bluuebunny/crossref_metadata_2025 huggingface dataset:
Instrument and Operator Effects on Apple Firmness Readings
Authors: Lehman-Salada Laura
Published: February 2019

Three apple (Malus domestica Borkh.) cultivars of various maturity levels and flesh firmness were used to compare firmness readings obtained by three trained operators using Magness-Taylor (MT), Effegi (EF), and Electronic Pressure Tester (EPT) penetrometers. For all cultivars and operators, use of the MT resulted in the lowest mean readings, while use of the EPT operated in the MT testing mode resulted in the highest readings. Operator differences were observed for all instruments except when the electronic tester was used in the default mode. Comparisons between instruments and modes resulted in significantly different firmness readings across operators, except for the comparison of EF vs. EPT in default mode. For most comparisons, firmness variance due to instrument or mode was larger than the variance due to operator. Apple maturity did not significantly alter firmness trends due to instrument or operator. Thus, caution should be used to interpret apple firmness changes of a single lot of apples when several instruments and/or operators are used.
Thermal Death Kinetics of Some Common Postharvest Pathogens of Papaya
Authors: Chan Harvey T. , Nishijima Kate A. , Taniguchi Myles H. , Linse Edward S.
Published: February 2019

Thermal death kinetics, decimal reduction times (D-values), and rate constants, k, at 43 to 49 °C were determined for spore or cell suspensions of Colletotrichum gloeosporiodes (Penz.) Penz. & Sacc. in Penz., Guignardia psidii Ullasa & Rawl, Guignardia sp. Viala & Ravaz., and Enterobacter cloacae (Jordan) Hormaeche & Edwards. D-values for Monilinia fructicola (Wint.) Honey, Rhizopus stolonifer (Ehr.: Fr.) Vuill., and Stemphylium lycopersici (Enjoji) Yamamoto were calculated and extrapolated from published reports. We compared the relative heat resistances of the various postharvest pathogens to their expected survival during quarantine heat treatments and found that Guignardia, Rhizopus, and E. cloacae could be expected to survive quarantine heat treatments.
Planting Arrangement and Density of Transplants Influence Sweet Spanish Onion Yields and Bulb Size
Authors: Stoffella Peter J.
Published: February 2019

Sweet Spanish onion (Allium cepa L. cv. Granex 33) was transplanted in two, three, or four rows per bed at 7.6, 15.2, or 22.9 cm in-row spacings resulting in plant populations ranging from 41,000 to 246,000 plants/ha during Winter 1991. Interactions between number of rows per bed and in-row spacings were nonsignificant for onion yield and bulb size traits. As number of rows per bed increased or in-row spacings decreased, marketable onion yield linearly increased and mean bulb size (g/bulb) decreased. Percentage of small, medium, and large bulbs was unaffected by number of rows per bed, but percentage of small and medium-sized bulbs increased and percentage of large bulbs decreased as in-row spacing decreased. Onion yields linearly increased, but at the expense of smaller-sized bulbs, whether plant populations were increased by more rows per bed or narrower in-row spacings.
Container Volume Affects Growth and Development of Wax-apple
Authors: Hsu Y.M. , Tseng M.J. , Lin C.H.
Published: February 2019

The wax-apple [Syzygium samarangense (Bl.) Merr. & Perry] is a vigorous tropical fruit tree species that has five to six growth flushes per year. One-year-old, root-bearing wax-apple trees were grown in different-sized containers filled with potting mixture to test if container volume restricts shoot and/or root growth and thereby lends itself to forcing culture. The trunk cross-sectional area (TCSA) at 15 cm above the soil was measured to assess vegetative growth. After 6 months, the TCSA had increased quadratically with container volume. At the end of the first and second year, leaf count, leaf area, leaf dry mass, stem dry mass, shoot dry mass, and root dry mass were positively correlated with container volume. However, the shoot: root ratios remained fairly constant among treatments during the experimental period. Thus, root restriction is an effective means of reducing shoot and root growth of the wax-apple.
Silica Sprays Reduce the Incidence and Severity of Bract Necrosis in Poinsettia
Authors: McAvoy Richard J. , Bible Bernard B.
Published: February 2019

Silica sprays (Na2SiO3 or SiO2·nH2O) markedly reduced the incidence and severity of bract necrosis (BN) of Euphorbia pulcherrima Willd. cv. Supjibi Red compared to plants not sprayed with silica. BN has been associated with low Ca concentrations or high K: Ca ratios in tissues of bract margins. Silica had no effect on Ca or K concentrations in bract margin tissues, and BN was not associated with the macro- or micronutrient composition of bract margin tissues. Sixteen days after initial anthesis, nontreated and deionized-water-sprayed poinsettias developed a higher incidence of BN than did plants sprayed with Na2SiO3 or CaCl2. However, sprays of 3.56, 5.34, and 7.12 mm Na2SiO3 were as effective as 9.98 mm CaCl2 sprays in protecting against BN of `Supjibi Red' and `Angelika White' bracts for up to 30 days after initial anthesis. `Supjibi Red' developed a higher incidence of bract necrosis than did `Angelika White', but both cultivars showed a similar response to the treatments and similar symptoms of necrosis. In both cultivars, initial symptoms appeared as small necrotic lesions on bracts at the looped ends of lateral veins that displayed a closed-vein pattern after the plants reached initial anthesis.
Gum Yield as Affected by Capsule Age, Firmness, Gum Collecting Methods, and Phenotypes in Opium Poppy
Authors: Acock Mary C. , Wang Zhongchun , Acock Basil , Jones Robert
Published: February 2019

