bluuebunny/crossref_metadata_2025 huggingface dataset:
Physicochemical Fruit Characteristics of Cornelian Cherry (Cornus mas L.) Genotypes from Serbia
Authors: Bijelić Sandra M. , Gološin Branislava R. , Ninić Todorović Jelena I. , Cerović Slobodan B. , Popović Boris M.
Published: February 2019

High variability in the natural population of the cornelian cherry in the region of Serbia is an important genetic potential for use in breeding programs. In the course of a 2-year study, significant differences have been noted in morphometric characteristics (fruit weight and flesh to stone ratio were 2.11 to 6.71 g and 78.52% to 88.74%, respectively) and chemical composition of the mesocarp [content of total dry matter (TSC), soluble solid content (SSC), total acids, total and reducing sugars, sucrose, Ca-pectates, vitamin C, proteins, cellulose, anthocyanins, and tannins was recorded 18.26% to 33.39%, 17.40% to 32.37%, 1.62% to 3.75%, 11.77% to 26.30%, 9.50% to 24.07%, 0.38% to 3.25%, 0.32% to 2.44%, 14.56 to 39.22 mg/100 g fruit, 0.20% to 2.71%, 0.43% to 0.95%, 35.63 to 126.53 mg/100 g fruit, and 0.56% to 1.47%, respectively] of 18 cornelian cherry genotypes from Vojvodina Province. The data were compared and analyzed by multivariate techniques [correlation matrix calculation and principal component analysis (PCA)]. The highest positive correlation was found between TSC–SSC and total sugar–reducing sugar (r > 0.95). Using PCA, different genotypes of cornelian cherry can be grouped in clusters based on similarity in their chemical composition.
Evaluation of Experimental Broccoli Hybrids Developed for Summer Production in the Eastern United States
Authors: Farnham Mark W. , Björkman Thomas
Published: February 2019

Broccoli (Brassica oleracea L. Italica Group) is a vegetable crop requiring relatively cool conditions (e.g., less than 23 °C) to induce and maintain vernalization and to allow normal floral and head development to proceed. In general, this requirement is a major limiting factor to production of broccoli in eastern states where growing seasons are often interrupted by high temperature spikes. The USDA, ARS, U.S. Vegetable Laboratory (USVL) is conducting a program to breed broccoli varieties adapted to summer conditions of the southeastern United States. The goal of the current study was to compare performance of three experimental broccoli hybrids from that program with some commonly raised commercial hybrids (‘Packman’, ‘Marathon’, ‘Arcadia’, ‘Greenbelt’, ‘Patron’, and ‘Gypsy’) by conducting trials in summer environments as well as in more conventional growing environments (e.g., in fall). All hybrids produced marketable heads with high quality ratings in fall field trials (2006, 2007, and 2008). Under the high temperatures that were characteristic of the summer (2007, 2008, and 2009) trials in South Carolina, the commercial hybrids ‘Marathon’, ‘Greenbelt’, ‘Arcadia’, and ‘Patron’ failed to produce broccoli heads at all. The remaining hybrids produced heads with similar mean head mass, stem diameter, and bead size in South Carolina summer trials. However, the three experimental hybrids produced marketable quality heads, but ‘Gypsy’ and ‘Packman’ did not. The primary flaws in ‘Gypsy’ and ‘Packman’ heads were increased yellow color, flattening of the dome, increased roughness, and non-uniformity of bead size. In New York trials, all tested hybrids developed heads, but ‘Packman’ and ‘Marathon’ produced relatively poor-quality heads when maturing in summer and better quality heads when maturing in the fall. The experimental hybrids exhibited more consistent quality across different maturity times in the New York tests. Results of this research indicate that broccoli response to summer conditions of the eastern United States is dependent on the cultivar grown. Many cultivars are not adapted to extreme summer conditions of the Southeast because they will not be effectively vernalized and will therefore not head. Others such as ‘Gypsy’ and ‘Packman’ will head, but non-uniform bud development results in a rough-appearing curd in which flower buds are at various stages of development. The experimental hybrids that are single crosses of inbreds selected for adaptation to southeastern summer conditions represent a unique class of broccoli hybrids that combine early maturity and the ability to produce heads under summer conditions of South Carolina. Additional tests of these latter hybrids in New York indicate that they may be generally adapted to summer environments of the eastern United States.
Substrate Amendment Effects on Potted Plant Production and Dry Weight Partition of Lantana camara
Authors: Nektarios Panayiotis A. , Kastritsis Serafim , Ntoulas Nikolaos , Tsiotsiopoulou Panayiota
Published: February 2019

