bluuebunny/crossref_metadata_2025 huggingface dataset:
Using Density Measurements to Study the Effect of Excision, Storage, Abscisic Acid, and Ethylene on Pithiness in Celery Petioles
Authors: Saltveit Mikal E. , Mangrich Mary E.
Published: January 2019

The density of excised 2-cm celery (Apium graveolens L.) petiole segments was highly correlated with a subjective evaluation of pithiness. Loss of density and the appearance of pithiness was stimulated by lengthening the duration of storage, raising the storage temperatures above 0C, and excising petiole segments. Segments excised from the upper two-thirds of the petiole lost less density during storage than segments excised from the bottom third of the petiole. Segments with initial high densities lost slightly less density during storage at 5C for 5 weeks than segments that were initially less dense. The extent of pithiness development varied significantly among six cultivars held at 5C for 2 weeks. Treating whole petioles with 1 μm abscisic acid for 4 days significantly increased density loss. Exposing petiole segments to up to 100 μl·liter-1 ethylene in humidified air for up to 2 weeks at 5C did not significantly change density over air controls. The loss of density and the development of pithiness in lightly processed celery petioles could be reduced by selecting resistant cultivars, monitoring water stress during growth, using only segments excised from the upper two-thirds of the petiole, and selecting segments with initial high densities.
Field Performance of Somaclonal Variants of Plantain (Muss spp., AAB Group)
Authors: Vuylsteke Dirk R. , Swennen Rony L. , De Langhe Edmond A.
Published: January 2019

Four types of morphologically distinct somaclonal variants were identified in a population of False Horn plantain (Musa spp., AAB group) plants produced by in vitro shoot-tip culture. Field performance of these variants was compared with true-to-type plantain to evaluate their horticultural traits. Significant variation was observed for plant and fruit maturity, leaf size, yield and its components, but not for leaf number, plant height, or suckering. Three of the four somaclonal variants were horticulturally inferior to the original clone from which they were derived. Yields of these variants were very poor due to inflorescence degeneration or abnormal foliage. Only the `French reversion' variant, which resembled an existing cultivar, outyielded the true-to-type clone. However, its fruit weight and size were lower. Somaclonal variation through micropropagation is of limited use in plantain improvement as it mostly mimics naturally occurring variation along with the observed poor horticultural performance of somaclonal variants.
Nitrogen Uptake Efficiency and Leaching Losses from Lysimeter-grown Citrus Trees Fertilized at Three Nitrogen Rates
Authors: Syvertsen J.P. , Smith M.L.
Published: January 2019

Four-year-old `Redblush' grapefruit (Citrus paradisi Macf.) trees on either the relatively fast-growing rootstock `Volkamer' lemon (VL) (C. volkameriana Ten. & Pasq.) or on the slower-growing rootstock sour orange (SO) (C. aurantium L.) were transplanted into 7.9-m3 drainage lysimeter tanks filled with native Candler sand, irrigated similarly, and fertilized at three N rates during 2.5 years. After 6 months, effects of N application rate and rootstock on tree growth, evapotranspiration, fruit yield, N uptake, and leaching were measured during the following 2 years. When trees were 5 years old, low, medium, and high N application rates averaged about 79,180, or 543 g N/tree per year and about 126,455, or 868 g N/tree during the following year. Recommended rates average about 558 g N/tree per year. A lysimeter tank with no tree and additional trees growing outside lysimeters received the medium N treatment. Nitrogen concentration in the drainage water increased with N rate and exceeded 10 mg·liter-1 for trees receiving the high rates and also for the no tree tank. Leachate N concentration and total N recovered was greater from trees on SO than from those on VL. Average N uptake efficiency of medium N rate trees on VL was 6870 of the applied N and 61 % for trees on SO. Nitrogen uptake efficiency decreased with increased N application rates. Trees outside lysimeters had lower leaf N and fruit yield than lysimeter trees. Overall, canopy volume and leaf N concentration increased with N rate, but there was no effect of N rate on fibrous root dry weight. Fruit yield of trees on SO was not affected by N rate but higher N resulted in greater yield for trees on VL. Rootstock had no effect on leaf N concentration, but trees on VI. developed larger canopies, had greater fibrous root dry weight, used more water, and yielded more fruit than trees on SO. Based on growth, fruit yield and N leaching losses, currently recommended N rates were appropriate for trees on the more vigorous VL rootstock but were 22% to 69 % too high for trees on SO.
Applying Soybean Oil to Dormant Peach Trees Alters Internal Atmosphere, Reduces Respiration, Delays Bloom, and Thins Flower Buds
Authors: Myers R.E. , Deyton D.E. , Sams C.E
Published: January 2019

