bluuebunny/crossref_metadata_2025 huggingface dataset:
Duplication of the Phytoene Synthase Gene in the Carotenoid Biosynthetic Pathway of Watermelon
Authors: Bang Haejeen , Kim Sunggil , Leskovar Daniel I. , Davis Angela , King Stephen R.
Published: February 2019

Gene identification and characterization can be utilized for the identification of respective functions and their relationship to flesh color inheritance. Phytoene synthase (PSY), which converts two molecules of GGPP into phytoene, is the first committed step of the pathway. Previous phylogenetic analysis of PSY has indicated that PSY duplication is common in Poaceae, but rare in dicots. Degenerate PCR and RACE were used for PSY cloning. Three members of PSY gene family (PSY-A, PSY-B and PSY-C) were identified. PSY-A shared higher identity with PSY-C than PSY-B. PSYC shared 96% identity with melon PSY. PSY-C also showed a high homology with tomato PSY1, even higher than PSY-A and PSY-B. It showed a similar gene expression pattern, so we propose that PSY-C is a homologue to PSY1. RT-PCR analysis indicated that PSY-B has a different transcriptional behavior from PSY-A, similar to tomato PSY2. Therefore, PSY genes appear to be under different regulatory mechanisms. Deduced protein sequence of PSY1 or PSY2 between species has higher homology than between PSY1 and PSY2 within species. Phylogenetic analysis indicated that watermelon PSY gene family is very distantly related. Watermelon and carrot PSY gene families did not appear to cluster as closely as in Poaceae or tomato. This indicates that watermelon and carrot PSY genes are not conserved as much as PSY in tomato or Poaceae. There was no particular pattern in phylogenetic relationship of dicots. Poaceae PSY genes showed a clustering into a PSY1 group and PSY2 group. PSY duplication in watermelon provides additional evidence that PSY duplication may be a common phenomenon in dicots. They are likely to be duplicated evolutionarily a long time ago, possibly even prior to the evolution of monocot and dicot divergence.
Gene Expression Affecting Spider Mite Herbivory: A Comparison of Sulfur-dusted and Nondusted Grapevines
Authors: Poor Danielle
Published: February 2019

Sulfur application is a common practice in viticulture fungus control. This application has been suspected to increase grape susceptibility to spider mites. We hypothesize that sulfur may initiate a pathway that increases spider mite infection. RNA was isolated from grape leaves with various sulfur applications. Evaluation of genes being expressed will allow us to determine if sulfur application is regulating grape leaf defense mechanisms.
The Effects of Girdling on Root Respiration, Carbohydrate Concentration, and NaCl Uptake in Citrus Trees
Authors: Raveh Eran
Published: February 2019

Carbohydrates are the energy source for most root activities, including membrane maintenance and osmotic adjustment. Yet, the relationship between root carbohydrate status and selective sodium chloride uptake remains unknown. The following study examined the effects of root carbohydrate starvation due to girdling on sodium and chloride uptake in mature citrus trees. Trees were girdled during the spring or during the autumn, when girdling is known to have more dramatic affects. In spring-girdled trees, 4 days after girdling, root total carbohydrate and starch decreased by 25% and 30%, respectively. The decrease in root carbohydrates was followed by a 20% reduction in root respiration rate. Based on root mineral analysis, spring-girdled trees were characterized by having 42% more sodium and 30% more chloride. The effects of girdling on shoot xylem sap mineral concentration were similar to trends in root mineral status; xylem sap from spring-girdled trees had 43% more sodium and 22% more chloride. Leaf chloride concentration measured 6 months after girdling was 74% higher in girdled trees and reached toxicity levels (0.65% vs. 0.37% dry mass, for girdled and nongirdled trees, respectively). The differences in leaf sodium, however, were nonsignificant (0.14% vs. 0.13% dry mass, for girdled and nongirdled trees, respectively). In autumn-girdled trees, the effects on leaf sodium and chloride concentration were more dramatic. Leaves from autumn-girdled trees (sampled 10 months later) had about two times more sodium and about five times more chloride in comparison to nongirdled trees (0.39 % vs. 0.20% dry mass sodium and 1.02% vs. 0.22% dry mass chloride, respectively). The above results link root carbohydrate status and selective sodium or chloride uptake in citrus trees.
Fine Root Growth in Late-season `Valencia' Sweet Orange Trees Harvested by Trunk Shaker
Authors: Li Kuo-Tan , Syvertsen Jim , Burns Jackie
Published: February 2019

Mechanical harvesting using trunk shakers on late-season `Valencia' sweet orange [Citrus sinensis (L.) Osb.] trees can remove young fruit for the next crop and occasionally cause root exposure or severe bark scuffing on the trunk. To evaluate the effects of these physical injuries on fine root growth and lifespan, we installed minirhizotrons in the root zone of 15-year-old fruiting `Valencia' trees on Swingle citrumelo [C. paradise Macf. × Poncirus trifoliate (L.) Raf.] rootstocks. Images of roots against the minirhizotron tubes were captured biweekly with a custom-made video-DVD recorder system. Trees were harvested in early June by hand or with a linear-type trunk shaker in two consecutive years. Bark injury after trunk shaking was mimicked by removing part (42%) of the bark tissue from the main trunk with a sharp knife. Numbers of fine roots, root activity and lifespan as indexed by the color of the root, and the distribution of new fine roots after harvest were analyzed. Although root exposure was common with the normal operations during mechanical harvesting, few disturbances reached the major fine root zone. There was no clear correlation between root growth and trunk shaking with or without bark injury. The root system might benefit from less competition after the loss of young fruit from mechanical harvesting, as a greater availability of carbohydrates or other resources may compensate for any potential damage due to mechanical harvesting.
Using SSR Markers to Verify Crapemyrtle Hybrids
Authors: Rinehart Tim , Pounders Cecil , Scheffler Brian
Published: February 2019

