bluuebunny/crossref_metadata_2025 huggingface dataset:
Potential Sources of Resistance to Broad Mites (Polyphagotarsonemus latus) in Watermelon Germplasm
Authors: Kousik Chandrasekar S. , Shepard B.M. , Hassell Richard , Levi Amnon , Simmons Alvin M.
Published: February 2019

Two hundred nineteen U.S. plant introductions (PI) belonging to the watermelon core collection were evaluated for broad mite, Polyphagotarsonemus latus (Banks), infestation and injury that occurred naturally in a field planting. Of the 219 PIs, nine (4%) had no visible broad mite injury in the field compared with a commercial cultivar, ‘Mickey Lee’, which was severely injured. Injury mainly occurred on the growing terminals and the tender apical leaves. The growing terminals and the apical leaves were bronzed, grew poorly and, in some cases, they were distorted and curled upward. Broad mites were extracted by washing the growing terminals of 22 selected PIs with boiling water and counting the mites under a stereomicroscope. ‘Mickey Lee’ had more broad mites on growing terminals compared with some of the PIs with no visible injury. Fourteen selected PIs were further evaluated in the greenhouse to confirm their resistance by artificially infesting them with broad mites that had been cultured on susceptible watermelon plants. PIs in accessions belonging to Citrullus lanatus var. lanatus (PI 357708), Citrullus lanatus var. citroides (PI 500354), Citrullus colocynthis (PI 386015, PI 386016, PI 525082), and Parecitrullus fistulosus (PI 449332) had significantly lower broad mite injury ratings and counts compared with ‘Mickey Lee’ and other susceptible PIs. Broad mites have not been reported on watermelons in the United States before; however, it can emerge as a serious pest. The previously mentioned accessions can serve as potential sources of broad mite resistance for use in breeding programs aimed at enhancing pest resistance in watermelon.
Correction of Zinc Deficiency in Pecan by Soil Banding
Authors: Wood Bruce W.
Published: February 2019

Zinc (Zn) deficiency is common in commercial pecan [Carya illinoinensis (Wangenh.) C. Koch] orchards. Correction by multiple annual foliar spray applications is expensive but effective in eliminating Zn deficiency. Correction by soil application is also expensive and is usually impractical or noneffective. There is a need for more economical and long-lasting methods for satisfying tree Zn nutritional needs. It is reported here that tree foliar Zn needs [(i.e., 50 μg·g−1 dry weight (dw) or greater] are potentially met through one-time “banding” of Zn sulfate (ZnSO4·7H2O) or Zn oxide (ZnO) onto orchard floors. Zinc needs of 4-year-old ‘Desirable’ trees growing on acidic soil were satisfied over a 4-year period by a single-banded soil application of either Zn sulfate or ZnO over underground drip irrigation lines at a Zn rate of 2112 g Zn per tree (giving foliar Zn concentrations of 60–115 μg·g−1 dw). Rates of Zn at 264 to 1056 g per tree are occasionally efficacious, but rates less than 264 g Zn per tree (0, 33, 66, and 132) were always ineffective for meeting a leaf sufficiency threshold of 50 μg·g−1 dw. Sulfate and oxide Zn forms were equally effective in meeting tree Zn needs. Foliar Zn concentrations increased quadratically with increasing soil-banded Zn treatments; however, foliar Zn concentrations did not necessarily increase over the 4-year period within each Zn rate treatment. Increasing amounts of banded Zn per tree also increased foliar Mn concentration (from ≈150 to 269 μg·g−1 dw) of treated trees the fourth year posttreatment but did not affect foliar concentration of other key micronutrients (i.e., Fe, Co, Cu, or Ni). This fertilization strategy offers an efficacious alternative to annual foliar Zn sprays for orchards established on acidic soils and provides a means of ensuring rapid and long-term Zn absorption through soil application. The approach indicates that soil banding of Zn on certain acidic soils can satisfy the nutritional needs of pecan trees for several years after a single application.
Potassium Nutrition Affects Phalaenopsis Growth and Flowering
Authors: Wang Yin-Tung
Published: February 2019

Bare-root, vegetatively propagated plants (average 15-cm leaf spread) of a white-flowered Phalaenopsis Taisuco Kochdian clone were imported in late May and planted either in a mix consisting of three parts medium-grade douglas fir bark and one part each of perlite and coarse canadian sphagnum peat (by volume) or in chilean sphagnum moss. All plants were given 200 mg·L−1 each of nitrogen and phosphorus, 100 mg·L−1 calcium, and 50 mg·L−1 magnesium at each irrigation with 0, 50, 100, 200, 300, 400, or 500 mg·L−1 potassium (K). After 8 months, K concentration did not alter the number of new leaves on plants in either medium. Plants grown in moss produced four to five leaves, whereas those planted in the bark mix produced only two to three leaves. K concentration did not affect the length of the uppermost mature leaves when grown in the bark mix. However, in moss, plants had increasingly longer and wider top leaves as K concentration increased. The lower leaves on plants in the bark mix lacking or receiving 50 mg·L−1 K showed symptoms of yellowing, irregular purple spots, and necrosis after spiking and flowering, respectively. Yellowing and necrosis started from the leaf tip or margin and progressed basipetally. Symptoms became more severe during flower stem development and flowering. All of the plants lacking K were dead by the end of flowering. Leaf death originated from the lowest leaf and advanced to the upper leaves. K at 50 mg·L−1 greatly reduced and 100 mg·L−1 completely alleviated the symptoms of K deficiency at the time of flowering. However, by the end of flowering, plants receiving 50 or 100 mg·L−1 K had yellowing on one or two lower leaves. Plants grown in moss and lacking K showed limited signs of K deficiency. All plants in the bark mix bloomed, whereas none in sphagnum moss receiving 0 mg·L−1 K produced flowers. For both media, as K concentration increased, flower count and diameter increased. Flower stems on plants in either medium became longer and thicker with increasing K concentration. To obtain top-quality Phalaenopsis with the greatest leaf length, highest flower count, largest flowers, and longest inflorescences, it is recommended that 300 mg·L−1 K be applied under high N and high P conditions regardless of the medium.
Competitive Effect of In-row Diploid Watermelon Pollenizers on Triploid Watermelon Yield
Authors: Freeman Joshua H. , Olson Stephen M. , Stall William M.
Published: February 2019