The U.S. State Dept. annually publishes estimates of narcotic drug crop production worldwide. The areas under cultivation are well known but yields per unit land area are not. Determining opium gum yield from illicitly grown poppy Papaver somniferum L. is difficult and dangerous. Removing plants from the field and harvesting gum in a safe place would allow us to measure gum yield from one short field visit. To interpret these results in terms of total gum yield from the field, one must know how the measured gum is affected by gum collecting method, capsule age, and phenotype. Opium poppy seeds from three phenotypes (purple, white, and red-white flowers) were grown in a greenhouse and plants were either cut at the soil level or left intact for opium gum harvest at 7, 12, and 22 days after flowering (DAF). Capsule firmness was measured to estimate gum yield and capsule age, and the relationship between total gum yield and yield from the first lancing was examined. The average gum yield (8.4 mg·g–1 dry weight capsule) for the purple-flowered phenotypes was 17% and 25% lower than for the white- and red/white-flowered phenotypes, respectively. Capsule firmness of the three phenotypes varied from ≈800 to 2300 N·m–1 as the capsule aged. Gum yield and capsule firmness increased with capsule age but the timing of those changes differed among phenotypes. No significant correlations were found between capsule firmness and gum yield or between capsule firmness and age. Therefore, capsule firmness cannot be used to predict gum yield or capsule age. Gum yield from the first lancing was linearly correlated with total gum yield (r2 = 0.82). Since this relationship changes with growing condition, it is insufficient to predict total gum yield. Gum yield from cut plants was significantly lower than from intact plants for all three phenotypes at 22 DAF and for white-flowered phenotypes at 12 DAF. No difference in gum yield was observed between cut and intact plants at 7 or 12 DAF for purple and red/white-flowered phenotypes. The relationship between gum yield from cut and intact plants was too variable to predict gum yield from intact plants by measuring gum yield from cut plants.
Established `Tifblue' Rabbiteye Blueberries Respond to Irrigation and Fertilization
Authors: Spiers James M.
Published: February 2019

The effects of varying rates of a complete fertilizer and irrigation on the growth and fruit yields of `Tifblue' rabbiteye blueberries (Vaccinium ashei Reade) established 3 years before treatment initiation were determined in a field study. Increased rates of irrigation resulted in increased plant growth and fruit yields. Five- and 6-year-old plants were more responsive to increasing irrigation rates than older plants. Irrigation water efficacy was greatest at lower rates and progressively less at higher rates of irrigation. Five- and 6-year-old plants fertilized with the lowest rate (14N–4P–7K; 150 g/plant) grew and yielded less than those fertilized with higher rates. Older plants did not respond to fertilization rates higher than 150 g/plant. Yearly rates of fertilization above 300 g/plant did not influence plant growth or fruit yields. Fertilization and irrigation responses were independent.
`Bing' Sweet Cherry Leaf Nutrition is Affected by Rootstock
Authors: Neilsen Gerry , Kappel Frank
Published: February 2019

Leaf nutrient concentration of `Bing' sweet cherry (Prunus avium L.) was affected by rootstock over 4 years in the Pacific Northwest. Trees on GM 79, GI 148/1, GI 195/1, and GI 196/4, which had higher yields than Mazzard, also had lower leaf K and, excepting GM 79, lower leaf Mg concentration. Use of GI 195/1 and 196/4 resulted in lower leaf N than use of Mazzard. These higher-yielding rootstocks will require greater attention to these macronutrients, especially on infertile soil sites. Micronutrient nutrition was little affected by rootstocks, which tended to have the low leaf Zn concentrations typical of irrigated Pacific Northwest orchards. GM 9 and GM 61/1 rootstocks were more dwarfing than Mazzard, with GM 9 leaves having lower K, but higher P, Mg, and Mn concentrations. GM 61/1 had lower leaf concentrations of most nutrients relative to Mazzard.
Characteristics of Litchi Seed Germination
Authors: Prasad J.S. , Kumar Raj , Mishra Mukund , Kumar Rajesh , Singh A.K. , Prasad U.S.
Published: February 2019

Seed germination of four Litchi chinensis Sonn. cultivars (`Deshi', `Kasba', `Purbi', and `Early Bedana') was studied under various conditions, viz. in soil beds exposed to sunlight or in shade, in sand beds exposed to sunlight or in shade, and on moist filter paper. Among all, shaded, humid sand at 35 ± 2C gave the highest germination. Delaying sowing seeds after removal from the fruit significantly reduced germination. Litchi seeds held in polyethylene bags up to 4 days at 37 ± 2C at 90% relative humidity delayed loss of seed viability. Germination was improved by ethephon in `Deshi' and `Early Bedana', by IBA in `Deshi' and `Purbi', and by 100 mm GA3 in all litchi cultivars. Cultivars responded differently to growth regulators, with `Deshi' responding significantly better than `Purbi', `Kasba', or `Early Bedana'. These studies point to the recalcitrant nature of litchi seeds. Chemical names used: gibberellic acid (GA3); indole butyric acid (IBA); 2-chloroethylphosphonic acid (ethephon).
Cover Crops Resistant to Root-lesion Nematodes in Raspberry
Authors: Vrain Thierry , DeYoung Robyn , Hall John , Freyman Stan
Published: February 2019

