bluuebunny/crossref_metadata_2025 huggingface dataset:
Inoculating Acacia koa with Bradyrhizobium and Applying Fertilizer in the Nursery: Effects on Nodule Formation and Seedling Growth
Authors: Dumroese R. Kasten , Jacobs Douglass F. , Davis Anthony S.
Published: February 2019

Restoration of Acacia koa A. Gray (koa) forests on degraded sites in Hawaii is important for conservation of rare, endemic plants and animals and is often accomplished by planting nursery-grown seedlings. To be successful after outplanting, koa seedlings must access sufficient nutrients from the soil and outcompete other vegetation. Forming symbiotic associations with nitrogen-fixing microorganisms may help alleviate inherent nutrient deficiencies found on volcanic sites, but interactions between inoculation and fertilization during production of koa seedlings are not well studied. Under operational nursery conditions, we fertilized koa seedlings at six controlled-release fertilizer (CRF) rates (ranging from 0 to 11.9 kg·m−3 Osmocote Plus 15N–9P–12K), which were also either inoculated with a locally collected source of nitrogen-fixing Bradyrhizobium spp. or not. Fertilized seedlings were significantly larger than the control; on average, fertilized seedlings were 300% taller and had 180%, 700%, and 350% more root-collar diameter, shoot biomass, and root biomass, respectively. Nitrogen (N) concentration was 23% to 119% greater in fertilized seedlings than nonfertilized seedlings. Inoculation with Bradyrhizobium had no significant affect on seedling characteristics except for root N concentration, which was 8% higher for inoculated seedlings. Fertilizer rate and inoculation interacted to significantly affect nodule number and nodule biomass/seedling. With inoculation, we observed an increase in nodule number (16.5 to 25.5) and biomass (5.8 mg to 11.7 mg) with fertilizer rate up to 4.7 kg·m−3 but a decline to nearly zero at the highest rates. Without inoculation, nodule formation was scarce (3.2 nodules/seedling or less) and only observed when CRF was 2.3 kg·m−3 or less. Our results suggest that high rates of fertilization and successful nodulation are not mutually exclusive nursery practices. Concurrent use of fertilization and inoculation in the nursery may provide opportunity to produce larger seedlings that have high potential to reduce the time needed to achieve canopy closure and thereby help achieve restoration objectives.
Nutrient and Chemical Properties of Aging Golf Course Putting Greens as Impacted by Soil Depth and Mat Development
Authors: McClellan Ty A. , Gaussoin Roch E. , Shearman Robert C. , Wortmann Charles S. , Mamo Martha , Horst Garald L. , Marx David B.
Published: February 2019

Nutrient and chemical changes in turfgrass sand-based root zones are not well understood. This study was conducted to characterize nutrient and chemical properties in putting greens influenced by root zone mixture and establishment treatment, putting green age, and soil depth. Putting greens were constructed and established with Agrostis stolonifera L. in sequential years from 1997 to 2000. Treatments included root zone mixtures of 80:20 (v:v) sand and sphagnum peat and 80:15:5 (v:v:v) sand, sphagnum peat, and soil, and accelerated versus controlled establishment. In the establishment year, the accelerated treatment received 2.6-, 3.0-, and 2.6-fold more nitrogen, phosphorus, and potassium, respectively, than the controlled treatment. Soil samples were taken in Fall 2001, Spring 2004, and Summer 2004 and were analyzed for nutrient and chemical properties such as pH, cation exchange capacity (CEC), organic matter (OM), total soluble salts (TSS), and 12 nutrients. The root zone mixture and establishment treatments had minimal effects on most nutrient and chemical properties with the exception of phosphorus and pH. Cation exchange capacity, OM, TSS, and all nutrients decreased with soil depth, whereas soil pH increased. The putting green age × soil depth interaction was significant for many of the nutrient and chemical properties, but separating soil samples into mat and original root zone instead of predetermined soil sampling depths eliminated most of these interactions. The mat layer had higher CEC and OM values and nutrient concentrations and lower pH values than the original root zone mixture.
Evaluation of Persistence of Selected Miticides Against the Twospotted Spider Mite, Tetranychus urticae
Authors: Cloyd Raymond A. , Galle Cindy L. , Keith Stephen R. , Kemp Kenneth E.
Published: February 2019

Twospotted spider mite, Tetranychus urticae, is a major arthropod pest in greenhouses. Greenhouse producers typically use miticides to control twospotted spider mite (TSM) populations. This study, which involved two replicated experiments, was designed to assess the persistence or longevity and efficacy of translaminar miticides with the active ingredient (a.i.) etoxazole, chlorfenapyr, abamectin, and spiromesifen by applying these miticides to either butterfly bush (Buddleia davidii) or marigold (Tagetes erecta) plants, depending on the experiment, and then artificially infesting the plants with TSM. Based on percent mortality and number of live and dead TSM, several miticides provided adequate control of TSM even after having been applied to the test plants 14 days before being artificially infested with TSM. This suggests that these miticides have extended residual activity. The etoxazole 10 to 12 μm and etoxazole water-dispersible formulations provided control (greater than 85% mortality) of TSM over the course of Expt. 1 with four or less live TSM recovered from treated plants across the three evaluation times (21, 28, and 42 days). Spiromesifen, in Expt. 2, was significantly more effective against both the nymph (89% to 99.2%) and adult (37.3% to 87.9%) stages of the TSM than the other miticides and killed more nymphs (165 to 227) than the other treatments. In general, none of the miticides provided consistent or adequate control of TSM adults across all three evaluation times (49, 56, and 70 days).
Efficient Propagation Technique of Euphorbia ×lomi Thai Hybrids
Authors: Fascella Giancarlo , Zizzo Giovanvito
Published: February 2019