Ten substrates were evaluated for their capacity to promote the growth of potted Lantana camara. The substrates consisted of different volumetric proportions of sandy loam soil (S), peat (P), perlite (Per), and urea formaldehyde resin foam (UFRF referred to as F), the latter in an effort to substitute peat use in horticulture. The substrates studied were: S, S60:P40, S40:P60, S60:F40, S40:F60, P60:F40, P40:F60, S40:P30:Per30, S40:F30:Per30, and P50:Per50. Measurements included: 1) substrate physical and chemical characteristics such as water characteristic curves, bulk density, total porosity, easily available water, and pH; 2) biometric measurements such as shoot length and number and number of flowers; and 3) determination of main and lateral stems, leaf, flower, and root dry weights. Results showed that substrates P60:F40 and P40:F60 retained excessive water in all tensions, whereas substrate P50:Per50 exhibited increased water retention at saturation that was quickly reduced after 10 cm of tension. The non-amended soil (S) had the least water retention capacity and proved to be a slow-draining substrate. Supplementation either with peat or peat and perlite (S60:P40, S40:P60, and S40:P30:Per30) significantly increased water retention in the soil-based substrates. Soil-based substrates supplemented with UFRF retained less water compared with peat-amended soil-based substrates. Concerning plant growth, Lantana plants growing in the UFRF-amended substrates were unable to recover from frost injury and their evaluation was interrupted after winter as a result of total plant loss. The injury was attributed to the reduction of plant growth in UFRF-supplemented substrates before the occurrence of frost stress events. Soil-based substrates (S, S60:P40, S40:P60, and S40:P30:Per30) provided greater shoot growth, which was almost twofold compared with substrate P50:Per50. Substrate S40:P30:Per30 produced the most lateral shoots and flowers over the whole study period, whereas S40:P60 produced the most flowers during the summer. Dry weights of both stem and lateral stems followed a similar pattern with the biometric measurements. However the non-amended soil (S) produced the highest leaf and root dry weights followed by substrates S60:P40 and S40:P60. It was concluded that both substrates S40:P60 and S40:P30:Per30 can successfully be used for Lantana nursery production as a result of their decreased bulk density, increased water retention capacity, adequate porosity, and promotion of shoot growth and flowering. Despite its high bulk density, substrate S could be used in the production of Lantana plants for landscape use as a result of the increased root production.
The Acidification of Sphagnum Moss Substrate during Phalaenopsis Cultivation
Authors: Yen Wan-Yi , Alex Chang Yao-Chien , Wang Yin-Tung
Published: February 2019

Sphagnum moss has been used as the major substrate for cultivating Phalaenopsis spp. in China, Japan, and Taiwan. With a lengthened duration of cultivation, the pH of the moss gradually declines. It is not understood what causes this decline in substrate pH. Using the vegetatively propagated Phal. Sogo Yukidian ‘V3’, this study investigated if substrate, fertilization, light, and plant roots could be the cause of pH decline in the substrate. The results showed that, although increasing fertilizer concentration resulted in a low initial pH (pH measured by the pour-through technique at first fertilization), fertilization itself was not the primary cause of the long-term pH decline. Regardless of whether the sphagnum moss was fertilized, the pH of the substrate without plants increased as time progressed, whereas the pH of the substrate in which living Phalaenopsis plants were growing declined with time. Although the magnitude and course of pH decline were different in various substrates, the pH of sphagnum moss, artificial textile fiber, and pine bark substrates in which living plants were growing declined with time. Whether the substrate was exposed to light (clear pots) or not (opaque pots) had no effect on substrate pH, indicating that algae were not a factor in pH decline. Therefore, the roots of Phalaenopsis may be the major contributor to substrate pH decline during production.
Physiological Advantages of Grafted Watermelon (Citrullus lanatus) Seedlings under Low-temperature Storage in Darkness
Authors: Ding Ming , Bie Beibei , Jiang Wu , Duan Qingqing , Du Hongmei , Huang Danfeng
Published: February 2019

Low-temperature storage in darkness is usually used for preserving seedlings for a short period. To investigate whether grafted watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] seedlings are superior to non-grafted ones under low-temperature storage in darkness and to study their physiological differences during storage, watermelon (‘Zaojia 84-24’) scions were grafted to pumpkin (Cucurbita moschata Duch. ‘Zhuangshi’) rootstocks. Carbohydrate levels; chlorophyll and malondialdehyde contents; the activities of superoxide dismutase, catalase, and peroxidase; and photochemical efficiency were assayed during 6 days of storage at 15 °C in darkness. After that, seedlings were transplanted into an artificial climate chamber. The net photosynthetic rate and stomatal conductance (gS) were measured on the first and third days after transplanting. The results showed that the grafted watermelon seedlings had more soluble sugar and chlorophyll contents, higher activities of antioxidant enzymes, and less malondialdehyde content than the non-grafted ones after 6 days of storage. In addition, low-temperature storage in darkness damaged the photosystem II of non-grafted watermelon seedlings more than that of grafted ones. After transplanting, grafted seedlings had a higher net photosynthetic rate. The results suggest that grafted watermelon seedlings were more suitable for the low-temperature storage in darkness than the non-grafted ones.
In Vitro Regeneration through Direct Organogenesis from Protocorms of Oncidium tigrinum Llave & Lex. (Orchidaceae), an Endemic and Threatened Mexican Species
Authors: Mata-Rosas Martín , Baltazar-García Rosario Julieta , Chávez-Avila Victor Manuel
Published: February 2019

A protocol for in vitro propagation from protocorms of Oncidium tigrinum Llave & Lex., a threatened species distributed in Mexico and highly appreciated as an ornamental, was developed. Two different explants, entire protocorms and longitudinal halves of protocorms, were used. In addition, the effect of two different culture media, Murashige and Skoog (MS) and modified Knudson (KCm), supplemented with N6-benzyladenine (BA) (0, 0.5, 1, 2, 3, and 5 mg·L−1) and/or α-naphthaleneacetic acid (NAA) at 0, 0.1, and 0.5 mg·L−1 was investigated. Adventitious shoot formation by direct organogenesis was obtained in all treatments; in some cases, the formation of protocorm-like bodies was induced. Shoot formation was greater for entire protocorms; the best treatment was MS medium containing at BA 1 to 2 mg·L−1 in combination with at NAA 0.1 mg·L−1. The average height of shoots was three times greater in MS medium than in KCm medium. Subculturing individual shoots in MS medium without plant growth regulators, but with 1 g·L−1 activated charcoal, allowed further development and rooting. An ex vitro survival rate of almost 100% was achieved. This study represents a comprehensive application for propagation, conservation, and sustainable use of this valuable natural resource.
Growth Characteristics and Ginsenosides Production of In Vitro Tissues of American Ginseng, Panax quinquefolius L.
Authors: Obae Samuel G. , Klandorf Hillar , West Todd P.
Published: February 2019