Successful fruit set in triploid watermelons [Citrullus lanatus (Thunb.) Matsum. & Nakai] requires a diploid watermelon cultivar, or pollenizer, to be planted nearby as a pollen source. Pollenizer cultivars have been developed to be planted in-row with triploid plants without spacing change, which decreases area per plant. These cultivars have different growth habits, from highly reduced foliage to standard foliage, and it is uncertain how pollenizer growth habit may affect triploid plant growth and yield. Two diploid watermelon pollenizers, ‘Mickylee’ and ‘SP-1’, with markedly different growth habits were planted at five in-row spacings from triploid plants to determine the effect of plant competition on triploid watermelon yield. All treatments used a 1:1 pollenizer to triploid ratio to measure the direct effect of pollenizer growth on associated triploid yields. Experiments were conducted at two locations during Spring 2006 (Quincy and Citra, FL) and one during Fall 2006 (Quincy). Triploid plants paired with ‘Mickylee’ yielded 11.4% (Citra) and 22.4% (Quincy) less weight in the spring and 8.5% less in the fall than plants paired with ‘SP-1’ and also produced fewer fruits per plant. However, the results from the fall trial were not significant. Pollenizer to triploid spacing had a linear effect on yield per plant and fruits per plant, and there was no interaction between pollenizer cultivar and spacing. The use of ‘Mickylee’ as a pollenizer may be an attractive option because of lower seed costs compared with other pollenizers, but these results indicated lower triploid watermelon yields from plants paired with ‘Mickylee’, which is most likely a result of increased plant competition.
Severity of Leaf Harvest, Supplemental Nutrients, and Sulfur Application on Long-term Leaf Production of Aloe barbadensis Miller
Authors: Wang Yin-Tung
Published: February 2019

This is the first report on how leaf harvest techniques and sulfur may affect leaf initiation and yield of Aloe barbadensis Miller (syn. Aloe vera L.). Two long-term experiments were conducted to determine the effects of supplemental mineral nutrients, severity of harvest, and sulfur application on leaf yield of this species. Plants were each grown in a 38-L pot with or without monthly applications of a 20N–8.6P–16.6K water-soluble fertilizer. In the first experiment, beginning in June 1994 (7 months after initiation), the lower leaves were harvested every 3 months with 12, 15, or 18 leaves remaining per plant. All plants were harvested to 12 leaves at the final harvest in Mar. 1997. Fertilized plants that were harvested to 12 leaves produced 81 leaves each during the 3-year period, whereas those harvested to 15 or 18 leaves each produced 76 leaves. In contrast, each of the nonfertilized plants produced 36 leaves. Fertilization tripled the cumulative weight of harvested leaves over a 3-year period. The initial quarterly and cumulative leaf weights were higher in plants harvested to 12 leaves than those harvested to 15 or 18 leaves. However, this difference diminished and disappeared over time. Fertilized plants harvested to 18 or 15 leaves yielded over 10.8 kg annually, whereas nonfertilized plants with 12 leaves produced an average of 3.5 kg leaves per plant. In the second experiment (with or without fertilizer and micronutrient and 0, 25, 50, or 100 g/pot of powdered sulfur per year), plants responded similarly to fertilization as they did in the first experiment. The added micronutrients (25 g/pot per year) had no effect on plant growth. The highest rate of sulfur resulted in few leaves being harvested and reduced cumulative leaf weight in fertilized plants, but did not affect the number of harvestable leaves or their total weight in nonfertilized plants. Soil pH declined from 7.6 to 4.6 as a result of fertilization regardless of the amount of sulfur being applied. In both experiments, plants that received fertilizer had slight cold injury on the abaxial side of some south-facing leaves. The results suggest the importance of fertilizer application to enhance leaf initiation rate. Plants should be harvested to leave no fewer than 15 leaves, preferably 18, on the plant to maintain high leaf yield.
The Influence of Climate on Fruit Shape of Four Low-chill Peach Cultivars
Authors: Wert Todd W. , Williamson Jeffrey G. , Chaparro José X. , Miller E. Paul , Rouse Robert E.
Published: February 2019

Fruit shape of four low-chill peach [Prunus persica (L.) Batsch] cultivars was evaluated in north-central, central, and southwest Florida. During 2005, measurements were taken at all locations for cheek diameter, suture diameter, and tip protrusion. A suture deformation index was calculated (suture diameter/cheek diameter) to determine suture deformation. Fruit had more protruding tips and suture deformation was more pronounced at the southwest location than at the north-central or central locations. Overall, ‘TropicBeauty’ had more protruding tips than the other cultivars. It was concluded that warmer temperatures at the southwest location during fruit development affected fruit shape by increasing the incidence of protruding tips and pronounced sutures.
Daily Light Integral, Prevernalization Photoperiod, and Vernalization Temperature and Duration Control Flowering of Easter Cactus
Authors: Rohwer Charles L. , Heins Royal D.
Published: February 2019