Dormant `Georgia Belle' peach [Prunus persica (L.) Batsch.] trees were sprayed in early February 1992 with single applications of 0%, 2.5%, 5.0%, 10.0%, or 20.0% (v/v) crude soybean oil. `Redhaven' trees were sprayed in February 1993 with single applications of 0%, 2.5%, 5.0%, 10.0%, or15% degummed soybean oil. Additional treatments of two applications of 2.5% or 5.0% oil were included each year. Both crude and degummed soybean oil treatments interfered with escape of respiratory CO2 from shoots and increased internal CO2 concentrations in shoots for up to 8 days compared to untreated trees. Respiration rates, relative to controls, were decreased for 8 days following treatment, indicating a feedback inhibition of respiration by the elevated CO2. Thus, an internal controlled atmosphere condition was created. Ethylene evolution was elevated for 28 days after treatment. Flower bud development was delayed by treating trees with 5% crude or degummed soybean oil. Trees treated with 10% crude or degummed soybean oil bloomed 6 days later than untreated trees. Repeated sprays of one half concentration delayed bloom an additional four days in 1992, but < 1 day in 1993 compared to a single spray of the same total concentration. Application of soybean oil caused bud damage and reduced flower bud density (number of flower buds/cm branch length) at anthesis. In a trial comparing petroleum oil and degummed soybean oil, yields of trees treated with 6% or 9% soybean oil were 17% greater than the untreated trees and 29%more than petroleum treated trees. These results suggest that applying soybean oil delays date of peach bloom and may be used as a bloom thinner.
Variability and Grouping of Northwestern Spanish Chestnut Cultivars. I. Morphological Traits
Authors: Pereira-Lorenzo S. , Fernández-López J. , Moreno-González J.
Published: January 2019

Different chestnut (Castanea sativa Mill.) cultivars are at present grown in the region of Galicia, northwestern Spain, but no distinguishing traits among cultivars have been defined so far. The objectives of this research were to 1) describe the intra and intercultivar variability of chestnut cultivars; 2) define primary morphological traits to be useful for a simple morphological classification system of the cultivars; and 3) study the association between some environmental variables and the morphological traits. Seventeen morphological traits in a sample of 373 trees belonging to 82 local cultivars of chestnut were studied by methods of numerical taxonomy, principal component and cluster analysis. These traits were selected from 135 previously studied as having possible discriminating taxonomic value. Significant variability among cultivars and among trees within cultivars was found for most of the traits. The trees were grouped according to the degree of dissimilarity on the basis of the Mahalanobis generalized distance. Most of the clones collected under a specific cultivar name were included within the same cluster group enabling us to classify 53 of the cultivars studied. A hierarchical classification system that identifies eight cultivar groups is proposed based on four discriminating levels: nut size, fruit shape, male flower type and length of burr spines. Most of the correlations between the environmental variables and the morphological traits were no significant or had a low value. The lack of correlation between the environmental variables and nut size indicates that this important trait is under strong genetic control, it is not influenced by environmental conditions and it is consistent throughout the area sampled.
Variability and Grouping of Northwestern Spanish Chestnut Cultivars. II. Isoenzyme Traits
Authors: Pereira-Lorenzo S. , Fernández-López J. , Moreno-González J.
Published: January 2019