American ginseng (Panax quinquefolius L.) is an economically important perennial herb whose root is highly valued in the Orient for its medicinal properties. The root grows into different morphotypes, notably “bulb or round” (BLB), “man-like” (ML), and “straight or stick” (STK), and these roots are valued differently by consumers because they are assumed to have different medicinal qualities. Currently, wild-growing and field-cultivated plants are the major source of ginseng roots available on the market; however, because of declining wild populations and the lengthy time required in field cultivation to produce marketable root size, in vitro propagation has been sought as a potential alternative to supply ginseng's bioactive components (ginsenosides). The objectives of this study were: 1) to evaluate how explants derived from the three root morphotypes (lines), BLB, ML, and STK, responded to in vitro callus induction and growth; 2) to compare ginsenosides profiles and content among stock roots and their callus tissues; and 3) to assess genetic diversity among stock roots. Root explants were cultured on solid Murashige and Skoog medium supplemented with 1.0 mg·L−1 2,4-D and 0.1 mg·L−1 kinetin for 12 weeks. Explants from the three lines exhibited varied callus induction response, growth, and ginsenosides production. Explants from the ML line induced callus faster, were prolific in growth, and accumulated more biomass compared with explants from BLB and STK lines. ML lines (both stock roots and calluses) had significantly higher total ginsenosides content than either BLB or STK lines. There were positive and highly significant correlations between total ginsenosides content of stock roots and callus tissues and callus dry weights. Ginsenosides profiles varied among lines. ML lines exclusively exhibited low Rg1/high Re ginsenosides profiles, whereas BLB and STK lines exhibited mixed Rg1/Re profiles. Random amplified polymorphic DNA (RAPD) analysis of stock roots showed genetic variations within and among lines; however, there was no clear link between DNA bands or band patterns and ginsenoside profiles or content. Overall, these results showed that ginsenoside content of stock roots directly influenced callus induction response and subsequent callus biomass and ginsenoside content. These results provide information that could be useful in selecting suitable stock plants for in vitro production of ginsenosides. Also, because there are no ginseng cultivars, this information would be useful in advancing breeding efforts toward selecting superior cultivars for this species. Chemical names used: 2,4-dichlorophenoxyacetic acid (2,4-D)
Differential Nutrient Uptake and Its Transport in Tomato Plants on Different Fertilizer Regimens
Authors: Kinoshita Takafumi , Masuda Masaharu
Published: February 2019

Application of controlled-release fertilizer (CRF) to a root-proof capillary wick irrigation system (a type of subirrigation method) has both economical and environmental benefits, because it does not require any equipment for fertigation and minimizes water leaching. In this study, we examined the effects of CRF and liquid fertilizer (LF), a conventional fertigation method, on fruit production and nutrient uptake and transport in forcing tomato cultures for harvesting 15 trusses per plant from October to June. No significant difference was noted in marketable fruit yield between CRF- and LF-treated plants. The quantity of nutrient uptake per plant and per fruit yield was lower with CRF than with LF, indicating that nutrients were used more efficiently for fruit production in plants grown with CRF. Analysis of the volume and mineral concentrations of xylem exudates indicated that the amount of nutrients absorbed was greater with LF than with CRF, particularly after the tenth truss was harvested. Mineral concentrations in the substrate solution of CRF-treated plants were initially higher than those in the substrate solution of LF-treated plants but extremely low after the second truss was harvested, whereas mineral concentrations in the xylem exudates were similar in CRF and LF plants until the eighth truss was harvested. Thus, the difference in mineral concentrations between the xylem exudates and substrate solution was much larger in the case of CRF than in the case of LF, indicating that the plants absorbed the bulk of nutrients immediately after their release from the CRF surface. Therefore, CRF is suitable in this system, because it combines high fruit production with high nutrient utilization efficiency.
Irrigation Frequency and Amount Effect on Root Extension during Sod Establishment of Warm-season Grasses
Authors: Sinclair Thomas R. , Schreffler Andrew , Wherley Benjamin , Dukes Michael D.
Published: February 2019

Although root development is critical in the establishment of turfgrass sod, there appears to be no information on the response of root development during sod establishment to the frequency and amount of irrigation. Two alternate hypotheses for the root development response are that 1) frequent and high amounts of irrigation are needed to support sod growth and root development; and 2) deficit irrigation encourages more rapid and deeper rooting. The objective of this study was to observe root development of four warm-season turfgrasses subjected to various frequencies and amounts of irrigation. Root extension of the grasses was observed directly in soil contained in 90-cm tall, clear acrylic columns. No difference in root development was observed for any of the grasses among irrigation frequency treatments of daily, twice weekly, and once weekly. There were differences in response to the amount of irrigation. Zoysiagrass root development was maximal at the full amount of irrigation (35 mm per week). On the other hand, St. Augustinegrass, bermudagrass, and bahiagrass required deficit irrigation of only 13 mm water per week to achieve full root development. The results of this study showed that each of the two hypotheses were appropriate depending on the specific species.
Genotypic and Phenotypic Variation among Pepper Accessions Resistant to Phytophthora capsici
Authors: McGregor Cecilia , Waters Vickie , Nambeesan Savithri , MacLean Dan , Candole Byron L. , Conner Patrick
Published: February 2019