Experiments were performed on Hatiora gaertneri (Regel) Barthlott ‘Jan’ and ‘Rood’ and H. ×graeseri (Wedermann) Barthlott ‘Evita’ to determine their flowering responses to 1) daily light integral (DLI) before and during vernalization; 2) 0 to 6 weeks of short-day (SD) or long-day (LD) photoperiods before vernalization at 10, 12.5, or 15 °C; 3) propagation from April to July; 4) timing of leveling before or during inductive treatments; and 5) SD photoperiods before vernalization under darkness at 0 to 10 °C. ‘Jan’ grown under elevated DLI before vernalization and low DLI during vernalization flowered more prolifically than plants grown under low DLI before vernalization or high DLI during vernalization at 15 °C. Six weeks of SD photoperiods before vernalization increased the number of buds per flowering phylloclade after vernalization at 10 °C and increased flowering uniformity when vernalization duration was insufficient at 10 °C or vernalization temperature was 12.5 or 15 °C. For plants flowering in January, propagation the previous April produced better flowering than propagation in May, June, or July. Removal of apical phylloclades during prevernalization SD or during vernalization was deleterious to flowering. Vernalization in the dark produced marginal flowering, but SD treatment before vernalization increased the percentage of apical phylloclades flowering, buds per flowering apical phylloclade, and percentage of plants flowering after dark vernalization. ‘Evita’ flowered more poorly than either ‘Jan’ or ‘Rood’. Collectively, the most uniform flowering in January occurred when plants were exposed to a sequence of 4 to 6 weeks of SD, vernalization at 7.5 to 15 °C for 8 weeks, then growth under LD for 7 weeks.
Effect of Blossom Density and Crop Load on Growth, Fruit Quality, and Return Bloom in ‘Honeycrisp’ Apple
Authors: Embree Charles G. , Myra Marina T.D. , Nichols Douglas S. , Wright A. Harrison
Published: February 2019

From 2003 to 2006, the blossom level and crop load of ‘Honeycrisp’ apple (Malus × domestica Borkh.) trees on M.26 rootstocks were adjusted to improve fruit quality and return bloom. The treatments consisted of manually removing flower clusters to 50, 100, and 150 per tree, then at ≈50 d after full bloom, the crop load was adjusted to 3, 6, and 9 fruit/cm2 trunk cross-sectional area (TCSA), respectively. All flower and crop load adjustment significantly increased TCSA and canopy volume compared with the control. Classic biennial bearing was observed on the untreated control trees and those thinned to 150 blossom clusters per tree and 9 fruit/cm2 TCSA and was mitigated for trees with 50 and 100 blossom clusters followed by crop load adjustment to 3 and 6 fruit/cm2 TCSA, respectively. Fruit color the “on” year was always lower on the control trees; no difference was found in the “off” year. The treatments increased fruit weight proportional to crop load except for the 2004 “off” year. This study illustrates that for trees with ≈1 m3 canopy volume, the combined effects of blossom and crop load adjustment to 100 blossom clusters/tree followed by fruitlet adjustment to 6 fruit/cm2 TCSA and below will induce consistent annual production for ‘Honeycrisp’.
Leaf Cutin Monomers, Cuticular Waxes, and Blackspot Resistance in Rose
Authors: Goodwin S. Mark , Edwards Christopher J. , Jenks Matthew A. , Wood Karl V.
Published: February 2019

The fungal pathogen Diplocarpon rosae causes rose blackspot disease, a serious problem for roses (Rosa) in the managed landscape. To prevent this disease, homeowners and professional growers often apply chemical fungicide. However, increased use of fungicides poses an environmental hazard and an economic burden to the user. New landscape rose cultivars like ‘Knockout’ possess increased disease resistance, but the biological basis for this resistance is still unknown. To investigate the potential role of leaf cuticle in blackspot resistance in rose, five rose cultivars known to vary greatly in blackspot resistance were examined for variation in the major lipids of the leaf cuticle, specifically the monomers of the cutin polyester and the free cuticular waxes. This is the first report of cutin monomers in the Rosa genera. The rose cultivars selected for this study were ‘Knockout’, ‘Mister Lincoln’, ‘Garden Party’, ‘Purple Passion’, and ‘Bicolor’. ‘Knockout’ and ‘Garden Party’ had significantly lower total cutin monomer amount per leaf area than the other cultivars, whereas the most cutin monomers were observed on ‘Purple Passion’, ‘Bicolor’, and ‘Mister Lincoln’. Five major cutin monomers (mostly hydroxylated 16 carbon fatty acids) dominated the cutin profiles of both adaxial and adaxial surfaces of all cultivars, with the 10,16-dihydroxy hexadecanoic acids being most abundant. The proportion of 10,16-dihydroxy hexadecanoic acids was slightly higher in the adaxial than abaxial leaf cuticles of all cultivars. Correspondingly, other cutin monomers were relatively lower in the adaxial cuticle, except 16-hydroxy hexadecanoic acid that differed little. Uniquely, this is the first report of cutin monomer composition of isolated abaxial and adaxial leaf cuticles of any plant. Total leaf cuticular wax amounts were lowest on ‘Purple Passion’ and ‘Knockout’, intermediate in ‘Mister Lincoln’ and ‘Garden Party’, and highest on ‘Bicolor’, with alkanes as the most abundant wax class. Consistent with previously published disease susceptibility ratings, our visual scores showed that ‘Knockout’ was most resistant to blackspot pathogen infection with a visual disease rating score of 1.0, followed by ‘Mister Lincoln’ at 1.8, ‘Garden Party’ at 5.4, ‘Bicolor’ at 7.5, and ‘Purple Passion’ with the most visible disease damage at 8.8. Regression analysis revealed that the alkane and ester proportions were most closely associated with blackspot disease susceptibility ratings, being inversely (R2 = 0.63, P = 0.05) and directly (R2 = 0.81, P = 0.05) correlated, respectively. More studies on the role of cuticle in rose susceptibility to blackspot are now clearly warranted.
Bell Pepper (Capsicum annuum L.) Fruits are Susceptible to Chilling Injury at the Breaker Stage of Ripeness
Authors: Lim Chae Shin , Kang Seong Mo , Cho Jeoung Lai , Gross Kenneth C. , Woolf Allan B.
Published: February 2019