Two-hundred and ninety-five trees sampled from seventy-five local chestnut (Castanea sativa Mill.) cultivars in northwestern Spain, which had been previously studied morphologically, were further analyzed for five isoenzyme systems, encoded by seven loci. Objectives of this study were to 1) describe the intracultivar and intercultivar variability by isoenzyme analysis and to compare it with the morphological variation and 2) establish a classification of the cultivars and to discuss its relation to the morphological classification. Variability within and among cultivars was detected, confirming the previous morphological results. The level of the observed heterozygosity in this Spanish population was higher than expected and also higher than that found in other European populations. Because of the great diversity discovered, this material seems to be worthy for introducing and maintaining in a germplasm bank. Nineteen main clusters were identified for the twenty-three most widely distributed cultivars. On the average, 61% of the trees belonging to a specific cultivar was included in the same cluster. The remaining 39% was scattered in other clusters, which indicates intracultivar variability. Therefore there is opportunity for selection within cultivars. Two clusters included three important cultivars each. This suggests possible synonymies. No correlation between morphological traits and the isoenzymic alleles was detected. The isoenzyme technique identified a higher number of cultivars increasing the information obtained with morphological traits. Correlations between the frequency of some of the alleles and the altitude and other environmental variables suggest that selection of the best adapted genotypes has occurred.
Endopolygalacturonase and the Melting Flesh (M) Locus in Peach
Authors: Lester Diane R. , Sherman Wayne B. , Atwell Brian J.
Published: January 2019

Southern analysis of two ripening-related polygalacturonase (PG) genes of peach [Prunus persica (L.) Batsch] detected a restriction fragment length polymorphism (RFLP) in one that had been previously identified as encoding the endoPG enzyme of melting flesh fruit. This RFLP distinguished the melting flesh cultivars Flavorcrest and Flordaking from the nonmelting flesh cultivars Carolyn, Early Gold Queen, Fla. 86-28C, and Fla. 9-26C. Complete deletion of endoPG-related genomic sequences was demonstrated in the nonmelting flesh variety Fla. 9-20C. In a blind trial, segregation of the endoPG RFLP was followed in relation to the melting flesh trait in a population of 20 trees from `Fla. 86-28C' × `Springcrest' in which the trait was segregating 1:1. Cosegregation of the RFLP with the trait occurred for 17 out of 20 trees. Practical aspects of scoring the melting flesh trait in a genetically variable population may account for incomplete segregation. EndoPG protein was detected by western blotting in fruit of the melting flesh cultivars Flavorcrest and Fragar, but not in fruit of the nonmelting flesh cultivar Carolyn. Results from this study and earlier work are used to discuss the hypothesis that the endoPG gene corresponds to the melting flesh (M) locus of peach.
Air-filled Porosity, Gas Relative Diffusivity, and Tortuosity: Indices of Prunus ×cistena sp. Growth in Peat Substrates
Authors: Allaire Suzanne E. , Caron Jean , Duchesne Isabelle , Parent Léon-Étienne , Rioux Jacques-André
Published: January 2019

A 2-year experiment with Prunus ×cistena sp. was conducted in pots using seven substrates composed of various proportions of primarily peat, compost and bark. Peat substrates significantly affected root and shoot dry weight. Water desorption characteristics and saturated hydraulic conductivity were measured in situ to estimate the pore tortuosity factor and the relative gas diffusion coefficient. The pH, electrical conductivity, C/N ratio, total and hydrolyzable N, as well as NO3--N and NH4+-N in solution were also measured. Estimates of the physical properties suggest that a lack of aeration limited plant growth. Plant growth was significantly correlated with both the gas relative diffusivity and the pore tortuosity factor. Among the chemical factors, pH and soil nitrate level were also correlated with plant growth. No significant correlation was found between plant growth and air-filled porosity or any other measured chemical properties. This study indicates that an index of gas-exchange dynamics could be a useful complementary diagnostic tool to guide substrate manufacturing.
Groundcover Management Systems Influence Fungicide and Nitrate-N Concentrations in Leachate and Runoff from a New York Apple Orchard
Authors: Merwin Ian A. , Ray John A. , Steenhuis Tammo S. , Boll Jan
Published: January 2019

