’ and ‘Liberty’ (cardboard tube only) but not ‘Aurora’. Pruning plants to allow for limited early fruit production (≈0.6 kg/plant) in Year 2 did not reduce yield in Year 3 (≈2.7 kg/plant). Whereas grow tubes reduced root and crown growth in the first season, there appeared to be no longer-term adverse effect on aboveground plant growth or yield.
Production Costs of Field-grown Cercis canadensis L. ‘Forest Pansy’ Identified during Life Cycle Assessment Analysis
Authors: Hall Charles R. , Ingram Dewayne
Published: February 2019

University researchers have recently quantified the value of carbon sequestration provided by landscape trees (Ingram, 2012, 2013). However, no study to date has captured the economic costs of component horticultural systems while conducting a life cycle assessment of any green industry product. This study attempts to fill that void. The nursery production system modeled in this study was a field-grown, 5-cm (2-in) caliper Cercis canadensis ‘Forest Pansy’ in the Lower Midwest. Partial budgeting modeling procedures were also used to measure the sensitivity of related costs and potential benefits associated with short-run changes in cultural practices in the production systems analyzed (e.g., transport distance, post-harvest activities, fertilization rates, and plant mortality). Total variable costs for the seedling and liner stages combined amounted to $2.93 per liner, including $1.92 per liner for labor, $0.73 for materials, and $0.27 per liner for equipment use. The global warming potential (GWP) associated with the seedling and liner stages combined included 0.3123 kg of carbon dioxide equivalents (CO2e) for materials and 0.2228 kg CO2e for equipment use. Total farm-gate variable costs (the seedling, liner, and field production phases combined) amounted to $37.74 per marketable tree, comprised of $9.90 for labor, $21.11 for materials, and $6.73 for equipment use, respectively. However, post-harvest costs (e.g., transportation, transplanting, take-down, and disposal costs) added another $33.78 in labor costs and $27.08 in equipment costs to the farm-gate cost, yielding a total cost from seedling to end of tree life of $98.60. Of this, $43.68 was spent on labor, $21.11 spent on materials, and $33.81 spent on equipment use during the life cycle of each marketable tree. As per an earlier study, the life cycle GWP of the described redbud tree, including greenhouse gas emissions during production, transport, transplanting, take-down, and disposal, would be a negative 63 kg CO2e (Ingram et al., 2013). These combined data can be used to communicate to the consuming public the true (positive) value of trees in the landscape.
Evaluating Ethylene Sensitivity within the Family Solanaceae at Different Developmental Stages
Authors: Edelman Nichole F. , Jones Michelle L.
Published: February 2019

The family Solanaceae, which includes both important crop and ornamental species, is generally considered to have high sensitivity to ethylene. Our objectives were to evaluate ethylene sensitivity between accessions with the family Solanaceae and to determine whether similar sensitivity was observed in seedlings and mature plants. For the seedling evaluations, seeds were germinated and grown in the dark on filter paper saturated with 0 or 100 μM 1-aminocyclopropane-1-carboxylic acid (ACC; the immediate precursor to ethylene). The relative hypocotyl length at 100 μM ACC was compared with untreated control (0 μM) seedlings. Mature plants were treated with 0 or 10 μL·L−1 ethylene in the dark for 24 hours. Ethylene responses including flower abscission, flower senescence, and epinasty were observed and quantified. Seedlings and mature plants were classified as having no response, low, medium, or high ethylene sensitivity based on the severity of the ethylene responses observed. Sensitivity differences were observed among seedling, juvenile, and mature plants, and a range of ethylene responses and symptom severity was observed between accessions within a species. The majority of the accessions were classified as medium or high ethylene sensitivity at both the seedling and mature plant stages. Solanum melongena ‘Black Beauty’ (eggplant) had a low response to ethylene at the seedling stage and a high response at the mature plant stage, whereas Petunia ×hybrida ‘Daddy Orchid’ had a high response at the seedling stage and a low response at the mature plant stage. Peppers (Capsicum annum), tomatoes (Solanum lycopersicum), and tomatillos (Physalis ixocarpa) exhibited both floral and vegetative symptoms of ethylene damage, whereas calibrachoas (Calibrachoa ×hybrida), eggplants, nicotianas, and petunias exhibited only floral symptoms. The most common floral response to ethylene treatment was flower abscission, which was observed in almost all of the Solanum, Capsicum, and Nicotiana accessions. We consistently observed ethylene-induced epinasty in the genus Capsicum and in all of the Solanum except eggplant. Our results indicated that developmental stage influenced ethylene sensitivity, and there was not a consistent correlation between seedling and mature plant responses within the Solanaceae accessions that we evaluated.
Seasonal Performance and Spatial Heterogeneity of Soil Salt Ions in a Semiarid Orchard of Northwest China
Authors: Guo Quanen , Guo Tianwen , Ma Zhongming , Che Zongxian , Nan Lili , Wang Yiquan , Palta Jairo A. , Xiong Youcai
Published: February 2019