To study ripening-related chilling injury (CI) of bell pepper (Capsicum annuum L.), fruit at mature green, breaker, and red-ripe stages were stored at 1, 5, 7, and 10 °C for 4 weeks. Surface pitting was evaluated after storage at 1 °C for 2 weeks followed by a 2-day exposure to room temperature (20 °C). Exposing fruit to 1 °C enhanced water loss, respiration, ethylene production, and electrolyte leakage, but slowed color change. Weight loss, respiration, ethylene production, electrolyte leakage, and color change increased more in breaker than in mature green and red-ripe fruit. No pitting symptom was observed at temperatures of 5 to 10 °C. After storing peppers at 1 °C for 2 weeks, breaker stage fruit exhibited chilling symptoms of severe surface pitting with more sheet pitting and deeper peel depression. Mature green fruit showed only moderate pitting. However, red-ripe peppers showed no injury and cells showed a normal appearance after low-temperature storage (1 °C). These results show that bell peppers tended to be more susceptible to chilling temperature while at the breaker stage and that the increase in visible CI is correlated with increased water loss, respiration, ethylene production, electrolyte leakage, and color change during storage.
Factors Affecting Plant Regeneration from Leaf Tissues of Buddleia Species
Authors: Dai Wenhao , Castillo Cielo
Published: February 2019

The effects of genotype, basal medium, plant growth regulator (PGR), dark treatment, and antibiotics on shoot regeneration of two Buddleia cultivars, B. davidii ‘Potters Purple’ and Buddleia ‘Lochinch’, were investigated. In vitro shoots were regenerated from leaf tissues in either Murashige and Skoog (MS) or woody plant medium (WPM) media supplemented with benzyladenine (BA). In general, more shoots were regenerated in WPM medium than in MS medium. Dark treatment for 3 to 5 weeks dramatically increased shoot regeneration. Addition of indole-3-butyric acid (IBA) or naphthalene acetic acid (NAA) significantly enhanced the regeneration rate and shoots of each explant. The maximum regeneration rate (100%) of B. davidii ‘Potters Purple’ was achieved when cultured in WPM containing 5 μm BA plus 5 μm IBA. The maximum regeneration rate (98.4%) of Buddleia ‘Lochinch’ was found in WPM supplemented with 20 μm BA plus 4 μm IBA. Carbenicillin at 250 to 500 mg·L−1 and cefotaxime at 125 to 250 mg·L−1, individually or combined, promoted shoot regeneration. Interactions between genotype and medium or PGRs were found. In vitro shoots were easily rooted in half-strength MS medium with or without NAA. Rooted plants were transferred to potting mix and grown in the greenhouse. This research will facilitate genetic improvement and fast propagation of Buddleia species using biotechnology.
Nutrient Recovery by Seven Aquatic Garden Plants in a Laboratory-scale Subsurface-constructed Wetland
Authors: Polomski Robert F. , Bielenberg Douglas G. , Whitwell Ted , Taylor Milton D. , Bridges William C. , Klaine Stephen J.
Published: February 2019

Commercial nurseries use large amounts of water and nutrients to produce container-grown plants. The large volume of runoff containing nitrogen (N) and phosphorus (P) that leaves nurseries can contaminate surface and groundwater. Subsurface flow-constructed wetlands have been shown to effectively treat agricultural, industrial, and residential wastewater and to be well-suited for growers with limited production space. We investigated the possibility of using commercially available aquatic garden plants in subsurface-constructed wetlands to remove nutrients in a laboratory scale, gravel-based system. Seven popular aquatic garden plants received N and P from Hoagland's nutrient solution every 2 days for 8 weeks. These rates (0.39 to 36.81 mg·L−1 of N and 0.07 to 6.77 mg·L−1 P, respectively) encompassed low to high rates of nutrients found at various points between the discharge and inflow points of other constructed wetland systems currently in use at commercial nurseries. Plant biomass, nutrient recovery, and tissue nutrient concentration and content were measured. Whole plant dry weight positively correlated with total N and P supplied. Louisiana Iris hybrid ‘Full Eclipse’, Canna × generalis Bailey (pro sp.) ‘Bengal Tiger’, Canna × generalis Bailey (pro sp.) ‘Yellow King Humbert’, Colocasia esculenta (L.) Schott ‘Illustris', Peltandra virginica (L.) Schott, and Pontederia cordata L. ‘Singapore Pink’ had the greatest N recovery rates. The P recovery rates were similar for the cannas, Colocasia esculenta ‘Illustris’, Louisiana Iris ‘Full Eclipse’, Pe. virginica, and Po. cordata ‘Singapore Pink’. The potential exists for creating a sustainable nursery and greenhouse production system that incorporates a subsurface-constructed wetland planted with marketable horticultural crops that provide remediation and revenue.
Soil Calcium Status Unrelated to Tipburn of Romaine Lettuce
Authors: Hartz Timothy K. , Johnstone Paul R. , Smith Richard F. , Cahn Michael D.
Published: February 2019