Commercial apple (Malus domestica Borkh.) orchards in the northeastern United States receive heavy pesticide inputs and are often located on well-drained soils near surface and groundwater resources. Nonpoint-source water pollution by agrichemicals has been monitored in agronomic crop systems and simulated using computer models and laboratory soil columns, but inadequately studied at field scale in orchards. We monitored the concentrations of agrichemical tracers, nitrate-N, and benomyl fungicide in water samples from two apple orchards under mowed sodgrass (Mowed-Sod), shredded bark mulch (Bark-Mulch), preemergence residual herbicides (Resid-Herb), and postemergence herbicide (Post-Herb) groundcover management systems (GMSs). In one orchard, we evaluated subsurface spatial patterns and flow rates of a weakly adsorbed blue dye (pesticide analog) and potassium bromide (nitrate analog) under trees after six years of Post-Herb and Mowed-Sod treatments. Nitrate and pesticide tracers leached more rapidly and in higher concentrations under Post-Herb treatments, apparently via preferential macropore flowpaths such as root channels, soil cracks, and macrofauna burrows. At another orchard, we monitored subsurface leaching and surface runoff of benomyl and nitrate-N on a whole-field scale. Peak concentrations of benomyl (up to 29 mg·liter-1) and nitrates (up to 20 mg·liter-1) were observed in subsoil leachate under Resid-Herb plots during 1993. In 1994, nitrate concentrations were greater in leachate from all GMSs, with upper ranges from 48 to 66 mg·liter-1, while benomyl concentrations were lower in all GMSs compared with the previous summer. In surface water runoff during 1993, the highest benomyl concentrations (387 mg·liter-1) and most frequent outflows occurred in Resid-Herb plots. During 1994, benomyl runoff was more frequent in both herbicide GMSs, with concentrations up to 61 mg·liter-1 observed in the Post-Herb plots. Weather patterns, irrigation intensity, differing soil conditions under each GMS, and the turfgrass/clover drive lanes affected the relative frequency and concentrations of benomyl and nitrate leaching and runoff. Preferential bypass flow appeared to be a major subsurface leaching pathway, and erosion sediment an important factor in surface movement of these agrichemicals. Our studies suggest that nitrate-N and benomyl fungicide may be more prone to leaching or runoff from orchard soils under some herbicide GMSs in comparison with mowed sodgrass or biomass mulch systems.
Interacting Effects of Photoperiod and Photosynthetic Photon Flux on Net Carbon Assimilation and Starch Accumulation in Potato Leaves
Authors: Stutte Gary W. , Yorio Neil C. , Wheeler Raymond M.
Published: January 2019

The effect of photoperiod (PP) on net carbon assimilation rate (Anet) and starch accumulation in newly mature canopy leaves of `Norland' potato (Solanum tuberosum L.) was determined under high (412 ∝mol·m-2·s-1) and low (263 ∝mol·m-2·s-1) photosynthetic photon flux (PPF) conditions. The Anet decreased from 13.9 to 11.6 and 9.3 μmol·m-2·s-1, and leaf starch increased from 70 to 129 and 118 mg·g-1 drymass (DM) as photoperiod (PP) was increased from 12/12 to 18/6, and 24/0, respectively. Longer PP had a greater effect with high PPF conditions than with low PPF treatments, with high PPF showing greater decline in Anet. Photoperiod did not affect either the CO2 compensation point (50 μmol·mol-1) or CO2 saturation point (1100-1200 μmol·mol-1) for Anet. These results show an apparent limit to the amount of starch that can be stored (≈15% DM) in potato leaves. An apparent feedback mechanism exists for regulating Anet under high PPF, high CO2, and long PP, but there was no correlation between Anet and starch concentration in individual leaves. This suggests that maximum Anet cannot be sustained with elevated CO2 conditions under long PP (≥12 hours) and high PPF conditions. If a physiological limit exists for the fixation and transport of carbon, then increasing photoperiod and light intensity under high CO2 conditions is not the most appropriate means to maximize the yield of potatoes.
A Heat Unit Model to Predict Growth and Development of Muskmelon to Anthesis of Perfect Flowers
Authors: Jenni Sylvie , Cloutier Daniel C. , Bourgeois Gaétan , Stewart Katrine A.
Published: January 2019