A simple and efficient in vivo propagation protocol of two cultivars of Euphorbia ×lomi Rauh is described. Mother plants of ‘Nguen Muang’ and ‘Porn Ying Yai’ were soilless grown in 1 coconut coir dust:1 perlite (by volume) and 2 sphagnum peat:1 perlite (by volume) to produce cuttings. Plants cultured in peat-based substrate showed thicker stems (36.0 versus 30.5 mm, respectively), higher production of cuttings (10.4 versus 5.6 per plant), higher water absorption (265.7 versus 153.5 mL/plant/d), and higher content of nutrients in the root zone as compared with those cultivated in coir dust mixture. Cuttings harvested from 1-year-old mother plants of both cultivars were treated with 4000 ppm of α-naphthalene acetic acid (NAA) powder and inserted into bottom-heated benches filled with different substrates [perlite, 1 perlite:1 coir dust (by volume), coir dust] for rooting. Cuttings in pure perlite evidenced higher rooting percentage (86.2%) and longer roots (6.2 cm) than those in other media. Application of NAA resulted in higher rooting capacity (78.8 versus 68.3%, respectively) and higher amount of roots per cutting (13.4 versus 10.2) than treatment without auxin. Rooted cuttings grown in 1 peat:1 perlite medium (by volume) produced higher marketable potted plants than in 2 peat:1 perlite medium.
Effect of Composted Biosolids on Soil Organic Carbon Storage During Establishment of Transplanted Sod
Authors: Dai Xiaoyan , Vietor Donald M. , Hons Frank M. , Provin Tony L. , White Richard H. , Boutton Thomas W. , Munster Clyde L.
Published: February 2019

Large, volume-based applications of composted municipal biosolids (CMB) can enhance turfgrass growth and quality and soil physical and chemical properties. In addition, CMB additions could affect short-term dynamics of soil organic carbon (SOC) and enhance C sequestration and environmental quality compared with turfgrass fertilized with inorganic nutrients in mineral soil. The objective was to compare changes in SOC among contrasting sources of Tifway bermudagrass sod (Cynodon dactylon L. Pers. × C. transvaalensis Burtt-Davey) after transplanting. Three sod sources from fields grown with two commercial sources of CMB or inorganic phosphorus fertilizer were transplanted on silica sand in replicated box lysimeters. Storage of SOC within 0 to 5-cm and 5 to 50-cm depths was greater in CMB than fertilizer-grown sod during 10 months of establishment and maintenance. Leaching losses of dissolved organic C (DOC) were two times greater for CMB than for fertilizer-grown sod over seven simulated rain events, but the ratio of DOC in leachate to total SOC mass was 0.3% or less for CMB-grown sod. An increase in δ13C values of SOC over sampling dates indicated the proportion of SOC derived from turfgrass increased, whereas that from CMB decreased. The benefit of greater rates of SOC storage during establishment and maintenance of CMB compared with fertilizer-grown sod was achieved without substantive loss of DOC in leachate.
Agrobacterium-mediated Transformation of Buddleia Species
Authors: Dai Wenhao , Su Yuanjie , Wang Hongxia , Castillo Ceilo
Published: February 2019

Two Buddleia cultivars, B. davidii ‘Potters Purple’ and Buddleia ‘Lochinch’, were transformed using Agrobacterium tumefaciens strain EHA105 harboring the binary vector pBI121 carrying the neomycin phosphotransferase gene and β-glucuronidase gene (uidA). Transgenic plants were recovered from the Agrobacterium-infected leaf tissues through organogenesis in the selection medium (woody plant medium containing 250 mg·L−1 cefotaxime plus 500 mg·L−1 carbenicillin plus 40 mg·L−1 kanamycin). The rate of shoot regeneration from transformed leaf tissues increased from 5.7% to 32% through extending cocultivation time from 3 to 9 days. Integration of marker genes was verified with polymerase chain reaction (PCR) and Southern blot analysis. Southern blot analysis confirmed that one to three copies of transgenes were integrated into the buddleia genome. This transformation system could be used for improvement of buddleia or other related species. Chemical names used: 6-benzyladenine (BA), naphthalene acetic acid (NAA), acetosyringone (AS), 5-Bromo-4-chloro-3-indoxyl-beta-D-glucuronide cyclohexylammonium (X-Glu), cefotaxime (Cef), carbenicillin (Carb), kanamycin (Km).
Vegetative Growth and Flowering of Primocane Raspberry ‘Ariadne’ as Affected by Prohexadione–calcium Treatments
Authors: Palonen Pauliina , Mouhu Katriina
Published: February 2019

Maintaining an appropriate balance between vegetative and generative growth is a prerequisite for profitable raspberry (Rubus idaeus L.) production. The objective of our study was to test the effect of prohexadione–calcium (ProCa) on vegetative growth and flowering of primocane fruiting red raspberry ‘Ariadne’ in greenhouse conditions. ProCa was applied either once or twice in a concentration of 100 ppm or 200 ppm. Double applications of ProCa reduced cane height by 33 cm (100 ppm) or by 46 cm (200 ppm). Growth reduction was the result of shortening of the internodes, because total node number in plants was unaffected. Furthermore, cane diameter was reduced in plants treated with 200 ppm ProCa. ProCa treatments reduced the total aboveground dry weight by 32% to 55% but did not affect the allocation of dry weight into different plant parts. All ProCa treatments reduced the number of flowers by 22% to 42%. In conclusion, ProCa proved effective in controlling vegetative growth of red raspberry. However, because the number of flowers was reduced, ProCa cannot be recommended for growth regulation of primocane fruiting raspberry without further studies.
Evaluation of Olives Cultivated in Southern Italy by Simple Sequence Repeat Markers
Authors: Muzzalupo Innocenzo , Stefanizzi Francesca , Perri Enzo
Published: February 2019