Cover crops used in red raspberry plantings (Rubus idaeus L.) are often good hosts of the root-lesion nematode (Pratylenchus penetrans Filipjev & Sch. Stekoven), a major soilborne pathogen of raspberry. The effects of two susceptible cover crops, white clover (Trifolium repens L.) and barley (Hordeum vulgare L.), planted in between rows, on nematode density and growth of raspberry plants were compared to those of three cover crops resistant to the nematode: redtop (Agrostis alba L.), creeping red fescue (Festuca rubra L.), and `Saia' oat (Avena sativa L.). Nematode multiplication in raspberry roots and in cover crop roots was assessed over 4 years. Growth and vigor of plants were estimated at the end of the experiment by counting primocanes and determining height and biomass. Nematode multiplication was suppressed in roots of `Saia' oat, fescue, and redtop compared to barley or white clover. Nematode density in roots and rhizosphere soil of raspberry was not affected by the choice of cover crops. Nematode suppression in the three resistant cover crops did not translate into increased vigor of raspberry plants.
Nondestructive Acoustic Measurement of Firmness for Nectarines, Apricots, Plums, and Tomatoes
Authors: Muramatsu Noboru , Sakurai Naoki , Yamamoto Ryoichi , Nevins Donald J.
Published: February 2019

A nondestructive, acoustic method was applied to evaluate firmness of nectarines (Prunus persica Batch.), apricots (Prunus mume Sieb. et Succ.), plums (Prunus salicina Lindl.), and tomatoes (Lycopersicon esculentum Mill. `Beiju'). Sound with frequencies from 200 to 2000 Hz, generated by a miniature speaker attached to the fruit surface, was received by a small microphone attached to the opposite side. The signal was monitored by an oscilloscope. Sound frequency did not change during propagation in the fruit. However, as the microphone was moved along the circumference of the fruit, a phase shift in the received signal was observed. When the distance the microphone was displaced along the surface of the fruit corresponded to a shift of exactly one wavelength, the sound wavelength propagated within the fruit could be determined. The number of sound waves within the fruit over half its circumference was calculated as a function of this distance. Mature fruit propagated shorter wavelengths and consequently more sound waves than immature fruit, indicating that the sound velocity in the mature fruit was lower than in immature fruit. This relatively simple method for measuring lower frequency suggests that the sound velocity propagated through fruit can be determined without measuring the absolute velocity.
Interspecific Hybrid Verification of Rosa with Isozymes
Authors: Kim Young-ju , Byrne David H.
Published: February 2019

The hybrid origin of 23 rose (Rosa spp.) accessions was examined with three isozymes: acid phosphatase (E.C.3.1.3.2), malate dehydrogenase (E.C.1.1.1.37), and phosphoglucose isomerase (E.C.5.3.1.9). All three isozymes were useful for interspecific hybrid verification. This procedure was effective if the putative parents were known and differed in isozyme phenotype. To verify the origin of hybrid species or cultivars with hybrid origins, isozymes were useful but limited by the number of generations since the original hybridization and the number of accessions of the putative parental species assayed.
Random Amplified Polymorphic DNA Markers in Sweetpotato Infected with Fusarium lateritium
Authors: Buffone Frank A. , La Bonte Don R. , Clark Christopher A.
Published: February 2019

DNA isolated from Fusarium lateritium Nees: Fr.-infected `Jewel' sweetpotato [Ipomoea batatas (L.) Lam.] plants was compared to F. lateritium-free `Jewel' plants for differences in random amplified polymorphic DNA (RAPD) marker products. Differences in RAPD marker products were detected. Amplified DNA isolations from F. lateritium-infected `Jewel' plants generated additional, unique DNA fragments not found in amplified DNA isolations of F. lateritium-free `Jewel' plants. These unique amplified DNA fragments were consistent with those obtained from amplified DNA isolations of the F. lateritium isolate, 91-27-2, used for inoculation. We found that F. lateritium DNA successfully competes with sweetpotato DNA in the polymerase chain reaction for priming sites in a 3: 1 ratio of sweetpotato DNA to F. lateritium DNA. Our results indicate the importance of avoiding plant material infested with pathogens to avoid spurious marker bands.
Detachment Force and Fruit Characteristics of Tabasco Pepper at Several Stages of Development
Authors: Motsenbocker Carl E.
Published: February 2019

Field and greenhouse studies examined the fruit detachment force (FDF) and fruit and pedicel characteristics of two lines of tabasco pepper (Capsicum frutescens L.) at several stages of maturity. The detachment force of red-mature `McIlhenny Select' fruit at the calyx-fruit detachment area was lower than that of less mature fruit stages. The force required to detach red-mature Hard Pick (HP) tabasco fruit was higher than that of redmature `McIlhenny Select' fruit in the field and greenhouse. The fruit detachment force of red field-grown HP fruit was higher, and in the greenhouse was lower, than that of green or breaker fruit. HP fruit of all maturity stages, except red-mature, separated similarly to `McIlhenny Select' fruit with little or no fruit tissue attached to the calyx. Fruit detachment force was not correlated with any fruit or pedicel characteristics studied.
Micropropagated Banana Infected with Meloidogyne javanica Responds to Glomus intraradices and Phosphorus
Authors: Pinochet Jorge , Fernández Carolina , Jaizme María de Carmen , Tenoury Pedro
Published: February 2019

The effects of the interaction between the vesicular-arbuscular mycorrhizal fungus Glomus intraradices Schenk and Smith and the root-knot nematode Meloidogyne javanica (Treub) Chitwood on growth and nutrition of micropropagated `Grand Naine' banana (Musa AAA) were studied under greenhouse conditions. Inoculation with G. intraradices significantly increased growth of plants in relation to nonmycorrhizal plants and was more effective than P fertilization in promoting plant development. Mycorrhizal colonization did not affect nematode buildup in the roots, although plants with the nematode and mycorrhiza were more galled. Meloidogyne javanica had no effect on the percentage of root colonization in mycorrhiza-inoculated plants. No element deficiency was detected by foliar analysis. All elements were within sufficiency levels for banana with exception of N, which was low. Potassium levels were lower in mycorrhizal plants, while Ca and Mg levels were higher with mycorrhiza than without, with or without the nematode. Early inoculation with G. intraradices appears to favor growth of banana plants by enhancing plant nutrition.
Postharvest Physiology and Quality of Cilantro (Coriandrum sativum L.)
Authors: Loaiza Julio , Cantwell Marita
Published: February 2019