Crapemyrtles (Lagerstroemia) are deciduous shrubs or trees with prolific summer flowers. Their popularity is due in large part to low maintenance requirements in sunny climates, wide range of growth habits, disease resistance, and bark characteristics, as well as having a long flowering period (up to 120 days). Once well-established, they are extremely tolerant to heat and drought. Lagerstroemia was first introduced to the southern U.S. from southeast Asia more than 150 years ago, and is comprised of at least 80 known species. Most modern cultivars are L. indica and L. fauriei hybrids. L. speciosa is a tropical crapemyrtle with very large flowers, but lacks cold hardiness. It is a vigorous plant, but only when grown in Hardiness zones 9 or 10. We recently established microsatellite markers for Lagerstroemia and evaluated their utility for verifying interspecific hybrids. Here we verify F1 hybrids between L. indica `Tonto', `Red River', and L. speciosa. We also genotyped two commercially available L. speciosa hybrids. Currently, we are using crapemyrtle SSRs for cultivar identification and germplasm conservation. Future research includes marker-assisted breeding to produce powdery mildew and flea beetle resistant cultivars, as well as improved growth habit and fall foliage color.
Determining Water Use and Crop Coefficients in Five Woody Ornamental Plants
Authors: Niu Genhua , Rodriguez Denise S. , Cabrera Raul I. , McKenney Cynthia , Mackay Wayne
Published: February 2019

Relatively little work has been done to determine the water requirements of ornamental plants. To meet this need, five woody ornamental species including Abelia grandiflora `Edward Goucher', Buddleia davidii `Burgundy', Ilex vomitoria `Pride of Houston', Euonymus japonica, and Nerium oleander `Hardy Pink' were investigated to determine their water use and crop coefficients. Parallel experiments were conducted by growing the shrubs both in 56-L (15 gal) drainage lysimeters and in aboveground 10-L containers. Water use per plant, crop coefficients, and overall growth parameters differed by species and culture system. Of the five species tested, Buddleia and Nerium had higher water use per plant in the lysimeters than in the containers. There was no significant difference in water use per plant for Abelia, Euonymus, and Ilex between the two culture systems. Crop coefficients and growth indices of Abelia, Euonymus, and Ilex were statistically similar between the two systems. The growth index of Buddleia and Nerium was much higher in the lysimeters than in the containers. Abelia and Euonymus had more growth in the containers than in the lysimeters while Ilex had slightly larger leaf area in the lysimeters than in the containers. The culture system did not affect the water use per unit leaf area of all species. Therefore, our results indicated that by quantifying the leaf area, the plant water use in the two culture systems is convertible.
Regulation of Starch Degradation in Mature Leaves of Transgenic Apple Trees with Decreased Sorbitol Synthesis
Authors: Zhou Rui , Cheng Lailiang , Dandekar Abhaya
Published: February 2019

Considering starch synthesis was enhanced in leaves of transgenic apple trees with decreased sorbitol synthesis, we hypothesized that starch degradation must be up-regulated correspondingly to maintain carbon supply to sink tissues. Compared with the untransformed control, mature leaves of the transgenic plants had a larger drop in starch concentration between dusk and pre-dawn, higher maltose concentration, and higher activities of two key enzymes in starch degradation: -amylase and cytosolic glucosyltransferase during the day and night. 14C-maltose and 14C-glucose were fed to the apple leaves to study the fate of starch breakdown products in the synthesis of sorbitol and sucrose. Under light, a larger proportion of both 14C-maltose and 14C-glucose were converted to sorbitol than to sucrose in the untransformed control, whereas conversion of 14C-maltose and 14C-glucose to sucrose predominated over that to sorbitol in the transgenic apple leaves. The leaf samples fed with 14C-maltose and 14C-glucose in the dark are still being analyzed, but it appears that sucrose is the main product in both the untransformed control and the transgenic plants. These results support the hypothesis that starch degradation is up-regulated in the transgenic plants.
Modeling Fruit Tree Architectural Growth, Source–Sink Interactions, and Physiology with L-PEACH
Authors: DeJong Ted M. , Favreau Romeo , Allen Mitch , Prusinkiewicz Przemyslaw
Published: February 2019

Modeling source–sink interactions and carbohydrate partitioning in plants requires a detailed model of plant architectural development, in which growth and function of each organ is modeled individually and carbohydrate transport among organs is modeled dynamically. L-PEACH is an L-system-based graphical simulation model that combines supply/demand concepts of carbon partitioning with an L-system model of tree architecture to create a distributed supply/demand system of carbon allocation within a growing tree. The whole plant is modeled as a branching network of sources and sinks, connected by conductive elements. An analogy to an electric network is used to calculate the flow and partitioning of carbohydrates between the individual components. The model can simulate multiple years of tree growth and be used to demonstrate effects of irrigation, crop load, and pruning on architectural development, tree growth, and carbon partitioning. Qualitative model outputs are viewed graphically as the tree “grows” on the computer screen while quantitative output data can be evaluated individually for each organ or collectively for an organ type using the MatLab software.
The Photoperiod Pathway in Fragaria (Rosaceae)
Authors: Stewart Philip J. , Winslow Ashley R. , Folta Kevin M.
Published: February 2019