Olive (Olea europaea L.) is a species of great economic importance in the Mediterranean basin. Italy is very important for the olive industry; in fact, olive's genetic patrimony is very rich and characterized by an abundance of cultivars. At present, the majority of ancient landraces are vegetatively propagated by farm. It is likely that the number of cultivars is underestimated because of inadequate information on minor local cultivars that are widespread in different olive-growing areas. The existence of many cultivars reinforces the need for a reliable identification method. It is important to improve the ex situ plant germplasm collection and fairly to characterize all cultivars for future breeding programs. In the present report, we used 11 loci microsatellites to characterize 211 olive cultivars of an olive collection cultivated in six regions of southern Italy. These regions represent the major area for olive cultivation in Italy and have a strategic geographical location in the Mediterranean basin. The dendrogram obtained, using the unweighted pair group method with arithmetic mean clustering algorithm, depicts the pattern of relationships between the studied cultivars. There is a clear structuring of the variability relative to the geographic origin of olive cultivars. This work, for the very high number of the Italian olive cultivars analyzed, highlights the degree and distribution of genetic diversity of this species for better exploitation of olive resources and for the design of plant breeding programs. Besides, the use of molecular markers, like simple sequence repeats, is imperative to build a database for cultivar analysis, for traceability of processed food, and for appropriate management of olive germplasm collections.
A 33-year Evaluation of Resistance and Pathogenicity in the Apple Scab–crabapples Pathosystem
Authors: Beckerman Janna , Chatfield James , Draper Erik
Published: February 2019

Crabapples (Malus spp.) are popular ornamental trees in the commercial and residential landscape. Over a 33-year period at the Secrest Arboretum, Wooster, OH, 287 accessions of ornamental crabapple were evaluated for their resistance to apple scab caused by the fungus Venturia inaequalis. Of these 287 accessions, 31 had no symptoms of scab for longer than a 10-year period and were identified as resistant to the disease. Of these 31 resistant accessions, 14 eventually displayed symptoms, presumably as a result of infection by one or more newly present races of the pathogen in the trial plot. Notable resistance breakdowns in accessions previously classified as resistant include the development of scab on M. × ‘Prairifire’, M. × ‘Bob White’, M. × ‘Red Jewel’, and M. floribunda. Corresponding to these changes of resistance is the putative development of new V. inaequalis races in North America: Race 5, possessing virulence to the Vm gene in ‘Prairifire’; Race 3 that infects M. × ‘Geneva’ but not M. baccata ‘Dolgo’; and the first identification and report of scab on a M. floribunda population that was reported as resistant even before the first 25 years of the evaluation. The detection of scab on this species suggests the presence of Race 7 in North America for the first time. Five named accessions remained free from scab for the entire 33-year trial: M. sargentii ‘Sargent’, M. baccata ‘Jackii’, M. × ‘Beverly’, M. × ‘Silver Moon’, and M. × ‘White Angel’ and may serve as sources of durable resistance in crabapple and commercial apple breeding in the Midwest.
Toward Fine Mapping of the Tomato Yellow Leaf Curl Virus Resistance Gene Ty-2 on Chromosome 11 of Tomato
Authors: Ji Yuanfu , Scott John W. , Schuster David J.
Published: February 2019

The whitefly-transmitted Tomato yellow leaf curl virus (TYLCV) is a major pathogen of tomatoes grown in tropical and subtropical regions of the world. Several genes of different origins conferring resistance to TYLCV have been introgressed to the cultivated tomato (Solanum lycopersicum), including the single dominant gene, Ty-2, that originated from S. habrochiates and was previously mapped to a 19-cM region on the long arm of chromosome 11 delimited by restriction fragment length polymorphism markers TG36 and TG393. In the present study, we confirmed the dominant inheritance of the Ty-2 gene from TYLCV evaluation and molecular marker analysis of an F2 segregating population derived from a commercial hybrid that carries the Ty-2 gene. Evaluating recombinants recovered from the F2 progeny for TYLCV resistance localized the Ty-2 gene to a marker interval of 5.5 cM between C2_At1g07960 (82.5 cM) and C2_At4g32930 (88 cM). Additional recombinants were identified for the target region carrying the Ty-2 gene. TYLCV evaluation of the progeny from these recombinants further delimited the Ty-2 gene to a 4.5-cM interval between C2_At1g07960 (82.5 cM) and cLEN-11-F24 (87 cM). The smaller introgressions no longer include the fusarium wilt race 2 resistance locus (I-2), which should facilitate combining the two resistance genes in cis configuration. The polymerase chain reaction-based markers developed from the present study can be used to precisely monitor the introgression of the Ty-2 gene, thus offering the opportunity to pyramid TYLCV resistance genes from different sources as well as resistance genes for other pathogens into elite tomato cultivars.
Screening Winter-sown Onion Entries for Iris Yellow Spot Virus Tolerance
Authors: Multani Parminder S. , Cramer Christopher S. , Steiner Robert L. , Creamer Rebecca
Published: February 2019