Respiration rates of freshly harvested cilantro were moderately high (CO2 at 15 to 20 μL·g-1·h-1) and ethylene production rates were low (<0.2 nL·g-1·h-1) at 5 °C and were typical of green leafy tissues. Cilantro stored in darkness at a range of temperatures in air or controlled atmospheres was evaluated periodically for visual quality, decay, aroma, off-odor, color, and chlorophyll content. Cilantro stored in air at 0 °C had good visual quality for 18 to 22 days, while at 5 and 7.5 °C good quality was maintained for about 14 and 7 days, respectively. An atmosphere of air plus 5% or 9% CO2 extended the shelf-life of cilantro stored at 7.5 °C to about 14 days. Quality of cilantro stored in 3% O2plus CO2 was similar to that stored in air plus CO2. Atmospheres enriched with 9% to 10% CO2 caused dark lesions after 18 days; 20% CO2 caused severe injury after 7 days. Although visual quality could be maintained for up to 22 days, typical cilantro aroma decreased notably after 14 days, regardless of storage conditions.
Essential Oils and Chilling Injury in Lemon
Authors: Obenland D.M. , Margosan D.A. , Houck L.G. , Aung L.H.
Published: February 2019

Release, localization, and concentration of essential oils in chilling-injured and noninjured lemon [Citrus limon (L.) Burm.] fruit were investigated to enhance understanding of how chilling injury (CI) occurs in lemon. CI in the form of moderate to severe pitting of the flavedo was initially apparent after 3 weeks at 1 °C, followed by a gradual increase in severity until termination of the experiment after 7 weeks at 1 °C. Curing the fruit at 15 °C for 1 week before cold treatment greatly reduced the severity of CI. Release from the fruit of d-limonene, a major component of essential oil in lemon, increased with increasing amounts of CI. The enhancement of d-limonene release, however, lagged behind the development of CI. Studies of the internal anatomy of the flavedo using confocal microscopy indicated that essential oils were abundantly present inside the oil gland and in oil bodies outside the gland. Chilling-injured flavedo exhibited no obvious disruption of either the oil glands or the oil bodies. Extraction and quantification of d-limonene from chilling-injured and noninjured flavedo indicated that similar amounts of oil were present in the tissue, regardless of injury. Damage to the flavedo after 3 weeks at 1 °C was noted in the form of flattened or collapsed cells between the top of the gland and the epidermis, whereas collapse of the oil gland only was observed in later stages of injury development.
Pre- and Postharvest Temperature Conditioning of Greenhouse-grown Sweet Basil
Authors: Lange Diana L. , Camero Arthur C.
Published: February 2019

Postharvest shelf life (defined by visual quality) of fresh, greenhouse-grown sweet basil (Ocimum basilicum L.) at 5 °C was only 3 to 4 d due to the appearance of chilling injury symptoms. Plants chill-hardened at 10 °C for 4 h daily (2 h at the end of the light period and 2 h at the beginning of the dark period) for 2 d, before harvesting and packaging, had ≈3 d longer postharvest life. Four- to 6-week-old plants were chill-hardened for 1 week at several periods during the day. Chill-hardening at the beginning of the day extended the average shelf life of cuttings from 4- to 5-week-old plants by 1 and 1.5 d, respectively. Shelf life either was decreased or not affected by the other periods of preharvest hardening. More importantly, postharvest chill-hardening of packaged sweet basil for 1 day at 10 °C in darkness before transfer to 5 °C increased average shelf life by 5 d. Good potential exists for postharvest chill-hardening of packaged sweet basil since this method is effective and convenient.
Identification of Poinsettia Cultivars Using RAPD Markers
Authors: Ling Jing-Tian , Sauve Roger , Gawel Nick
Published: February 2019

Randomly amplified polymorphic DNA (RAPD) techniques were used to compare the DNA from leaf tissues of nine commercial poinsettia (Euphorbia pulcherrima Wild ex Klotzsch) cultivars. Amplification occurred in 57 out of 60 (95%) tested primers. Nine primers that revealed polymorphisms among cultivars were selected for further evaluation. Forty-eight RAPD bands were scored from these primers, and 33 (69%) were polymorphic. All tested cultivars could be discriminated with seven bands generated from primers OPB7 and OPC13. Results of a UPGMA cluster analysis and principal components analysis placed the nine cultivars into two groups: one group consisted of `Jingle Bells', `Supjibi', and `V-17 Angelika', the other of `V-14 Glory', `Red Sails', `Jolly Red', and `Freedom'. `Lilo Red' and `Pink Peppermint' belonged to the latter group, but were relatively distant from other cultivars in that group. These results indicate that RAPDs are efficient for identification of poinsettia cultivars and for determination of the genetic relationships among cultivars.
An Automated Chamber System for Measurements of Whole-vine Gas Exchange
Authors: Poni S. , Magnanini E. , Rebucci B.
Published: February 2019