The transition from vegetative growth to reproductive growth is carefully controlled by a number of independent signal transduction systems, one of which interprets photoperiod. Photoperiodic control of flowering time has been well-described in Arabidopsis and rice, revealing the presence of a generally common network of regulatory proteins. Timely and appropriate progression to flowering is critical to profitable production of cultivated strawberry (Fragaria ×ananassa), a species that includes long-day, short-day, and day-neutral cultivars. In an effort to characterize the photoperiodic flowering control mechanism in strawberry, the Fragaria orthologs of the photoperiod pathway genes were cloned and sequenced. Strawberry versions of Constans, Constans-like, Leafy, Flowering Locus T, and Suppressor of Constans Overexpression 1 were identified by screening cDNA libraries and through degenerate PCR approaches. Expression of these transcripts in short-day and day-neutral cultivars was tested under long and short photoperiods. Functional complementation of Arabidopsis mutants was performed where appropriate, alleles were identified, genetic linkage was determined where possible, and relationships between the strawberry genes and homologs from other species were studied. These trials define the mechanistic elements of an agriculturally important pathway in this valuable crop, and lays the foundation for transgenic studies in strawberry to manipulate the floral transition.
Effect of Cropload on Eastern European Grapevine Cultivars
Authors: Masabni Joseph , Kurtural S. Kaan , Wolfe Dwight , Smigell Chris
Published: February 2019

The effect of cropload (kg yield/kg pruning weight) on yield components and fruit composition of 17 eastern European grapevine cultivars was evaluated from 2000 to 2004 in a vineyard, at the research station in western Kentucky, characterized by a long and warm season. There was a cubic relationship between number of clusters retained per vine and the cropload (R2 = 0.6374, P < 0.0001). Similar relationship was evident between yield per vine and cropload (R2 = 0.5908, P < 0.0001). Of the observed variation in cluster weight, 28% was attributed to variation among predictions, based on the value of cropload in a quadratic relationship (P < 0.0001). As cropload increased, pruning weight per meter of row decreased (R2 = 0.4513, P < 0.0001). However, there was very little effect of cropload on the percentage of total soluble solids and juice pH measured at harvest. Optimum cropload values fell in between 13–18 (kg yield/kg pruning weight) depending upon cultivar evaluated, based on optimum ranges for pruning weight per meter of row for optimum vine balance in the lower Midwest.
Evaluating Hornfaced Bees (Osmia cornifrons) as Pollinators of Highbush Blueberry
Authors: West Todd P. , McCutcheon Thomas W.
Published: February 2019

The objective of this study was to investigate the use of hornfaced bees (Osmia cornifrons Radoszkowski) as a successful sustainable alternative for pollination of commercial highbush blueberry (Vaccinium corymbosum L.). The hornfaced bee is native to Japan and introduced to the United States in 1977 by the USDA. Hornfaced bees have been shown to be 300× more efficient in pollinating apples than honey bees. Hornfaced bees are active for 4–6 weeks (April to June), and then the adults die. The rest of the year (10 months), dormant hornfaced bees exist inside nest cells located in cardboard straws stored away from berry production areas. Currently, there are no reports on hornfaced bee use available for blueberry farmers. Five pollinator treatments were compared in 2005 including: hornedfaced bees; honey bees; bumble bees; natural pollinators; and no pollinators. Enclosed pollination cages were constructed around mature field-grown highbush blueberry plants to prevent mixing of pollinator treatments. Each cage contained a single pollinator treatment except for the natural pollinator treatment. The five pollinator treatments were replicated three times inside separate netted cages on the farm. Three branches per plant were randomly selected that had a minimum of five fruiting buds and blossom number recorded. After pollination occurred the cages were removed to allow the berries to ripen. Ripe fruit were picked weekly over the season (July to August), with the fruit from each sample being counted and weighed. Blossom number was compared to fruit number and weight to determine efficiency of pollination as a result of the pollinator treatments. The results showed that hornfaced bees pollinated blueberries as well as or better than the other pollinators.
(68) The Role of Proteins in Leaf Re-greening
Authors: Paparozzi Ellen T. , Widhalm Joshua R. , Conley M. Elizabeth
Published: February 2019

Common swedish ivy plants when exposed to nitrogen (N) stress display typical nitrogen deficiency symptoms such as reddening of stems and petioles and yellowing of leaves. When N levels are restored, leaves of swedish ivy plants will re-green without leaf loss. An experiment was conducted to determine how proteins change when leaves were re-greened after N deficiency. Cuttings of Plectranthus australis were rooted under mist and allowed to yellow. Plants were then potted up and fertilized with one of two treatments: complete nutrients with N at 150 ppm or complete nutrients with 0.8 ppm N. The experimental design was a randomized complete-block design with six blocks. Each block had the two N treatments and six plants per treatment. After 3–4 weeks, all plants in the 150-ppm N treatment had re-greened and leaf samples for protein analysis were taken. Plants in four of the six blocks were then switched to the other treatment. After leaves had re-greened once again, leaf samples were taken and the experiment was terminated. Two-dimensional polyacrylamide gel electrophoresis was used to compare the treatments. No obvious differences in protein absence or presence were noted. However, Rubisco appeared to be differentially expressed between the two treatments. 2-D gel analysis with subsequent Western blots showed that for most of the leaf samples, the large subunit of Rubisco (56kD) was quantitatively about 1.3 times more concentrated in the N-deficient plants and possibly modified. The small subunit (12kD) was not reliably detectable. Additional protein results for repeated leaf re-greening and the role Rubsico may play in leaf re-greening will be discussed.
(234) Aesculus Pollen Viability and Longevity under Frozen Storage
Authors: Chanon Ann M. , Jourdan Pablo S. , Scheerens Joseph C.
Published: February 2019

