bluuebunny/crossref_metadata_2025 huggingface dataset:
Water Movement through a Pine-bark Substrate during Irrigation
Authors: Hoskins Tyler C. , Owen James S. , Niemiera Alex X.
Published: February 2019

Regulatory and economic incentives to improve water and fertilizer use efficiency have prompted the nursery industry to seek new and advanced techniques for managing the production of ornamental crops. The development of best management practices, especially with regard to fertilizer and irrigation management, is largely based on research that looks at season-long trends in water and nutrient use. Understanding how water moves through a substrate during a single irrigation event may allow for the refinement of recommended best management practices that improve water and fertilizer use efficiency in container-grown plant production systems. Therefore, a study was conducted to characterize the movement of irrigation water at three growth stages [4, 9, and 17 weeks after transplanting (WAT)] throughout the production cycle of Ilex crenata Thunb. ‘Bennett’s Compactum’ that were container-grown in a bark-based substrate alongside fallow (i.e., without a plant) containers. Tensiometers were placed at three horizontal insertion depths and three vertical heights throughout the substrate profile to detect changes in matric potential (ψ; kPa), during individual irrigations. At 4 WAT, the pre-irrigation ψ in the upper substrate profile was 12.3 times more negative (i.e., drier) than the substrate near the container’s base and 6.0 times more negative than the middle of the container. This gradient was decreased at 9 and 17 WAT as roots grew into the lower portion of the substrate profile. On average, water began to drain from the base of containers 59.9 s ± 1.0 se and 35.7 s ± 1.3 se after irrigation commencement for fallow containers and plant-containing treatments, respectively, indicating channeling through the substrate of plant-containing treatments. A pattern of plant water uptake by roots induced a gradient in the substrate’s pre-irrigation moisture distribution, where portions of the substrate profile were relatively dry where plant roots had taken up water. Consequently, the application of water or fertilizer (i.e., fertigation) through irrigation has the potential to be highly inefficient if applied under dry substrate conditions where channeling may occur. Therefore, water application using cyclic irrigation or substrate moisture content (MC) thresholds (not letting MC fall below an undetermined threshold where channeling may occur) may improve water application efficiency. Furthermore, fertigation should occur when the substrate MC in the upper portion of the container is higher than the pre-irrigation MCs observed in this study to minimize the occurrence of channeling. The effect of root growth should also be taken into account when seeking the proper balance between pre-irrigation substrate MC and irrigation application rate to reduce the risk of unwanted channeling.
Growth Responses of Zoysia spp. under Tree Shade in the Midwestern United States
Authors: Peterson Kenton W. , Fry Jack D. , Bremer Dale J.
Published: February 2019

‘Meyer’ zoysiagrass (Zoysia japonica Steudel) is commonly planted on home lawns and golf courses in the transition zone; however, poor shade tolerance limits its widespread use. This study was conducted to determine changes and differences in growth among selected Zoysia cultivars and progeny under a natural shade environment over a 3-year period in the transition zone. The study was initiated in June 2010 at the Rocky Ford Turfgrass Research Center in Manhattan, KS. Soil type was a Chase silt loam (fine, montmorillonitic, mesic, Aquic, Argiudoll). Zoysia genotypes were sodded in 0.37-m2 plots and arranged in a randomized complete block with five replications under silver maple (Acer saccharinum L.) shade that resulted in a 91% reduction in photosynthetically active radiation (PAR). Genotypes included ‘Zorro’ [Z. matrella (L.) Merrill], ‘Emerald’ [Z. japonica × Z. pacifica (Goudswaard) Hotta & Kuroki], ‘Meyer’, Chinese Common (Z. japonica), and experimental progeny Exp1 (Z. matrella × Z. japonica), and Exp2 and Exp3 [(Z. japonica × Z. pacifica) × Z. japonica]. ‘Zorro’ and ‘Emerald’ experienced winter injury, which negatively affected their performance. Tiller numbers decreased 47% in ‘Meyer’ from June 2010 to June 2012, but declines in [(Z. japonica × Z. pacifica) × Z. japonica] progeny were only 1% for Exp2 and 27% for Exp3, and both Exp2 and Exp3 maintained high percent green cover throughout the study. In general, by the third year of evaluation, progeny of [(Z. japonica × Z. pacifica) × Z. japonica] had higher quality ratings and higher tiller numbers than ‘Meyer’ and may provide more shade-tolerant cultivar choices for transition zone turf managers.
Effect of Preemergence Herbicides on Hybrid Bermudagrass Divot Resistance and Recovery
Authors: Jones Patrick A. , Brosnan James T. , Breeden Gregory K. , Vargas José J. , Horvath Brandon J. , Sorochan John C.
Published: February 2019

Divoting is a common occurrence on golf courses and athletic fields. Research was conducted at the University of Tennessee Center for Athletic Field Safety (Knoxville, TN) during 2012–13 evaluating the effects of preemergence (PRE) herbicide applications on hybrid bermudagrass [C. dactylon (L.) Pers. × C. transvaalensis Burtt-Davy, cv. Tifway] divot resistance and recovery. Plots were subjected to the factorial combination of seven herbicide treatments (indaziflam at 35 and 52.5 g·ha−1; prodiamine at 840 g·ha−1; pendimethalin at 3360 g·ha−1; dithiopyr at 560 g·ha−1; oxadiazon at 3360 g·ha−1; non-treated control) and three divot timings [1, 2, and 3 months after herbicide treatment (MAT)]. Rates were based on label recommendations for preemergence crabgrass (Digitaria spp.) control. Herbicides were applied on 15 Mar. 2012 and 2013. Divots were generated using a weighted pendulum apparatus designed to impart 531 J of impact energy to the turf sward with a golf club. Divot resistance was quantified by measuring divot volume at each timing while divot recovery was quantified by measuring turf cover in the divot scar using digital image analysis. All herbicide-treated plots produced divots with volumes ≤ the non-treated control. In 2013, volumes were greater for divots produced 1 MAT (215 cm3) than those created 2 MAT (191 cm3) or 3 MAT (157 cm3). No differences in divot recovery were detected as a result of herbicide treatment in either year. Under the conditions of this study, applications of PRE herbicides at labeled rates did not affect divot resistance or recovery.