The reported system interfaces a commercially available portable infrared gas analyzer with a measurement and control module for continuous and automated measurements of whole-canopy gas exchange. Readings were taken for several days, under mostly sunny or partly cloudy conditions, on two potted vines (total leaf area per vine of ≈1.3 m2) enclosed in inflated polyethylene chambers. The air flow rate through the chambers was provided by a centrifugal blower and set at 5 L·s-1 by a butterfly valve. It prevented ΔCO2 from dropping below –40 mL·L-1. Switching of the two CO2 analysis channels to the infrared gas analyzer (operated in a differential mode) was achieved by solenoid valves, whereas wet and dry-bulb temperatures at chambers' inlet and outlet were measured by low-cost, custom-made thermocouple psychrometers. Whole-vine assimilation rate (WVA) and whole-vine transpiration rate were calculated from the inlet—outlet differences in CO2 and absolute humidity. When compared to assimilation measured on single leaves (SLA) under saturating light at equivalent times, the WVA reduction (area basis) was ≈50%, suggesting that whole-canopy photosynthetic efficiency based on SLA readings can be greatly overestimated.
Lime, Water Source, and Fertilizer Nitrogen Form Affect Medium pH and Nitrogen Accumulation and Uptake
Authors: Argo William R. , Biernbaum John A.
Published: February 2019

Hybrid impatiens (Impatiens wallerana Hook. F.) were planted into media containing two dolomitic liming materials {hydrated [Ca(OH)2 and Mg(OH)2] or carbonate (CaCO3 and MgCO3) lime} and subirrigated for 17 weeks with four irrigation water sources (IWS) and three water-soluble fertilizers (WSF). The WSF contained 200N–20P–200K mg·L-1 but varied in NH4+-N content (50%, 25%, or 3%, respectively). Depending on the IWS and lime type used in the media, root-medium pH ranged from 4.5 to 6.0, 4.8 to 7.1, and 6.0 to 8.5 when treated with WSF containing either 50%, 25%, or 3% NH4+-N, respectively, between 8 and 17 weeks after planting. The accumulation of NH4+-N and NO3--N in the root medium was different for treatments receiving the same WSF and depended on root-medium pH. The critical root-medium pH for NH4+-N accumulation was between 5.4 and 5.7, and for NO3--N, accumulation was between 5.3 to 5.9. Above this pH, minimal NH4+-N concentrations were measured in the medium, even with 50% or 25% NH4+-N WSF, while below this pH, NH4+-N began to accumulate in the medium with a corresponding decrease in the NO3--N concentration. The NH4-N: NO3-N ratios in the WSF had minimal effect on shoot fresh and dry weights. Tissue N concentration was higher with the higher NH4-N : NO3-N ratio WSF at all four sampling dates. There was a linear relationship between higher tissue N and lower root-medium pH with the same WSF, possibly due to differences in the ratio of NH4-N: NO3-N actually taken up by the plant.
Nitrogen, Magnesium, and Boron Applications Affect Cauliflower Yield, Curd Mass, and Hollow Stem Disorder
Authors: Batal K.M. , Granberry D.M. , Mullinix B.G.
Published: February 2019

The effects of three rates of N, Mg, and B on cauliflower (Brassica oleracea, Botrytis group) yield, average curd mass, and hollow stem disorder were evaluated on sandy and clay loam soils. Cultivars White Empress and Stovepipe were tested on the sandy loam soil and `White Empress' was tested on the clay loam soil. Maximum mean curd mass and maximum yields were obtained with the highest N rates (269 and 381 kg·ha-1) applied to sandy loam and clay loam soils, respectively. Yield response to increased N rates varied with cultivar. Increasing Mg from 22.5 to 90 kg·ha-1 did not affect yield or curd mass on clay loam soil, but increased yield and mean curd mass on sandy loam soil. The Mg effect on curd mass was influenced by N and B rates. On both soil types, the higher Mg and B rates reduced the incidence of hollow stem, but the Mg effect was influenced by N applications. On clay loam soil, increasing B from 2.2 to 8.8 kg·ha-1 reduced hollow stem but had no effect on yield or curd mass. On sandy loam soil, B at 4.4 kg·ha-1 maximized yield and curd mass, but the hollow stem disorder continued to decrease as B rates were increased from 2.2 to 8.8 kg·ha-1.
Induction of Seedlessness in `Triumph' Muscadine Grape (Vitis rotundifolia Michx.) by Applying Gibberellic Acid
Authors: Lu Jiang , Lamikanra Olusola , Leong Stephen
Published: February 2019

Gibberellic acid (GA3), a plant growth regulator used routinely in the production of seedless bunch grapes, was sprayed on the seeded muscadine grape cultivar Triumph. GA3 at 100, 200, and 300 mg·L-1 was sprayed on the leaves and fruit clusters at late bloom; a second spray followed 1 week later. The sprayed vines produced more than 20% seedless berries and the size of the berries with seeds increased significantly. GA3 application in commercial muscadine grape production may have potential benefits.
Spectral Quality Affects Disease Development of Three Pathogens on Hydroponically Grown Plants
Authors: Schuerger Andrew C. , Brown Christopher S.
Published: February 2019