The genus Aesculus (buckeyes and/or horsechestnuts) is composed of 13 species and a number of interspecific hybrids. Pollen from 11 genotypes from five Aesculus species and the hybrid Aesculus ×carnea were used to develop an in-vitro germination test to evaluate pollen viability under various storage treatments. This test was optimized using samples of both fresh pollen and pollen that had been stored up to 1 year. The most effective medium contained 20% sucrose, 100 mg·L-1 H2BO3, 150 mg·L-1 Ca(NO3)2, and 1% agar. The highest germination percentage was observed at 15 °C across all storage treatments. Fresh pollen germinated in excess of 80% over a wide range of germination temperatures. Based on this, all specimens studied would be good pollen parents. The differences in pollen germination between storage at -20 and -80 °C were nonsignificant, but the duration of the storage period was highly significant. At 3 months, viability remained above 60% for four of the six species/hybrid tested. However, at 12 months, all pollen tested dropped below the threshold for good fruit set based on in-vitro pollen germination. Based on these observations, short-term pollen storage may permit crosses between parents with temporally separate flowering phenologies. However, conventional storage procedures are inadequate to maintain pollen collected from a male parent for crosses in subsequent growing seasons.
(237) Chemical Mutagenesis in Snapdragon (Antirrhinum majus)
Authors: Heffron Leslie , Blowers Alan , Korban Schuyler
Published: February 2019

Seeds of Antirrhinum majus (snapdragon), proprietary line OAK564, were treated with 0%, 0.10%, 0.25%, 0.5%, 0.75%, and 1.0% ethyl methanesulfonate (EMS) for 8, 10, and 12 h at room temperature. The experiment was replicated three times over time. Data were collected on percent seed germination, seedling survivability, and pollen viability to determine optimal conditions for induced mutagenesis in OAK564 seeds. In the pilot experiment, M1 seeds treated with 1.0% EMS for 12 h had the lowest seed germination rate among all 18 treatments. Based on this pilot experiment, a large-scale mutagenesis experiment was performed using three levels of EMS (0.5%, 0.75%, and 1.0%) for 10-h exposure period. Mutants were induced on all these treatments, and morphological changes in the M1 population were detected. These included dwarfism, chlorophyll deficiency, and leaf morphology abnormality. This indicated that the EMS treatments were successful in inducing mutations, and mutants were further characterized for morphological traits.
(86) Isolation and Molecular Characterization of Putative Ascorbate Peroxidase from Citrus
Authors: Kunta Madhurababu , del Rio H. Sonia , Louzada Eliezer
Published: February 2019

Reactive oxygen species (ROS) are continuously produced during the normal aerobic metabolism and also under environmental stress conditions. They are the major damaging factors to the photosynthetic machinery under stress conditions and need to be scavenged for the normal growth of the plant. Ascorbate peroxidase (APX) is the key enzyme in detoxifying H2O2, one of ROS from chloroplast and cytosol. A cDNA encoding a putative APXcit was isolated from mature `Dancy' tangerine (Citrus reticulata Blanco) juice vesicles using differential display reverse transcription-polymerase chain reaction (RT-PCR). Subsequently, full-length APXcit cDNA clone and genomic clone were obtained and sequenced. The full-length APXcit sequence is composed by 1082-bp nucleotides, including an open reading frame (ORF) of 753 bp, encoding a protein of 250 amino acids (27 kDa). The 5' un-translated region (UTR) of the APXcit gene consisted of 91 nucleotides and the 3' UTR consisted of 238 nucleotides. Homology search for APXcit at GenBank database showed high similarity to APX from several plant species.
(87) Molecular Characterization of Cold Acclimation in Poncirus and Citrus
Authors: Lang Ping , Zhang Can-kui , Dane Fenny , Meng Shasha , Ebel Robert , Singh Narendra
Published: February 2019

Commercial citrus species, some of the most important fruit crops worldwide, are sensitive to sub-freezing temperatures. Poncirus trifoliata, a species closely related to commercial citrus and tolerant to –30 °C, has been used in breeding programs or as a rootstock to impart greater freeze tolerance. Gene expression of P. trifoliata and C. unshiu (Satsuma mandarin) were investigated and compared under slow and fast cold-acclimation regimes. The mRNA differential display-polymerase chain reaction (DDRT-PCR) and cDNA-AFLP, coupled with quantitative relative RT-PCR or real-time PCR were used. Many unique gene fragments were isolated and found to be up- or down–regulated as a result of exposure to low temperature. The up-regulated fragments in Poncirus show high similarities to genes involved in osmotic regulation (betaine/proline transporter, water channel protein, and nitrate transporter), oxidative stress (aldoketo reductase, early light induced protein), and protein interaction (tetratricopeptide-repeat protein, F-box protein, and ribosomal protein L15). In C. unshiu the up-regulated genes show high similarities to genes involved in transcription (zinc finger and GTP-binding protein-related), signal transduction (14–3–3 protein and extension-like protein), protein synthesis and amino acid translocation (permease and ribosomal proteins), chromosome folding (chromosome condensation, structural maintenance of chromosomes-like protein), and carbohydrate metabolism (glycosyl transferase). Several genes involved in photosynthesis, defense and cell wall metabolism were down regulated. Characterization of cold responsive genes will be discussed.
(299) The Use of Worm Castings As an Alternative to Sphagnum Peat Moss in Tomato (Lycopersicon esculentum Mill.) Transplant Production in Chile
Authors: Ozores-Hampton Monica , Mardones Brain
Published: February 2019