Chemical names: N-[(1R,2S)-2,3-dihydro-2,6-dimethyl-1H-inden-1-yl]-6-(1-fluoroethyl)-1,3,5-triazine-2,4-diamine (indaziflam), 2,4 dinitro-N3,N3-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine (prodiamine), N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin), S,S-dimethyl 2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl)-3,5-pyridinedicarbothioate (dithiopyr), 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon)
Ascorbic Acid, Thiamin, Riboflavin, and Vitamin B6 Contents Vary between Sweetpotato Tissue Types
Authors: Barrera Wilmer A. , Picha David H.
Published: February 2019

Sweetpotato is considered a good source of ascorbic acid (vitamin C) and certain B vitamins. These water-soluble vitamins (WSV) play essential roles in sustaining human health. Besides the root, sweetpotato vegetative tissues are also edible and considered high in nutritional value. Despite the availability of general reference values for sweetpotato WSV content in the root and leaves, little is known about the distribution of these vitamins in specific sweetpotato root and vegetative tissues. The objective of this study was to determine the ascorbic acid (AA), thiamin (B1), riboflavin (B2), and vitamin B6 content in a range of foliar tissues including buds, vines, young petioles, young leaves, mature petioles, and mature leaves and root tissues including the skin, cortex, and pith tissue at the proximal, distal, and center regions of the root. Among foliar tissues of ‘Beauregard’ sweetpotatoes, the AA content was highest in young leaves (108 to 139 mg/100 g fresh weight) and lowest in mature petioles (7.2 to 13.9 mg). No thiamin was detected in foliar tissue, whereas mature leaves contained the highest riboflavin and vitamin B6 content (0.22 to 0.43 mg and 0.52 to 0.58 mg, respectively). In root tissues of ‘Beauregard’ and ‘LA 07-146’ sweetpotatoes, the AA content was lower in the skin (1.9 to 5.6 mg and 2.54 to 3.82 mg, respectively). The AA content in the cortex and pith tissue at the proximal, distal, and center of the root was generally similar. The thiamin content was variable among root tissues, whereas the skin contained the highest riboflavin content and the lowest vitamin B6 content across root tissues of both cultivars. The results of this study confirmed earlier reports suggesting that sweetpotato leaves can be a good source of multiple WSV in the human diet.
Screening Cotoneaster for Resistance to Fire Blight by Artificial Inoculation
Authors: Rothleutner Joseph J. , Contreras Ryan N. , Stockwell Virginia O. , Owen James S.
Published: February 2019

Cotoneaster Medik. is a genus of ornamental landscape plants commonly affected by fire blight. Fire blight is a disease caused by the bacterial pathogen, Erwinia amylovora (Burrill) Winslow et al., that attacks a wide range of taxa in the apple subfamily (Maloideae; Rosaceae). To assess susceptibility of species and identify potential sources of resistance, we inoculated 52 taxa of Cotoneaster with E. amylovora. Disease severity was scored by percent shoot necrosis (lesion length/total shoot length). Disease screenings were conducted over 2 years and varying levels of susceptibility were observed. Some taxa were highly susceptible to fire blight and the disease resulted in whole plant mortality (C. rhytidophyllus Rehder & E.H. Wilson, C. rugosus E. Pritzel ex Diels, and C. wardii W.W. Smith). Other taxa repeatedly exhibited moderate to high levels of disease resistance [C. arbusculus G. Klotz, C. chungtinensis (T.T. Yu) J. Fryer & B. Hylmö, C. delsianus E. Pritzel var. delsianus, C. sikangensis Flinck & B. Hylmö, C. simonsii Baker, and C. splendens Flinck & Hylmö]. Ongoing studies are being conducted to determine if taxa with high levels of resistance under artificial inoculation will exhibit high levels of resistance in the field under natural disease pressure. Identifying sources of disease resistance will be useful for breeding programs to increase tolerance of these landscape plants with desirable horticultural characteristics to fire blight.
Quantitative Inheritance of Resistance to Loquat Canker (Pseudomonas syringae pv. eriobotryae, Group C) in Loquat Progenies from Crosses between a Resistant Cultivar, ‘Champagne’, and Susceptible Cultivars
Authors: Hiehata Naofumi , Fukuda Shinji , Sato Yoshihiko , Tominaga Yukiko , Terai Osamu , Yamada Masahiko
Published: February 2019