Identification of resistant or tolerant onion (Allium cepa L.) cultivars is crucial for the development of integrated management strategies for Iris yellow spot virus (IYSV). Exclusively vectored by onion thrips (Thrips tabaci), IYSV is a potentially devastating tospovirus of onion that has been confirmed to be present in 15 countries all over the world. In this study, 18 winter-sown onion entries were screened for IYSV symptom expression over two seasons. Over the growing season, straw-colored, necrotic lesions typical of IYSV infection were observed and rated for disease severity. Entries, NMSU 03-52-1, NMSU 04-41, NMSU 04-44-1, and ‘NuMex Jose Fernandez’, exhibited fewer symptoms than many other entries tested. ‘Caballero’, NMSU 04-57-1, NMSU 04-78-1, and ‘Cimarron’ exhibited more symptoms. Disease progression over time was rapid for entries exhibiting more symptoms and slow for entries exhibiting fewer symptoms. Enzyme-linked immunosorbent assay (ELISA) optical densities correlated poorly with the severity of disease symptoms. Trends in the disease progression over time emphasize the importance of rating IYSV symptoms late in the crop's development and to search for delayed disease progression rather than early symptom expression to determine IYSV susceptibility.
Characterization of Adventitious Root Development in Sweetpotato
Authors: Villordon Arthur Q. , La Bonte Don R. , Firon Nurit , Kfir Yanir , Pressman Etan , Schwartz Amnon
Published: February 2019

Adventitious roots of ‘Beauregard’ and ‘Georgia Jet’ sweetpotato were observed and anatomically characterized over a period of 60 days of storage root development. The majority of ‘Beauregard’ and ‘Georgia Jet’ adventitious roots sampled at 5 to 7 days after transplanting (DAT) possessed anatomical features (five or more protoxylem elements) associated with storage root development. The majority of ‘Beauregard’ (86%) and ‘Georgia Jet’ (89%) storage roots sampled at 60 to 65 DAT were traced directly to adventitious roots extant at 5 to 7 DAT. The two varieties, however, differed in the timing in which regular and anomalous cambia were formed. Regular vascular cambium development, i.e., initiation and completion, was observed in both varieties at 19 to 21 DAT. Formation of complete regular vascular cambium was negligible for ‘Beauregard’ (4%) in comparison with ‘Georgia Jet’ (32%) at 26 to 28 DAT. However, anomalous cambia development adjacent to xylem elements was greater in ‘Beauregard’ (30%) in comparison with ‘Georgia Jet’ (13%). Nearly 40% to 50% of samples in both varieties showed extensive lignification in the stele region. At 32 to 35 DAT, 62% to 70% of the adventitious roots for both varieties had either been initiated (developed anomalous cambium) or were lignified. The remaining adventitious roots showed intermediate stages of vascular cambium development. The adventitious root count increased up to 19 to 21 DAT and then remained constant up to 32 to 35 DAT. These accumulated results suggest that the initial stages of adventitious root development are critical in determining storage root set in sweetpotato.
Response of Lotus (Nelumbo nucifera Gaertn.) to Planting Time and Disbudding
Authors: Tian Daike , Tilt Ken M. , Sibley Jeff L. , Woods Floyd M. , Dane Fenny
Published: February 2019

Lotus (Nelumbo) is a highly valued plant with a long history for vegetable, ornamental, and medicinal use. Little information is available on the effects of planting time on performance of lotus, especially when grown in containers. The objectives of this study were to find a suitable planting time and to determine best management practices that are of importance for container lotus production. Effects of planting time and disbudding on plant growth indices in southeast Alabama were evaluated in a container production system for the ornamental lotus, N. nucifera ‘Embolene’. Results indicated that plant growth indices were little influenced by different planting dates in March, but were much influenced by planting dates with a difference over a month between February and May. Plants potted and placed outdoors in March and April performed best, and lotus planted in the greenhouse in February and planted outdoors in February and May performed worst. Flower number was not largely influenced by the planting time, but flowering characteristics, especially the flowering peaks, were different among treatments. Planting lotus outdoors between March and May produced the largest return. Influence of planting time on plant growth indices of lotus appeared to be explained by effects of growth-season climate conditions after planting. Disbudding had no impact on plant height but significantly increased underground fresh weight and the number of propagules. Therefore, disbudding should be considered a best management practice to maximize the yield of rhizomes or propagules. Positive linear, quadratic, or cubic relationships were detected among emerging leaf number, underground fresh biomass, and propagule number. Based on the regression models, the yield of lotus rhizomes or propagules can be predicted by the number of emerging leaves. This research provided a guide for nurseries, researchers, and collectors to select the best time to plant lotus outdoors.
Growth and Physiology of Newly Planted Fraser Fir (Abies fraseri) and Colorado Blue Spruce (Picea pungens) Christmas Trees in Response to Mulch and Irrigation
Authors: Cregg Bert M. , Nzokou Pascal , Goldy Ron
Published: February 2019