Intensive peat mining in Chile and worldwide produces a significant increase in production costs and less market availability. Alternative systems to promote peat mining sustainability are an immediate necessity. A viable alternative for replacing peat in tomato transplant production is to use worm castings or vermicompost. Vermicomposting is a biological process that relies on the action of earthworms (Eisenia sp.) to stabilize waste organic materials. The objective of this study was to evaluate the use of Ecobol-S® worm castings as a replacement for peat in tomato transplant production. Three experiments were designed using a randomized complete-block design containing two factors (planting date and worm casting rate). Tomatoes were seeded in a growth chamber using five growth media made up of the different ratios of worm castings, peat, and rice hulls [0:70:30 (control) 18:52:30; 35:35:30; 52:18:30; and 70:0:30], respectively. It was determined that Ecobol-S® worm castings have an adequate C:N and particle size for tomato transplant production. However, limitations were observed due to its high EC and low C content. During early fall, with high temperature in the growth chamber, it is not recommended to use worm castings in transplant production due to nutrient leaching caused by frequent irrigation. In mid-fall, it is recommended to use a rate of 35% worm castings, while in early winter it is recommended to use a rate of 52% to obtain strong and healthy transplants. Therefore, worm castings can be used as a viable alternative in the tomato transplant industry in Chile and possibly worldwide.
(226) Tissue Culture of Vitis sp. for Protoplast Isolation
Authors: Bona Claudine M. , Gould Jean H. , Miller J. Creighton , Stelly David M. , Louzada Eliezer S.
Published: February 2019

The highly appreciated Euvitis subgenera species (2n=38) are very susceptible to pests and diseases. Tolerance/resistance may be found in the closely related Vitis rotundifolia cultivars (2n=40), but the poor rooting characteristic of this species is a problem, and conventional crossings between Euvitis and V. rotundifolia are complicated because of different chromosome numbers. Therefore, somatic hybridization may be an alternative for gene transference between these species. The establishment of an efficient in vitro procedure may facilitate future genetic manipulations. Furthermore, in vitro success may be an indicative of protoplast totipotency. The goal of this research was to test 11 cultivars from different species for their in vitro cultivation and protoplast isolation capacity. Different doses of benzyladenine (BA) were tested and explants were cultivated in both Lloyd and McCown's Woody Plant Medium (WPM) and Murashige and Skoog medium (MS). We established an efficient in vitro procedure and plants of C. sauvignon, Syrah, SV 12-375, Scuppernong, Magnolia, Higgens and B. beauty were regenerated. No rooting problem was observed in vitro. Black spanish and Herbemont callus were kept in vitro, but plants were not regenerated. SV-12327 and Jumbo died. WPM was more efficient than MS for most cultivars. The V. vinifera cultivars C. sauvignon and Syrah developed well in both media. Protoplast isolation was more efficient using leaves rather than callus or suspension cells. BA at 3 μM·L-1 induced organogenesis while 10 μM·L-1 induced callogenesis except for Syrah, where 1 μM·L-1 induced organogenesis. Protoplasts were isolated from Herbemont and C. sauvignon and microcallus were obtained.
(228) In Vitro Rooting of Surinam Cherry
Authors: Griffis John L.
Published: February 2019

Surinam cherry (Eugenia uniflora L.) has value as a minor tropical fruit crop and as an ornamental plant in tropical and subtropical regions. In the United States, Surinam cherry is propagated by seed, as stem cuttings do not root. Elite selections are propagated by grafting, but grafts have not had high rates of success. Micropropagation of Surinam cherry has also been mostly unsuccessful. In this trial, 100 seeds from a self-cross of the cultivar Zill Dark were surface-disinfested and placed in vitro in 150 × 25-mm tubes on a medium of deionized water solidified with 8 g/L of agar. Seed cultures were placed on unlighted shelves. After 3 weeks without lights, seed cultures were transferred to lighted shelves where they readily germinated (100%) over the next 7 to 14 days. Seedlings were strongly tap-rooted and the roots quickly reached the bottoms of the tubes. After the 2 weeks under lights, 2 mL of autoclaved, half-strength liquid McCown's Woody Plant Medium (WPM) were added to each tube, creating a two-phase culture environment. Every 4 weeks, another 2 mL of half-strength WPM liquid medium were added to the cultures. Most seedlings elongated and produced three or more stems nodes with leaves after 10 weeks under lights. After this 10-week growth period, several of the seedlings had also produced adventitious roots at the first, second, and third stem nodes. After an additional 4 weeks in culture, 50% of the seedlings (50) had produced adventitious roots at one or more nodes. Additionally, tip cuttings taken from some of the seedlings that did not initially produce adventitious roots, produced roots at nodes when the stems were inserted directly in WPM medium supplemented with 20 g/L sucrose and various auxins.
(230) Effect of Five Doses of Indole Butyric Acid on the Aerial Layer Induction Root of Litchi
Authors: Gonzalez-Gonzalez Juan Manuel , Guzman-Gonzalez Salvador , Medina-Grijalva Jorge
Published: February 2019

