bluuebunny/crossref_metadata_2025 huggingface dataset:
Mycorrhizal Infection Reduces Shortterm Aluminum Uptake and Increases Root Cation Exchange Capacity of Highbush Blueberry Plants
Authors: Yang Wei Qiang , Goulart Barbara L.
Published: February 2019

Aluminum (Al) uptake by and root cation exchange capacity (CEC) of mycorrhizal (M) and nonmycorrhizal (NM) blueberry (Vaccinium corymbosum L.) plants were studied. Root CEC was higher in M plants than in NM plants, but total and root Al contents were higher in NM plants. Leaf Al content was higher in NM than in M plants after 1 and 5 hours of exposure. The aurintriboxylic acid stain for Al indicated the presence of Al in the M symbiont. Despite a larger root system and higher root CEC, regression analysis indicated roots of M plants absorbed less Al in the first 5 hours, suggesting that Al sequestration in the M symbiont is responsible for reduced total Al uptake. Differences in dry matter partitioning between M and NM plants were also observed.
Control of Height and Flowering of Ixia Hybrids as Container Plants
Authors: Wulster George J. , Ombrello Thomas M.
Published: February 2019

Growth and flowering of Ixia hybrids as potted plants can be controlled environmentally by cool preplant storage of corms, regulation of greenhouse forcing temperatures, and application of a growth retardant. Paclobutrazol applied as a preplant corm soak, a postemergent drench, or a postemergent spray in combination with a 2- to 4-week preplant storage of corms at 7 °C, and an 18 °C day/10 °C night forcing temperature produced attractive and marketable plants. Chemical name used: β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol, Bonzi®).
Phytoplasmas as Causal Agents of Celosia Disease in Israel
Authors: Tanne E. , Kuznetsova L. , Cohen J. , Alexandrova S. , Gera A.
Published: February 2019

Recently, yellows diseases have become more common in Israel, and phytoplasmas have been detected in some of these diseased crops. Commercial fields of two celosia species (Celosia plumosa L. and C. cristata L.) also have exhibited yellows symptoms and total crop failure. Typical mycoplasma-like bodies were observed in infected but not in healthy plants. The same plants were analyzed for the presence of phytoplasma by polymerase chain reaction (PCR), using the universal oligonucleotide pair r16SF2/r16SR2, followed by nested PCR using group-specific primers. Restriction analyses performed with these products indicated that two different types of phytoplasmas are infecting celosia. PCR-RFLP analysis of one type revealed a restriction pattern typical of aster yellows. Similar analysis of the second type indicated possible relatedness, though not identity, to the pattern of phytoplasmas of the Western-X group. This is, to our knowledge, the first report of phytoplasma infection in celosia.
Molecular Markers for Self-compatibility in Japanese Apricot (Prunus mume)
Authors: Tao Ryutaro , Habu Tsuyoshi , Yamane Hisayo , Sugiura Akira , Iwamoto Kazuya
Published: February 2019

Self-compatible cultivars of Japanese apricot (Prunus mume Sieb. et Zucc.) have a horticultural advantage over self-incompatible ones because no pollinizer is required. Self-incompatibility is gametophytic, as in other Prunus species. We searched for molecular markers to identify self-compatible cultivars based on the information about S-ribonucleases (S-RNases) of other Prunus species. Total DNA isolated from five self-incompatible and six self-compatible cultivars were PCR-amplified by oligonucleotide primers designed from conserved regions of Prunus S-RNases. Self-compatible cultivars exhibited a common band of ≈1.5 kbp. Self-compatible cultivars also showed a common band of ≈12.1 kbp when genomic DNA digested with HindIII was probed with the cDNA encoding S2-RNase of sweet cherry (Prunus avium L.). These results suggest that self-compatible cultivars of Japanese apricot have a common S-RNase allele that can be used as a molecular marker for self-compatibility.
Screening the Cucumber Germplasm Collection for Combining Ability for Yield
Authors: Wehner Todd C. , Shetty Nischit V. , Clark Raymond L.
Published: February 2019

Cucumber (Cucumis sativus L.) plant introduction (PI) accessions from the regional PI station at Ames, Iowa were evaluated in open-field production for single-harvest yield at Clinton, N.C. and Ames, Iowa. Check cultivars and experimental inbreds were also tested for comparison with the PI accessions (the three groups hereafter collectively referred to as cultigens). In order to make the evaluation more uniform for all cultigens regardless of sex expression and fruit size, all were crossed with Gy 14, a gynoecious pickling cucumber inbred used commonly in the production of commercial hybrids. The resulting 761 gynoecious hybrids were tested for early, total, and marketable yield using recommended cultural practices. Results were obtained for 725 cultigens at both locations. Significant differences were observed among cultigens for all traits evaluated. Differences between the two locations were also significant for total yield, corrected total yield, and percentage of early fruit. The interaction of cultigen and location was significant for standardized total yield and standardized corrected total yield. The highest yielding hybrids at both locations were produced using the following cultigens as male (paternal) parents: PI 422185, PI 390253, PI 175120, PI 173889, PI 267087, PI 175686, PI 178888, PI 385967, PI 458851, and PI 171601. The highest and lowest yielding paternal parents from the germplasm screening study were retested, along with check cultigens in a multiple-harvest trial at Clinton, N.C. Cultigens were evaluated directly, rather than as hybrids with Gy 14, and fruit number, fruit weight, and sex expression were recorded. Most cultigens performed as expected for the yield traits in the retest study. The exceptions were `Wautoma' and PI 339250, which were among the low and high yielders in the first test, but were ranked as medium and low, respectively, in the retest study.
Short-term Storage of Almond Pollen
Authors: Martínez-Gómez P. , Gradziel T.M. , Ortega E. , Dicenta F.
Published: February 2019