We evaluated height growth, diameter growth, and survival of newly planted fraser fir and colorado blue spruce Christmas trees in southwest Michigan in response to mulch, weed control, and irrigation. Mulches included black polyethylene, white polyethylene, VisPore mulch mats, and wood chips. Seedlings were also established with or without raised beds and with or without complete weed control. Weed control (mulches or a combination of chemical weed control and hand weeding) improved survival and growth of both species after 2 years. Growth was similar for trees in irrigated plots or with wood chip mulch without irrigation. Polyethylene mulch increased growth compared with similar production systems with raised beds and bare ground. Among production systems, variation in growth and survival reflected patterns of predawn water potential and midday shoot gas exchange, suggesting that differences were largely related to plant moisture stress. White mulch improved growth relative to similar production systems with black mulch and wood chip mulch improved growth compared with similar production systems without irrigation. Overall, the ranking of magnitude of growth response effects were weed control > irrigation > mulch. These results underscore the importance of weed control for establishment and maintenance of high-quality Christmas tree plantations.
The Influence of Climate on Fruit Development and Quality of Four Low-chill Peach Cultivars
Authors: Wert Todd W. , Williamson Jeffrey G. , Chaparro Jose X. , Miller E. Paul , Rouse Robert E.
Published: February 2019

The effect of climate was observed on fruit quality of four low-chill peach cultivars (Flordaprince, Flordaglo, UFGold, and TropicBeauty). The cultivars were evaluated in three locations (north–central, central, and southwest Florida). Soluble solids content (SSC), titratable acidity (TA), SSC:TA ratio, fruit weight, blush, and fruit development period (FDP) were determined. Longer FDPs were observed at the north–central location than at the southwest location. Fruit development and the expression of quality attributes were affected by location during fruit growth with higher color and SSC and shorter FDP occurring under warmer conditions. Within locations, ‘UFGold’ had the shortest FDP except at the southwest location where its chilling requirement may not have been met. At the central and southwest locations, ‘UFGold’ also tended to have lower TA values and higher SSC;TA ratios than the other cultivars.
Assessments of Bare-root Liner Quality and Purchasing Decisions Made by Green Industry Professionals
Authors: Jeffers Andrew , Palma Marco , Klingeman William E. , Hall Charles , Buckley David , Kopsell Dean
Published: February 2019

Production of high-quality nursery liners has long been a foundation principle for enabling success and business longevity in the competitive nursery industry. Unfortunately, many different characteristics can be used to define liner “quality,” ranging from physiological parameters measurable in scientific studies field establishment success and transplant production performance to gut-level hunches on the part of growers. A more complete understanding of what buyers are looking for in a bare-root liner would significantly enhance the success of producers in meeting the demands of end-users. As a result, a choice study involving a point-of-purchase simulation was designed to assess preferences of green industry professionals when viewing bare-root 1 + 0 nursery liners. A conjoint design was used for this study and involved six key attributes of liners: 1) number of first-order lateral roots (FOLR); 2) price; 3) production region; and uniformities of 4) height; 5) canopy density; and 6) liner caliper. A visual survey based on a large, color graphic depicting six distinct bare-root 1 + 0 liners with different combinations of attributes was administered together with a demographic questionnaire at four different green industry tradeshows and extension grower education and outreach venues in the southeastern United States. Results from 248 completed surveys corroborated previously reported results suggesting that high FOLR is the most important attribute influencing preference for 1 + 0 liner products followed by uniform liner height and canopy density. Contrary to a priori expectations, neither price nor region of production substantially influenced product preference. Utility values were calculated for each attribute level using outputs from the experimental model. These values can be used by growers to adjust production methods to improve liners with attributes that end-users value most. In addition, growers will be able to better estimate product ratings, redirect marketing efforts, and assess sales potential for various bare-root 1 + 0 liner products in U.S. markets.
Phenotypic Characteristics as Predictors of Phytosterols in Mature Cycas micronesica Seeds
Authors: Marler Thomas E. , Shaw Christopher A.
Published: February 2019

The relationship between mature Cycas micronesica K.D. Hill seed sterol concentration and content and plant or seed phenotypic characteristics was established by multiple regression. Combined models were significant for free but not glycosylated sterols. Reduced models revealed leaf number as the only significant predictor. Free and glycosylated sterol concentrations were unaffected throughout the range of several predictors: tree height (1.7 to 5.8 m), seed fresh weight (48 to 120 g), seed load (one to 76 seeds per plant), and estimated tree age (32 to 110 years). The free and glycosylated sterol phenotypes were also not dependent on the presence/absence of developed embryos in mature seeds. The significant response to leaf number was subtle with an increase of 43 leaves associated with a 0.1-mg increase in free sterol per gram seed fresh weight. This is the first report for any cycad that discusses reproductive or physiological traits in the context of allometric relations. Results indicate a highly constrained phenotypic plasticity of Cycas gametophyte sterol and steryl glucoside concentration and seed content in relation to whole plant and organ size variation.
Relating Objective and Subjective Ratings of Snap Bean Pod Color to Likelihood of Purchase
Authors: Kahn Brian A. , McGlynn William G.
Published: February 2019

Snap bean (Phaseolus vulgaris L.) cultivars with pods representing a range of greenness were grown in Oklahoma field trials in 2001 and 2004. Objective color evaluations (L* value and hue angle) performed on raw and cooked pod samples from 10 (2001) or 12 (2004) of these cultivars indicated that color testing of raw snap bean pods may not be sufficient to determine the color after cooking. Although L* values may be expected to decrease after cooking, the magnitude of the changes may not be predictable. Changes in hue angle values after cooking appear to be even more variable among cultivars. Therefore, if the color of the cooked beans is expected to be a deciding factor in cultivar selection, we would recommend conducting color tests on cooked bean pods as well as the raw product. Twenty relatively straight, unblemished pods per cultivar were harvested on 20 June 2001 and on 30 June 2004 from plants of ‘Blue Lake 274’, ‘Brio’, ‘Charon’, ‘Jade’, and ‘Seville’. The five most uniform pods per cultivar (all sieve Size 4) were presented as raw samples that same day to an untrained panel consisting of seven males and 18 females (2001) or nine males and 18 females (2004). This was an affective test; panelists were asked to evaluate intensity of color and likeliness to buy using a 5-point semantic differential scale. Correlation coefficients for the two attributes were calculated. Sensory panelists were able to make subjective distinctions among the cultivars based on color. However, these differences did not necessarily correlate with either objective color measures or likelihood of purchase. Snap bean pod color is not an overriding selection criterion, but only one of many criteria considered by consumers.
Microstructural Study of Chilling Injury Alleviation by 1-Methylcyclopropene in Persimmon
Authors: Pérez-Munuera Isabel , Hernando Isabel , Larrea Virginia , Besada Cristina , Arnal Lucía , Salvador Alejandra
Published: February 2019