We evaluated the effect of five doses (0, 500, 1000, 5000, and 10,000 ppm) of indole butyric acid (IBA) on the aerial layer induction root of Litchi (Litchi chinensis Sonn.). The experiment was conducted in the coastal zone of Tecoman, Colima, Mexico, at the La Perla farm (18°15'N; 103°52'W and 33 m above sea level). The ambient conditions were dry tropics with an average yearly rainfall of 710 mm and 26 °C annual medium temperature (BS1). The evaluated variables were: 1) the number of roots emitted by layer, and 2) percentage of layers taken root by treatment. The experiment was carried out under a randomized block arrangement. We used five treatments with 12 repetitions, considering one tree to be a block, in which five treatments were effected with four repetitions into every one tree utilized. Results of Duncan's test averaged 5%. The results obtained indicated that dose of 500 ppm was the best IBA level as the percentage of layers taken root by treatment (96.7%). They are statistically different.
(37) Irrigation and Fertilizer Placement Affects Plant and Weed Growth In Container Tree Production
Authors: Fain Glenn B. , Knight Patricia R.
Published: February 2019

On 24 Apr. 2003, 3-gallon (11.4-liter) Quercus shumardii were potted into 13.2-gallon (50-liter) containers using a standard nursery mix. Treatment design was a 3 × 2 × 2 factorial with two fertilizer placements, three irrigation methods, and two herbicide rates. Controlled-release fertilizer 17N–2.9P–9.8K was dibbled (placed 10.2 cm below the surface of the container media at potting) or top-dressed at a rate of 280 grams per container. Irrigation was applied using one of three methods: 1) a spray stake attached to a 3-gallon- (11.4-L-) per-hour pressure compensating drip emitter; 2) a surface-applied pressure-compensating drip ring delivering water at a rate of 2.3 gallons (8.9-L) per hour; and 3) the same drip ring placed 4 inches (10.2 cm) below the container substrate surface. A granular preemergent herbicide (oxyfluorfen + oryzalin) was applied at 2.0 + 1.0 lb/acre (2.24 + 1.12 kg·ha-1). At 75 days after treatment (DAT), containers with no herbicide and top-dressed fertilizer had a percent weed coverage of 46% compared to 18% for dibbled containers with no herbicide. At 180 DAT weed top dry weight was greater for top-dressed containers compared to dibbled. None of the treatments in the study had any effect on height increase. At 240 DAT, trees irrigated with drip rings at the surface had a 28% greater caliper increase among the dibbled fertilizer-treated containers. Trees irrigated with the drip ring placed below the surface and fertilizer top-dressed had the smallest caliper increase. Irrigation method had no effect on weed control in this study; however, a repeat fall application showed a significantly greater weed control with the drip ring below surface compared to the spray stake.
(100) Effect of Cropload, Irrigation, and Fertilization on Yield and Postharvest Bitter Pit Incidence of `Honeycrisp' Apple
Authors: Lopez-Cuevas Sergio , Robinson Terence
Published: February 2019

A factorial field experiment was conducted at the New York State Agricultural Experimental Station in Geneva, N.Y., during 2004 and 2005 with `Honeycrisp' apple trees on M.9 rootstock. The main plot factors were three levels of applied nitrogen (0 kg/ha, 50 k/ha, and 100 k/ha); three levels of applied K2O (0 k/ha, 100 kg/ha, and 200 kg/ha); ± foliar nutrient sprays containing N, B, Zn, and Mg, ± foliar sprays of CaCl2 and ± trickle irrigation. The subplot factor was cropload (3, 6, 9, 12, and 15 fruits/cm2 TCA). Trees receiving irrigation or potassium had higher yields and the effect was greater as cropload was increased. There was no effect of nitrogen fertilization, foliar Ca, and foliar N, B, Zn, and Mg on yield. Irrigation and increased potassium fertilization rate reduced fruit soluble solids at harvest. Foliar calcium applications, foliar N, B, Zn, and Mg applications, and nitrogen fertilization rate did not affect fruit soluble solids at harvest. No treatment factor had an effect on fruit firmness at harvest, but, after 4 months on cold storage, fruits from irrigated trees had greater firmness. Bitter pit incidence was lower on apples from trees that did not receive irrigation compared to irrigated trees. The difference was constant under all cropload levels. Foliar calcium applications, foliar N, B, Zn, and Mg applications, nitrogen fertilization rate and potassium fertilization rate did not affect bitter pit incidence.
(101) Effects of Fall Applications of Urea and Zinc Sulfate to `Bing' Sweet Cherry Spring Budbreak
Authors: Glozer Kitren , Grant Joseph A.
Published: February 2019