Almond [Prunus dulcis (Mill.) D.A. Webb] breeding programs require successful techniques for pollen storage. We studied the pollen viability of two almond cultivars, `Ramillete' and `Desmayo Largueta', during 8 weeks of storage, in conditions that simulated standard situations including storage at 4, 22, and 4 °C alternating with 22 °C (4 °C/22 °C). Viability remained at 60% or more for 2 weeks under all three conditions. After the second week, germination capacity decreased rapidly at 22 °C, but remained above 50% for as long as 8 weeks at 4 °C or 4 °C/22 °C.
Discrimination among Cultivars of Cabbage Using Randomly Amplified Polymorphic DNA Markers
Authors: Cansian Rogério L. , Echeverrigaray Sergio
Published: February 2019

Randomly amplified polymorphic DNA (RAPD) markers were used to discriminate among 16 commercial cultivars of cabbage (Brassica oleracea L. Capitata Group). A set of 18 decamer primers was selected from 100 random sequences and used to characterize cultivars and to evaluate distances. The selected primers produced 105 (54%) polymorphic bands ranging in size from 100 and 2500 base pairs, out of a total of 195 bands, which allowed for discrimination of all cultivars. Similarity indices between cultivars were computed from RAPD data, and ranged from 0.72 to 0.87 with an average of 0.82. Unweighted pair-group method with arithmetic average (UPGMA) cluster analysis revealed two groups, one formed by two cultivars recommended for summer cropping, and the other by 14 cultivars. This large group was additionally divided into two subgroups. RAPD analysis provides a quick and reliable alternative for the identification of cabbage cultivars and for determination of the relationships among them.
Media Composition and Light Affect Storability and Poststorage Recovery of Micropropagated Hosta Plantlets
Authors: Wilson Sandra B. , Rajapakse Nihal C. , Young Roy E.
Published: February 2019

Hosta (Hosta tokudama Makeawa `Newberry Gold') plantlets were micropropagated photoautotrophically (without sucrose in medium) or photomixotrophically (with 2% sucrose in medium) for 3 weeks at 23 °C under 80 μmol·m-2·s-1 photosynthetic photon flux (PPF) prior to long-term storage. Plantlets were stored for 4, 8, or 12 weeks at 5, 10, or 22 °C in darkness or under white (400-800 nm), blue (400-500 nm), or red (600-700 nm) light at or near light compensation points. Illumination during storage was necessary to maintain dry weight and regrowth potentials of plantlets in vitro, but light quality had no effect on these parameters. All photoautotrophic plantlets stored in darkness were of poor quality at the time of removal from storage and died when transferred to the greenhouse. Dark-stored photomixotrophic plantlets survived storage for 12 weeks at 5 °C, but declined in appearance (visual quality) as the storage duration increased. Decline in visual quality was greater when plantlets were stored at 10 and 22 °C. Leaf dry weight of illuminated plantlets increased and percentage of leaf yellowing decreased as storage temperature increased. Recovery of illuminated plantlets from photomixotrophic storage was best when plantlets were stored at 22 °C. These plantlets were characterized by increased visual quality (color and form) and increased dry weight compared with those in other treatments. After 60 days in the greenhouse, the dry weight of these plantlets was similar for 4-, 8-, and 12-week storage durations, indicating flexibility in storage time if specific light and temperature provisions are met.
Date of Seeding Affects Establishment of Cool-season Turfgrasses
Authors: Reicher Zachary J. , Throssell Clark S. , Weisenberger Daniel V.
Published: February 2019

Little documentation exists on the success of seeding cool-season turfgrasses in the late fall, winter and spring. The objectives of these two studies were to document the success of seeding Kentucky bluegrass (Poa pratensis L.), perennial ryegrass (Lolium perenne L.), and tall fescue (Festuca arundinacea Schreb.) at less-than-optimum times of the year, and to determine if N and P fertilizer requirements vary with seeding date of Kentucky bluegrass. `Ram I' Kentucky bluegrass, `Fiesta' perennial ryegrass, and `Mustang' tall fescue were seeded on 1 Sept., 1 Oct., 1 Nov., 1 Dec., 1 Mar., 1 Apr., and 1 May ± 2 days beginning in 1989 and 1990. As expected, the September seeding date produced the best establishment, regardless of species. Dormant-seeding Kentucky bluegrass and tall fescue in November, December, or March reduced the establishment time compared with seeding in April or May. Seeding perennial ryegrass in November, December, or March may not be justified because of winterkill potential. To determine the effect of starter fertilizer on seedings made at different times of the year, `Ram 1' Kentucky bluegrass was seeded 1 Sept., 1 Nov., 1 Mar., and 1 May ± 2 days in 1989 and 1990, and the seedbed was fertilized with all combinations of rates of N (0, 24, and 48 kg·ha-1) and P (0, 21, and 42 kg·ha-1). Fertilizer rate had no effect on establishment regardless of seeding date, possibly because of the fertile soil on the experimental site.
Physiological and Morphological Traits Associated with Increased Water Use Efficiency in the Willow-leaf Peach
Authors: Glenn D. Michael , Scorza R. , Bassett C.
Published: February 2019