Developing high levels of resistance to Phytophthora blight (Phytophthora capsici Leonian) of pepper (Capsicum annuum L.) is a goal of many pepper breeding programs. Genetic diversity and plant characteristics were evaluated on 21 pepper accessions previously identified as having high levels of Phytophthora root rot resistance. Accessions were evaluated for plant height, fruit size and shape, pericarp thickness, and pungency. Accessions varied widely from very unadapted material to those with more obvious breeding potential. Genetic diversity among the accessions was estimated using 22 simple sequence repeat (SSR) loci. Phytophthora capsici resistant accessions were identified that were not closely related to previously described sources of resistance. This information will allow breeders and researchers to further identify and incorporate novel sources of resistance to P. capsici into breeding programs. Accessions PI 201237 and PI 640532 appear to have the most potential for introgressing P. capcisi resistance into bell pepper.
Growth, Gas Exchange, Foliar Nitrogen Content, and Water Use of Subirrigated and Overhead-irrigated Populus tremuloides Michx. Seedlings
Authors: Davis Anthony S. , Aghai Matthew M. , Pinto Jeremiah R. , Apostol Kent G.
Published: February 2019

Because limitations on water used by container nurseries has become commonplace, nursery growers will have to improve irrigation management. Subirrigation systems may provide an alternative to overhead irrigation systems by mitigating groundwater pollution and excessive water consumption. Seedling growth, gas exchange, leaf nitrogen (N) content, and water use were compared between overhead irrigation and subirrigation systems used to produce trembling aspen (Populus tremuloides Michx.) seedlings. After 3 months of nursery culture, subirrigation resulted in a 45% reduction in water use compared with overhead irrigation. At the end of the growing season, subirrigated seedlings had lower net photosynthetic assimilation, stomatal conductance (gS), and leaf area, indicating earlier leaf senescence. However, no significant differences were detected for biomass, leaf N content, height, root-collar diameter, or root volume. Thus, we suggest that subirrigation systems offer promising potential for aspen seedling production when compared with overhead irrigation given the added benefits of water conservation and reduced nutrient runoff. Continuing emphasis on refinement such as determining the plant water requirements based on growth and development as well as container configuration is needed so that the intended benefits of using subirrigation can be realized.
Alternative Organic Fungicides for Apple Scab Management and Their Non-target Effects
Authors: Cromwell Morgan L. , Berkett Lorraine P. , Darby Heather M. , Ashikaga Takamaru
Published: February 2019

A major challenge in organic apple production in humid production regions is the available fungicide options for apple scab [Venturia inaequalis (Cooke) Wint.] management. The standard sulfur/lime sulfur fungicide program can be injurious to the applicator, the apple ecosystem, and the apple tree itself. The objectives of this study were to compare the efficacy of three potential alternative fungicides [potassium bicarbonate (PB), neem oil (NO), and Bacillus subtilis (Bs)] with a standard organic sulfur/lime sulfur (SLS) fungicide program and a non-treated control (NTC) for management of apple scab and to evaluate potential non-target impacts on pest and beneficial arthropod populations. The five treatments were applied to ‘Empire’ trees arranged in a completely randomized design with five single-tree replications at the University of Vermont Horticultural Research Center in South Burlington, VT. Fungicides were applied with a handgun to drip using maximum label rates. Applications began on 26 Apr. 2007 and 23 Apr. 2008 and continued on approximately a weekly schedule through the end of June and then every 2 weeks through 23 July 2007 and 17 July 2008, respectively. The standard SLS treatment resulted in the best scab control in both years. The NO treatment reduced foliar and fruit scab compared with the NTC and the other alternatives at the end of the 2008 growing season and had insecticidal activity. However, both the SLS and NO treatments had disadvantages, including phytotoxic burning on the fruit and/or significantly more russeting on the fruit at harvest. In each year of the study, one or more of the alternative treatments, particularly Bs, resulted in higher insect damage than the non-fungicide-treated control. This research showed that PB, Bs, and NO do not offer advantages over the standard SLS fungicide program in organic apple production and in some cases offer distinct disadvantages in terms of non-target impacts. Chemical names used: potassium bicarbonate (Armicarb “O”), Bacillus subtilis (Serenade MAX), neem oil (Trilogy), sulfur (Microthiol Sulfur)/lime sulfur (Miller Lime Sulfur)
Hot Water Treatment and Pre-processing Storage Reduce Browning Development in Fresh-cut Potato Slices
Authors: Tsouvaltzis Pavlos , Deltsidis Angelos , Brecht Jeffrey K.
Published: February 2019