Loquat canker, caused by Pseudomonas syringae pv. eriobotryae, is a serious disease of loquat [Eriobotrya japonica (Thunb.) Lindl.] in some countries such as Japan. Therefore, improved canker resistance is an important objective for loquat breeding. The resistance to loquat canker Group C in descendants of ‘Shiromogi’ was expressed only in homozygotes with a recessive gene at a single locus, which was designated pse-c/pse-c. ‘Champagne’, which is distantly related to ‘Shiromogi’, is another cultivar with resistance to Group C. The inheritance of this resistance in progenies of crosses between ‘Champagne’ and susceptible cultivars was examined. The offspring seedlings from 14 crosses between ‘Champagne’ (pse-c/pse-c) and 12 susceptible cultivars (Pse-c/Pse-c or Pse-c/pse-c) were classified into two types of resistant and susceptible. All of the hybrid progenies between ‘Champagne’ (pse-c/pse-c) and Pse-c/Pse-c parents showed two types of resistant and susceptible. The proportion of resistant offspring showed great differences significantly, depending on the hybrid combinations. It ranged from 0.203 to 0.596 with an average of 0.407. It indicated that the resistance was controlled by one or more additional genes or loci other than the Pse-c (pse-c) locus. In addition, the proportion of resistant offspring from crosses between ‘Champagne’ (pse-c/pse-c) and Pse-c/pse-c parents ranged from 0.463 to 0.701 (and averaged 0.601), which seriously deviated from the segregation of 1:1, indicating that the segregation was both Mendelian and polygenic in a threshold character. The proportion of resistant seedlings cannot be predicted by the phenotype and the genotype in the Pse-c (pse-c) locus. Therefore, the general combining ability of ‘Champagne’ resulting from the additional gene effect was estimated, which was 0.407 and 0.101 for ‘Champagne’ × Pse-c/Pse-c and ‘Champagne’ × Pse-c/pse-c cultivars, respectively. The gene effect of susceptible cultivars ranged from –0.204 (‘Yougyoku’) to +0.189 (‘Togoshi’) for ‘Champagne’ × Pse-c/Pse-c cultivars and from –0.138 (‘Taisho’) to +0.089 (‘Nagasakiwase’) for ‘Champagne’ × Pse-c/pse-c cultivars.
A New Approach for Analyzing and Interpreting Data on Fruit Drop in Mango
Authors: Hagemann Michael H. , Roemer Malte G. , Kofler Julian , Hegele Martin , Wünsche Jens N.
Published: February 2019

Mango yields are frequently reduced by premature fruit drop, induced by plant stresses during the fruit set period in response to unsuitable climatic or crop management conditions. There are varying strategies for assessing premature fruit drop, which render the comparison and interpretation of published data difficult to draw general conclusions. Therefore, the objective was to provide a mathematical model that is generally valid for describing fruit losses of mango. The model was tested and validated by monitoring the fruit drop for the two local North Vietnamese cultivars, Hôi and Tròn, in different management systems over six consecutive growing seasons: 1) mango–maize intercropping and mango monocropping; 2) irrigation; and 3) plant growth regulator applications with 10 ppm N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU), 40 ppm 1-naphthaleneacetic acid (NAA), and 40 ppm gibberellins (GA3 and GA4+7). The timely pattern of fruit drop was best described with a sigmoid function (r2 = 0.85) and formed the basis for defining three distinct drop stages. The post-bloom drop, from full bloom to the maximum daily rate of fruit drop [FD(x)], had the highest fruit losses. The following midseason drop stage ends at 1% FD(x), a threshold that is suggested after a comprehensive literature review. Thereafter, during the preharvest drop stage, treatment and cultivar differences appear to remain constant despite continued fruit drop. In contrast to other mango intercropping studies, fruit loss was not greater in the mango–maize intercropping than in the mango monocropping. Irrigation resulted in approximately three times higher fruit retention compared with the non-irrigated control. A single application of NAA at marble fruit stage (BBCH-scale 701) resulted consistently in the highest fruit retention for both cultivars in midseason and at harvest. The model permits the separation between the drop stages, thus allowing the evaluation of 1) natural variation before treatment effects during post-bloom drop; 2) treatment efficacies during midseason drop; and 3) yield forecasting at the beginning of the preharvest stage.
Biomass Production and Withaferin A Synthesis by Withania somnifera Grown in Aeroponics and Hydroponics
Authors: von Bieberstein Philipp , Xu Ya-ming , Gunatilaka A.A. Leslie , Gruener Raphael
Published: February 2019

The medicinal herb Withania somnifera (L.) Dunal (Solanaceae) was grown in two soilless systems to determine optimal conditions for production of biomass and withaferin A, the major secondary metabolite responsible for its claimed medicinal properties. Withaferin A content was analyzed using high-performance liquid chromatography (HPLC). The results show that there was no statistically significant difference (P > 0.05; t test) in biomass production between the plants grown aeroponically and hydroponically. Aeroponically grown plants produced an average of 49.8 g dried aerial plant material (DW) (sd 20.7) per plant, whereas hydroponically grown plants produced an average of 57.6 g DW (sd 16.0). In contrast, withaferin A content was statistically higher in plants grown hydroponically. These plants contained an average of 7.8 mg·g−1 DW (sd 0.3), whereas the aeroponically grown plants contained an average of 5.9 mg·g−1 DW (sd 0.6). These results demonstrate that hydroponic techniques are optimal in reproducibly and efficiently generating withaferin A. These findings may be of importance to the natural products industry in seeking to maximize production of biologically active compounds from medicinal plants.
Mineral Nutrition of Adenium obesum ‘Red’
Authors: McBride Kaitlyn M. , Henny Richard J. , Mellich Terri A. , Chen Jianjun
Published: February 2019