The storage of persimmon cv. Rojo Brillante (Diospyros kaki L.) at low temperatures is limited by the susceptibility to chilling injury (CI), the main symptom being a drastic reduction of firmness when the fruit are transferred from low to moderate temperature. 1-Methylcyclopropene (1-MCP), an ethylene action inhibitor, has been shown to alleviate CI of persimmon, prolonging the storage period. In this article, the microstructural changes produced in the flesh of chilling-injured persimmon and fruit treated with 1-MCP were studied. The drastic softening displayed by chilling-injured fruit was related to a loss of cell wall integrity as well as to low intercellular adhesion. 1-MCP treatment alleviated CI by preserving the fruit firmness; it was linked to a preservation of the cell wall's integrity and to a higher intercellular adhesion observed during storage at low temperatures as well as when fruit were transferred to shelf temperatures.
Changes in Chemical and Physical Properties of Pine Tree Substrate and Pine Bark During Long-term Nursery Crop Production
Authors: Jackson Brian E. , Wright Robert D. , Seiler John R.
Published: February 2019

The objective of this study was to evaluate a pine tree substrate (PTS) for decomposition, changes in physical and chemical properties, and substrate carbon dioxide (CO2) efflux (microbial activity) during a long-term production cycle under outdoor nursery conditions. Substrates used in this study were PTS constructed using a 4.76-mm hammer mill screen and aged pine bark (PB). Plastic nursery containers were filled with each substrate and amended with either 4.2 or 8.4 kg·m−3 Osmocote Plus fertilizer and planted with Cotoneaster horizontalis or left fallow. Substrate solution chemical properties and nutrient concentrations were determined each month during the summers of 2006 and 2007 in addition to measuring substrate CO2 efflux (μmol CO2/m−2·s−1) as an assessment of microbial activity. Substrate breakdown (decomposition) was determined with particle size analysis and physical property determination on substrates at the conclusion of the study (70 weeks). Substrate solution pH was higher in PTS than in PB at both fertilizer rates in 2006, but pH levels decreased over time and were lower in PTS at both fertilizer rates in 2007. Substrate solution electrical conductivity levels, nitrate, phosphorus, and potassium concentrations were all generally higher in PB than in PTS at both fertilizer rates through both years. Pine tree substrate decomposition was higher when plants were present in the containers [evident by an increase in fine substrate particles (less than 0.5 mm) after 70 weeks], but breakdown was equal at both fertilizer rates. Shrinkage of PTS in the presence of plants was equal to the shrinkage observed in PB with plants, but shrinkage was higher in fallow PTS containers than PTS with plants. Substrate air apace (AS) was highest in PTS and container capacity (CC) was equal in PB and PTS at potting. Substrate AS decreased and CC increased in both substrates after 70 weeks but remained in acceptable ranges for container substrates. Substrate CO2 efflux rates were higher in PTS compared with PB at both fertilizer rates indicating higher microbial activity, thereby increasing the potential for nutrient immobilization and substrate breakdown. This work provides evidence that PTS decomposition is unaffected by fertilizer rate and that substrate shrinkage in containers with plants is similar to PB after two growing seasons (70 weeks), which addresses two major concerns about the use and performance of PTS for long-term nursery crop production. This work also shows that the higher microbial activity in PTS increases the potential of microbial nutrient immobilization, which is likely the reason for the lower substrate nutrient levels reported for PTS compared with PB over 70 weeks.
Tissue Responses and Solution Movement After Stem Wounding in Six Cycas Species
Authors: Fisher Jack B. , Lindström Anders , Marler Thomas E.
Published: February 2019

We made drill holes in the stems of six Cycas species and used a standard microtechnique and microscopy methods to determine the structural responses of the soft-wooded, parenchymatous (manoxylic) stems after 2 and 12 months of recovery. We also injected an aqueous stain to one plant per species to determine the transverse hydraulic pathways among the discrete tissue categories. Expanding secondary tissue decay and insect larva infestations were evident in some wounds after 2 months. Wounds that lacked the secondary complications had recovered as a result of wound periderm after 2 months. Large areas of secondary rotting after 2 months were bounded by wound periderm after 12 months. The wound periderm formed a thick, leathery phellem (cork) that was continuous across cortex, vascular, and pith tissues. The six species represent a range in ease of horticultural management, yet the form of recovery from the wounds was similar for all species. Mucilage exudation from cut surfaces was copious, and species differences in volume of mucilage were also not related to extent or form of recovery from the wounds. Stain injected into the hole moved longitudinally and laterally within a vascular cylinder to adjacent vascular cylinders and to the cortex by way of persistent leaf traces. Results indicate a transverse hydraulic connection among the concentric vascular cylinders and leaf traces that extend into the cortex. Moreover, the succulent nature of this manoxylic stem is highly susceptible to secondary infection whenever the protective bark is removed or the internal tissues are injured. Therefore, use of prophylactic treatments to minimize the risk of secondary complications is warranted whenever pruning or amputation of adventitious shoots for propagation remove the protective bark from the succulent cortex tissue.
Evaluation of the Risk of Spreading Fire Blight in Apple Orchards with a Mechanical String Blossom Thinner
Authors: Ngugi Henry K. , Schupp James R.
Published: February 2019