The relationship between spatial and temporal dynamics of major salt ions and their toxicology is still unclear, particularly in perennial orchard fields. A seasonal soil sampling was conducted from Apr. to Oct. 2011 in a salinized orchard soil in semiarid northwest China. Soil moisture content and concentrations of total soluble salt and eight salt ions were measured every 2 weeks in the soil at 0 to 2, 2 to 5, 5 to 10, 10 to 15, 15 to 20, 20 to 25, 25 to 40, 40 to 60, 60 to 80, and 80 to 120 cm during the growing period of apple trees. Soil moisture content decreased early in the growth season (Period 1) but with increasing rainfall in the middle of growing season (Period 2 and Period 3) and reached a maximum at late season (Period 4) at all depths. Soil salt concentration increased along with soil profile, particularly in the 60- to 120-cm soil layer at all periods. The highest soil salt level was observed in Period 4. The contents of HCO3–, Ca2+, and Mg2+ were almost uniform in all soil layers, but the contents of Cl–, SO42–, and Na+ increased with soil layer. The content of K+ decreased from the upper to the deeper layers of soil profile. The distribution of CO32– had a high temporal and spatial heterogeneity with soil depths and season. Analysis of the charge balance on positive and negative salt ions indicated that the horizontal movement of ions and the transfer of soil water were likely the driving factors affecting soil salinization. The movement of Na+ and Mg2+ ions in the top soil may be responsible for rhizospheric ions composition and toxin effect to restrain apple tree growth in the early growth period.
Environmental Variance and Broad-sense Heritability of Nut Traits in Japanese Chestnut Breeding
Authors: Nishio Sogo , Yamada Masahiko , Takada Norio , Kato Hidenori , Onoue Noriyuki , Sawamura Yutaka , Saito Toshihiro
Published: February 2019

We evaluated the nut harvesting date (NHD), nut weight (NW), pericarp splitting (PS), and infestation by insects (II) in eight cultivars/selections of Japanese chestnut, including a Japanese–Chinese hybrid, over 6 years. Data were analyzed by analysis of variance (without transformation for NHD, after log-transformation for NW and PS, and after square root transformation for II). The among-tree variance accounted for only 1.1% to 8.5% of the total variance. The variance component resulting from residual factors for the tree × year interaction and sampling errors was the largest component for NW, PS, and II, accounting for 46% to 54% of the total environmental variance. Because tree replication is costly and time-consuming in chestnut breeding, increasing the number of yearly repetitions is more efficient than increasing the number of tree replicates. Broad-sense heritability was 0.84 for NHD, 0.27 for NW, 0.48 for PS, and 0.17 for II in evaluations with one tree without yearly repetition. It increased to 0.91 for NHD, 0.40 for NW, 0.62 for PS, and 0.29 for II in evaluations with one tree in 2 years. For NHD, the heritabilities are sufficiently high to distinguish genetic differences among cultivars/selection. In contrast, the low heritability of II suggests that this trait should not be evaluated with an emphasis on the initial selection stage but rather with an emphasis on the secondary selection stage based on testing at several locations with a large number of yearly and tree replications.
Effect of Two-week High-temperature Treatment on Flower Quality and Abscission of Rosa L. ‘Belinda’s Dream’ and ‘RADrazz’ (KnockOut®) under Controlled Growing Environments
Authors: Greyvenstein Ockert , Pemberton Brent , Starman Terri , Niu Genhua , Byrne David
Published: February 2019

The decline in sales of garden roses can, in part, be attributed to the lack of well-adapted cultivars. Successful selection for any trait requires an accurate phenotyping protocol. Apart from field screening, a protocol for phenotyping high-temperature tolerance in garden roses is yet to be established. An experiment was conducted to determine the stage of development when flowers were most sensitive to high-temperature stress. Liners of Rosa L. ‘Belinda’s Dream (BD) and the Knock Out® rose ‘RADrazz’ (KO) were planted in a soilless medium and grown in a greenhouse. Established plants were pruned retaining several nodes with leaves on two main shoots and treatments started. The experiment was conducted in growth chambers held at either 24/17 °C (control) or 36/28 °C (stress) day/night temperatures. Six time and duration temperature treatments included 8 weeks of continuous control conditions, 8 weeks of continuous stress conditions, and four sequential 2-week high-temperature shock treatments. Continuously stressed plants flowered in the least amount of days but did not differ from the continuous control-treated plants based on nonlinear thermal unit accumulation until flowering. Both cultivars had a 70% reduction in flower dry weight under continuous stress conditions. Flowers were most sensitive to high-temperature stress at the visible bud stage, which corresponds to Weeks 5 to 6 and Weeks 7 to 8 for BD and Weeks 3 to 4 and Weeks 5 to 6 for KO, respectively. KO was more resistant to flower abscission than BD when treated at the visible bud stage, but no difference in flower dry weight reduction between BD and KO was found. The number of vegetative nodes to the flower was unaffected by treatment and differed between the cultivars.
Landscape Performance and Fruiting of Nine Heavenly Bamboo Selections Grown in Northern and Southern Florida
Authors: Wilson Sandra B. , Knox Gary W. , Deng Zhanao , Nolan Keona L. , Aldrich James
Published: February 2019