Plants were grown under light-emitting diode (LED) arrays with various spectra to determine the effects of light quality on the development of diseases caused by tomato mosaic virus (ToMV) on pepper (Capsicum annuum L.), powdery mildew [Sphaerotheca fuliginea (Schlectend:Fr.) Pollaci] on cucumber (Cucumis sativus L.), and bacterial wilt (Pseudomonas solanacearum Smith) on tomato (Lycopersicon esculentum Mill.). One LED (660) array supplied 99% red light at 660 nm (25 nm bandwidth at half-peak height) and 1% far-red light between 700 to 800 nm. A second LED (660/735) array supplied 83% red light at 660 nm and 17% far-red light at 735 nm (25 nm bandwidth at half-peak height). A third LED (660/BF) array supplied 98% red light at 660 nm, 1% blue light (BF) between 350 to 550 nm, and 1% far-red light between 700 to 800 nm. Control plants were grown under broad-spectrum metal halide (MH) lamps. Plants were grown at a mean photon flux (300 to 800 nm) of 330 μmol·m-2·s-1 under a 12-h day/night photoperiod. Spectral quality affected each pathosystem differently. In the ToMV/pepper pathosystem, disease symptoms developed slower and were less severe in plants grown under light sources that contained blue and UV-A wavelengths (MH and 660/BF treatments) compared to plants grown under light sources that lacked blue and UV-A wavelengths (660 and 660/735 LED arrays). In contrast, the number of colonies per leaf was highest and the mean colony diameters of S. fuliginea on cucumber plants were largest on leaves grown under the MH lamp (highest amount of blue and UV-A light) and least on leaves grown under the 660 LED array (no blue or UV-A light). The addition of far-red irradiation to the primary light source in the 660/735 LED array increased the colony counts per leaf in the S. fuliginea/ cucumber pathosystem compared to the red-only (660) LED array. In the P. solanacearum/ tomato pathosystem, disease symptoms were less severe in plants grown under the 660 LED array, but the effects of spectral quality on disease development when other wavelengths were included in the light source (MH-, 660/BF-, and 660/735-grown plants) were equivocal. These results demonstrate that spectral quality may be useful as a component of an integrated pest management program for future space-based controlled ecological life support systems.
A Model to Predict Peach Phenology and Maturity Using Meteorological Variables
Authors: Schwartz Mark D. , Carbone Gregory J. , Reighard Gregory L. , Okie William R.
Published: February 2019

This paper outlines the development of regional-scale peach [Prunus persica (L.) Batsch] phenology models for the southeastern United States. We constructed regression-based models to predict full bloom and first harvest using phenological data for eight peach cultivars grown in Georgia, South Carolina, and Texas and meteorological data from nearby cooperative weather stations. The mean absolute error (MAE, absolute value of predicted date minus observed date) of the all-cultivar full bloom model was 3.48 days. Bloom model errors were roughly 6 to 7 days (or less) 90% of the time, while comparable natural bloom date variability at a single station is about 12 to 13 days. Only two cultivars (`Dixired' and `Elberta') had first harvest models with 90% error thresholds at or less than the natural harvest date variability at a single station (9 to 10 days). Thus, first harvest appears to be less predictable than full bloom, at least in terms of the temperature variables used in this study. The bloom model could serve as a prognostic tool, while the two cultivar harvest models are appropriate only for diagnostic studies, such as evaluating the potential response of a peach cultivar in a new location. The appeal of the models is that they consider numerous cultivars over a wide region and they use readily available meteorological data.
Nitrogen Requirements of Fresh-market Tomatoes on Hairy Vetch and Black Polyethylene Mulch
Authors: Abdul-Baki Aref A. , Teasdale John R. , Korcak Ronald F.
Published: February 2019

A 3-year experiment was conducted to determine the optimum fertilizer N requirements of fresh-market tomato (Lycopersicon esculentum Mill.) `Sunbeam' grown on a hairy vetch (Vicia villosa Roth.) or black polyethylene mulch. In 1993 and 1994, four rates of fertilizer N (0, 56, 112, and 168 kg·ha-1) as water-soluble NH4NO3 were applied in 14 equal applications through the trickle irrigation system starting 1 week after planting. Four additional rates (224, 280, 336, and 392 kg·ha-1) were applied in 1995 to assess the plant response to supra-optimal levels of N. Hairy vetch produced 3.3–4.5 t·ha-1 of above-ground biomass and a total N content of 126–169 kg·ha-1 in the above-ground biomass. Leaf N content at 7 weeks after transplanting of tomatoes correlated positively with yield from black polyethylene but did not correlate with yield from the hairy vetch plots where leaf N content was optimal at all N rates. Predicted tomato yields were higher for the hairy vetch than for the black polyethylene treatment at all applied N rates in all years. Tomatoes grown in black polyethylene required N at 130 to 144 kg·ha-1 to achieve yields equivalent to those grown following unfertilized hairy vetch. Tomato yield increased in response to applied N in both mulches in all 3 years; optimum N rates of 89 and 190 kg·ha-1 in hairy vetch and black polyethylene, respectively, were predicted by a linear plateau model, and 124 and 295 kg·ha-1 by a quadratic plateau model. The linear plateau model is recommended because it would allow less N to become available for runoff and leaching.
Using Impedance for Mechanical Conditioning of Tomato Transplants to Control Excessive Stem Elongation
Authors: Garner Lauren C. , Björkman Thomas
Published: February 2019

Mechanical stimulation is known to control excessive stem elongation in high-density tomato (Lycopersicon esculentum Mill.) transplants. Mechanical stimulation using physical impedance provided height control equivalent to that obtained using brushing. Low-cost materials can be used to apply the impedance. Mylar film in a plastic frame was equivalent to expensive acrylic sheets in its effect on plant height (40 mm shorter than nontreated, a 40% reduction in the elongation rate during the treatment period), stem diameter (18% thicker), and biomass (14% lighter) when they applied a pressure of 66 N·m-2. Stem elongation was not reduced if less pressure was applied (25 or 50 N·m-2). Height control was equally effective with a solid material (mylar film) and a permeable material (fiberglass insect screen), indicating that restricting air movement is not an important mechanism for the growth response. Overnight treatments resulted in the desired growth response (27 mm shorter than nontreated, a 30% reduction in elongation rate), but 0.5-h treatments had insufficient effect for commercial use (11 mm shorter, 10% reduction in elongation rate). These experiments demonstrate that impedance can be used in commercial production conditions to control tomato transplant height with inexpensive materials. However, satisfactory height control requires a large applied force and a long daily treatment period.
Nitrogen and Potassium Application Scheduling Effects on Drip-irrigated Tomato Yield and Leaf Tissue Analysis
Authors: Locascio Salvadore J. , Hochmuth George J. , Rhoads Fred M. , Olson Steve M. , Smajstrla Alan G. , Hanlon Ed A.
Published: February 2019