While rest-breaking agents have become commonly used in California cherry production, application timing continues to involve a certain amount of uncertainty from year to year. In order to use any chilling model adequately and thereby schedule rest-breaking treatments, both the beginning point of dormancy and the beginning point of chill accumulation must be understood. One method of testing dormancy onset is tree defoliation, which may be used to alter the pattern of budbreak and regrowth in spring. Defoliation is used in many tropical and subtropical fruit-growing regions to promote budbreak and flowering in species that are not adapted to less than adequate chilling conditions. Recent trials in California compared hand defoliation to applications of urea and zinc sulfate to determine effects on budbreak and flowering of sweet cherry, as well as to better identify entry into dormancy. Chemical applications were at concentrations lower than those used to effect complete defoliation. We found that chemical applications tended to advance bloom and that the most effective timings were consistent, based on chill portion accumulation and the Dynamic Model. In one of two years, chemical treatments tended to decrease floral bud death and increase fruit set when compared to hand defoliation and untreated trees.
(158) Gardening Made Easy—Teaching Organic Gardening at a Land-grant University
Authors: Motsenbocker Carl , Allain Sandra
Published: February 2019

An organic gardening class was developed to provide nonhorticulture students an opportunity to become acquainted with horticultural science and the basics of gardening organically. The course was developed as a 3-hour (1 hour lecture, 2 hours lab), two-credit course taught in the fall semester using an organic gardening textbook. A major component of the lab is the development and maintenance of a small individual garden plot during the semester. Students grow their own plant materials, plant, fertilize, and monitor pests, and harvest at the end of the semester. The organic gardening class was taught for 7 years and evolved into having a mandatory service-learning component that supports service projects in the local community. Projects included working with the local farmers' market, supporting school projects such as growing plants, school grounds beautification, gardening, or mulching, and gleaning product from research and garden plots for the local food bank. The poster will provide information on the class syllabus and materials, record of service projects, and reflections of the students during and at the end of the class.
(166) Weed Suppression and Nitrogen Management of Organic Broccoli
Authors: Schellenberg Daniel , Morse Ronald , Welbaum Gregory
Published: February 2019

Weed suppression and nitrogen (N) management present the greatest challenges to organic growers. Cover crops, the strategic use of tillage, and multiple nitrogen sources are being investigated in order to develop integrated management practices. Combinations of legume and grass cover crops are being utilized as alternative N sources and as tools for weed suppression. Another objective is to compare conventional and no-till practices to determine when the strategic use of tillage is most beneficial for N management and weed control. The last objective is to evaluate the fate of applied N and N released from cover decomposition on crop development. The best combinations of cover crop species, the frequency and intensity of tillage, and optimum N rates will be determined for the production of organic broccoli. This project will aid growers interested in transitioning to organic farming. In addition, integrated management practices that balance the short-term needs for crop productivity and the long-term interests of sustainable production will be reported.
(220) Pelargonic Acid Weed Control Parameters
Authors: Webber Charles L. , Shrefler James W.
Published: February 2019

Producers and researchers are interested in pelargonic acid (nonanoic acid) as a broad-spectrum postemergence or burn-down herbicide. Pelargonic acid is a fatty acid naturally occurring in many plants and animals, and present in many foods we consume. The objective of this research was to determine the effect of pelargonic acid concentration, adjuvants, and application timing on weed control efficacy as a burn-down herbicide. Field research was conducted at Lane, Okla. (southeast Oklahoma), during the 2005 growing season. One month prior to spraying the weed control treatments, the land was cultivated to kill the existing weeds and provide a uniform seed bed for new weed growth. The factorial weed control treatments included three application concentrations of Scythe (57.0% pelargonic acid) applied at 3%, 6.5%, and 10%; three adjuvants (none, orange oil, and non-ionic surfactant); and two application dates. All herbicide treatments were applied with an application volume of 935 L/ha to seedling weeds. The experiment had a high weed density with multiple species of grass and broadleaf weeds. Weed control across species increased as the herbicide concentrations increased from 0% to 10%. At all concentrations applied, pelargonic acid produced greater weed control for a longer time period for the broadleaf weeds than the grass weeds. Visual damage to the weeds was often apparent within a few hours after application. There was a significant increase in weed control when applied to the younger weeds. In this research, pelargonic acid was effective in controlling both broadleaf and grass weeds as a burn-down herbicide, although crabgrass was tougher to control.
(274) Genetic Diversity of Wild Pyrus communis L.
Authors: Volk Gayle , Richards Christopher , Henk Adam , Reilley Ann , Bassil Nahla , Postman Joseph
Published: February 2019

Edible European pears (Pyrus communis sp. communis L.) are thought to be derived from wild relatives native to the Caucasus Mountain region and eastern Europe. We collected genotype, phenotype, and geographic origin data for 145 P. communis individuals derived from seeds collected from wild relatives. These individuals are currently maintained in the USDA–ARS National Plant Germplasm System (NPGS) in Corvallis, Ore. Pear genotypes were obtained using 13 microsatellite markers. A Bayesian clustering method grouped the individual pear genotypes into 12 clusters. The subspecies of pears native to the Caucasus Mountains of Russia, Crimea, and Armenia could be genetically differentiated from the subspecies native to eastern European countries. Pears with large fruit clustered closely together and are most closely related to a group of genotypes that are intermediate to the other groups. Based on the high number of unique alleles and heterozygosity in each of the 12 clusters, we conclude that the genetic diversity of wild P. communis is not fully represented in the NPGS
(53) Freezing Tolerance of Twenty-Seven Saltgrass Ecotypes Was Similar in 2004 and 2005
Authors: Rukavina Hrvoje , Hughes Harrison , Qian Yaling
Published: February 2019