A chimeric, willow-leaf mutation of a standard peach [Prunus persica (L.) Batsch.] phenotype was evaluated for its water use efficiency (WUE). The willow-leaf phenotype had greater WUE than its standard-leaf parent under both nonstressed and well-watered conditions, and this was supported by isotopic carbon discrimination. Under water-stress conditions, willow-leaf trees developed less water potential gradient from the roots to the leaves. The mechanisms associated with increased WUE by the willow-leaf phenotype include a reduced water potential gradient within the plant and uncoupling of the leaf from the aerial environment. Willow-leaf peach trees in seedling populations, descended from a different willow-leaf parent, also had reduced carbon isotopic discrimination than did sibling standard-leaf seedlings.
Night Interruption Lighting Is Beneficial in the Production of Plugs of Dahlia `Sunny Rose'
Authors: Legnani Garry , Miller William B.
Published: February 2019

Experiments were conducted to evaluate effects of photoperiod on growth and dry-weight partitioning in Dahlia sp. `Sunny Rose' during both seedling (plug) production and subsequent production in 10-cm pots. Plugs were grown under short days [9-hour natural photosynthetic photon flux (PPF)] or long days (same 9-hour PPF plus a 4-hour night interruption with incandescent light). Total plant dry weight was unaffected by photoperiod; however, long days (LD) inhibited tuberous root development and increased shoot dry weight, fibrous root dry weight, leaf area, shoot length, and number of leaf pairs. Long days reduced plug production time by ≈1 week compared with short days (SD). Following transplanting to 10-cm pots, shoot growth and foliar development were superior under LD. There was no effect of photoperiod on foliar N concentration. The superior growth of LD plugs following transplanting can be attributed to the plant being in a physiological state conducive to shoot expansion instead of storage.
Shoot and Root Characterization of Rudbeckia hirta L. Mowed at Different Heights
Authors: Neigebauer Amy L. , Horst Garald L. , Steinegger Donald H. , Davis Greg L.
Published: February 2019

Significant research has been conducted on wildflower sod, but the reasoning behind the production system methods is not clear. The purpose of this research was to determine the influence of mowing height on the subsequent leaf growth and root biomass distribution in a wildflower sod production system. Rudbeckia hirta was grown in sand in polyvinyl chloride (PVC) tubes in simulating field conditions. Plants were either not mowed (control) or hand-clipped to 5.1, 7.6, or 10.2 cm to simulate mowing. After the initial mowing, plants were mowed at ≈7-day intervals. Total root depth, number of root axes in the top 2.5 cm, root: shoot ratio, total root dry weight, and root dry weight at depths of 0.0-2.5, 2.5-21.7, 21.7-40.8, and 40.8-60.0 cm were measured at the end of the study. Comparing the total root dry weight of all segments indicates that mowing significantly reduces root biomass. As mowing height increased, the depth of longest root increased linearly. Plants not mowed or plants mowed to 10.2 cm produced significantly more root axes in the top 2.5 cm of sand than did mowing heights of 5.1 or 7.6 cm. Root dry weight in the top 2.5 cm was considerably greater in nonmowed plants. Increased root axes in sod with higher mowing heights indicated a greater root density, which may also increase wildflower sod stability.
Recycled Paper as a Growth Substrate for Container Spirea Production
Authors: Craig Paulette B. , Cole Janet C.
Published: February 2019

Spiraea japonica L. f. `Froebelii' were grown in 3.8-L containers filled with substrates consisting of recycled paper (RP) and pine bark at rates of 0%, 25%, 50%, 75%, or 100% (by volume) RP. Fertilizer treatments included 100% of the recommended rate of N as controlled release (CRF) or liquid fertilizer (LF) or both. The same amounts of N (as NO3--N and NH4+-N), P and K were supplied with each fertilizer treatment. Plants were irrigated in Fall 1996 based on substrate water-holding capacity and to achieve a 25% to 50% leaching fraction. In Spring 1997 regardless of substrate water holding capacity, plants were irrigated weekly initially, then twice weekly later in the study when plants were larger. Fertilizer treatment did not affect plant size, but plant diameter and shoot and root dry weight decreased as substrate RP concentration increased in Fall 1996. All plant size parameters measured decreased as substrate RP concentration increased regardless of fertilizer treatment in Spring 1997. In Fall 1996, shoot and root N concentration increased as CRF decreased (and LF increased), but substrate RP concentration did not affect shoot or root N concentration. In Spring 1997, shoot and root N concentration generally decreased as substrate RP concentration increased with 50% CRF, 50% LF, or 100% LF. Leachate NO3--N, NH4+-N and total N generally increased as CRF decreased but decreased as substrate RP concentration increased in both years. Substrate volume and percentage of air space decreased, but bulk density increased, as RP concentration increased. Although N leaching decreased as substrate RP concentration increased in both years, reasonable plant growth occurred only in those substrates containing ≤50% RP.
Bloom and Postbloom Applications of NAD/NAA Mixture Have Minimal Effects on Yield and Fruit Size of Field-grown Tomatoes and Peppers
Authors: Stover E.W. , Stoffella P.J. , Garrison S.A. , Leskovar D.I. , Sanders D.C. , Vavrina C.S.
Published: February 2019