Enzymatic browning is a serious quality limitation for fresh-cut potato (Solanum tuberosum L.) that has been successfully controlled by heat treatment in other commodities. The use of brief heat treatments with 55 °C water (HW) applied to ‘Russet Burbank’ tubers for 10, 20, 30, or 40 min before cutting was evaluated for potential implementation to control tissue browning. After heat treatment, tubers were held at 20 °C for 0 or 1 day before peeling and slicing. Control tubers were not previously immersed in hot water. All slices were placed in perforated plastic bags and stored at 5 °C for 6 days. Exposure to HW for 30 or 40 min caused severe heat injury. Browning developed in all treatments as indicated by color measurements and discoloration scores (index of extent of discolored area on the slice surface) during storage. Hot water treatment for 10 min best reduced browning, but only when treated tubers were stored intact for 1 day at 20 °C before cutting, as indicated by discoloration scores and changes in L*, a*, and Ho values, which were significantly different from either the control or the other HW treatments. Generally, the severe browning that developed in control slices during storage was associated with significant increases of 25% and 71% in phenolic content and antioxidant capacity, respectively. On the other hand, phenolic synthesis increased by only 6.25% to 13.2% in HW-treated slices during storage and polyphenoloxidase (PPO) activity was 24% to 31% lower compared with the activity before storage. Immersing potato tubers in 55 °C water for 10 to 20 min followed by storage at 20 °C for 1 day before processing reduced but did not prevent browning of peeled slices in terms of color changes and discoloration score. There was no significant correlation between browning and phenolic content or PPO activity.
Models to Describe Cycas micronesica Leaf and Strobili Development
Authors: Marler Thomas E. , Dongol Nirmala
Published: February 2019

Cycas micronesica leaf and strobili expansion patterns were measured in three locations and seasons on Guam and then were fitted with non-linear models to evaluate the use of the parameters for informing management decisions. All growth curves except for microstrobili height conformed to a negative exponential function. Microstrobili height development could not be fitted with any traditional linear or non-linear function, so spline models were used to smooth the effect of elapsed days. Leaf and leaflet expansion patterns were influenced by habitat and season, indicating development of the vegetative organ is plastic. In contrast, the models that described development of megasporophyll length, microstrobili height, and microstrobili diameter were not influenced by habitat or season. Moreover, seed diameter developmental patterns were only minimally influenced by location. These results indicate developmental patterns of the reproductive structures were primarily constitutive. We have demonstrated two empirical approaches to fitting models of Cycas micronesica organ growth and development and that both methods are useful for determining the influence of spatial or temporal factors in the timing of organ development. This approach may be used to inform horticultural or conservation questions of other rare cycad species.
Should You Blame the Weather? The Influence of Weather Parameters, Month, and Day of the Week on Spring Herbaceous Plant Sales in the U.S. Midwest
Authors: Behe Bridget K. , Getter Kristin L. , Yue Chengyan
Published: February 2019

Sales of many products, including umbrellas and skis, depend on weather conditions. Anecdotal evidence from plant producers and retailers indicate that their sales are also heavily reliant on weather conditions. Still, little published literature documents weather's influence on plant sales. Daily sales data of herbs, vegetables, and flowering annuals were acquired from 42 retail stores in Indiana, Ohio, and Michigan (which were divided into four regions based on zip code). The multisite Midwestern retailer sells food and household items year-round but seasonally sells plants in outdoor covered areas. The data were analyzed using time series regression and the model produced significant results, but the amount of variance captured by region, weather parameters, month, and day of the week was only ≈40% for herbs and vegetables (H+V) and flowering annual plants (FA). Precipitation amount had no effect on sales of H+V and FA, likely because the plants were merchandised under cover. Increasing units of sunshine lowered sales by 1%. H+V sales were greatest in the southeast Michigan region but for FA were greatest in the mid-Michigan region. Lower minimum air temperature reduced sales for sales of both H+V and FA, whereas higher maximum air temperature increased sales. Sales were substantially higher in May and lower in June and July compared with April. Sales were higher in 2009 than 2007. Compared with Wednesday, sales were higher everyday and highest on Saturday. Day of week and month had a greater impact on sales than did any weather parameter. Thus, region, weather, month, and weekday do influence daily plant sales but did not account for most of the variability in 42 U.S. midwestern retail outlets.
The Papaya in Hawai’i
Authors: Manshardt Richard
Published: February 2019

Dioecious papayas were introduced shortly after Cook’s 1778 discovery of Hawai’i but were supplanted for commercial uses by the gynodioecious solo papaya brought from the Caribbean in 1911. Growth of a local papaya industry based on hermaphrodite plants was enabled by research allowing prediction of seedling sex segregation and by development of cultivars with high quality, symmetrical fruits free of stamen carpellody, and carpel abortion. The industry expanded into export markets after 1940 by providing an alternative use for land and expertise abandoned by declining sugar plantations, adopting a cultivar capable of tolerating long-distance shipping, developing postharvest technology to overcome fruit fly quarantine restrictions, capitalizing on a growing tourism industry for marketing and air freight logistics, and forming an organization to support industry growth. In recent years, the industry has withstood pest and disease challenges by adopting innovative technologies that have allowed high-quality solo papayas to continue to participate in an increasingly competitive export market.
Effect of Loosening Agent Sprays on the Efficiency of the Mechanical Harvesting of ‘Arbequina’ Olives
Authors: Ninot Antònia , Romero Agustí , Tous Joan , Batlle Ignasi
Published: February 2019