A wild-type selection of heavenly bamboo (Nandina domestica) and eight cultivars were evaluated in northern and southern Florida for 144 weeks. Onset of flowering generally began by April and May in southern Florida and 4 to 8 weeks later in northern Florida. Fruit was first noted 4 to 8 weeks after most cultivars began flowering. Landscape performance and fruit production varied widely among taxa and location. ‘AKA’, ‘Firehouse’, ‘Firepower’, and ‘Firestorm’ heavenly bamboo did not flower or fruit in either location. Greater plant growth, survival, and fruiting were observed in northern Florida than in southern Florida. In both locations, the wild-type form of heavenly bamboo produced more fruit than ‘Alba’, ‘Gulf Stream’, ‘Monfar’, and ‘Moyer’s Red’. Seed viability was fairly consistent among fruiting cultivars, ranging from 69% to 89%. Nuclear DNA content and ploidy analysis indicated that all nine nandina cultivars were diploids, suggesting that tetraploidy is not the genetic cause of the non-fruiting trait in ‘AKA’, ‘Firehouse’, ‘Firepower’, and ‘Firestorm’. Results of this study offer insight into future non-invasive heavenly bamboo breeding efforts and emphasize the importance of cultivar and geographic distinctions when regarding the invasive status of a species.
Deficit Irrigation Affects Growth, Yield, Vitamin C Content, and Irrigation Water Use Efficiency of Hot Pepper Grown in Soilless Culture
Authors: Ahmed Adel F. , Yu Hongjun , Yang Xueyong , Jiang Weijie
Published: February 2019

Hot pepper (Capsicum annuum cv. Battle) was grown in a 1:1 v/v sand-to-cotton stalk compost and subjected to four irrigation treatments: 100% of water-holding capacity (control) and 85%, 70%, and 55% of water-holding capacity, which were considered deficit irrigation treatments. All treatments were given to the plants at the first day of transplanting and continued during the whole growing season. Our results demonstrated that deficit irrigation had a negative effect on plant growth and yield. Increasing irrigation deficiency exhibited a reduction in vegetative growth, fruit parameters, and yield and a nonsignificant increase in irrigation water use efficiency and a corresponding reduction in the amount of irrigation water. Vitamin C content in fruit was significantly decreased by deficit irrigation treatments at various ripening stages. Water-holding capacity of 100% and 85%, respectively, resulted in the highest content of vitamin C obtained at the ripening stage. We concluded that ‘Battle’ hot pepper is sensitive to deficit irrigation. Supplying this cultivar with water at 85% of water-holding capacity could be a practical irrigation technique for high value of vitamin C production as well as saving a large amount of water, which outweighs the decrease in total fresh yield of fruit, especially in areas suffering from water shortage.
Growth of Impatiens, Petunia, Salvia, and Tomato Seedlings under Blue, Green, and Red Light-emitting Diodes
Authors: Wollaeger Heidi Marie , Runkle Erik S.
Published: February 2019

Plant growth and architecture are regulated in part by light quality. We performed experiments to better understand how young plants acclimate to blue (B), green (G), and red (R) light and how those responses can be used to produce plants with desirable morphological characteristics. We grew seedlings of impatiens (Impatiens walleriana), salvia (Salvia splendens), petunia (Petunia ×hybrida), and tomato (Solanum lycopersicum) under six sole-source light-emitting diode (LED) treatments or one cool-white fluorescent treatment that each delivered a photosynthetic photon flux (PPF) of 160 µmol·m−2·s–1 for 18 h·d−1. Leaf number was similar among treatments, but plants grown under 25% or greater B light were 41% to 57% shorter than those under only R light. Plants under R light had 47% to 130% greater leaf area and 48% to 112% greater fresh shoot weight than plants grown under treatments with 25% or greater B. Plants grown under only R had a fresh shoot weight similar to that of those grown under fluorescent light for all species except tomato. In impatiens, flower bud number at harvest generally increased with B light, whereas in tomato, the number of leaflets with intumescences decreased with B light. This research discusses how light quality can be manipulated for desired growth characteristics of young plants, which is important in the production of specialty crops such as ornamentals, herbs, and microgreens.
The Effect of Substrate Moisture Content on Growth and Physiological Responses of Two Landscape Roses (Rosa hybrida L.)
Authors: Cai Xiaoya , Starman Terri , Niu Genhua , Hall Charles
Published: February 2019