Adenium obesum (Forssk.), Roem. & Schult. has been increasingly produced as a flowering potted plant; however, there is no information regarding its tissue mineral composition. This study evaluated plant performance of A. obesum ‘Red’ grown in two container sizes and under four rates of a controlled-release fertilizer. Nutrient concentrations in flowers, leaves, stems, and roots were analyzed. Results showed that canopy height and width, stem caliper, top and root dry weights, and average flower count of A. obesum ‘Red’ increased linearly with the increased rate of fertilizer regardless of pot size. Tissue analysis indicated that nitrogen (N), phosphorus (P), and potassium (K) concentrations were lower in all organs compared with those reported for other ornamental potted plants such as Bouvardia Salisb., Euphorbia L., Rhododendron L., and Rosa L. The lower levels of tissue N and P accompanied with higher dry matter accumulation suggest that A. obesum ‘Red’ is efficient in use of N and P. The low tissue K levels were largely attributed to sodium (Na) substitution for K. Leaf K and Na concentrations were almost equal except at the highest fertilizer treatment in 1.25-L pots and the last two higher treatments in 3.0-L pots. The levels of other mineral elements were comparable to those of other reported ornamental potted plants. To produce high-quality plants in 1.25-L pots, Adenium ‘Red’ should be fertilized with 1.08 g N per liter of potting mix. For plants grown in 3.0-L pots, N rates of 0.36 g or 0.72 g per liter of potting mix would be recommended with a preference for 0.36 g.
Does CaCl2 Play a Role in Improving Biomass Yield and Quality of Cardoon Grown in a Floating System under Saline Conditions?
Authors: Borgognone Daniela , Cardarelli Mariateresa , Lucini Luigi , Colla Giuseppe
Published: February 2019

Supplemental calcium application has been reported to alleviate the detrimental effect of NaCl-induced salinity on crop growth. Iso-molar solutions of NaCl and NaCl plus CaCl2 were used to study the osmotic and ionic effects of salinity on leaf dry biomass production and nutraceutical quality of cardoon (Cynara cardunculus L. var. altilis DC) grown in a floating system. A basic nutrient solution (control; T1) was enriched with 15 mm of NaCl + 10 mm of CaCl2 (T2), 30 mm of NaCl (T3), 30 mm of NaCl + 20 mm of CaCl2 (T4), or 60 mm of NaCl (T5). NaCl at 60 mm induced a 52% reduction of total leaf dry biomass compared with the control (T1); the iso-molar solution enriched with 20 mm of CaCl2 (T4) increased the total leaf dry biomass production in comparison with treatment containing NaCl at 60 mm (T5). Moreover, at moderate salinity (T2 and T3), the partial replacement of NaCl with 10 mm of CaCl2 (T2) in treatment containing 30 mm of NaCl did not help to reduce the adverse effect of NaCl on total leaf dry biomass production. Results of leaf mineral analysis demonstrated that the partial replacement of NaCl with CaCl2 reduced the accumulation of sodium and the nutrient imbalance. Nutrient solutions enriched with CaCl2 did not increase the accumulation of the osmoprotectant proline in leaves. Nutraceutical value of cardoon leaves was generally improved by saline treatments compared with the control. The regression analysis between phenolic compounds and antioxidant activity showed that total phenols and chlorogenic acid were the major determinants of antioxidant activity in cardoon leaf biomass. In conclusion, the partial replacement of NaCl with CaCl2 improved the leaf dry biomass production of cardoon only at the highest salinity levels with a limited effect on nutraceutical quality of leaves.
A New Local Sustainable Inorganic Material for Soilless Culture in Spain: Granulated Volcanic Rock
Authors: Pozo Judith , Álvaro Juan E. , Morales Isidro , Requena Josefa , La Malfa Tommaso , Mazuela Pilar C. , Urrestarazu Miguel
Published: February 2019

Volcanic rock has been used for decades as a horticultural substrate worldwide. In Spain, the use of this material as a substrate is ancient; it was initially used in the Canary Islands because of its volcanic geological origin. At the University of Almería (Almería, Spain), three independent vegetable crops were grown under greenhouse conditions: sweet pepper, tomato, and melon. The volcanic rock came from a location in the geographic center of Spain, which facilitated logistics. Bags of volcanic rock (25 L) were used and were compared with a commercial coconut fiber substrate of an equal volume. All physical, physical–chemical, and chemical parameters of the volcanic rock were determined using European standard analytical procedures. Fertigation was applied, independently adapted to the physical, physical–chemical, and chemical characteristics of each substrate. The cultures were performed under a randomized complete block experimental design. Fertigation parameters, pollutant emissions, fruit production, and the quality of each culture were measured. The results showed that the assessed parameters of the volcanic rock substrate are not a limiting factor for its use as a horticultural substrate. The resultant production and quality were very similar among the three crops compared with a widely used commercial control. Therefore, volcanic rock emerges as a local, sustainable alternative to be used for soilless crop cultivation.
Evaluation of a Mobile Steam Applicator for Soil Disinfestation in California Strawberry
Authors: Fennimore Steven A. , Martin Frank N. , Miller Thomas C. , Broome Janet C. , Dorn Nathan , Greene Ian
Published: February 2019

Steam-disinfestation of soil as an alternative to chemical fumigation was investigated in both research and commercial strawberry (Fragaria ×ananassa Duch.) production field trials at four sites over 2 years (2011–13) using new prototype commercial application equipment: a tractor-drawn device that physically mixed the steam with the soil as it passed through the shaped planting beds. Results included significant suppression of weeds and soilborne pathogens equal to commercial chemigation of chloropicrin with 1,3-dichloropropene (Pic-Clor 60). Also, the combination of steam treatment with soil amendments of mustard seed meal (MSM; two of four trials included treatment), a fertilizer and source of additional organic matter, showed very favorable strawberry production in terms of yield as well as weed and pathogen control. Soil nitrogen-containing ions were monitored at two of the sites and the MSM treatment significantly elevated available soil nitrates by the time of transplanting as did the steam treatment alone, but only significantly at one of the sites.
Nitrogen Release Properties of Controlled-release Fertilizers during Tomato Production
Authors: Carson Luther C. , Ozores-Hampton Monica , Morgan Kelly T. , Sartain Jerry B.
Published: February 2019