The aim of this work was to evaluate the effect of ethephon (2-chloroethylphosponic acid), applied either alone or in combination with phosphorus compounds, on olive trees (Olea europaea L.) to improve the efficiency of mechanical harvesting. The trial was carried out in mature ‘Arbequina’ olive trees located in northeast Spain during the 2007 and 2008 olive crop seasons. In 2007, the olive trees were sprayed with 300 or 500 mg·L−1 of ethephon combined with two phosphoric formulations: monopotassium phosphate (MKP), at 15 g·L−1 or 30 g·L−1 and monoammonium phosphate at 15 g·L−1. In 2008 olive trees were sprayed with two ethephon concentrations (150 or 300 mg·L−1) in combination with 15 g·L−1 or 30 g·L−1 MKP or alone. Harvesting was performed with a commercial trunk shaker. Data were analyzed as a randomized complete block design with eight replications. Fruit removal force (FRF), ripeness index, fruit weight, natural drop, shaking efficiency (SE), leaf drop (LD), oil content, and bloom intensity of the next year’s bloom were measured. The trial treatments did not significantly affect ripeness index or oil content. Ethephon reduced FRF and increased shaking efficiency with significant differences. P compounds did not seem to affect FRF and LD. Small amounts of ethephon (150 mg·L−1) caused a large degree of fruit loosening (a 77% reduction in FRF at 11 days), which was sufficient to improve the efficiency of mechanical harvesting with minimal leaf drop.
Sodium Distribution in Salt-stressed Citrus Rootstock Seedlings
Authors: Gonzalez Pedro , Syvertsen James P. , Etxeberria Ed
Published: February 2019

Although citrus trees are considered relatively salt-sensitive, there are consistent differences in Na+ and Cl– tolerance among different citrus rootstocks. We grew uniform seedlings of rough lemon (RL) and the more Na+-tolerant Swingle citrumelo (SC) with and without 50 mm NaCl for 42 days. Salinity reduced leaf chlorophyll and plant transpiration rate (Ep) more in RL than SC. Confocal laser scanning analyses using the Na+-specific cell-permeant fluorescent probe CoroNa-Red revealed a higher capacity for Na+ sequestration in root tissue vacuoles of SC than in RL roots and that cell walls within the stele acted as Na+ traps. In leaves, however, RL had significantly higher Na+-dependent fluorescence than SC. Thus, the sequestration of Na+ in root tissue vacuoles and its immobilization by cell walls were key contributing mechanisms enabling SC leaves to maintain lower levels of Na+ than RL leaves. Examination of intracellular distribution of CoroNa-Green fluorescence in SC root protoplasts verified a vacuolar localization for Na+ in addition to the presence of a 2- to 6-μm unidentified endosomal compartment containing significantly higher Na+ concentrations.
Turfgrass Establishment from Polymer-coated Seed Under Saline Irrigation
Authors: Serena Matteo , Leinauer Bernd , Sallenave Rossana , Schiavon Marco , Maier Bernd
Published: February 2019

A study was conducted at New Mexico State University in Las Cruces, NM, in 2009 and 2010 to investigate the establishment of five turfgrass species {‘Barrister’ kentucky bluegrass [Poa pratensis L.], ‘Barvado’ tall fescue [Festuca arundinacea Schreb.], ‘Premier II’ perennial ryegrass [Lolium perenne L.], ‘Bargusto’ bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon. transvalensis Burtt-Davy], and ‘Sea Spray’ seashore paspalum [Paspalum vaginatum O. Swartz]} from coated and uncoated seed. The grasses were irrigated at 100% reference evapotranspiration (ET0) during fall, winter, and spring and at 120% ET0 during summer with either saline [electrical conductivity (EC) = 2.3 dS·m−1] or potable water (EC = 0.6 dS·m−1). Generally, seed coating did not affect seedling emergence negatively when irrigated with saline water. During fall, perennial ryegrass exhibited fastest emergence under both saline and potable irrigation and bermudagrass was the only grass to show greater emergence when irrigated with saline water. Perennial ryegrass and tall fescue were the fastest to emerge in spring, regardless of seed coating or water quality. Seed coating delayed early establishment (less than 50% coverage) but did not affect days to reach 95% coverage (DAS95). Bermudagrass and seashore paspalum required the most DAS95 when seeded in the fall; however, bermudagrass needed fewest DAS95 when seeded in the spring. All grasses established faster when seeded in spring compared with fall. Fall-seeded perennial ryegrass and kentucky bluegrass required similar DAS95, whereas kentucky bluegrass seeded in spring was slower to reach 95% coverage than perennial ryegrass. Saline water had no effect on establishment when grasses were sown in fall. Surprisingly, grasses established in spring and irrigated with saline water reached 95% coverage 26 days faster than plots irrigated with potable water. Moreover, the growing degree-day model used in this study did not produce similar values for the different air temperatures and irrigation water qualities.
Self-fertility Evaluations of Northern-adapted Rabbiteye Blueberry Hybrids
Authors: Ehlenfeldt Mark K. , Kramer Matthew
Published: February 2019

Rabbiteye blueberry hybrids that the U.S. Department of Agriculture, Agricultural Research Service (USDA-ARS) program has bred for northern adaptation are combinations of 6x V. ashei Reade, 6x V. constablaei Gray, 4x V. corymbosum L., and 2x V. darrowii Camp germplasm at the hexaploid level and are generally composed of 50% or greater V. ashei (rabbiteye) germplasm. Four northern-adapted rabbiteye (NRE) selections (US 1043, US 1045, US 1056, US 1057), four rabbiteye standards (‘Brightwell’, ‘Climax’, ‘Tifblue’, ‘Woodard’), two rabbiteye × V. constablaei derivatives (‘Little Giant’, ‘Snowflake’), and two highbush standards (‘Duke’, ‘Bluecrop’) were pollinated under greenhouse conditions with either self-pollen or a multicultivar, bulk-pollen mixture (appropriate to ploidy level and species) to determine the relative requirements for cross-pollination among NRE selections. Fruit set, berry weight, and seed set were subsequently evaluated. The results suggest that NRE selections, in general, exhibit cross-pollination needs intermediate to the parent types such that: rabbiteye > northern rabbiteye > highbush (i.e., rabbiteye has the lowest self-fertility and the greatest need for cross-pollination). Considerable variation existed among the NRE selections tested, which suggests that it might be possible to select clones with good levels of self-fertility, potentially equivalent to that of highbush blueberry.
The Effect of PcGA2ox Overexpression on Creeping Bentgrass (Agrostis stolonifera L.): Performance under Various Light Environments
Authors: Studzinska Aneta K. , Gardner David S. , Metzger James D. , Shetlar David , Harriman Robert , Danneberger T. Karl
Published: February 2019