Application of calcium (Ca) fertilizers is a common practice of California lettuce growers to minimize the occurrence and severity of tipburn, particularly in romaine lettuce (Lactuca sativa L. var. longifolia Lam.). An evaluation of the effect of soil Ca availability on the severity of tipburn in romaine lettuce was conducted in the Salinas Valley of central California in 2005 to 2006. Twenty representative soils from this region were evaluated for Ca availability by ammonium acetate extraction, saturated paste extraction, and extraction of soil solution through centrifugation of soil at field-capacity moisture content. Soil solution Ca in these soils was generally high, ranging from 5 to 80 mmolc·L−1, representing 44% to 71% of cations on a charge basis. Soil solution Ca was highly correlated with saturated paste Ca (r
2 = 0.70) but not with exchangeable Ca (r
2 = 0.01). However, saturated paste extraction significantly underestimated soil solution Ca concentration (regression slope = 0.19). A survey of 15 commercial romaine lettuce fields showed tipburn severity to be unrelated to either leaf Ca concentration or soil Ca availability. The most severe tipburn was observed in fields in which transpiration was reduced by foggy weather during the final 2 weeks of growth. Ca fertilizers (calcium nitrate, calcium thiosulfate, and calcium chloride) applied through drip irrigation during the final weeks of lettuce growth were ineffective in increasing romaine leaf Ca concentration in three field trials; tipburn was present in only one trial, and Ca fertigation had no effect on tipburn severity. We conclude that under typical field conditions in this region, tipburn severity is primarily a function of environmental conditions. Soil Ca availability plays no substantive role in tipburn severity, and Ca fertigation does not improve lettuce Ca uptake or reduce tipburn.
A Gasometric Procedure to Measure Residual Lime in Container Substrates
Authors: Huang Jinsheng , Fisher Paul R. , Argo William R.
Published: February 2019

Unreacted residual limestone in the container substrate is key in buffering pH change over time. Our goal was to develop a substrate test protocol to measure residual lime [in units of CaCO3 equivalent (CCE)] by applying a strong mineral acid (HCl) to a substrate sample and measuring the evolved CO2 gas with a gasometric method based on a Chittick apparatus. In one experiment, CaCO3 was added to a substrate that had previously been neutralized to pH 7.35 with Ca(OH)2 so that there would be minimal CaCO3 reaction with the substrate at this high pH. The gasometric method was then used to estimate residual CCE. Measured CCE and applied CaCO3 were similar, indicating reliable CCE estimation. In a second experiment, a pH titration method was used to quantify the relationship between substrate-pH and milliequivalents of reacted base and provided an additional validation of the estimated reacted and residual CCE. The gasometric method demonstrated declining residual CCE over time as a dolomitic limestone reacted to raise substrate-pH and increasing residual CCE as applied CaCO3 concentration increased. Residual CCE in a substrate is an important property that should be considered for pH control and management in greenhouse crop production. Our results indicate that the gasometric system may be useful for optimizing lime application rate, lime source, or management of residual CCE during crop production.
Evaluating Bispyribac-sodium and Sulfosulfuron for Control of Roughstalk Bluegrass
Authors: Morton Debbie , Weisenberger Daniel , Reicher Zachary , Branham Bruce , Sharp Bill , Gaussoin Roch , Stier John , Koeritz Eric
Published: February 2019

Roughstalk bluegrass (Poa trivialis L.) is a troublesome weed on golf courses, home lawns, and athletic fields from the Midwest to the mid-Atlantic states. Bispyribac-sodium and sulfosulfuron have recently been labeled for roughstalk bluegrass control, but their use needs to be refined. Our objective was to determine the most effective herbicide strategies for control of roughstalk bluegrass. Initial studies were conducted during 2005 in Illinois and Indiana and follow-up studies in 2006 in Indiana, Illinois, South Dakota (partial shade and full sun), and Wisconsin. Applications starting in the warmer temperatures of late May and June 2005 were more effective than those starting in mid-May. Bispyribac-sodium (a.i.) was applied at 74 or 114 g·ha−1 four times at 2-week intervals decreased roughstalk bluegrass cover to 1% and 0% 12 weeks after initial treatment (WAIT) in Illinois and Indiana in 2005, respectively, whereas sulfosulfuron (a.i.) at 13 or 27 g·ha−1 applied twice at 2-week intervals decreased cover to no less than 18%. In 2006, bispyribac-sodium was most effective in Indiana and Illinois decreasing cover to as low as 4%, whereas sulfosulfuron was most effective in South Dakota resulting in a decrease in cover to as low as 7%, and both herbicides performed similarly in Wisconsin. Three applications of sulfosulfuron (a.i.) at 27 g·ha−1 at 2-week intervals or four applications of bispyribac-sodium (a.i.) at 56 or 74 g·ha−1 at 2-week intervals were most effective for roughstalk bluegrass control.
‘Ayelet’ and ‘Galya’: New Seedless Lemon Cultivars
Authors: Spiegel-Roy Pinchas , Vardi Aliza , Yaniv Yosef , Fanberstein Luba , Elhanati Avraham , Carmi Nir
Published: February 2019

Two lemon (Citrus × limon L. Burm. F.) cultivars, Eureka and Villafranca, were subjected to a mutation-inducing process, which led to the production of seedless mutants in both cultivars. This mutation-inducing process did not affect many other lemon traits.
Onion Inbred Line ‘B8667 A&B’ and Synthetic Populations ‘Sapporo-Ki-1 A&B’ and ‘Onion Haploid-1’
Authors: Havey Michael J. , Bohanec Borut
Published: February 2019

The U.S. Department of Agriculture, Agricultural Research Service, announces the release of onion inbred ‘B8667 A&B’ and synthetic population ‘Sapporo-Ki (SKI) -1 A&B’. Both of these releases represent a cytoplasmic male-sterile (A) line with its maintainer (B) for seed propagation of male-sterile plants. ‘B8667 A&B’ is intended for production of red, long-day, well-storing hybrids. ‘SKI-1’ combines the earliness of the Japanese population ‘Sapporo-Ki’ with maintenance of cytoplasmic male sterility. The long-day synthetic population ‘Onion Haploid-1’ (‘OH-1’) is a joint release of the U.S. Department of Agriculture, Agricultural Research Service, and the University of Ljubljana, Slovenia. ‘OH-1’ is intended to serve as a responsive control for extraction of gynogenic haploids of onion.
Anthocyanin, Carotenoid Content, and Antioxidant Values in Native South American Potato Cultivars
Authors: Brown Charles R. , Culley David , Bonierbale Meredith , Amorós Walter
Published: February 2019