A greenhouse study was conducted to quantify the irrigation requirements of two rose (Rosa hybrida L.) cultivars, RADrazz and Belinda’s Dream, which are widely valued for their ease of maintenance in landscapes, grown at four constant volumetric substrate moisture contents (SMCs) of 10%, 20%, 30%, and 40%. In both cultivars, there were no differences in growth and physiological responses between 30% and 40% SMC. In ‘RADrazz’, shoot dry weight (DW) was reduced by 25% and 86%, root DW was reduced by 27% and 71%, and flower number was reduced by 27% and 86% at 20% and 10% SMC, respectively, compared with 30% SMC. Midday leaf water potential (ψ), photosynthesis (Pn), stomatal conductance (gS), and transpiration (E) were highest at 30% and 40% SMC and they were lowest at 10% SMC. In ‘Belinda’s Dream’, shoot DW was reduced by 30% and 87%, root DW was reduced by 35% and 81%, and flower number was reduced by 42% and 75% at 20% and 10% SMC, respectively, compared with 30% SMC. Midday ψ was least negative at 40% SMC, whereas it was most negative at 10% SMC. There were no significant differences in midday ψ between 20% and 30% SMC. Pn, gS, and E were highest at 30% and 40% SMC and lowest at 10% SMC. In summary, plants at 30% and 40% SMC maintained the highest shoot and root DW, flower number, midday ψ, Pn, gS, and E. Water applied at 30% and 20% SMC was reduced by 31% and 70% compared with 40% SMC with excellent performance at 30% SMC and acceptable growth and quality at 20% SMC. The 10% SMC led to significant growth reduction, poor quality, and 25% mortality.
Consumer Preferences for Longevity Information and Guarantees on Cut Flower Arrangements
Authors: Rihn Alicia L. , Yue Chengyan , Hall Charles , Behe Bridget K.
Published: February 2019

Choice experiments were conducted to explore the market potential or value added when using longevity information and guarantees on cut flower arrangements in the retail setting. The objective of our study was to determine consumer preferences and willingness to pay for different vase life longevities and guarantees on cut flower arrangements. The choice experiment data were collected using online surveys with 525 U.S. consumers in July 2011. The choice experiment scenarios included single species or mixed species cut flower arrangements with varying vase life longevity (5 to 7 days, 8 to 10 days, 11 to 14 days), presence or absence of vase life longevity guarantee, personal or gift use, and price range ($7.99 to $11.99, $34.99 to $43.99). Two types of arrangements were used in the experiment, mixed arrangements consisting of different species of cut flowers and single-species arrangements consisting of six red roses plus a filler flower. We analyzed the data with a mixed logit model and Ward’s linkage cluster analysis. As expected, participants were willing to pay higher prices for cut flower arrangements with longer vase life longevity. The presence of a guarantee improved participants’ probability of selecting the corresponding cut flower arrangement. Using Ward’s linkage cluster analysis, we found there were three distinct consumer clusters: guarantee seekers (49% of the sample), value-conscious consumers (31%), and spenders (20%). Among the three clusters, guarantee seekers were more likely to select cut flower arrangements with guarantees. Value-conscious consumers were interested in both guarantees and longevity indicators. Spenders were least interested in longevity indicators and guarantees. We conclude floral retailers could successfully implement the use of longevity indicators and guarantees to increase consumer interest in cut flowers and generate profits. Target marketing strategies could then be developed by floral retailers to attract different consumer clusters.
Calcium Ameliorates the Tolerance of Lisianthus [Eustoma grandiflorum (Raf.) Shinn.] to Alkalinity in Irrigation Water
Authors: Gómez-Pérez Lucina , Valdez-Aguilar Luis Alonso , Sandoval-Rangel Alberto , Benavides-Mendoza Adalberto , Mendoza-Villarreal Rosalinda , Castillo-González Ana María
Published: February 2019

Irrigation water high in alkalinity can severely compromise the growth and marketability of ornamental plants. In the present study we investigated the response of lisianthus to increased calcium (Ca) when irrigated with solutions containing high levels of bicarbonate (HCO3−)-induced alkalinity. Alkalinity in irrigation water reduced the growth of lisianthus; however, plants supplemented with an increased concentration of Ca at alkalinity levels from 4 to 7 meq·L−1 of HCO3– exhibited improved growth and dry mass (DM) accumulation or were not detrimentally affected, demonstrating that Ca contributes to the increase of the tolerance of lisianthus to alkalinity. Supplementary Ca did maintain a high stomatal conductance (gS) and transpiration rate when alkalinity was at 4 meq·L−1, which explained the lower water potential in young leaves. Plants irrigated with solutions containing supplementary Ca had higher total DM, which was associated with a higher gS; however, when conductance was higher than 0.280 cm·s−1, like in plants with no supplementary Ca, DM tended to decrease. At a typical Ca concentration, there was a disruption on stomata functioning as gS and transpiration rate increased, which was associated with a reduction in shoot potassium (K). Calcium ameliorated the uptake of K when alkalinity was 4 meq·L−1 by allowing a less marked reduction in shoot K concentration. Chlorophyll was reduced by increasing alkalinity as a result of a decrease in shoot iron (Fe); however, supplementary Ca also contributed in increasing plant tolerance to alkalinity at 4 meq·L−1 by sustaining a high shoot Fe concentration. Supplementary Ca increased catalase and peroxidase activities, indicating that lisianthus responded to the stress by enhancing the activity of these enzymes to reduce oxidative damage.
Effect of Fertilizer Rate on Plant Growth and Leachate Nutrient Content during Production of Sedum-vegetated Green Roof Modules
Authors: Clark Mary Jane , Zheng Youbin
Published: February 2019