A commercial mixture of 1-naphthaleneacetamide and 1-naphthaleneacetic acid (Amcotone) was applied to tomato (Lycopersicon esculentum Mill.) and pepper (Capsicum annuum L.) at various timings from early bloom through early fruit development to evaluate effects on fruit size and both early and total marketable yield. Amcotone was applied at rates from 10 to 40 mg·L-1, at three sites for each of the species studied. Measured yield response variables in tomato did not differ between the control and Amcotone treatments, regardless of location. Amcotone treatments did not affect yields or fruit size for pepper at the New Jersey or Texas sites. However, at Ft. Pierce, Fla., early marketable yield of pepper was increased in plots receiving three Amcotone applications at 10 mg·L-1, but total marketable yield was significantly reduced in all plots receiving more than two Amcotone sprays, and mean fruit weight was reduced by all Amcotone treatments. Early and total marketable yield of pepper at Ft. Pierce were markedly reduced in plots receiving four applications of 40 mg·L-1, which was a high rate used to assess potential phytotoxicity. While minimal benefit from auxin application was observed in this study, earlier studies suggest that these results may have been influenced by favorable environmental conditions for fruit development or negative effects on unopened flowers during all Amcotone spray applications.
Evaluation of Turfgrass Selections for Resistance to Fall Armyworms (Lepidoptera: Noctuidae)
Authors: Braman S.K. , Duncan R.R. , Engelke M.C.
Published: February 2019

Turfgrass selections including 21 paspalums (Paspalum vaginatum Swartz) and 12 zoysiagrasses (Zoysia sp.) were compared with susceptible `KY31' tall fescue (Festuca arundinacea Schreb.) and more resistant common bermudagrass (Cynodon dactylon Pers.) and common centipedegrass [Eremochloa ophiuroides (Munro.) Hack] for potential resistance to fall armyworm [Spodoptera frugiperda (J.E. Smith)], an occasionally serious pest of managed turf. Turfgrass and pasture grasses annually suffer sporadic damage by this pest, often severe in the Gulf Coast states. Resistant grasses offer an alternative management tool for the fall armyworm, reducing the need for pesticide use. Laboratory evaluations assessed the degree of antibiosis and nonpreference present among more than 30 turfgrass genotypes to first and third instar fall armyworms, respectively. Zoysiagrasses exhibiting high levels of antibiosis included `Cavalier', `Emerald', DALZ8501, DALZ8508, `Royal', and `Palisades'. Paspalum selections demonstrating reduced larval or pupal weights or prolonged development times of fall armyworm included 561-79, Temple-2, PI-509021, and PI-509022.
Host Range of a California Sting Nematode Population
Authors: Bekal S. , Becker J.O.
Published: February 2019

Recently, sting nematodes were discovered associated with dying turfgrass in several golf courses in Coachella Valley, Calif. Based on their morphology and internal transcribed spacer (ITS) rDNA restriction pattern, the pests were identified as Belonolaimus longicaudatus Rau. This study was undertaken to determine the host status of 60 different plant species and cultivars for a California population of B. longicaudatus. The host range tests were conducted under greenhouse conditions at 25 ± 2 °C and ambient light. At the second-leaf stage, each pot was infested with 55 ± 12 adults or fourth-stage juveniles per 150 g of blow sand. The population densities determined after 7 weeks of incubation qualified >80% of the plants tested as good hosts with a reproduction factor (Rf = Pf/Pi) > 4. The majority of those were grasses, although reproduction was best on Gossypium hirsutum L. with Rf = 58.6. While Capsicum annuum L., Medicago sativa L., Arachis hypogaea L., Euphorbia glyptosperma Engelm., Cucumis sativus L., and Daucus carota L. were less suitable host plants with Rf < 4, only Abelmoschus esculentus (L.) Moench, Citrullus lanatus Thunb., and Nicotiana tabacum L. were nonhosts among the tested species. This sting nematode population had a high reproductive fitness on a majority of species tested and must be considered a major threat for most agricultural and horticultural crops grown in sandy soils.
Tolerance of Selected Orange and Mandarin Hybrid Fruit to Low-dose Irradiation for Quarantine Purposes
Authors: Miller W.R. , McDonald R.E. , Chaparro J.
Published: February 2019

Tolerance of many citrus cultivars to low-dose irradiation treatment is not known. Ten citrus cultivars grown in Florida, including the five orange [Citrus sinensis (L.) Osbeck] cultivars, Ambersweet, Hamlin, Navel, Pineapple, and Valencia, and the five mandarin hybrids (Citrus reticulata Blanco), `Fallglo', `Minneola', `Murcott', `Sunburst', and `Temple', were exposed to irradiation at 0, 0.15, 0.3, and 0.45 kGy, and stored for 14 days at 1 °C or 5 °C plus 3 days at 20 °C, to determine dose tolerance based on fruit injury. Softening of `Valencia', `Minneola', `Murcott', and `Temple' was dose-dependent, but that of other cultivars was unaffected. Only `Ambersweet', `Valencia', `Minneola', and `Murcott' did not develop peel pitting at 0.15 kGy or higher. Total soluble solids of `Ambersweet' and `Sunburst' declined slightly with increasing dose. Titratable acidity (TA) of oranges was not affected, but TA of `Sunburst' and `Temple' juice was slightly reduced by irradiation at 0.45 kGy. Juice flavor of `Hamlin', `Navel', `Valencia', and `Minneola', and pulp flavor of `Hamlin', `Valencia', `Fallglo', `Minneola', and `Murcott' was less acceptable after irradiation at 0.3 or 0.45 kGy. The appearance of all cultivars was negatively affected by the loss of glossiness with the 0.45 kGy dose. Less than 1.0% of fruit decayed and irradiation treatment had no effect on decay. Our study indicates that growers and shippers need to be aware that the effects of irradiation on citrus fruits are highly variable and both cultivar-dependent and dose-dependent.
ReTain™ Affects Maturity and Ripening of `Bartlett' Pear
Authors: Clayton M. , Biasi W.V. , Southwick S.M. , Mitcham E.J.
Published: February 2019