Tubers of 38 native potato cultivars of different taxonomic groups from South America were analyzed to determine the total anthocyanins, total carotenoids, and antioxidant values. Total anthocyanin ranged from zero to 23 mg cyanidin equivalents/100 g fresh weight (FW). Total carotenoid ranged from 38 to 2020 μg zeaxanthin equivalents/100 g FW. Oxygen radical absorbance capacity (ORAC) was measured for the anthocyanin (hydrophilic) and carotenoid (lipophilic) extracts. The hydrophilic ORAC ranged from 333 to 1408 μm Trolox equivalents/100 g FW. The lipophilic ORAC ranged from 4.7 to 30 nM α-tocopherol equivalents/100 g FW. The cultivars consisted of 23 diploids, seven triploids, and eight tetraploids. Total carotenoids was negatively correlated with total anthocyanins. Total anthocyanins was correlated with hydrophilic ORAC. Among clones with less than 2 mg cyanidin equivalents/100 g FW, total carotenoid and lipophilic ORAC were correlated, but this was not true for analysis of all 38 clones. Although total anthocyanins or hydrophilic ORAC values reported here were not outside of the ranges found in North American and other breeding materials, total carotenoids and lipophilic ORACs are higher than previously reported, suggesting that native cultivars of South America with high levels of total carotenoids and high lipophilic ORAC are a unique germplasm source for introgression of these traits into specific potato cultivars outside the center of origin.
Effect of Arbuscular Mycorrhizal Colonization on Nitrogen and Phosphorus Uptake and Growth of Aloe vera L.
Authors: Tawaraya Keitaro , Turjaman Maman , Ekamawanti Hanna Artuti
Published: February 2019

The effect of arbuscular mycorrhizal (AM) colonization on nitrogen (N) and phosphorus (P) uptake and shoot growth of Aloe vera was investigated. Plants were inoculated with one of two AM fungi, Glomus clarum or Gigaspora decipiens. Control plants were not inoculated. Plants were grown under glasshouse conditions in a peat land soil without fertilizers for 12 months. Inoculated A. vera plants were colonized with AM fungi. Total length of leaves and number of leaves were higher in inoculated plants than uninoculated plants 12 months after inoculation. Shoot N and P concentrations were higher in inoculated plants than uninoculated plants. Shoot fresh weight was increased by AM colonization. This result suggests that AM colonization can increase the nutrient uptake and growth of A. vera.
Suppression of Ethylene Responses Through Application of 1-Methylcyclopropene: A Powerful Tool for Elucidating Ripening and Senescence Mechanisms in Climacteric and Nonclimacteric Fruits and Vegetables
Authors: Huber Donald J.
Published: February 2019

The discovery of 1-methylcyclopropene (1-MCP) as an inhibitor of ethylene action has provided yet another effective tool for understanding the role of this hormone in the development of higher plants. In the nearly 12 years since the description of the effects of this growth regulator on ethylene action, the subsequent introduction of stable formulations has resulted in an explosive increase in 1-MCP-targeted research, particularly, although not exclusively, in the discipline of postharvest science. The vicinal relationship between 1-MCP and postharvest biology is understandable in view of the established roles of ethylene, both beneficial and detrimental, in the handling and storage behaviors of a vast majority of harvested fruit and vegetative organs. The use of 1-MCP is proving to be supplemental to molecular approaches for identifying and understanding the spectrum of senescence and ripening processes under the direct control of ethylene perception. Climacteric fruits have served as the predominant target for investigations of 1-MCP, and the responses of these fruits have confirmed that the antagonist operates in opposition to ethylene. Studies of nonclimacteric fruits challenged with 1-MCP and other ethylene action inhibitors have identified both ethylene-dependent and ethylene-independent ripening processes and have posed interesting questions regarding the canonical distinctions between climacteric and nonclimacteric fruits.
Morphological Characterization of Three Intergeneric Hybrids Among Gloriosa superba ‘Lutea’, Littonia modesta, and Sandersonia aurantiaca (Colchicaceae)
Authors: Amano Junji , Kuwayama Sachiko , Mizuta Yoko , Nakano Masaru , Godo Toshinari , Okuno Hajime
Published: February 2019

Three intergeneric hybrids among colchicaceous ornamentals, Gloriosa superba ‘Lutea’ (2n = 2x = 22), Littonia modesta (2n = 2x = 22), and Sandersonia aurantiaca (2n = 2x = 24), were subjected to morphological characterization and chromosome observation. Hybrid plants produced flowers 2 to 3 years after transplantation of ovule culture-derived plantlets to the greenhouse. All the hybrid plants, L. modesta × S. aurantiaca, L. modesta × G. superba ‘Lutea’, and S. aurantiaca × G. superba ‘Lutea’, showed a climbing habit like those of L. modesta and G. superba ‘Lutea’. Plants of L. modesta × S. aurantiaca and L. modesta × G. superba ‘Lutea’ were taller and shorter than their respective parents, whereas plant height of S. aurantiaca × G. superba ‘Lutea’ was nearly intermediate between the parents. Leaves of all the hybrids had a tendril at the tip like those of L. modesta and G. superba ‘Lutea’. Flower morphologies of all the hybrids were nearly intermediate between the parents. Flower colors of all the hybrids were similar to the seed or pollen parent. Although hybrids of L. modesta × G. superba ‘Lutea’ showed low pollen fertility as assessed with acetocarmine staining, the other two kinds of hybrids had nondehiscent anthers or no fertile pollen grains. Chromosome observation in root tip cells revealed that all the hybrids had a diploid number of chromosomes: L. modesta × S. aurantiaca (2n = 2x = 23), L. modesta × G. superba ‘Lutea’ (2n = 2x = 22), and S. aurantiaca × G. superba ‘Lutea’ (2n = 2x = 23). Novel morphological characteristics of the hybrids may be valuable for future breeding of colchicaceous ornamentals.
Genetic Resistance to Cucurbit Leaf Crumple Virus in Melon
Authors: McCreight James D. , Liu Hsing-Yeh , Turini Thomas A.
Published: February 2019