Determination of nutrient release duration from controlled-release fertilizers (CRFs) or soluble fertilizers encapsulated in polymer, resin, or sulfur covered fertilizer coated with a polymer differs among manufacturers, but may be determined as 75% to 80% nitrogen (N) release at a constant temperature (e.g., 20 to 25 °C). Increases or decreases in temperature compared with the manufacturer release determination temperature increase or decrease CRF N release; thus, coated fertilizer may release more rapidly than stated during the fall season when soil temperatures in seepage-irrigated tomato (Solanum lycopersicum) production can reach 40.1 °C. The objectives of this study were to evaluate N release duration of CRFs by measuring N release from CRFs incubated in pouches under polyethylene mulch-covered raised beds and to determine the CRF duration suitable for incorporation into a fall tomato fertility program. In 2011 and 2013, 12 and 14 CRFs from Agrium Advanced Technologies, Everris, Florikan, and Chisso-Asahi Fertilizer were sealed in fiberglass mesh pouches (12.7 × 14 cm) that were buried 10 cm below the bed surface in a tomato crop grown using commercial production practices. A data logger collected soil temperature 10 cm below the bed surface. Pouches were collected and N content was measured eight times through two fall seasons. A nonlinear regression model was fit to the data to determine N release rate. During the 2011 and 2013 seasons, minimum, average, and maximum soil temperatures were 21.2 and 19.2, 25.7 and 23.5, and 32.2 and 27.7 °C, respectively. Seasonal total CRF N release was between 77.6% and 93.8% during 2011 and 58.3% and 94.3% in 2013. In 2011, PCU90 and in 2013, PCU90 and PCNPK120 had the highest seasonal total percentage N release (PNR) and FL180 had the lowest in both years. A nonlinear regression fit N release from CRF with R2 = 0.85 to 0.99 during 2011 and 0.49 to 0.99 during 2013. Nitrogen release from all CRFs was faster than the manufacturer’s stated release, probably as a result of high fall bed temperatures. A CRF or CRF mixture containing CRFs of 120- to 180-day release duration may be recommended, but the CRFs must release greater than 75% N during the season.
Prediction of Controlled-release Fertilizer Nitrogen Release Using the Pouch Field and Accelerated Temperature-controlled Incubation Methods in Sand Soils
Authors: Carson Luther C. , Ozores-Hampton Monica , Morgan Kelly T. , Sartain Jerry B.
Published: February 2019

Controlled-release fertilizers (CRFs), a vegetable production best management practice in Florida, are soluble fertilizers (SFs) coated with a polymer, resin, or a hybrid of polymer coating sulfur-coated urea. In 1994, a Controlled Release Fertilizer Taskforce developed an accelerated temperature-controlled incubation method (ATCIM) to predict column-incubated CRF nitrogen (N) release for regulatory purposes. Determination of CRF field N release uses a field method such as a pouch field study, which requires multiple samples and high costs for laboratory N analysis. If the ATCIM may be used to predict CRF N release in the field, then vegetables growers will have a faster and lower-cost method to determine N release compared with the pouch field method. Therefore, the objective of this study was to evaluate the correlation of the ATCIM and the pouch field method as a predictor of N release from CRFs in tomato production in Florida. In 2011 and 2013, 12 and 14 CRFs, respectively, were incubated in pouches placed in polyethylene mulched raised beds in Immokalee, FL, and extracted in the ATCIM during 2013. The ATCIM CRF results were used individually and grouped by release duration to create predicted N release curves in a two-step correlation process. The two-step processes predicted the percentage N release of individual CRF with R2 of 0.95 to 0.99 and 0.61 to 0.99 and CRFs grouped by release duration with R2 of –0.64 to 0.99 and –0.38 to 0.95 in 2011 and 2013, respectively. Modeling CRF N release grouped by release duration would not be recommended for CRF 180-d release (DR), because coating technologies behaviors differ in response to high fall soil temperature in polyethylene mulched beds. However, with further model calibration, grouping CRFs of 90 to 140 DR to simulate the CRF N release profile may allow the ATCIM to predict CRF N release without performing the pouch field method, which currently negated the usefulness of the ATCIM in a tomato production system.
The Intersection of Plant Breeding, Human Health, and Nutritional Security: Lessons Learned and Future Perspectives
Authors: Patil Bhimanagouda S. , Crosby Kevin , Byrne David , Hirschi Kendal
Published: February 2019

In recent years, concerns about global, sustainable, and nutritional security have gained substantial momentum propelled by rapid increases in global population and food insecurity. Historically, plant breeding has played a key role in improving crop yield to keep pace with the rising global population; however, current plant breeding efforts focusing on increasing yield may need to be realigned toward nutritional security issues. Although traits affecting yield and disease resistance remain essential, emerging research highlights the importance of nutrition, flavor, quality, and enhanced health-promoting properties in reducing food and nutritional impoverishment. We review plant breeding efforts to address nutritional impoverishment and the importance of consumer perception of flavor, nutrition, and quality. The Vegetable and Fruit Improvement Center (VFIC)’s interdisciplinary research related to “Foods for Health” in pepper, cantaloupe, citrus, carrot, peach, and plum provides specific examples of improvements in vegetable and fruit quality and health-promoting properties. We discuss historical perspectives, case studies, current programs, and a future outlook on the role of plant breeding in nutritional security. Our work focuses on the nexus of plant breeding, human health, and nutritional security as a foundation for future plant improvement strategies.
Fruit Quality of Pear Psylla-resistant Parental Germplasm
Authors: Bell Richard L.
Published: February 2019