Freezing is the major abiotic stress that limits geographical distribution of warm-season turfgrasses. Prior studies have indicated variation in freezing tolerance in saltgrass clones. Therefore, this 2-year study examined the freezing tolerance of 27 saltgrass clones as related to collection sites in three zones of cold hardiness. Furthermore, these clones were evaluated for time of leaf browning in the fall with the intent to determine if there was a correlation between this trait and freezing tolerance. Rhizomes were sampled during 2004 and 2005 midwinters from clones established in Fort Collins, Colo., and then subjected to a freezing test. Saltgrass freezing tolerance was highly influenced by the climatic zone of clone origin in both years of the experiment. Clones with greater freezing tolerance turned brown earlier in fall in both seasons. Ranking of zones for the average LT50 was: zone 4 (–17.2 °C) < zone 5 (–14.4 °C) < zone 6 (–11.1 °C) in 2004 and zone 4 (–18.3 °C) < zone 5 (–15.7 °C) < zone 6 (–13.1 °C) in 2005. Clones from northern areas tolerated lower freezing temperatures better overall. This confirmed that freezing tolerance is inherited. Large intraspecific variation in freezing tolerance may be effectively used in developing cold-hardy cultivars.
(54) Utilization of Herbaceous Groundcovers for Weed Suppression and Aesthetic Appeal in Landscapes and Roadsides
Authors: Weston Leslie A. , Senesac Andrew F.
Published: February 2019

For the past 5 years, we have evaluated more than 100 herbaceous perennial groundcovers, including both grasses and grass mixtures, as well as ornamental broadleaf materials, for their ability to establish, suppress weeds, provide aesthetic appeal, and resist pests in various landscape and roadside settings across New York State. By working in cooperation with the NYSDOT, we have developed recommendations for materials that have performed well in difficult, potentially stressful, roadside and landscape settings. We have performed replicated research and demonstration trials that have clearly shown that certain species and cultivars provide effective weed suppression; great aesthetic appeal due to foliar texture, color, or flowering, resist pests and diseases; and require low maintenance over time. In addition, certain materials tolerate high levels of salt (NaCl), simulating roadside salt application exposure, in supplemental greenhouse studies. Materials generally suppressed weeds effectively by forming a dense canopy in a short period of time, and reducing light interception at the soil surface under this dense canopy. Certain groundcovers also appeared to exhibit strong potential allelopathic properties when grown either in field or laboratory settings. The selection of new plant materials for use in low-maintenance landscape settings offers potential to reduce time and maintenance inputs in difficult landscape or roadside settings, with the added benefit of reducing pesticide application in these settings for weed management. Additional studies are currently underway to develop further recommendations for use of warm- and cool-season turfgrasses in these settings.
(111) Evaluation of the Salt Tolerance of Walnut Rootstocks
Authors: Caprile Janet , Grattan Steve
Published: February 2019

In areas of California with a high incidence of walnut blackline disease, walnut orchards are increasingly being planted on English walnut (Juglans regia) rootstocks that are tolerant to the virus. There is limited documentation on the salt tolerance of this rootstock. This work was done to quantify the response of English walnut rootstocks to high boron (B), chloride (Cl), and sodium (Na) and to compare this to the more common rootstocks, Northern California Black (J.hindsii) and Paradox (J. hindsii × J. regia). The trial was configured as a randomized complete-block design with 20 plots. Plots consisted of three proximate, matched `Chandler' trees, each on a different rootstock. Leaf samples over a 2-year period showed that trees on the English rootstock had a significantly higher salt uptake than trees on Paradox, which had a significantly higher uptake than trees on Black. Bark cores showed little difference in B uptake between any of the rootstocks. Bark cores also showed that all rootstocks accumulated significantly more B than the scion portion of the tree, indicating that B transport may be limited by the graft union. Trees on English rootstock had significantly more B in the scion bark cores than trees on either Black or Paradox, indicating that rootstocks with a J. hindsii parent may be better at reducing salt transport across the graft union.
(240) Cytological Analyses of BC1 Hybrids Derived from IMR 2n Gamete of Interspecific Hybrid Between L. auratum and L. henryi
Authors: Chung Mi-Young , Chung Jae-Dong , Van Tuyl Jaap , Lim Ki-Byung
Published: February 2019

Intergenomic F1 hybrids between L. auratum and L. henryi were made and backcrossed to Oriental hybrids to produce BC1 progenies. The F1 intergenomic hybrids produced a relevant frequency of 2n-gamete and fertile pollen. Analyses of pollen size, viability, and germination ability were checked under microscopic observation. GISH analysis confirmed that F1 intergenomic hybrids possess a set of chromosomes from both parents and showed an intermediate morphological phenotype. Twenty BC1 plants were generated by in vitro embryo rescue technique, and analyzed for genome composition by GISH. All plants were triploid, showing 12 from female parent (2× Oriental) and 24 from male (2× F1 hybrid). Based on the GISH analyses, 19 BC1 plants were derived from FDR 2n-gamete and only one plant was derived from IMR 2n-gamete of F1 hybrid. The genome composition of 19 BC1 plants from FDR 2n-gamete possess 12 Orientals + 12 L. auratum + 12 L. henryi chromosomes with some extent of homoeologous recombination between L. auratum and L. henryi. However, one plant from IMR 2n-gamete origin contains an odd number of parental chromosomes from F1 hybrid, showing 12 Oriental + 14 L. auratum + 10 L. henryi chromosomes. In this case, two L. auratum chromosomes recombinant with L. henryi chromosome segments were added and L. henryi counterpart chromosomes were deleted, respectively.