With the increasing popularity of green roofs, efficient green roof plant production is required to adequately supply the industry. Applying fertilizer at an appropriate rate can provide sufficient plant nutrition for efficient plant growth without excess nutrient leaching into the environment. This study compared rates of controlled-release fertilizer (CRF) applied to green roof modules at the plant production stage to determine an optimum CRF rate for encouraging plant growth and vegetative coverage while minimizing the amount and concentration of leached nutrients. After sedum cuttings were rooted in green roof modules on 29 Aug. 2011, CRF was applied at 5, 10, 15, 20, 25, 30, and 35 g·m−2 nitrogen (N) and modules were compared with an unfertilized control. Plant growth, vegetative coverage, and overall appearance requirements were met after fertilization at 20 g·m−2 N. Modules fertilized at less than 20 g·m−2 N did not reach the target proportion coverage during the study. When fertilized at 20 g·m−2 N, green roof modules reached the target proportion coverage after 240 days of growth. Differences in leachate volumes were observed among treatments 35 days after fertilization and fertilization at 20 g·m−2 N minimized leaching of most nutrients. Therefore, with the green roof module system used in this study, an application of 20 g·m−2 N for green roof module or sedum cutting production is an optimum CRF rate for plant growth and vegetative coverage while minimizing negative environmental impacts.
Consumer-assisted Selection of Blueberry Fruit Quality Traits
Authors: Gilbert Jessica L. , Olmstead James W. , Colquhoun Thomas A. , Levin Laura A. , Clark David G. , Moskowitz Howard R.
Published: February 2019

Blueberries are a high-value fruit that has experienced extraordinary growth in consumption in the past decade. Maintaining this growing market requires an understanding of the current market and its potential for expansion. To assay the impact of 36 specific blueberry sensory and psychological traits on consumer interest, a blueberry fruit quality study was constructed using techniques that allow many features to be tested in an analysis by combining specifics from different categories that describe a product. Individual traits that most impact the likelihood of fruit purchase were identified. Sweet and intense blueberry flavor yielded the most positive purchase interest, whereas bad texture attributes such as seediness were the most detrimental to interest. It was also possible to define two interest segments within the survey population that shared similar responses to particular experimentally assayed traits. The larger segment of the sample population (61%) was most interested in the aspects of blueberry flavor, whereas the second segment of respondents (39%) was most influenced by health aspects commonly associated with blueberry fruit consumption. Both segments responded negatively to bad texture. This study suggests that breeders and producers should exploit genetic and environmental variables that contribute to improved blueberry flavor and that marketing strategies to sell blueberry cultivars of superior flavor may be appropriate.
Stomatal Development and Associated Photosynthetic Characteristics of Watermelon (Citrullus lanatus) Plug Seedlings during Light Storage
Authors: Duan Qingqing , Lin Ye , Jiang Wu , Huang Danfeng
Published: February 2019

Illumination during storage was proven to extend the storability of seedlings, but little attention has been given to the underlying mechanism. To determine how light conditions affect photosynthetic status in watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] plug seedlings, differences of stomatal development and relative photosynthetic characteristics of expanding new leaves when stored for 8 days at 15 °C in light at a photosynthetic photon flux (PPF) of 15 μmol·m−2·s−1 or darkness were investigated. The stomatal density (SD) increased with time to a peak and then decreased from the start of storage in light to the subsequent transplantation. Dark storage retarded the stomatal development and delayed the appearance of the peak of SD. Compared with those under dark storage, light-stored seedlings showed significantly higher SD and stomatal index (SI) in leaves accompanied by higher maximal photochemical efficiency of PSII (Fv/Fm) and quantum yield of PSII (ΦPSII). During storage in darkness, Fv/Fm and ΦPSII declined steeply with increasing storage duration but recovered gradually to reach the same level of those in light at the fourth day after transplanting. Seedlings stored in light for 8 days showed higher net photosynthesis rate (Pn), stomatal conductance (gS), intercellular CO2 concentration (Ci), and transpiration rate (Tr) than in darkness. The post-storage recovery of Pn, gS, and Tr were closely related to the SI, which ensured the fast recovery of photosynthesis during the early stage of transplanting. In agreement with the change of SD, no differences in Pn, gS, Ci, and Tr between light and dark storage were observed after 8 days of transplantation. Seedlings stored in light appeared vigorous and the shoot dry weight was significantly higher than that of dark-stored ones. Although seedlings in dark storage had a poor appearance during storage, they showed inhibited regrowth potentials during the subsequent transplanting stage. This study exhibited that light in short-term storage contributed to maintaining stomatal development as well as photosynthetic efficiency in watermelon, which could also extend to post-storage for ensuring the transplant quality of seedlings after removal from storage.
“Late Winter/Early Spring” Xylem Sap Characteristics Influence Pecan Crop Load
Authors: Wood Bruce W.
Published: February 2019