Cucurbit leaf crumple virus (CuLCrV) is a geminivirus transmitted by Bemisia tabaci (Gennadius) biotype B (SPW-B) and common in melons (Cucumis melo L.) planted from July through September in the desert southwestern United States. Symptoms include chlorotic leaf spots, leaf curling and crumpling, and interveinal yellowing, and plants may be stunted. Melon breeding line MR-1, and six plant introductions (PIs; PI 124111, PI 124112, PI 179901, PI 234607, PI 313970, and PI 414723) exhibited partial resistance to CuLCrV in naturally infected field tests and controlled inoculation greenhouse tests. PI 236355 was completely resistant in two greenhouse tests. Partially resistant plants exhibited chlorotic spots, or mild expression of other typical CuLCrV symptoms; all such plants were positive for presence of virus using polymerase chain reaction analysis with a CuLCrV-specific primer pair from the BC1 region. Genetic resistance to CuLCrV in melon was recessive. Field and greenhouse data from F1, F2, and backcrosses of the F1 to ‘Top Mark’ and PI 313970 demonstrated a single, recessive gene for resistance to CuLCrV. Progenies from crosses of four partially resistant cultigens with ‘Top Mark’ were susceptible. Resistance in PI 313970 appeared to be allelic, with resistance in the other six cultigens based on F1 data. The name cucurbit leaf crumple virus and symbol culcrv are proposed for this gene.
Amplified Fragment Length Polymorphism Analysis Provides Strategies for Improvement of Bitter Gourd (Momordica charantia L.)
Authors: Gaikwad Ambika B. , Behera Tusar Kanti , Singh Anand K. , Chandel Devanshi , Karihaloo Jawahir L. , Staub Jack E.
Published: February 2019

Monoecious bitter gourd (Momordica charantia L. var. minima and maxima Williams & Ng), a cucurbit of major economic importance, is widely cultivated in India, China, Africa, and South America. Although the morphology (i.e., growth habit and fruit shape, size, color, and surface texture) of Indian bitter gourd is diverse and gynoecious sex forms exist, a comprehensive diversity assessment of ecotypes has not been performed. Therefore, the genetic relatedness of 38 Indian cultigens (commercial varieties and cultivated landraces originating from different agroecological zones) was determined by amplified fragment length polymorphism (AFLP) analysis. Six primer combinations yielded a total of 519 bands of which 404 (77.8%) were polymorphic among the cultigens examined. Unweighted pair group cluster analyses were performed using Jaccard's genetic similarities to define genetic relationships among cultigens. Genetic similarities among cultigens ranged between 0.44 and 0.88, indicating that the bitter gourd cultigens examined were genetically diverse. Moreover, putative AFLP loci defined genetic relationships that allowed for partitioning of cultigens into two distinct groups [Group 1 and Group II (node 1); bootstrap = 100%] after cluster analysis. With rare exception, cultigens were grouped with respect to geographical region, in which cultigens within a group and subgroups possessed high degrees of genetic similarity. The relatively high marker indices (6.2 to 19.4), polymorphic information content of the markers used (0.20 to 0.25), and multiplex ratios (28.9 to 77.4) collectively indicate that the AFLP markers used are discriminatory in bitter gourd and that the analysis of the broad-based cultigens described provides valuable baseline information for advancing initial breeding strategies for this crop species.
A Survey of Watermelon Germplasm for Inhibitory Seed Exudates
Authors: Harrison Howard F. , Levi Amnon , Kousik C.S.
Published: February 2019

Watermelon [Citrullus lanatus v. lanatus (Thunb.) Matsum & Nakai] seed exudates are inhibitory to germination and seedling growth of other plant species. A miniature bioassay experiment that measured proso millet (Panicum miliaceum L.) radicle growth was used to assess the inhibition caused by seed exudates of 125 genotypes of watermelon and related Citrullus species. Exudates of most genotypes were not inhibitory; however, exudates of 53 accessions reduced radicle growth in comparison with the control. In subsequent proso millet radicle growth experiments, genotypes were found to vary in inhibitory potential, and concentration response curves generated using filtered, pasteurized exudates were different among genotypes. Filter-sterilized seed exudates of Citrullus accessions also varied in the level of inhibition in a bioassay that measured their effect on sporangia formation by the watermelon pathogen, Phytophthora capsici. These observations suggest that constituents in Citrullus seed exudates affect organisms in the spermosphere and that the inhibitory potential of seed exudates varies among genotypes. Differences in concentration response curves in the millet bioassay and differences in the relative inhibition of genotypes in the millet and fungus bioassays indicate that the inhibitory constituents in seed exudates vary among genotypes.
Potassium Nutrition Affects Leaf Growth, Anatomy, and Macroelements of Guzmania
Authors: Lin Chao-Yi , Yeh Der-Ming
Published: February 2019