Turf grown in shade exhibits increased stem elongation. Dwarfism could improve turfgrass quality by reducing elongation. The purpose of this study was to examine the effect of GA2-oxidase (GA2ox) overexpression on creeping bentgrass (Agrostis stolonifera L.) performance under restricted light conditions and low mowing heights. Greenhouse studies were conducted at The Ohio State University, Columbus, OH, from 1 Sept. to 31 Oct. in both 2008 and 2009. Two experimental lines, Ax6548 and Ax6549, transformed with CP4 EPSPS and PcGA2ox gene; and a nontransformed control (NTC) was subjected to four light environments: full sun, reduced red to far red light ratio (R:FR), neutral shade [reduced photosynthetic photon flux (PPF)], and canopy shade (reduced PPF and R:FR). Turf was evaluated every 10 days for color and percent coverage. GA2ox overexpression resulted in darker green color in both transgenic lines under all light treatments as compared with NTC plants. No differences in overall turfgrass coverage were noted in full sun conditions among the lines. A significant decrease in turf coverage occurred for all shade treatments regardless of line. However, Ax6549 decreased the least. Overall data indicated that GA2ox overexpression can improve quality of turfgrass under reduced light conditions.
Efficacy of Microbial Amendments on Vegetables in Greenhouse and Field Trials
Authors: Russo Vincent M. , Fish Wayne W.
Published: February 2019

Possible effects of microbe-containing amendments on vegetable development need clarification. Eight-week-old, organically grown seedlings of a bell, cv. Jupiter, and a non-pungent jalapeño, cv. Pace 105, pepper, both C. annuum L., were transplanted into pots containing an organic potting medium in a greenhouse experiments repeated over 2 years. Pots were fertilized with Neptune's Harvest®, a fish emulsion. One of eight amendments [Actinovate AG®, Bio Inoculant®, Bio-S.I.®, Compost Tea® (a decoction of biological material), Mpact®, ‘PMSLA and EO-12’®, Soil Activator®, Super Bio®] was applied at label rates and application timings. The control was Neptune's Harvest only. Three plants from each treatment were periodically harvested. Heights and total fresh and dry weights were determined. At a single terminal harvest, numbers and weights and chlorophyll, carotenoids, and vitamin C contents of fruit were determined. At the conclusion of the study the control, Bio-S.I., Compost Tea, PMSLA and EO-12, and Soil Activator generally produced bell pepper plants that were taller and heavier than those produced by Actinovate AG, Bio Inoculant, Mpact, and Super Bio. Numbers and weights of bell pepper fruit were not consistent over amendments or years. Heights for cv. Pace 105 plants treated with Compost Tea were similar to the control and taller than all others. Plant fresh weights for the control and Compost Tea were similar to that for Bio-S.I. and greater than all others. Dry weight, number and fresh weight of fruit and levels of chlorophylls, carotenoids, and vitamin C in fruit were unaffected. Compost Tea, PMSLA, and Soil Activator were tested in field trials in 2010 and 2011 using both peppers, cucumber (Cucumis sativus L.), cv. Earli Pik, and sweet corn (Zea mays var. rugosa Bonaf), cv. Incredible. Amendments provided no particular benefits under greenhouse or field conditions.
Tolerance to Fusarium Root Rot and Changes in Antioxidative Ability in Mycorrhizal Asparagus Plants
Authors: Mohammad Nahiyan Abu Shamim , Matsubara Yoh-ichi
Published: February 2019

Tolerance to fusarium root rot caused by Fusarium oxysporum f. sp. asparagi (Foa, MAFF305556 and N9-31) and the changes in antioxidative abilities in mycorrhizal asparagus (Asparagus officinalis L., cv. Welcome) plants were investigated. Asparagus plants were inoculated with arbuscular mycorrhizal fungus (AMF, Glomus sp. R10) and Foa was inoculated 10 weeks after AMF inoculation. AMF plants accumulated higher dry weight of ferns and roots than non-AMF plants before and after Foa inoculation. AMF colonization level reached more than 70% and no difference noted among the treatments. As for disease tolerance, non-AMF plants showed 100% in incidence of root rot and highest severity in both Foa isolates; the severity of symptom was relatively higher in MAFF305556 compared with N9-31. However, AMF plants showed lower severity than non-AMF plants in both Foa isolates. Before and after Foa inoculation, antioxidative abilities increased in most of the AMF plants than non-AMF in the following items: activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, and total contents of polyphenol and ascorbic acids. These results suggest that plant growth enhancement and tolerance to fusarium root rot appeared in mycorrhizal asparagus plants. In this case, the disease tolerance might be associated with the increase in antioxidative ability.
Reaction to Plasmodiophora brassicae Pathotype 6 in Lines of Brassica Vegetables, Wisconsin Fast Plants, and Canola
Authors: Adhikari Kalpana K.C. , McDonald Mary Ruth , Gossen Bruce D.
Published: February 2019