Alternate bearing (AB) by individual trees is a major biological problem faced by pecan [Carya illinoinensis (Wangenh.) K. Koch] nut producers. The linkage between flowering and subsequent cropload with xylem sap characteristics at the time of floral bud swelling and expansion is unknown. Multiyear field studies of mature ‘Cheyenne’ and ‘Moneymaker’ trees, in “on” or “off” phases of AB, were evaluated regarding this linkage. Xylem sap flowing from trunks of ‘Cheyenne’ trees just before, and at the time of, budbreak (i.e., “late winter/early spring”) consisted of a variety of simple sugars. These were hexoses (fructose and glucose), a disaccharide (sucrose), polysaccharides (raffinose and stachyose), and sugar alcohols (xylitol and sorbitol). Sucrose was the overwhelmingly dominant simple carbohydrate at this growth stage, comprising 55% to 75% of the total molar composition, regardless of tree bearing status or sampling time during the seasonal transition from late winter to early spring as buds swell, break, and begin to produce shoots and flowers. Both sap flow volume and concentration of individual carbohydrates were much greater in “on” phase than “off” phase trees. “On” phase xylem sap contained ≈19.9-fold more sucrose than sap from “off” phase trees. The concentration of all sap carbohydrates was much greater at flow inception, declining quickly as buds transition from “bud swell” to “budbreak” and subsequent “shoot growth.” Depending on crop year, individual “on” phase ‘Cheyenne’ trees (≈25 years old) exhibited flow volumes 5.5- to 20.2-fold greater than “off” phase trees. In-shell nut yield by both ‘Cheyenne’ and ‘Moneymaker’ trees (110 years old) increased hyperbolically with increasing “late winter/early spring” sap flow volume. Sap flow from ‘Cheyenne’ and ‘Moneymaker’ resulted in near maximum nut yield when flow volume per xylem tap peaked was at ≈10 L/tree and ≈15 L/tree, respectively, over a 16-day sampling period. These findings are suggestive that sucrose, and possibly other simple carbohydrates, moving acropetally toward axillary bud meristems of shoots during “late winter/early spring” at about the time of “bud swelling” influences the final phase of floral development and therefore subsequent cropload.
Comparative Physiological Analysis of Salinity Effects in Six Olive Genotypes
Authors: Aparicio Carolina , Urrestarazu Miguel , Cordovilla María del Pilar
Published: February 2019

Changes caused by NaCl salinity on growth, gas exchange, chemical composition, and oxidative stress symptoms have been measured in six olive (Olea europaea L.) cultivars (Casta Cabra, Cornicabra, Frantoio, Ocal, Picual, and Picudo) grown in nutrient solution in a growth chamber pot experiment. Six-month-old plants were transplanted to a sand–perlite culture and irrigated with half-strength Hoagland nutrient solution containing 0 and 200 mm NaCl for 12 weeks. Salinity significantly depressed growth and leaf gas exchange, but to a different degree in each cultivar, Picudo was the cultivar that showed less growth inhibition. The effectiveness of Na+ exclusion mechanism in the roots differed significantly among studied cultivars, working effectively in ‘Ocal’ and ‘Picudo’ and being less efficient in ‘Picual’. Furthermore, ‘Picudo’ showed the ability to maintain the concentration of leaf K+ under the stress condition. ‘Ocal’ accumulated phenolic compounds and did not reduce carotenoid or total thiol concentration under saline stress. Between the cultivars studied, ‘Picudo’ and ‘Ocal’ were the most tolerant.
Effect of a Physical Barrier on Adult Emergence and Egg Survival Associated with the Fungus Gnat, Bradysia sp. nr. coprophila (Diptera: Sciaridae), under Laboratory Conditions
Authors: Raudenbush Amy L. , Cloyd Raymond A. , Echegaray Erik R.
Published: February 2019

This study was conducted to assess the direct and indirect effects of Growstones™ aggregates, which are made from recycled glass, on fungus gnat, Bradysia sp. nr. coprophila (Diptera: Sciaridae), adult emergence, female egg-laying capacity, and egg survival. A series of experiments were performed under laboratory conditions to evaluate the effect of different sizes (2.0 to 10.0 mm) of Growstones™ aggregates, layer thicknesses (0.63 to 3.18 cm), and the use of the biological control agent, the rove beetle, Dalotia coriaria, along with different thicknesses (1.27 and 3.18 cm) of small Growstones™ aggregates on fungus gnat adult emergence. For each experiment, Growstones™ aggregates were applied to the surface of the growing medium in 473-mL polypropylene deli containers. This study demonstrated that the thickest (3.18 cm) layer of small (2.0 mm) Growstones™ aggregates significantly reduced or delayed the emergence of fungus gnat adults. In addition, the thickest layer of small Growstones™ aggregates may have indirectly affected egg survival. However, the use of Growstones™ along with rove beetle adults did not significantly reduce fungus gnat adult emergence.
Isolation and Identification of the Fungus Colletotrichum cordylinicola Causing Anthracnose Disease on Cordyline fruticosa in Florida
Authors: Sharma Kalpana , Goss Erica , van Bruggen Ariena H.C.
Published: February 2019