ReTain™, a commercial derivative of aminoethoxyvinylglycine, was applied as a single application at 124 g·ha-1 a.i. to `Bartlett' pear (Pyrus communis L.) trees 28, 21, 14, or 7 days prior to initial commercial harvest and at 62 g·ha-1 a.i. in combination with naphthaleneacetic acid (NAA) at 92 g·ha-1 a.i. 14 days prior to initial commercial harvest. Maturity and quality of treated fruits at harvest and following storage were compared with those of nontreated pears in 1996 and 1997. Ethylene production by mature green pears at harvest was not significantly affected by ReTain™ treatments, although softening, loss of chlorophyll, and starch clearance were usually inhibited by the 14- or 7-day treatment. ReTain™ suppressed ethylene production, softening and loss of chlorophyll in ripening pears and mature green pears cold-stored for 4 months, although loss of chlorophyll did not differ in the cold-stored fruit in 1997. ReTain™ had little effect on softening during a ripening period of 6 days after 4 months of cold storage. Application at 14 or 7 days prior to initial harvest appeared most effective, often with little difference between the two timings, and the 28- or 21-day treatment or combined ReTain™ and NAA treatment were seldom more effective. ReTain™ applied 14 or 7 days before initial harvest delayed fruit maturation by 4-10 days depending on the maturity index. The maturity or ripeness of pears from the combined ReTain™ and NAA, NAA only, and control treatments was often similar or differed only slightly. Premature ripening, prevalent in 1997, was dramatically suppressed in fruit treated with ReTain™. Ripening of both ReTain™- and non-ReTain™-treated fruit with ethylene reduced premature ripening by ≈50%.
The Progression of Ethylene Production and Respiration in the Tissues of Ripening `Fuji' Apple Fruit
Authors: Rudell D.R. , Mattinson D.S. , Fellman J.K. , Mattheis J.P.
Published: February 2019

`Fuji' apple (Malus ×domestica Borkh.) fruits were harvested periodically prior to and during fruit ripening. Ethylene evolution and respiration rates of skin, hypanthial, and carpellary tissue was determined in each fruit. Additionally, whole fruits were used for analyses of internal ethylene concentration, volatile evolution, starch content, flesh firmness, and soluble solids content. Ethylene production was greatest in the carpellary tissue at all sampling dates except the one occurring just before the rise in whole fruit internal ethylene concentration, when production in the skin and carpellary tissue was similar. Respiration was always highest in the skin, in which the climacteric rise was most drastic. Higher ethylene production in the carpellary tissue of pre- and postclimacteric fruit and higher respiration in the skin tissue, including a noticeable climacteric rise, is indicative of a ripening initiation signal originating and/or transduced through the carpels to the rest of the fruit.
Interaction of Monoterpenoids, Methyl Jasmonate, and Ca2+ in Controlling Postharvest Brown Rot of Sweet Cherry
Authors: Tsao Rong , Zhou Ting
Published: February 2019

The banning of synthetic fungicides for postharvest use on fruits in Canada has prompted a search for alternative control strategies for postharvest brown rot caused by Monilinia fructicola (Wint.) Honey on sweet cherry (Prunus avium L.). Thymol and carvacrol were the two most potent fungicides among the monoterpenoids tested. The brown rot incidences of M. fructicola-inoculated cherry dipped in 1000 μg·mL-1 thymol and carvacrol were 24% and 23%, respectively, compared with 81% for the control. The effects of thymol and carvacrol were not significantly enhanced by the addition of CaCl2 or CaB'y®, a foliar calcium fertilizer. Decco® 282 significantly reduced the activity of thymol. Methyl jasmonate, an elicitor of plant defense mechanisms, did not reduce brown rot by itself, and did not increase the efficacy of thymol and carvacrol when used as an additive in dipping or fumigation experiments. Thymol and carvacrol caused stem browning of cherry fruits in the fumigation experiment, however, 69% and 73%, respectively, of the browning was prevented when methyl jasmonate was used as a co-fumigant. Chemical names used: 5-methyl-2-(1-methylethyl)phenol (thymol); 2-methyl-5-(1-methylethyl)phenol (carvacrol); methyl 3-oxo-2-(2-pentenyl)cyclopentane acetate (methyl jasmonate).
Processing Line Effects on Storage Attributes of Fresh-cut Spinach Leaves
Authors: Hodges D. Mark , Forney Charles F. , Wismer Wendy
Published: February 2019

The degree of damage that may occur through harvesting and packing represents one of the major factors that can affect quality of fresh-cut produce. The purpose of this study was to examine the effects of different steps in a representative fresh-cut processing line on storage quality of spinach (Spinacia oleracea L.). To this end, spinach leaves were removed at successive points on the line: 1) before entry into the line (control); 2) after a shaking procedure but before initial rinsing with 10 °C water + 5 mg·L-1 chlorine dioxide; 3) after centrifugal drying; and 4) after commercial packaging. After removal from the different points in the line, the spinach samples were stored at 10 °C for 16 days, during which time malondialdehyde (MDA) concentration (lipid peroxidation assay), electrolyte leakage (membrane leakiness), chlorophyll content (a, b, and total), and color attributes (L, saturation, hue angle) were measured. Both lipid peroxidation and electrolyte leakage increased with time of storage and with stage of procesing. Electrolyte leakage increased most in material removed after the shaking procedure, but prior to hydrocooling. Overall total chlorophyll loss during storage did not change with time of removal from the processing line, although overall chlorophyll b content decreased in stored material 8 days following centrifugal drying and packaging. A more rapid loss in chlorophyll a relative to chlorophyll b over the first 8 days of storage was reflected in hue angle measurements regardless of the point of removal. The processing line under study, thus had both beneficial and detrimental effects on storage quality of spinach. Detrimental effects associated with centrifugal drying and packaging procedures could be modified to improve quality.
Comparison of Rambutan Quality after Hot Forced-air and Irradiation Quarantine Treatments
Authors: Follett Peter A. , Sanxter Suzanne S.
Published: February 2019