Field trials were conducted from 2008 to 2010 to assess the disease reaction to clubroot, caused by Plasmodiophora brassicae Woronin, in selected lines of Brassica spp., including short-season vegetable crops [Shanghai pak choy (B. rapa subsp. Chinensis var. communis)], Chinese flowering cabbage (B. rapa subsp. Chinensis var. utilis), and napa cabbage (B. rapa subsp. Pekinensis), the Rapid Cycling Brassica Collection (RCBC), also known as Wisconsin Fast Plants, and spring canola (B. napus). The trials were conducted on naturally infested soil with P. brassicae at the Muck Crops Research Station in Ontario, Canada, where pathotype 6 is predominant. Clubroot incidence and severity were higher in 2008 and 2010 compared with 2009. The lines of Shanghai pak choy and Chinese flowering cabbage were highly susceptible to clubroot, but each of the clubroot-resistant cultivars of napa cabbage, ‘Deneko’, ‘Bilko’, and ‘Yuki’, was highly resistant to pathotype 6. Among the RCBC lines, B. carinata and B. juncea were highly susceptible and could be used as susceptible models for further studies. Two RCBC lines, B. napus and R. sativus, were resistant to pathotype 6. Two of the canola cultivars, 46A76 and 46A65, were susceptible, but two others, ‘45H21’ and ‘Invigor 5020LL’, were highly resistant to pathotype 6. This difference in response can be exploited in future studies of clubroot reaction in canola.
Effects of Drip Irrigation Configuration and Rate on Yield and Fruit Quality of Young Highbush Blueberry Plants
Authors: Ehret David L. , Frey Brenda , Forge Tom , Helmer Tom , Bryla David R.
Published: February 2019

A 4-year study was conducted to establish the effects of drip irrigation configuration and rate on fruit yield and quality of young highbush blueberry plants (Vaccinium corymbosum L. ‘Duke’). Plants were grown in a silt loam soil on raised beds and were non-irrigated or irrigated using either one or two lines of suspended drip tape. Each line configuration had in-line emitters spaced every 0.3 or 0.45 m for a total of four drip configurations. Water was applied by each drip configuration at two rates, a moderate rate of 5 L/plant per irrigation event, and a heavy rate of 10 L/plant. The frequency of irrigation was guided by measurements of soil matric potential. Irrigation was applied each year, and plants were cropped beginning the second year after planting. Rainfall was above normal in the first 2 years of the study, and differences in soil moisture were most evident in the last 2 years, in which soil matric potential increased with irrigation volume. Neither the number of irrigation lines nor emitter spacing had an effect on yield or fruit quality. Yield was unaffected by irrigation rate until the fourth year after planting and was only higher when 5 L/plant was applied. The yield increase was the result of differences in fruit weight during the second of two harvests and was associated with delays in fruit maturation. Irrigation affected plant mineral concentrations but leaves and berries responded differently; affected minerals tended to decrease in leaves but increase in the fruit. Many irrigation-induced changes in fruit quality were evident 1 or 2 years before changes in yield. Higher irrigation volume increased fruit size and water content but reduced fruit firmness and soluble solids. Irrigation reduced fruit water loss during storage and thereby promoted longer shelf life. Irrigation also resulted in a change in anthocyanin composition in the fruit but did not affect antioxidants or total anthocyanin content.
Suppression of Pecan Scab by Nickel
Authors: Wood Bruce W. , Reilly Charles C. , Bock Clive H. , Hotchkiss Michael W.
Published: February 2019

The economic cost of pecan scab, caused by Fusicladium effusum G. Winter, can substantially limit profitability of pecan [Carya illinoinensis (Wangenh.) K. Koch] cultivation in humid environments. Laboratory, greenhouse, and field studies found nickel (Ni) to inhibit growth of F. effusum and reduce disease severity on fruit and foliage of orchard trees. Nickel was toxic to the fungus in vitro at concentrations applied to orchard trees, and Ni sprays reduced scab severity on foliage of pecan seedlings in greenhouse experiments. Host genotype appears to influence Ni efficacy with fruit tissue of cultivars of intermediate resistance (i.e., ‘Desirable’) being most responsive to treatment and those most susceptible to scab (i.e., ‘Wichita’ and ‘Apache’) being least responsive. Addition of Ni as a nutritional supplement applied in combination with fungicides applied as air-blast sprays to commercial orchards reduced severity of scab on both leaves and fruit depending on cultivar and date of disease assessment (e.g., scab severity on fruit was reduced by 6% to 52% on ‘Desirable’ in an orchard setting). Nickel-supplemented fungicide sprays to ‘Desirable’ trees in commercial orchards also increased fruit weight and kernel filling, apparently from improved disease control. Although the efficacy of Ni was typically much less than that of triphenyltin hydroxide (TPTH), a standard fungicide used in commercial orchards, Ni treatment of tree canopies for increasing tree Ni nutrition slightly lowered disease severity. These studies establish that foliar Ni use in orchards potentially reduces severity of scab on foliage and fruit in scab-prone environments. The inclusion of Ni with fungicides for management of pecan scab might reduce disease severity over that conferred by fungicide alone, especially if targeted cultivars possess at least a moderate degree of scab resistance. Similar benefit from Ni sprays might also occur in host–fungi interactions involving other crops.