Imported Hawaiian Ti Cordyline plants (Cordyline fruticosa) ‘Tipsy Pink’ with anthracnose symptoms were found in Gainesville, FL, in 2013. A Colletotrichum spp. was isolated from symptomatic Cordyline plants and Koch’s postulates were fulfilled. The colony color on acidified potato dextrose agar (PDA) was orange with slight shades of pink and light gray aerial mycelium. Sclerotia and setae were absent. Conidia were one-celled, hyaline, guttulate, and cylindrical with round ends. The mean size of the conidia was 14.7 × 5.0 μm and ranged from 12.5 to 17.5 × 3.8 to 7.5 μm. Polymerase chain reaction (PCR) was performed on the internal transcribed space (ITS) and 28S rDNA regions of the isolate, and the sequences were compared with those of Colletotrichum spp. in GenBank. Sequence analysis indicated that the isolate belonged to C. cordylinicola. This is the first report of C. cordylinicola on C. fruticosa in Florida and the United States. Anthracnose symptoms developed on healthy-looking, latently infected Hawaiian Ti plants within 2 to 3 months, and 34% to 44% of the non-inoculated plants became diseased in 3 months. Reactions of several Dracaena and Cordyline species and varieties including Hawaiian Ti to C. cordylinicola were assessed. Several Dracaena and Cordyline species and varieties including Hawaiian Ti exhibited a differential response when inoculated with C. cordylinicola, but none of them was resistant. Hawaiian Ti was the most and lucky bamboo (Dracaena sanderiana) the least susceptible [area under the disease progress curve (AUDPC) = 71 vs. 10 cm2·d–1] to C. cordylinicola. The slope of the log-transformed disease progress regression line was steepest on Hawaiian Ti and D. marginata variety ‘Colorama’ plants, intermediate on varieties ‘Tarzan’ and ‘Magenta’, and least on lucky bamboo [slope = 0.046, 0.044, 0.036, and 0.034 vs. 0.020 log(cm2 + 1)/d, respectively, with a mean se of 0.0006].
Production of Colchicine-induced Autotetraploids in Pummelo (Citrus grandis Osbeck) through Indirect Organogenesis
Authors: Grosser Jude W. , Kainth Divya , Dutt Manjul
Published: February 2019

Colchicine-induced stable autotetraploid plants were recovered through indirect organogenesis from stem sections of in vitro-grown zygotic seedlings of pink/red-fleshed pummelo (Citrus grandis L. Osbeck) selections cybrid Hirado Buntan (C-HBP) (pink), 5-1-99-3 (dark pink), and HBJL-5 (red), all derived from Hirado Buntan pink pummelo. Multiple shoot induction was achieved through indirect organogenesis from the callus produced from the cut ends of the treated explants. Ploidy levels of regenerated plantlets were determined through flow cytometry at a stage when recovered shoots had one to two expanded leaves. Recovered tetraploids proved to be stable after 2 years in the field. As expected, higher colchicine concentrations and treatment durations decreased the survival rates of the regenerated plantlets. Colchicine concentrations of 0.05% and 0.1% produced the most tetraploids; of the 19 total tetraploids produced, 10 were produced from the treatment with a colchicine concentration of 0.1% and six were produced from treatment with a concentration of 0.05%. After flowering, these stable pink/red-fleshed tetraploid plants generated should be useful as breeding parents in our grapefruit/pummelo improvement program, especially if any show canker tolerance or reduced furanocoumarins. Use of monoembryonic tetraploids in interploid citrus crosses eliminates the need for embryo rescue to recover seedless triploid progeny; this research expands our pool of available high-quality monoembryonic tetraploid parents.
Semi-sterilized Tissue Culture for Rapid Propagation of Grapevines (Vitis vinifera L.) Using Immature Cuttings
Authors: Shan Fucheng , Seaton Kevin
Published: February 2019