Insect disinfestation treatments are required for many of Hawaii's tropical fruits before export to the U.S. mainland. For rambutan, Nephelium lappaceum L., irradiation at 250 Gy is an Animal Plant Health Inspection Service (APHIS)-approved quarantine treatment, but a hot forced-air treatment has also been proposed for eliminating fruit fly pests. Two days after harvest, rambutan fruit (cultivars R134 and R167) were subjected to: 1) hot forced-air at a seed surface temperature of 47.2 °C, 2) irradiation treatment at 250 Gy, or 3) left untreated as controls. Fruit were then stored at 10 °C in perforated plastic bags, and quality attributes were evaluated after 4, 8, and 12 days. `R134' fruit treated with hot forced-air were significantly darker (lower L*) and less intensely colored (lower C*) than irradiated or nontreated fruits after 4 and 8 days of posttreatment storage; the external appearance was unacceptable after 4 days of storage, whereas irradiated fruit remained acceptable through 8 days of storage. Differences between treatments were less pronounced for `R167'. `R167' fruit treated with hot forced-air had lower L* and C* values and less acceptable external appearance ratings than did irradiated fruit at 4, 8, and 12 days posttreatment, but differences were not statistically significant. For both cultivars, external appearance of fruit in all treatments was unacceptable after 12 days of storage, whereas taste was rated as acceptable for all treatments on each day. Overall, under these experimental conditions, irradiation was superior to hot forced-air as a quarantine treatment on the basis of fruit quality maintenance.
Sources of Curly Top Virus Resistance in Capsicum
Authors: Bosland Paul W.
Published: February 2019

During a natural field epidemic of curly top virus, accessions within five species of Capsicum were evaluated for resistance. Accessions were considered resistant if 0% to 25% of the individual plants were devoid of curly top virus symptoms. Resistance was found in three accessions each of C. annuum L. and C. frutescens L. and one accession each of C. chacoense Hunz. and C. chinense Jacq. The resistant C. annuum accessions were `Burpee Chiltepin', `NuMex Bailey Piquin', and `NuMex Twilight', while the C. frutescens resistant accessions were USDA-Grif 9322 from Costa Rica, PI 241675 from Ecuador and `Tabasco'. The resistant C. chacoense accession was PI 273419 from Argentina and the C. chinense resistant accession was USDA-Grif 9303 from Colombia.
Selection Against Pratylenchus vulnus Populations Attacking Prunus Rootstocks
Authors: Pinochet Jorge , Fernández Carolina , Calvet Cinta , Hernández-Dorrego Adriana , Felipe Antonio
Published: February 2019

Twenty-nine commercial and experimental Prunus rootstocks, most with incorporated root-knot nematode [Meloidogyne javanica (Traub.) Chitwood] resistance, were evaluated against mixtures comprising nine populations of the root-lesion nematode Pratylenchus vulnus Allen and Jensen. Nearly all tested materials were susceptible. Five cultivars with high resistant levels were further challenged with seven P. vulnus populations individually. `Redglow' (Prunus salicina Lindl. × P. munsoniana Wight and Hedrick) was the only rootstock that showed broad resistance to all populations. The rootstocks `Torinel' (P. domestica L.), AC-595 (P. domestica × P. insititia L.), `Marianna 4001' (P. cerasifera Ehr. × P. munsoniana), and `Felinem' [P. dulcis (Mill.) D. A. Webb × P. persica (L.) Batsch] showed resistance to one or a few P. vulnus populations. Several supposedly resistant sources proved to be susceptible. Tests of crosses made between parents of diverse genetic background with partial resistance to P. vulnus indicate that a descendant with potential P. vulnus resistance is difficult to obtain. Pathogenic diversity among P. vulnus populations appears to be high.
Nitrate Uptake and Nitrogen Use Efficiency by Kentucky Bluegrass Cultivars
Authors: Jiang Zhongchun , Sullivan W. Michael , Hull Richard J.
Published: February 2019

Efficient utilization of fertilizer-nitrogen (N) by turfgrasses is probably related to N uptake efficiency of roots and metabolic efficiency of absorbed N in roots and shoots. This study evaluated Kentucky bluegrass (Poa pratensis L.) cultivars for potential differences in nitrate uptake rate (NUR), temporal variation in NUR, and the relationship between NUR and N use efficiency (NUE), defined as grams dry matter per gram N. Six cultivars were propagated from tillers of seeded plants, grown in silica sand, mowed weekly, and watered daily with a complete nutrient solution containing 1.0 mm nitrate. A nutrient depletion method from an initial nitrate concentration of 0.5 mm was used to determine NUR of 5-month-old plants. NUR (μmol·h-1 per plant) of the six cultivars ranked as follows: `Blacksburg' > `Conni' > `Dawn' > `Eclipse' = `Barzan' > `Gnome'. When NUR was based on root weight, `Conni' ranked highest; when NUR was based on root length, surface, or volume, `Eclipse' ranked highest. Averaged across cultivars, NUR on the second day was greater than NUR for the first day of nitrate exposure. Temporal variation was greatest in `Blacksburg', while none was noted in `Conni' or `Eclipse'. Cultivar differences in NUE were significant in fibrous roots, rhizomes, and leaf sheaths, but not in leaf blades and thatch. Total nitrate uptake was positively related to total N recovered and total plant dry matter, but NUR based on root weight was negatively correlated with NUE of the whole plant.
Drying and Cold Storage Affect Germination of Black Huckleberry Seeds
Authors: Shafii Bahman , Barney Danny L.
Published: February 2019