Growth of `Earligold' muskmelon (Cucumis melo L.), expressed as plant dry weight from transplanting to anthesis, could be predicted using a multiple linear regression based on air and soil temperatures for 11 mulch and rowcover combinations. The two independent variables of the regression model consisted of a heat unit formula for air temperatures, with a base temperature of 14C and a maximum reduced threshold of 40C, and a standard growing-degree day formula for soil temperatures with a base temperature of 12C. Based on 2 years of data, 86.5% of the variation in the dry weight (on a log scale) could be predicted with this model. The base temperature for predicting developmental time to anthesis of perfect flowers was established at 6.8C and the thermal time ranged between 335 and 391 degree days in the 2 years of the experiment.
Phenylalanine Ammonia-lyase (PAL) Activity and its Relationship to Anthocyanin and Flavonoid Levels in New Zealand-grown Apple Cultivars
Authors: Lister Carolyn E. , Lancaster Jane E. , Walker John R.L.
Published: January 2019

Phenylalanine ammonia-lyase (PAL) activity was measured in a range of New Zealand-grown apple (Malus domestica Borkh.) cultivars at three stages of fruit development. Anthocyanin and total flavonoid levels were also measured (by HPLC) in the same fruit. There was wide variation in the level of PAL activity, anthocyanin and total flavonoid levels in different apple cultivars and at different stages of development. There was no apparent correlation between average PAL activity over the three developmental stages and final anthocyanin concentration (r = 0.34, P > 0.1), but there was significant correlation between average PAL activity over the three developmental stages and the final concentration of total flavonoids (r = 0.75, P < 0.02). An inhibitor, PAL-IS, was also assayed in the same fruit but no correlation was found between PAL-IS and final anthocyanin levels (r = -0.30, P > 0.1) or total flavonoid levels (r = 0.15, P > 0.1). These results suggest that PAL activity has an influence on total flavonoid levels in the fruit but that PAL-IS does not. Anthocyanin levels are likely controlled at a point in the flavonoid pathway other than PAL or PAL-IS.
Spatial Variability of Photosynthetically Active Radiation in a Greenhouse
Authors: Guertal E.A. , Elkins C.B.
Published: January 2019

Photosynthetically active radiation (PAR) was measured at two times of day (8:00 am and noon Central Standard Time) in a 915 × 915-cm area of a 1006 × 915-cm gable roof greenhouse. PAR measurements were taken across a grid at 40-cm intervals, a total of 529 data points. Spatial variation of PAR in the greenhouse was evaluated through contour plots and the geostatistical technique of semivariogram construction. Semivariograms provide a visual guide to the degree of spatial correlation of a variable, allowing a quantification of the distance at which variables cease to be spatially correlated (the range) Measured PAR contained distinct zones of lowered values, a function of overhead greenhouse structures, wall-hung electrical boxes, and tall plants in adjacent greenhouses. Although the amount of PAR changed over time, zones of high and low PAR remained relatively constant, except at the sides of the greenhouse. Constructed semivariograms revealed that PAR contained strong spatial correlation (up to a 350-cm separation) as measured in the north-south direction, moving parallel to greenhouse bench placement. When PAR measurements perpendicular to benches (east-west) were used in directional semivariograms PAR was found to be completely random, plotting as a horizontal line called a nugget effect. Thus, plants placed perpendicular to the greenhouse benches (east-west) would not be affected by the spatial correlation of PAR.
Optimum Timing of Potassium Nitrate Spray Applications to `French' Prune Trees
Authors: Southwick S.M. , Olson W. , Yeager J. , Weis K.G.
Published: January 2019