Tomato (Lycopersicon esculentum Mill.) was grown with drip irrigation on an Arredondo fine sand and on an Orangeburg fine sandy loam to evaluate the effect of N and K time of application on petiole sap, leaf-N and -K concentrations, fruit yield, and to determine N and K sufficiency ranges in leaf tissue. On the sandy soil, N—K at 196-112 kg·ha-1 were applied 0%, 40%, or 100% preplant with the remainder applied in 6 or 12 equal or in variable applications in 12 weeks. With the variable application rate, most nutrients were applied between weeks 5 and 10 after transplanting. On the sandy loam soil that tested high in K, only N (196 kg·ha-1) was applied as above. Petiole sap K concentration declined during the season, but was not greatly affected by treatment. Petiole NO3-N concentrations decreased during the season from 1100 to 200 mg·L-1, and the decrease was greater with preplant N treatments. On the sandy soil, marketable fruit yields were lowest with 100% preplant, intermediate with 100% drip applied (no preplant N), and highest with 40% preplant and 60% drip applied. With 100% drip applied, yields were higher with 12 even applications than with either six even weekly applications or with 12 variable N and K applications. With 40% preplant, timing of application had little effect on yield. On the sandy loam soil in 1993, yields were highest with 100% preplant, intermediate with 40% preplant and 60% drip applied, and lowest with all N drip applied. In 1994 when excessive rains occurred, yields were similar with all preplant and with split N applications. Petiole N concentration was correlated with tomato yield, especially at 10 weeks after transplanting. The best correlation between sap-N and total yields occurred between 4 and 6 weeks at Gainesville and between 4 and 10 weeks at Quincy.
Fruit Composition of `Arapaho' Blackberry Following Nitrogen Fertilization
Authors: Alleyne Victorine , Clark John R.
Published: February 2019

An investigation was conducted over 2 years to evaluate the effect of N rate and time of application on fruit composition of `Arapaho' thornless erect blackberry (Rubus L., subgenus Eubatus). N from ammonium nitrate was applied at 56 or 112 kg·ha-1 in single applications, or at 112 kg·ha-1 as a split application with 0 kg·ha-1 as the control. Increasing N rates increased fruit N and pH but did not affect soluble solids concentration, titratable acidity, sugar-acid ratio, and total solids. Timing of N application had no effect on the fruit characteristics measured.
Nitrogen Fertilization Affects Quality of Peach Puree
Authors: Olienyk P. , Gonzalez A.R. , Mauromoustakos A. , Patterson W.K. , Rom C.R. , Clark J.
Published: February 2019

Clingstone peach [Prunus persica (L.) Batsch cv. Allgold] trees were fertilized once with 45 or 90 kg N/ha at budbreak or twice with 22.5 or 45 kg N/ha at budbreak and after harvest. A nonfertilized control was included. Fruits from all treatments were made into puree, and objective and subjective qualities were evaluated. Puree from the N treatments and the control did not show significant differences in Color Difference Meter (CDM) `L' and hue angle, pH, titratable acidity (TA), soluble solids concentration (SSC), SSC: TA ratio, viscosity, ascorbic acid, Ca, K, phenolic and nitrates concentration. Puree from the control and 22.5 kg N/ha applied twice had significantly lower CDM `a', `b', and chroma values than from the other treatments. The split applications of N significantly reduced levels of Ca and ascorbic acid. N rate and number of applications interacted for `a' and K. When N was applied twice at 22.5 kg·ha-1, `a' and K decreased, but this response was absent when N was applied twice at 45 kg·ha-1. Puree from the nonfertilized control was rated lower by panelists for sensory quality than that from the fertilized trees. Peach puree from trees fertilized once with 45 kg N/ha at budbreak had the best overall sensory quality.
A New Source of Peach Germplasm Containing Semi-freestone Nonmelting Flesh Types
Authors: Van Der Heyden C.R. , Holford P. , Richards G.D.
Published: February 2019

A freestone, nonmelting flesh peach would offer the opportunity to transport freestone peaches to distant markets, and so open lucrative export opportunities. Peach [Prunus persica (L.) Batsch.] germplasm segregating for semi-freestone and clingstone has been identified among the nonmelting flesh, open-pollinated progeny of the Univ. of Florida selection, Fla. 9-20C. The segregation approached a 1 : 1 ratio. No significant differences were detected between the two categories for titratable acidity, soluble solids concentration, or skin color. However, the semi-freestone progeny had significantly softer flesh than their clingstone siblings, although not soft enough to justify reclassification of the flesh texture. No simple genetic model can be proposed for the inheritance of this new phenotype. The semi-freestone, nonmelting germplasm represents a step towards a less perishable, freestone cultivar for the fresh market, as well as an opportunity to study the reason for the rarity of the freestone/nonmelting phenotype among peaches.
Irradiation and Heat Affect Peach Pollen Germination and Fertility
Authors: Pooler M.R. , Scorza R.
Published: February 2019