Trials were conducted to determine the effects of air drying and cold storage on black huckleberry (Vaccinium membranaceum Douglas ex Hooker) seeds. Treatments included fresh seeds, seeds air-dried for 7 days, and those air-dried and stored at 2 to 3 °C for either 1 or 7 years. Germination was measured every 7 days. The time course of germination was modeled using a logistic growth curve from which days to 50% germination (T50), germination rate index, and maximum germination percentages were estimated. Germination curves of dried and of dried and cold-stored seeds were significantly different from that of fresh seeds. Seeds stored for 1 or 7 years had germination percentages similar to those for the fresh, nondried seeds. Air drying for 7 days reduced the maximum germination percentage from 73% to 59% (fresh seeds). This induced dormancy was gradually lost during cold storage of dry seeds. Cold storage of air-dried seeds was an effective method for preserving V. membranaceum germplasm for at least 7 years.
Nutrient Accumulation and Associated Root Characteristics in Response to Drought Stress in Tall Fescue Cultivars
Authors: Huang Bingru
Published: February 2019

Drought is a major factor limiting the growth of turfgrasses in many areas. The functional relationship of drought stress and accumulation of various ions in turfgrasses is not well understood. The objective of this study was to investigate the effects of drought on root growth and accumulation of several major nutrients in three tall fescue (Festuca arundinacea Schreb.) cultivars varying in drought tolerance (Falcon II = Houndog V > Rebel Jr). Grasses were grown in well-watered or drying (nonirrigated) soil for 35 days in a greenhouse. Drought conditions limited total root length to a greater extent for `Rebel Jr' than for `Falcon II' and `Houndog V', while specific root length (SRL) was greater in `Falcon II' and `Houndog V' than in `Rebel Jr'. Concentrations of N, P, and Mg decreased, whereas those of K, Ca, and Fe increased, in shoots of drought-stressed plants of all three cultivars. Root N was not affected, but root P decreased in `Rebel Jr', and root K decreased in all three cultivars under drought conditions. Drought reduced the proportions of N and P in shoots and increased those in roots, while increasing the proportion of K in shoots and decreasing that in roots. During drought stress, both `Falcon II' and `Houndog V' maintained higher K concentration in shoots, and `Falcon II' in roots, than did `Rebel Jr', but `Rebel Jr' and `Houndog V' had higher Fe concentration in shoots than did `Falcon II'. The higher K and lower Fe accumulations in shoots could contribute to better drought tolerance of tall fescue cultivars.
Fertilizer Concentration Affects Growth and Flowering of Subirrigated Petunias and Begonias
Authors: James Erin C. , van Iersel Marc W.
Published: February 2019

Nitrate pollution and water conservation are two of the most important environmental concerns for greenhouse growers. Closed irrigation systems, such as ebb and flow, can minimize these problems. The objective of this study was to determine optimal fertilizer concentrations for petunia (Petunia×hybrida Hort. Vilm-Andr.) and begonia (Begoni××emperflorens-cultorum Hort.) grown with ebb-and-flow irrigation. `Ambassador Scarlet' begonia and `Dreams Mix' petunia were grown as bedding plants in three soilless media. Plants were fertilized with solutions of a 20N-4.4P-16.6K water-soluble fertilizer with electrical conductivities (EC) of 0.15, 0.6, 1.2, 1.8, 2.4, or 3.0 dS·m-1. Maximum growth occurred with a fertilizer EC of 2.2 dS·m-1 for petunia and 1.6 dS·m-1 for begonia. Petunia growth was best in the medium with the highest porosity (Metro-Mix 220), but choice of medium had little effect on begonia growth. Leachate EC and pH were determined throughout the experiment, using the pour-through method. Leachate EC rose with increasing fertilizer concentration, and increased over time. The pH of the leachate decreased with increasing fertilizer concentration and dropped 0.5 to 1 unit over the course of the experiment with the higher fertilizer concentrations (≥0.6 dS·m-1). Plant growth was not very sensitive to leachate EC. Begonia and petunia grew well when the EC at the end of the production cycle was between 1.7 to 6.1 and 2.1 and 5.4 dS·m-1, respectively.
Photoperiod, Chilling, and Light Quality during Daylight Extension Affect Growth and Flowering of Tissue-cultured Easter Lily Plants
Authors: Holcomb E. Jay , Berghage Robert
Published: February 2019

Easter lily plants (Lilium longiflorum Thunb.), derived from tissue culture and grown continuously, were subjected to various photoperiod and chilling treatments. Lilies grown with daylength extended either with high-intensity discharge (HID) or incandescent lights flowered in the same number of days, but had more flower buds with HID lamps. Flowering was delayed and plants produced more leaves as photoperiod was reduced from 16 to 12 hours. The numbers of leaves, primary, secondary, and tertiary flowers, and the time to flower were all significantly reduced as the duration of extended lighting was increased from 0 to 6 weeks. As the number of weeks of cooling at 5°C increased from 0 to 5, time to flower was significantly reduced.
Color of Plastic Mulch Affects Lateral Root Development But Not Root System Architecture in Pepper
Authors: Gough R.E.
Published: February 2019