During the fruit growing season, April through August 1990, 1991, and 1992, four sprays of 20-22 liters/tree of KNO3 were applied to `French' prune trees (Prunus domestica L. syn. `Petite d'Agen). Spray applications of KNO3 were compared to single annual soil applications of KCl (1.4-2.3 kg/tree) and sprays of urea + KNO3 with respect to leaf K and N, fruit size, drying ratio, and dry yield. Potassium nitrate sprays were as effective, or better, than soil-applied K in maintaining adequate levels of leaf K throughout the season. Treatment effects were not carried over into the next year. Lowest leaf K was found in trees where no K had been applied. Those values were below the adequate level of 1.3% K and the untreated group developed K deficiency symptoms. Consistent effects on leaf K were not obtained when urea was applied and no negative effect on leaf K was demonstrated. Equivalent dry yields per tree were obtained by foliar and soil K applications. There was no best time for KNO3 sprays. Yield per tree was not enhanced when foliar K-N sprays were applied to trees that had levels of 1.3% K or more as of 15 Apr. 1992. Trees that were below optimum K in April tended toward improved dry yields after four K-N sprays. Trees that had no applied K were lowest yielding. Drying ratios and fruit size (number of fruit per kilogram) were not different among K treatments. Dry yields per tree were increased without a decrease in fruit size or an increase in drying ratio with either soil or foliar K application. These results suggest that foliar KNO3 sprays applied four times throughout the growing season can be used to correct incipient K deficiency in `French' prune and to obtain dry yields equivalent to those obtained with soil applications of KCl.
Changes in Carbohydrate Composition of the Different Bulb Components of Nerine bowdenii W. Watson (Amaryllidaceae)
Authors: Theron K.I. , Jacobs G.
Published: January 2019

Flowering-size Nerine bowdenii bulbs were sampled from a commercial planting at 2-week intervals from 13 Aug. 1991 to 14 June 1992. They were dissected, the dry weight of foliage and leaf bases was recorded, and carbohydrate analysis was performed on the foliage leaves, leaf bases, and roots. Starch was the dominant storage carbohydrate, and leaf bases were the principal bulb structures where it was stored. Changes in starch content closely followed dry weight changes in the bulb. When exposed to low temperatures, starch was converted to sugars. Except for these high levels in the leaf bases, sugars, expressed both as concentration and total content, were low in bulb components, indicating continued export and conversion to starch. Low sugar levels during the period that florets in the current season's inflorescence develop to stage Late G (gynoecium elongated, carpels fused) is implicated in the abortion of the inflorescence.
Developing the Pecan Scab Fungus on Susceptible and Resistant Host and Nonhost Leaves
Authors: Yates I.E. , Maxey Donnie , Lee Seonju , Sparks Darrell , Reilly C.C.
Published: January 2019

Germ tube, appressorium, and subcuticular hypha development were analyzed on host and nonhost leaves for Cladosporium caryigenum (Ell. et Lang. Gottwald), the fungus causing scab on pecan [Carya illinoinensis (Wangenh.) C. Koch]. Plant features characterized for supporting fungal growth were genotype, adaxial and abaxial leaf surfaces, and leaf maturity. Germ tubes and appressoria developed on all plant leaves, despite genotype, leaf surface, or maturity. Germ tube frequency on the susceptible host, `Wichita', was lower than on the resistant host, `Elliott', but was not significantly different from the nonhost, tobacco (Nicotiana tabacum L.). Appressoria formed with equal frequency on leaves of both pecan cultivars and tobacco. Adaxial and abaxial leaf surfaces were not different within any given genotype for supporting fungal development. Immature leaves of `Elliott', but not of `Wichita', had a higher frequency of germ tubes and appressoria than mature leaves. Subcuticular hyphal development occurred only on immature leaves of susceptible `Wichita' pecan. Hence, subcuticular hyphal development is a prime candidate for being the fungal stage specific for host susceptibility. Resistance to C. caryigenum infection appears to be expressed at the plant site beneath the cuticle as fungal hyphae did not develop in a resistant pecan genotype or on nonhost leaves. Thus, resistance to the fungus causing pecan scab likely is expressed after both germ tube and appressorium development and operates beneath, not on the surface, of the leaf cuticle. Furthermore, technology developed to make these assessments would be adaptable in pecan breeding programs to screen for scab resistance.
Effects of Matric and Osmotic Priming Treatments on Broccoli Seed Germination
Authors: Jett Lewis W. , Welbaum Gregory E. , Morse Ronald D.
Published: January 2019