Pollen from the doubled haploid peach [Prunus persica (L.) Batsch] `Hall-D' was irradiated with 0, 290, 530, 820, 1000, 5000, or 9000 Gray (Gy) of gamma radiation, 113 μW·cm-2 of ultraviolet (UV) radiation, or exposed to 100 °C for 2 h. In vitro pollen germination percentages were recorded and pollen was used to pollinate more than 10,000 emasculated or male-sterile peach flowers. Although pollen germination in vitro was stimulated by <1000 Gy of gamma irradiation, seed set following pollination was greatly reduced in all treatments. These results suggest that low levels of irradiation are sufficient to render pollen infertile while still maintaining germination capacity. Such results may be useful for pollination-induced parthenogenetic egg division for the production of maternally derived haploids and for the production of interspecific hybrids.
Induction of In Vitro Cultured Masses of Shoot Primordia of Hybrid Statice and Its Cryopreservation by Vitrification
Authors: Matsumoto Toshikazu , Nako Yoji , Takahashi Chiaki , Sakai Akira
Published: February 2019

Bulbous structures consisting of meristematic clumps (designated “shoot primordia”) were induced from a meristematic culture of a hybrid statice (Limonium altaica Mill. × L. caspium Mill., cv. Blue Symphonet). The shoot tips were cultured in 25 mL of liquid 1/2 Murashige & Skoog (MS) medium supplemented with 0.44 μm BA and 0.054 μm NAA and 3% sucrose at pH 5.8 by vertically shaking at 2 rpm on rotating stages (1 m in diameter) at 25 °C. One month after inoculation of shoot tips, numerous small globular structures were formed and propagated vegetatively at a high rate following subculture. Segments of shoot primordia had developed into plantlets 2 weeks after transfer to solidified 1/2 MS medium supplemented with 0.44 μm BA and 1% sucrose. Plantlets successfully acclimated and grew into normal plants in a greenhouse. Cold-hardened, precultured small segments of shoot primordia were successfully cryopreserved in liquid N by vitrification. Vitrified and warmed segments plated on solidified 1/2 MS medium produced shoots about 21 d after plating. Cultured masses of shoot primordia appear promising for large-scale production and cryopreservation of annual and biennial statice. Chemical names used: 6-benzyladenine (BA); 1-naphthaleneacetic acid (NAA).
Nitrogen Transformation in Low pH Soils for Cranberry
Authors: Roper Teryl R. , Krueger Armand R.
Published: February 2019

Cranberry plants exclusively utilize ammonium forms of nitrogen. Nitrification of applied ammonium and subsequent leaching through sandy soils is a potential problem for growers. Peat, sand, and striped soils were collected in cranberry beds in central Wisconsin and soil pH was adjusted to 3.5, 4.5, or 5.5. Twenty-five grams of dry soil was placed in flasks and half the flasks were sterilized. Distilled water was added to half of the samples, and the other half received 15N-labeled ammonium. Flasks were incubated at 20°C for up to 70 days. Striped soils showed no nitrification at pH 3.5 or 4.5 during the 70 day incubation. At pH 5.5, nitrification began at 20 days and was almost complete at 70 days. Nitrification did not occur at any pH in sandy soils. This research suggests that ammonium fertilizer applied to cranberry is likely taken up before nitrification would occur.
Postemergence Control of Phyllanthus urinaria by Prodiamine and Phytotoxicity to Ornamentals
Authors: Aldrich James H. , Norcini Jeffrey G.
Published: February 2019

Postemergence control of Phyllanthus urinaria L. (chamberbitter) in nursery and landscape plantings has been primarily limited to hand-weeding. Prodiamine was evaluated for postemergence control of chamberbitter and phytotoxicity to containerized ornamentals. On 20 June 1995, prodiamine at 0, 1.68, 3.36, or 6.72 kg a.i./ha was applied over-the-top to immature chamberbitter growing in 3.8-L containers of established Buddleia davidii Franch. `White Bouquet' Cuphea hyssopifolia HBK. `Desert Snow', Lantana camara L. `Irene', and Lantana montevidensis (Spreng.) Briq. `Lavender Weeping'. Weed-free checks were included. Applications were made with a compressed air backpack sprayer. There were four replications per treatment placed in a randomized complete block design by species. Plants were established and maintained on a container bed under full sun and overhead irrigation. Growth of and phytotoxicity to the ornamentals species, and percent coverage and number of chamberbitter, were recorded periodically for 14 weeks after treatment (WAT). Chamberbitter shoots were harvested for dry weight analysis 14 WAT. Prodiamine provided some postemergence control of chamberbitter. However, Cuphea and both Lantana species exhibited leaf distortion and/or delayed flowering.
Tolerance of Selected Ornamentals for Phytoremediation of Atrazine, Simazine, and Metalaxyl Residues in Water
Authors: Wilson C. , Whitwell T. , Klaine S.
Published: February 2019

Atrazine, simazine, and metalaxyl residues are often present in sprayer rinsates and in runoff water following application of the formulated products. As an initial step in the development of a constructed wetland for the phytoremediation of these pesticides in water, several plant species were evaluated for their tolerances to each. Plant species were chosen based on their aesthetics, tolerance to wetland conditions, and their potential to produce much vegetative growth. Species included: Acorus gramenius, Canna hybrida `King Humbert', Myriophyllum aquaticum, and Pontederia cordata. Plants were exposed to various concentrations of each pesticide dissolved in 10% Hoagland's nutrient media for 7 days. Tests were conducted under metal halide lamps with a light intensity of 400 μmol/m2 per s and a photoperiod of 16 h light: 8 h dark. Test endpoints measured included 7-day fresh mass production and chlorophyll fluorescence. A completely randomized statistical design with four replications of each concentration was utilized for each plant species. These tests indicate that all plant species were susceptible to atrazine and simazine in the 0.1 to 1 μg/ml range. Effected plants displayed concentration-dependent degrees of chlorosis and necrosis. Plants were more tolerant to metalaxyl concentrations in water. However, leaf chlorosis and necrosis did occur at concentrations greater than 25 μg/ml. Future research will quantify the uptake and mineralization potential for these plants and pesticides.