In 1999, `Sweet Banana' pepper [Capsicum annuum L. (Grossum Group)] plants were grown under clean cultivation or with red, silver, or black polyethylene selective reflecting (SMR) mulches over the soil surface. Plants in each of three replications per treatment were field-set on 15 June. On 22 Sept., the plants were excavated and their root systems examined using a trench profile method and a succession of trench wall slices. The total numbers of roots of each plant at depths of 5, 10, 15, 20, and 25 cm and 10, 20, 30, 40, 50, and 60 cm from the plant stem were recorded. Distribution and architecture of the root systems were also examined. Plants grown under clean cultivation developed 50 to 60 adventitious roots each, while those grown under red mulch developed ≈20 and those under black and silver mulch about nine adventitious roots each. In all treatments, the adventitious roots radiated downward from the stem at an angle of 35° from the horizontal. No plants had vertical roots. Root system architecture was similar among treatments, with 40% of the roots in the upper 5 cm of soil and 70% in the upper 10 cm. Thirty percent of the roots were within 10 cm, 50% within 20 cm, and nearly 100% within 40 cm of the stem. Root numbers decreased with increasing depth and distance from the stem. The greatest number of lateral roots were produced under silver mulch, intermediate numbers under clean cultivation and black mulch, and the fewest roots under red mulch. Colored mulches influenced the total number of adventitious and lateral roots but not the root system architecture of pepper plants.
Temporal Effects of Chemical Weed Control on Tart Cherry Tree Growth, Yield, and Leaf Nitrogen Concentration
Authors: Al-Hinai Yahya K. , Roper Teryl R.
Published: February 2019

This experiment was conducted to determine temporal weed management parameters for tart cherry (Prunus cerasus L.) orchards. Annual ryegrass (Lolium multiflorum L.) and lambsquarter (Chenopodium album L.) were planted in tree rows of a 4-year-old tart cherry orchard. Weeds either were not controlled or controlled with nonresidual herbicides during the following intervals: all-summer; May, June, July, or August; preharvest (April-July); or postharvest (late July to frost). Trees in all-summer, June, and preharvest weed-free plots had more shoot growth, more nodes, longer internodes, greater leaf area, and higher concentrations of leaf nitrogen than did those in the weedy control and postharvest, July, or August treatments. A larger increase in trunk circumference was observed in all-summer and preharvest weed-free plots than in postharvest and weedy plots. Early-summer weed control was important for tree vegetative growth. Tree yield (fruit weight and number) was greater on trees without weed competition postharvest than in those treated in May, June, July, or in weedy controls. Late-season (after late July) weed control is therefore important for fruit yield.
Potassium Fertilization Affects Soil K, Leaf K Concentration, and Nut Yield and Quality of Mature Pistachio Trees
Authors: Zeng Qiupeng , Brown Patrick H. , Holtz Brent A.
Published: February 2019

A field experiment was conducted from 1996 to 1998 to examine the effects of K fertilization on leaf K, nut yield, and quality in pistachio (Pistacia vera L.). There were six treatments, including four annual rates of K application (0, 110, 220, and 330 kg·ha-1) and three K sources (K2SO4, KCl, and KNO3). Pistachio trees exhibited highly fluctuating seasonal leaf K levels. Leaf K concentration was low (<10 g·kg-1) during spring flush, increased dramatically during fruit development, and declined rapidly after harvest. Leaf K concentration increased following K fertilization. Potassium fertilization at the rate of 110 to 220 kg·ha-1 K significantly increased nut yield and quality, but nut yield tended to decrease when the annual rate exceeded 220 kg·ha-1 K. There were no significant differences among the K sources in their effects on leaf K concentration, nut yield, and quality. The use of KCl as a K source for 3 years did not increase leaf Cl concentration. There was a significant, positive correlation between nut yield and leaf K concentration during nut fill. The critical leaf K value for optimal pistachio production determined from 3 years' cumulative data was 16.9 g·kg-1. For sustained production in highly productive pistachio orchards, we recommend annual application rates of 110 to 220 kg·ha-1 K, using K2SO4, KCl, or KNO3.
Field Spectra and Airborne Digital Imagery for Detecting Phytophthora Foot Rot Infections in Citrus Trees
Authors: Fletcher Reginald S. , Skaria Mani , Escobar David E. , Everitt James H.
Published: February 2019

Phytophthora foot rot, caused by Phytophthora parasitica (Dast), can result in economic losses for the citrus industry in the Lower Rio Grande Valley of Texas. Therefore, locating foot rot-infected trees in citrus groves is important to citrus growers. Symptoms of the infection include leaf yellowing, canopy defoliation, twig dieback, and short growth flushes. This study evaluated the use of the latest remote sensing technology, that of airborne digital imagery, for the detection of citrus trees exhibiting mild symptoms of foot rot infection. Airborne color-infrared (CIR) digital imagery of two citrus orchards having problems with foot rot infection was acquired. In addition to the aerial digital imagery, ground spectroradiometric measurements were conducted to determine the visible and near-infrared (NIR) spectral reflectance differences between healthy and infected trees. These measurements were also used to help interpret the color tonal renditions between the trees. The CIR digital imagery distinguished infected from noninfected trees. The noninfected trees had a bright red-magenta color rendition, while the infected trees had a dull grayish red tonal response. The NIR spectroradiometric and digital readings were significantly lower for infected trees than for healthy ones (P ≤ 0.05), whereas the visible reflectance and digital data revealed no significant differences between the trees. The infected trees' dull tonal response in the CIR image was attributed to their lower NIR light intensity. These results indicated that digital imagery has potential for detecting foot rot-infected trees in citrus groves based upon NIR spectral differences. The advantage of airborne digital imagery is its real-time survey for quick field assessment.