The risk of spreading fire blight in apples after mechanical thinning with a rotating string blossom thinner was evaluated in field and potted-tree experiments. In the field experiment, using the mechanical thinner on noninoculated trees immediately after operating the equipment on inoculated trees significantly (P < 0.01) increased fire blight incidence resulting in 90 ± 20.01 (mean ± SE) infected shoots compared with 23.5 ± 8.97 diseased shoots in similar trees that were not thinned mechanically. A similar result was obtained in greenhouse experiments whereby healthy apple plants positioned adjacent to diseased plants before the group was subjected to the mechanical thinner developed more than twice the number of infected shoots as that on similar plants that were not thinned. These results indicate that under conditions conducive to infection, the mechanical blossom thinner significantly increases the risk of spreading Erwinia amylovora. The use of the thinner should therefore be limited to orchards with no history of disease in the last 3 years and on days when predicted weather is not suitable for tree infection by E. amylovora; otherwise, a severe fire blight epidemic could develop in the orchard.
Conferred Resistance to an Acetolactate Synthase-inhibiting Herbicide in Transgenic Tall Fescue (Festuca arundinacea Schreb.)
Authors: Sato Hiroko , Takamizo Tadashi , Shimizu Tsutomu , Kawai Kiyoshi , Kaku Koichiro
Published: February 2019

Herbicide-resistant turfgrass can be an efficient tool that will allow easier turf maintenance. Acetolactate synthase (ALS) is the first common enzyme in the biosynthetic pathways leading to the branched-chain amino acids, and amino acid substitutions in ALS have been known to confer resistance to ALS-inhibiting herbicides. A two-point mutated rice ALS gene [OsALS (dm)] has been shown to confer strong resistance to bispyribac-sodium (BS), an ALS-inhibiting herbicide. In this study, we introduced into turf-type tall fescue (Festuca arundinacea Schreb.) the OsALS (dm) gene by using Agrobacterium-mediated transformation for conferring herbicide resistance. Stable integration of the transgene was confirmed by Southern blot analysis. Transgenic and wild-type plants were sprayed on the leaves with herbicide containing BS; approximately half of the transgenic plants were unaffected by the treatment and showed resistance to the herbicide, whereas the wild-type plants died. ALS activity in the leaf tissue of transgenic-resistant plants incubated with BS was almost equivalent to that in wild-type plants without BS and was higher than in wild-type plants incubated with BS. These indicate that the transgenic-resistant plants actively produced OsALS (dm) protein under herbicide treatment. This is the first report of herbicide-resistant transgenic tall fescue after introduction of a mutated ALS gene.
Freezing Tolerance and Cold Acclimation in Guava (Psidium guajava L.)
Authors: Hao Wei , Arora Rajeev , Yadav Anand K. , Joshee Nirmal
Published: February 2019

Guava (Psidium guajava L.) is a tropical evergreen tree that tolerates a wide range of frost-free environments. In recent years, the American market demand for exotic and nutritious fruits, like guava, has been increasing, and, with a long harvest period, guava can be a potential alternative, high-value cash crop in the United States. However, the major limitation with commercializing guava cultivation in the United States is its low cold tolerance. In this article, we studied the physiology of freezing tolerance and cold acclimation in guava. Laboratory freeze–thaw tests (on leaves), shoot growth and leaf relative water content measurements, leaf anthocyanin content analyses, and leaf protein analyses were performed on nonacclimated and cold-acclimated guava cultivars Lucknow-49 and Ruby × Supreme. The leaf freezing tolerance (expressed as LT50 values) of nonacclimated tissues was ≈–2.5 °C and significantly enhanced to ≈–4.4 °C after an environmentally controlled cold acclimation regime for both cultivars. However, when compared based on actual injury sustained by leaves at various freezing temperatures in a freeze–thaw test, ‘Ruby × Supreme’ exhibited significantly less injury than ‘Lucknow-49’ at most temperatures. Growth and leaf relative water content reduced, whereas leaf anthocyanins accumulated during cold acclimation. Leaf protein analyses, which were performed after cold acclimation and drought stress, revealed that four proteins (69, 48, 23.5, and 17.4 kDa) accumulated in response to low temperatures, and two proteins (17.4 and 16 kDa) accumulated in response to drought stress. Antidehydrin immunoblots revealed that one common 17.4 kDa dehydrin accumulated in response to cold and drought stresses. Our data indicate that guava possesses leaf freezing tolerance, exhibits cold acclimation ability, and that ‘Ruby × Supreme’ leaves are relatively more freezing-tolerant than ‘Lucknow-49’ when compared up to –4 and –8 °C for nonacclimated and cold-acclimated tissues, respectively. Cold acclimation in guava appears to be a multifactorial process involving complex physiological and biochemical changes and also overlapping responses with drought stress.
High-temperature Inhibition of Flowering of Phalaenopsis and Doritaenopsis Orchids
Authors: Newton Linsey A. , Runkle Erik S.
Published: February 2019