Priming, a controlled-hydration treatment followed by redrying, improves the germination and emergence of seeds from many species. We compared osmotic and matric priming to determine which was the most effective treatment for improving broccoli seed germination and to gain a greater understanding of how seed vigor is enhanced by priming. Broccoli (Brassica oleracea L. var. italica) seeds were osmotically primed in polyethylene glycol (PEG 8000) at -1.1 MPa or matrically primed in a ratio of 1.0 g seed:0.8 g synthetic calcium silicate (Micro-Cel E):1.8 ml water at -1.2 MPa. In the laboratory, germination rates and root lengths were recorded from 5 to 42C and 10 to 35C, respectively. Broccoli seeds germinated poorly at >35C. Root growth after germination was more sensitive to temperatures >30C and <15C than radicle emergence. Matric and osmotic priming increased germination rate in the laboratory, greenhouse, and field. However, matric priming had a greater effect on germination and root growth rates from 15 to 30C. Neither priming treatment affected minimum or maximum germination or root growth temperatures. Both priming treatments decreased the mean thermal time for germination by >35%. The greater germination performance of matrically primed seeds was most likely the result of increased oxygen availability during priming, increased seed Ca content, or improved membrane integrity.
Iron Toxicity Stress Causes Bronze Speckle, a Specific Physiological Disorder of Marigold (Tagetes erecta L.)
Authors: Albano Joseph P. , Miller William B. , Halbrooks Mary C.
Published: January 2019

A specific physiological disorder, bronze speckle (J.P.A.'s nomenclature), was consistently induced in `First Lady' and `Voyager' marigold with Fe-DTPA concentrations greater than 0.018 mm Fe-DTPA (1 ppm) applied to a soilless medium. The disorder was characterized by specific symptomology distinguished visually by speckled patterns of chlorosis and necrosis, and downward curling and cupping of leaves. The percentage of total leaf dry weight affected with symptoms generally increased with increasing Fe-DTPA treatments. Symptomatic leaf tissue had a greater Fe concentration than corresponding asymptomatic leaf tissue. Leaf Mn concentrations in symptomatic and asymptomatic tissue were similar. In `First Lady', older leaf tissue accumulated more total Fe and was associated with more severe symptoms than younger tissue. Media leachate Fe concentrations increased over 6 weeks and were larger at greater Fe-DTPA treatments. Adjustment of nutrient solution pH to 4.0, 5.25, or 6.5 did not alter media pH, nor did it prevent disorder symptoms. Application of Fe-DTPA containing nutrient solution to a soilless medium resulted in leachate Fe levels 3 times greater than for FeSO4 treatments. Chemical names used: ferric diethylenetriaminepentaacetic acid, monosodium salt (Fe-DTPA).
The Effect of Lime, Irrigation-water Source, and Water-soluble Fertilizer on Root-zone pH, Electrical Conductivity, and Macronutrient Management of Container Root Media with Impatiens
Authors: Argo William R. , Biernbaum John A.
Published: January 2019