Sixteen interspecific backcross hybrid selections from various breeding programs have been selected as prospective parents for breeding for resistance of European-type pears to the pear psyllids (Cacopsylla spp.). The Pyrus communis × P. pyrifolia (n = 6) backcross selections are derived mostly from NJ 1, an open-pollinated P. pyrifolia seedling, and the Pyrus communis × P. ussuriensis (n = 9) backcross selections are derived from Illinois 76, an open-pollinated P. ussuriensis seedling, and one Pyrus communis × P. ussuriensis cultivar. Ratings of psylla resistance have been based primarily on multiyear orchard observations under no-pesticide and minimal pesticide conditions. To select the best prospective parents, data on fruit quality and tree traits were analyzed. Fruit characteristics included harvest date, fruit size and shape, skin color, percentage blush, russet, overall appearance, texture (flesh fineness), texture type, juiciness, overall grittiness and grit size, flavor acceptability and type, aroma, and a quality index, which was an unweighted total of the scores for appearance, texture, grit, flavor, and aroma. For this report, comparisons were made to ‘Bartlett’, the most widely grown U.S. pear cultivar. Both the P. communis × P. pyrifolia and Pyrus communis × P. ussuriensis backcross hybrid groups had significantly lower quality indices than ‘Bartlett’, and most individual traits were similar in this respect. There were significant differences among selections for all traits as were differences between years within genotype for most traits with some exceptions. Harvest date, percentage blush, appearance, juiciness, flavor, and the quality index were relatively stable from year to year. Flesh texture type varied within each group. The P. communis × P. pyrifolia selection NJ Rock R23 T252 had the highest quality index of the selections. For eight traits, various selections ranked higher than ‘Bartlett’, although the differences were not significantly higher with the exception of the russet score. Five selections appear to have sufficient quality and are being used as parents.
Controlled-release Fertilizer during Cutting Propagation Affects Growth and Tissue Nutrient Concentrations of Rooted Cuttings of Annual Bedding Plants
Authors: Currey Christopher J. , Lopez Roberto G.
Published: February 2019

Our objectives were to quantify the effects of controlled-release fertilizer (CRF) on the growth, morphology, and tissue nutrient concentration of annual bedding plants during propagation. Unrooted cuttings of Angelonia angustifolia ‘AngelFace White’ and ‘Sundancer Pink’, Impatiens hawkeri ‘Celebrette Apricot’ and ‘Celebrette Rose Hot’, Nemesia fruticans ‘Bluebird’ and ‘Raspberry Sachet’, Pelargonium ×hortorum ‘Savannah Red’, and Petunia ×hybrida ‘Cascadia Marshmallow Pink’ and ‘Suncatcher Yellow’ were received from a commercial propagator. Cuttings were immediately stuck individually in cells containing soilless substrate supplemented with 0, 3, 6, 12, or 24 g·L−1 CRF (Osmocote Plus 15–3.9–10 3–4 month) and placed under clear mist water or cuttings were stuck in substrate containing no CRF and fertilized with water-soluble fertilizer beginning immediately after placing cuttings into propagation. Shoot dry mass of cuttings grown in substrates containing up to 12 or 24 g·L−1 CRF increased by up to 150% for some taxa compared with unfertilized cuttings. Incorporating CRFs into propagation substrates increased the concentration of nitrogen (N), phosphorus (P), and potassium (K) in tissues by up to 103%, 42%, and 137%, respectively, compared with unfertilized cuttings. Additionally, tissue nutrient concentrations for cuttings fertilized with 6 g·L−1 CRF or greater were similar to cuttings receiving water-soluble fertilizer (WSF). When the impact of CRF on growth and nutrient concentrations are taken together, our results indicate that CRF is a fertilization application technology that holds promise for use during propagation of herbaceous stem-tip cuttings.
Effect of Daily Light Integral on Composition of Hydroponic Lettuce
Authors: Gent Martin P.N.
Published: February 2019

The concentrations of metabolites in plants are affected by sunlight integral and other factors such as plant size, water content, and time of day. Tissue composition was measured for various sizes of hydroponic lettuce (Lactuca sativa L.) grown under seasonal variation in sunlight in a greenhouse and harvested in the morning or afternoon. Daily sunlight integral varied from 4 to 14 mol·m−2·day−1 photosynthetically active irradiance, and plant size varied from 2 to 260 g fresh weight (FW)/plant in this study. Much of the variation in tissue composition on a FW basis could be explained by the increase in dry matter content with irradiance normalized per unit area. Except for nitrate, metabolite concentrations on a FW basis increased with irradiance, and the changes resulting from irradiance were greater when harvested in the afternoon than in the morning. Nitrate concentration decreased with normalized irradiance, and the trend was the same whether measured in morning or afternoon. Malic acid increased with irradiance but not enough to counter the decrease in nitrate on a charge equivalence basis. Irradiance normalized per unit leaf area explained many effects of light and plant size on dry matter content and soluble metabolite concentrations. Lettuce for human consumption is best harvested in the afternoon after growth under high light, when it has the least nitrate and more of other nutrients.
‘D’Anjou’ Pear Shoot Growth and Return Bloom, but Not Fruit Size, Are Reduced by Prohexadione-Calcium
Authors: Einhorn Todd C. , Pasa Mateus S. , Turner Janet
Published: February 2019