Guzmania lingulata (L.) Mez. ‘Cherry’ plants were grown in coconut husk chips. All plants were given 8 mm nitrogen (N), 2 mm phosphorus (P), 4 mm calcium (Ca), and 1 mm magnesium (Mg) at each irrigation with potassium (K) concentration at 0, 2, 4, or 6 mm. After 9 months, K concentration did not alter the number of new leaves, and shoot and root dry weights. Increasing K concentration did not affect the length but increased the width of the most recently fully expanded leaves (the sixth leaves). Plants under 0 K exhibited yellow spots and irregular chlorosis on old leaves being more severe at the middle of the blade and leaf tip. Numbers of leaves with yellow spots or chlorosis decreased with increasing K concentration. Chlorenchyma thickness was unaffected by K concentration, whereas water storage tissue and total leaf thickness increased with increasing K concentration. Leaf N concentration in the sixth or 10th leaf was unaffected by solution K concentration. However, plants at 0 mm K had higher N concentration in the 14th leaf than those in sixth and 10th leaves. Leaf P, Ca, and Mg concentrations decreased with increasing solution K concentration. K concentrations were higher in the sixth leaf than the 14th leaf in plants at 0, 2, or 4 mm K, whereas leaf K concentration was 15 g·kg−1 on dry weight basis in the sixth, 10th, or 14th leaves in plants treated with 6 mm K.
Effect on Production and Quality of Intensifying Triploid Watermelon Crops Using ‘Temporary Trellises’ and CPPU for Fruit Development
Authors: Núñez Francisco Javier , Huitrón Maria Victoria , Díaz Manuel , Diánez Fernando , Camacho-Ferre Francisco
Published: February 2019

In Spain, the adoption of the triploide ‘Queen of Hearts’ (Citrullus lanatus Thunb.) watermelon cultivar has brought important changes in the production of seedless watermelon thanks to its magnificent acceptance by the market. The experiments on triploid watermelon presented here examined innovative production techniques that would guarantee the productivity and quality of this cultivar in plastic greenhouses and improve cost-effectiveness, serving growers. Crop intensification was tested under a “temporary trellis” management system, increasing plant density from 2500 plants/ha in the traditional or creeping crop system to 10,000 plants/ha. The “temporary trellis” system was combined with fruit set through the localized application of a 150- to 200-mg·L−1 solution of 1-(2-chloro-4-pyridyl)-3-phenylurea (CPPU). The increase of grafted watermelon plant density to 1 plant/m2 gave rise to an increase in early harvest measured as the number of fruits per surface area compared with the traditional system with a density of 0.25 plant/m2. In addition, a process of temporary trellising facilitates choosing female flowers for applying CPPU. The °Brix and pulp firmness quality parameters did not show significant differences between “temporary trellised” and creeping crops.
Enhancement of Tomato Fruit Lycopene by Potassium Is Cultivar Dependent
Authors: Taber Henry , Perkins-Veazie Penelope , Li Shanshan , White Wendy , Rodermel Steven , Xu Yang
Published: February 2019

The purpose of this experiment was to determine the response of tomato (Solanum lycopersicum L.) cultivars with fruit of average and high lycopene to increased K fertilization. The field experiment was designed as a factorial, split-plot, randomized complete block with four replications. The main plot consisted of K rates ranging from 0 to 372 kg·ha−1 K as KCl, and the subplot was cultivar (‘Mountain Spring’ or the high-lycopene Florida hybrid, ‘Fla. 8153’). The soil type was a well-drained, central Iowa loam with a soil test level considered low. The soil K application effect on total marketable fruit yield was linear (P < 0.001, Y = 53 Mg·ha−1 + 0.084x, r2 = 0.51) with both cultivars responding similarly. Fruit K analysis indicated a linear response to fertilization across four harvest dates, from 1236 to 1991 mg·kg−1, fresh weight basis. Harvest date had no effect on fruit lycopene concentration, but there was a significant (P = 0.006) interaction of K fertilization rate and cultivar. Overall, ‘Fla. 8153’ contained 9.5 mg·kg−1 more lycopene in fruit tissue than ‘Mountain Spring’. ‘Mountain Spring’ lycopene concentration was not enhanced by higher K fertilization (44.2 mg·kg−1). ‘Fla. 8153’ lycopene concentration increased 21.7% at the highest K rate compared with lower rates (62.9 vs. 51.7 mg·kg−1, respectively). A controlled greenhouse study in the fall of 2005 with the same cultivars indicated similar results. Fruit K concentration for ‘Fla. 8153’ was significantly (P < 0.01) correlated to the fruit carotenoids, phytoene and phytofluene, indicating a possible role for K in one of the enzymes that synthesize phytoene. In the field and greenhouse studies, increasing fruit K concentration in the high-lycopene ‘Fla. 8153’ depressed fruit β-carotene by 53%. These results indicate that K fertilization can affect carotenoid biosynthesis, and the response of tomato to a high K rate is genotype dependent.
Tolerance of Eight Sweet Corn (Zea mays L.) Hybrids to Pyroxasulfone
Authors: Sikkema Sarah R. , Soltani Nader , Sikkema Peter H. , Robinson Darren E.
Published: February 2019

Pyroxasulfone is an experimental herbicide for use in field corn (Zea mays L.) and soybean that may have potential for weed management in sweet corn. Tolerance of eight sweet corn hybrids to pyroxasulfone applied preemergence (PRE) at rates of 0, 209, and 418 g·ha−1 a.i. were studied at two Ontario locations in 2005 and 2006. Pyroxasulfone applied PRE at 209 and 418 g·ha−1 caused minimal (less than 3%) injury in Harvest Gold, GH2041, GH9589, GSS9299, GG214, GG446, GG763, and GG447 sweet corn hybrids at 7, 14, and 28 days after emergence. Pyroxasulfone applied PRE did not reduce plant height, cob size, or yield of any of the sweet corn hybrids tested in this study. Based on these results, pyroxasulfone applied PRE at the rates evaluated can be safely used for weed management in Harvest Gold, GH2041, GH9589, GSS9299, GG214, GG446, GG763, and GG447 sweet corn.