Rapid expansion of grapevine plantings in many parts of the world has led to increased demand for desirable planting stocks. In countries that rely on importing new varieties and have strict quarantine rules, such as Australia, vines need to stay under quarantine for ≈2 years before they are released, at which time there is very limited wood available. Hence, rapid expansion of propagating stock after release is the key to multiplying up new varieties. A novel method, referred to as Semi-sterilized Tissue Culture (SSTC) using immature single-node cuttings, was established and evaluated as a way of rapid expansion of grapevine (Vitis vinifera L.) planting stock. In the SSTC method, immature single-node cuttings were surface-sterilized using methylated spirits and then cultured in the root pulsing medium [1/2 Murashige and Skoog (MS) medium supplemented with 40 μM indole-3-butyric acid (IBA)] for 24 hours. They were then planted in sterilized aerobic rooting medium (sphagnum peat:coarse river sand:perlite = 0.5:1:2) and cultured in a tissue culture room for ≈4 weeks for root initiation and development. The rooted immature single-node cuttings were then transferred to normal propagation beds in a greenhouse and potted on for acclimatization. Tube stock generated by SSTC easily acclimatized with a 15 times higher root strike rate than cutting propagation. It also took at least 50% less time than fully sterilized micropropagation methods to produce planting stocks. The advantages of the SSTC method are that it can be conducted under semisterilized conditions, avoiding degeneration and bacterial contamination problems encountered in micropropagation methods. By removing the time-consuming steps of the explant establishment, proliferation, and maintenance in vitro, the propagation process was simplified compared with conventional sterile tissue culture procedures. The SSTC procedure removed the need for high operator skill levels, reducing expense and allowing easier commercial adoption.
Genetic Diversity of Wild Peach (Prunus mira Koehne kov et. kpst) from Different Altitudes in the Tibetan Plateau by Pollen Morphous and RAPD Markers
Authors: Guan Fachun , Wang Shiping , Li Rongqin , Peng Mu , Meng Fanjuan
Published: February 2019

To analyze the evolutionary level of Prunus mira Koehne (Prunus mira Koehne Kov et. Kpst), 15 kinds of pollen grains from five altitudes were observed using a scanning electron microscope (SEM). This study demonstrates that pollen morphous P. mira has high variation; specifically, individuals from higher altitudes are much more evolved than those from lower altitudes. This is the first time the pollen morphology of P. mira has been systematically illustrated. Furthermore, 12 random amplified polymorphic DNA (RAPD) primers generated clear and repeatable bands among all individuals based on RAPD; 107 bands ranging from 200 bp to 2000 bp were generated with an average of 8.92 bands per primer. Thus, the RAPD technique proved to be a powerful tool to reveal variation on P. mira. This study provides comprehensive information for genetic diversity of P. mira from different altitudes.
Evaluation of a Commercial Extract of Giant Knotweed on Drought Tolerance of Impatiens
Authors: Cochran Diana R. , Harkess Richard L. , Knight Patricia R. , Tomaso-Peterson Maria , Blythe Eugene K. , Gilliam Charles H.
Published: February 2019

Regalia®, a commercial extract of giant knotweed [Fallopia sachalinensis F. Schmidt (synonyms: Reynoutria sachalinensis (F. Schmidt) Nakai, Polygonum sachalinense F. Schmidt, Tiniaria sachalinesis (F. Schmidt) Janch.)], was evaluated for its potential to enhance drought tolerance of container-grown impatiens (Impatiens walleriana Hook. f. ‘Super Elfin XP White’). In two separate experiments, Regalia® was foliar-applied once a week for 4 weeks at four different rates (0, 5, 10, or 15 mL·L−1). In Expt. 1, Regalia® was applied to impatiens grown under three target substrate volumetric water contents (TVWCs): 85%, 55%, or 25%. In Expt. 2, Regalia® was applied to impatiens watered with 1, 3, or 6 days between waterings (DBW). In Expt. 1, root dry weight (RDW) of impatiens receiving applications of Regalia® at the 0.5× rate was greater compared with the 0.0× rate across all TVWCs. Additionally, soluble protein content was greater after Regalia® application at the 0.5×, 1.0×, or 1.5× rates compared with the 0.0× rate for plants grown at 55% TVWC. In Expt. 2, leaf greenness (SPAD) and leaf net photosynthetic rate (Pn) were greater with Regalia® applied at the 0.5× and 1.0× rates compared with the 0.0× rate, respectively. Soluble protein content was greater in impatiens treated with Regalia® at the 1.5× rate and 1 DBW and the 0.5× rate with 3 DBW compared with the 0.0× rate with 1 or 3 DBW. However, there was no indication that impatiens grown under different moisture levels had increased drought tolerance after application of Regalia®.
An Economic Assessment of the Impact of Huanglongbing on Citrus Tree Plantings in Florida
Authors: Spreen Thomas H. , Baldwin Jean-Paul , Futch Stephen H.
Published: February 2019

Huanglongbing (HLB) was first discovered in Florida in 2005. It can now be found in all counties in the state where commercial citrus production takes place. HLB is a bacterial disease that is transmitted by the Asiatic citrus psyllid. HLB negatively affects citrus producers in several ways, including reduced yield, increased grove maintenance costs, and increased tree mortality. The research presented in this article suggests that another consequence of HLB is its adverse effect on the willingness of producers to invest in new plantings. Reduced plantings imply reduced fruit production in the future.