Prohexadione-calcium (P-Ca) was applied to ‘Anjou’ pear (Pyrus communis L.) trees in the lower and upper Hood River Valley (HRV), Oregon, to determine its effectiveness for managing the excessive vigor of ‘Anjou’ under different growing climates. Vegetative growth and development (weekly shoot growth rate, total annual extension growth, number of initiated shoots, internodal length, and number of nodes), yield (fruit number and fruit size), and return bloom dynamics were evaluated between 2010 and 2013. P-Ca consistently reduced shoot elongation by ≈40% in all years and at both sites when doses of 250 ppm were applied in early spring (i.e., ≈5 cm of annual shoot extension) compared with untreated trees. Shorter shoots were the result of both reduced internodal growth and fewer nodes. In the cooler, upper HRV, a single P-Ca application controlled shoot elongation for the entire season, but in the warmer, lower HRV, a second flush of growth was generally observed ≈60 days after the first application. A subsequent P-Ca application (250 ppm) provided added growth control in some instances. Yield was unaffected by P-Ca the season of application; however, in one year, an increase in fruit number indirectly led to reduced fruit size; otherwise, fruit size was unaffected by P-Ca. Postharvest fruit quality was not influenced substantially by P-Ca. Return bloom, however, was consistently reduced by P-Ca. Return yield, the year after P-Ca application (recorded in 2013 only), was reduced in proportion to the decrease in return bloom relative to untreated trees. In 2012, ethephon was also evaluated, alone or in combination with P-Ca. When applied on its own either once (150 ppm, 5-cm growth), or twice [150 ppm, 5-cm growth; 300 ppm, 57 days after full bloom (DAFB)], ethephon did not affect vegetative growth or yield components but did improve return bloom and return yield relative to other treatments; however, when combined with P-Ca, ethephon did not reverse reductions in return bloom or return yield induced by P-Ca. The most effective ethephon treatment for promoting flowering and return yield (300 ppm, 57 DAFB) was not tested in combination with P-Ca. We conclude that P-Ca is an effective tool for controlling vigor of ‘Anjou’ trees, but the decrease in return bloom requires additional investigation. Further work testing combinations of ethephon and P-Ca are warranted to optimize growth and productivity of ‘Anjou’ trees.
Hydroponic Production of Purslane as a Sodium-removing Vegetable in NaCl-rich Nutrient Solution
Authors: Kong Yun , Zheng Youbin
Published: February 2019

To evaluate the potential of producing purslane (Portulaca oleracea L.) as a sodium (Na)-removing vegetable hydroponically at moderate NaCl salinity, two cultivars (Green and Golden) were grown in solutions with added 0, 6, 8, and 10 mm NaCl (the actual Na+ concentrations ≈2, 8, 10, and 12 mm, respectively). At harvest, 26 days after transplanting, apparent growth and biomass accumulation were not negatively affected by 6 to 10 mm added NaCl compared with 0 mm added NaCl. However, with the increase of added NaCl concentration from 0 to 6 to 10 mm, the sodium removal showed a 1- to 3-fold increase up to 0.26 to 0.41 mmol/plant, and 225.7 to 300.2 mmol·kg−1 dry weight (DW) or 0.90 to 1.32 mmol·L−1 H2O, respectively. ‘Green’ produced greater biomass and removed more sodium per plant than ‘Golden’. ‘Golden’ had more of a dwarfed and compact canopy than ‘Green’. Sodium removal rate (mmol/plant/day) was the highest during the first 7 days after transplanting, but the fresh weight increase rate (g/plant/day) increased gradually as growth progressed. Results suggest that it is possible to hydroponically produce purslane in nutrient solutions with 8 to 12 mm Na+. Despite the high sodium-removal capability, purslane cannot be used to reduce Na+ concentrations in NaCl-rich hydroponic solutions. The biomass yield and the sodium removal of individual plants were affected by different cultivars and time after transplanting.
Volatile Toluene and Xylene Removal Efficiency of Foliage Plants as Affected by Top to Root Zone Size
Authors: Kim Kwang Jin , Jung Hyun Hwan , Seo Hyo Won , Lee Jung A. , Kays Stanley J.
Published: February 2019

Phytoremediation of volatile organic compounds in indoor air involves both the plant and microbes in the media; however, removal rate is typically expressed on a leaf area basis. We determined the effect of root media volume on phytoremediation rate of volatile toluene and xylene to determine if there is a change in phytoremediation efficiency. Phytoremediation rate was calculated based on the aboveground space occupied by the plant and on the leaf area. Foliage plants of Fatsia japonica and Draceana fragrans ‘Massangeana’ were grown in different-sized pots (1, 2, 4, 6, and 12 L) that gave aerial plant to root zone volume ratios of 21:1, 21:2, 21:3, and 21:6. Total root volume and root fresh weight increased in D. fragrans with increasing media volume, whereas root density per unit of media volume decreased in both species. The efficiency of volatile toluene and xylene removal by the plants was increased as the root zone volume increased, whereas removal efficiency per unit media volume increased and then decreased. The highest volatile toluene and xylene removal efficiency was at a ratio of 21:3 (aerial plant:root zone volume) in F. japonica and 21:2 in D. fragrans. When phytoremediation efficiency was expressed on a leaf area basis, the phytoremediation rate for toluene and xylene increased progressively for both species with increasing media volume and as root volume increased. Calculating the amount of plant material needed within a home or office to obtain sufficient volatile organic compound (VOC) removal cannot be accurately predicted base solely on a leaf area (LA) or aboveground volume basis.
Tolerance of Watermelon Seedlings to Low-temperature Chilling Injury
Authors: Kozik Elzbieta U. , Wehner Todd C.
Published: February 2019

Watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] is one of the Cucurbitaceae species and subtropical crops that exhibit chilling injury (CI) when exposed to low temperatures. Watermelon seedlings were tested for chilling tolerance using methods modified from cucumber. Three experiments were conducted using different combinations of chilling durations of 6, 12, 24, or 36 hours and chilling temperatures of 2 or 4 °C. Watermelon seedlings were more resistant to low temperatures than cucumber seedlings, so it was necessary to use long chilling durations to induce significant foliar damage. A diverse set of 16 watermelon cultigens was tested: Allsweet, Black Diamond, Chubby Gray, Charlee, Charleston Gray, Dixielee, Golden, Golden Honey, New Winter, NH Midget, Sugar Baby, Sugarlee, Sunshade, PI 189225, PI 244018, and PI 595203. Experiments were conducted in a controlled environment with a light intensity of 500 mmol·m−2·s−1 photosynthetic photon flux density (PPFD). Optimal conditions for chilling treatment were 36 hours at 4 °C or 24 hours at 2 °C. The most resistant cultigen was PI 244018, and the most susceptible cultigens were NH Midget and Golden.
Fatty Alcohol Application to Control Meristematic Regrowth in Bottle Gourd and Interspecific Hybrid Squash Rootstocks Used for Grafting Watermelon
Authors: Daley Shawna L. , Hassell Richard L.
Published: February 2019

Application of fatty alcohol compounds to rootstock meristems can control rootstock meristematic regrowth, thus decreasing the cost of producing grafted watermelon transplants by reducing the labor. Eight rates of Fair 85® and Off-Shoot T®, two commercially available fatty alcohol compounds, were applied to the meristem region of bottle gourd (Lagenaria sicereria cv. Emphasis) and interspecific hybrid squash (Cucurbita maxima × Cucurbita moschata cv. Carnivor) rootstocks to determine the optimal application rate to control regrowth without damaging the remaining plant parts. A water-only control treatment was also included. Rootstock seedlings were rated for damage and regrowth on Days 1, 7, 14, and 21 after treatment. Damage increased and regrowth decreased with increasing rates of fatty alcohol compound. In addition, a significant compound-by-rate interaction indicated that inert ingredients in the fatty alcohol formulation have an effect on both damage and regrowth. The optimal treatment rate, e.g., providing at least 95% control of regrowth with less than 10% damage, was found to be between a 5% (Off-Shoot T®) and 6.25% (Fair 85®) fatty alcohol application. At the optimal treatment rate, no adverse effects to grafting success were observed in the grafting procedure.
Evaluation of Fruit Rot Resistance in Cucurbita Germplasm Resistant to Phytophthora capsici Crown Rot
Authors: Krasnow Charles S. , Naegele Rachel P. , Hausbeck Mary K.
Published: February 2019

Phytophthora blight is a destructive disease of cucurbits affecting the fruit, leaves, crown, and/or roots. Ten cucurbit PIs with known partial resistance to Phytophthora capsici root and crown rot were evaluated for resistance to Phytophthora fruit rot. Unwounded fruit from field-grown plants of Cucurbita moschata and C. pepo were inoculated in a controlled environment at 7 to 10 or 21 to 24 days post-pollination (dpp) with virulent P. capsici isolates to examine the effect of fruit age on disease development. Inoculated fruit were rated for lesion area and pathogen mycelial growth 7 days post-inoculation (dpi); fruit length, diameter, and pericarp thickness were also rated. Two C. pepo accessions (PI 169417 and PI 181761) had significant resistance to Phytophthora fruit rot at both 7 to 10 dpp and 21 to 24 dpp. All accessions evaluated displayed reduced disease susceptibility as the fruit aged.
Effects of Daily Harvest Time on Postharvest Longevity, Water Relations, and Carbohydrate Status of Selected Specialty Cut Flowers
Authors: Ahmad Iftikhar , Dole John M. , Blazich Frank A.
Published: February 2019

Effects of harvest time (morning, noon, or afternoon) on water uptake, fresh weight changes, termination symptoms, leaf relative water content (LRWC), carbohydrate status, and vase life of cut ‘ABC Purple’ lisianthus (Eustoma grandiflorum Salisb.), ‘Double Eagle’ African Gold Coin Series marigold (Tagetes erecta L.), and ‘Deep Red’ Benary’s Giant Series zinnia (Zinnia elegans Jacq.) were studied. For stems of lisianthus harvested and then stored in the dark with the basal ends in water for 2 weeks at 3 ± 1 °C, those harvested at noon (1200 hr to 1300 hr) or in the afternoon (1700 hr to 1800 hr) had longer vase life compared with stems harvested in the morning (0700 hr to 0800 hr). However, stems of lisianthus evaluated without storage had no differences in vase life. Stems of marigold harvested in the afternoon had longer vase life than morning- or noon-harvested stems. Time of harvest had no effect on cut flower longevity of zinnia. However, vase life was considerably shorter for stems of all species when tested after 2 weeks storage compared with freshly harvested stems. Stems of zinnia harvested at noon had lower LRWC than morning- or afternoon-harvested stems. Marigold stems harvested in the afternoon and evaluated without storage had lowest LRWC on Day 7 of vase life. Harvest time or storage did not influence LRWC of lisianthus. Stems of marigold and lisianthus harvested at noon or in the afternoon had higher levels of carbohydrates compared with morning-harvested stems, whereas freshly harvested stems had higher concentrations of glucose and sucrose, which decreased during storage or the vase period. Sucrose concentrations varied more significantly among various tissues than other sugars presumably as a result of translocation during vase life. In summary, carbohydrate status of stems harvested at different times of the day varied greatly and affected postharvest longevity of cut marigold and lisianthus, but not zinnia.