Phalaenopsis orchids require a day temperature of 26 °C or less to initiate inflorescences, whereas the night temperature has little or no effect on inflorescence initiation. We determined the duration of high temperature required each day to prevent inflorescence initiation of four Phalaenopsis and Doritaenopsis clones. In Years 1 and 2, mature potted plants were grown in separate greenhouse sections with five daily durations at 29 °C: 0, 4, 8, 12, or 24 h. The high temperature was centered in the 16-h photoperiod (0600 hr to 2200 hr) and the remainder of the day was at 20 °C. Exposure to 29 °C for 8 h or longer inhibited inflorescence initiation of Phalaenopsis Miva Smartissimo × Canberra ‘Mosella’ and Phalaenopsis Brother Pink Mask × Brother Success ‘Explosion’, but Phalaenopsis Baldan's Kaleidoscope ‘Golden Treasure’ and Doritaenopsis ‘Newberry Parfait’ required exposure to 29 °C for 12 h or longer to inhibit inflorescence initiation. Flowering was completely suppressed only when high-temperature exposure time was continual for Doritaenopsis ‘Newberry Parfait’ and Phalaenopsis Baldan's Kaleidoscope ‘Golden Treasure’ and 12 h for Phalaenopsis ‘Mosella’. Plant leaf span generally increased as duration of exposure to 29 °C increased, but high-temperature exposure had few or no significant effects on flowering characteristics of flowering plants. These studies indicate that as few as 8 h of high temperature can prevent flowering of some Phalaenopsis hybrids, whereas others require greater than 12 h of high-temperature exposure.
Fruit Set and Yield Patterns in Six Capsicum Cultivars
Authors: Wubs A. Maaike , Ma Yuntao , Hemerik Lia , Heuvelink Ep
Published: February 2019

Fruit set and yield patterns were studied in detail in six pepper cultivars. Fruit set differed largely between the cultivars: cultivars with small fruits (fruit fresh weight 20 to 40 g) showed higher fruit set (≈50%) than cultivars with large fruits (fruit fresh weight 120 to 200 g; 11% to 19%). The former showed continuous fruit set (four to five fruits/plant/week), whereas the latter showed fluctuations in fruit set. Fluctuations in weekly fruit set, expressed as the ratio between standard deviation of weekly fruit set and the mean of weekly fruit set (cv), were much lower for the cultivars with small fruits (0.44 to 0.49) than for the cultivars with large fruits (1.1 to 1.6). Fluctuations in weekly fruit yield varied between 0.51 and 0.77 for cultivars with small fruits and between 1.04 and 1.45 for cultivars with large fruits. Fluctuations in fruit yield were significantly positively correlated (Pearson R = 0.87) with fluctuations in fruit set. The correlation between fruit set and fruit yield patterns was highest with a lag time of 8 weeks for the cultivars with small fruits and 9 to 10 weeks for the cultivars with large fruits. This corresponds with the expected lag time based on the average fruit growth duration. The cultivars produced the same amount of biomass, implying that source strength was more or less similar. Hence, differences in fruit set and fruit yield patterns between the cultivars were not the result of differences in source strength and must therefore be related to differences in sink strength.
Water Conservation, Growth, and Water Use Efficiency of Container-grown Woody Ornamentals Irrigated Based on Daily Water Use
Authors: Warsaw Aaron L. , Fernandez R. Thomas , Cregg Bert M. , Andresen Jeffrey A.
Published: February 2019

Irrigation scheduling based on plant daily water use (DWU) to conserve water without adversely affecting plant growth compared with a traditional irrigation rate was investigated for 25 common container-grown woody ornamentals. Ten different taxa were grown in 2006 and 2007 and five in 2008 in 10.2-L (No. 3) containers. Overhead irrigation was applied in four treatments: 1) a control irrigation rate of 19 mm (1.07 L per container) per application (control); 2) irrigation scheduled to replace 100% DWU per application (100DWU); 3) irrigation alternating every other application with 100% replacement of DWU and 75% DWU (100-75); and 4) irrigation scheduled on a three application cycle replacing 100% DWU followed by two applications of 75% DWU (100-75-75). Irrigation applications were separated by at least 24 h. Daily water use was calculated by measuring the difference in volumetric moisture content 1 h and approximately 24 h after irrigation. The three DWU treatments reduced total irrigation applied 6% to 75% compared with the control depending on treatment and species, except for Buddleja davidii ‘Guinevere’ in which total irrigation applied by the 100DWU, 100-75, and 100-75-75 treatments was 26%, 10%, and 5%, respectively, greater than the amount applied to the control. Final growth index [(plant height + width A + width B)/3] of all DWU treatments was greater than or equal to the control for all taxa. Forsythia ×intermedia ‘New Hampshire Gold’, Hydrangea arborescens ‘Dardom’, Hydrangea paniculata ‘Unique’, and Weigela florida ‘Wilma’ had higher water use efficiencies (estimated as the change in growth index per liter of water applied) at lower irrigation treatment volumes with no differences in growth index or growth index increase, indicating that further irrigation reductions may be possible without affecting growth. PourThru electrical conductivity of H. arborescens ‘Dardom’, Spiraea fritschiana ‘Wilma’, and Viburnum ×burkwoodii ‘Chenaultii’ measured in 2007 did not accumulate to damaging levels. Final plant size of all taxa under DWU treatments was the same or greater than the control and substantially less water was applied under DWU treatments except for B. davidii ‘Guinevere’.