Hybrid impatiens (Impatiens Wallerana Hook. F.) were planted in a peat-based medium containing two dolomitic liming materials (1.8 kg Ca(OH)2·Mg(OH)2/m3 or 8.4 kg CaCO3·MgCO3/m3) and subirrigated for 17 weeks using four irrigation-water sources (IWSs) with varied bicarbonate alkalinity, Ca2+, Mg2+, and SO4-S content and three water-soluble fertilizers (WSFs) that contained (in mg) 200N-20P-200K/liter but a variable NH4: NO3 ratio, Ca2+, Mg2+, and SO4-S content. The factorial arrangement of the IWS and WSF resulted in a range of Ca2+, Mg2+, and SO4-S concentrations varying by a factor of 10. After 8 weeks, medium pH ranged from 4.5 to 8.5. The maximum critical medium pH for PO4-P uptake was 7.4 to 7.7, which probably was due to a change in most of the water-soluble P to the less-available HPO42- form. Lime type did not affect the long-term increase in medium pH, Ca2+, and Mg2+ concentrations with nutrient solutions containing low NH4+-N and high Ca2+ and Mg2+. The carbonate lime buffered the medium pH and Ca2+ and Mg2+ concentrations with nutrient solutions containing high NH4+-N and low Ca2+ and Mg2+ compared to that measured with the hydrated lime. With both lime types, there was a linear increase in tissue Ca and Mg as the applied concentrations of the various nutrient solutions increased from 18 to 210 mg Ca2+/liter and 7 to 90 mg Mg2+/liter. The relationship was similar for both lime types up to week 8, after which tissue Ca and Mg decreased more rapidly with the hydrated lime and low solution Ca2+ and Mg2+ compared to that of the same carbonate lime treatments. The minimum critical SO4-S concentration in the applied nutrient solution for plant uptake was 30 to 40 mg S/liter. Below this concentration, tissue S decreased rapidly; above, there was little effect on tissue S.
Availability and Persistence of Macronutrients from Lime and Preplant Nutrient Charge Fertilizers in Peat-based Root Media
Authors: Argo William R. , Biernbaum John A.
Published: January 2019

Using incubation and container culture with subirrigation for up to 28 days, three experiments were conducted with six liming materials of different particle sizes and six blended preplant nutrient charge (PNC) fertilizers. Liming material, particle size, and incorporation rate had an effect on the initial pH (3.5 to 6.1) and the final stable pH (4.8 to 7.8) with one type of Canadian sphagnum peat that did not contain an incorporated PNC. Saturated media extract (SME) Ca and Mg concentrations were <25 and 15 mg·liter-1, respectively, for both pulverized and superfine dolomitic lime at incorporation rates up to 7.2 kg·m-3. For the blended PNC fertilizers in media containing lime, initial electrical conductivity (EC) and SME nutrient concentrations ranged from (EC) 1.0 to 2.9 dS·m-1, (mg·liter-1) 60 to 300 N, 4 to 105 PO4-P, 85 to 250 K, 120 to 400 Ca, and 60 to 220 Mg. However, within two days, the rapid stratification of fertilizer salts within the pot caused macronutrient concentrations to increase in the top 3 cm of root medium (top layer) by an average of 180% and decrease in the remaining root medium in the pot (root zone) by an average of 57% compared to that measured in the medium at planting. Nutrient concentrations in the top layer continued to increase even when those in the root zone fell below acceptable levels recommended for an SME. The importance of fertilizer salt stratification within a pot lies in the reduced availability of nutrients to the plant and illustrates the limited persistence of the PNC fertilizers. Testing nutrients in container media several days after planting rather than in freshly mixed media may be more representative of the starting point for a nutritional management program.
A System and Methodology for Measuring Volatile Organic Compounds Produced by Hydroponic Lettuce in a Controlled Environment
Authors: Charron Craig S. , Cantliffe Daniel J. , Wheeler Raymond M. , Manukian Ara , Heath Robert R.
Published: January 2019

A system and methodology were developed for the nondestructive qualitative and quantitative analysis of volatile emissions from hydroponically grown `Waldmann's Green' leaf lettuce (Lactuca sativa L.). Photosynthetic photon flux (PPF), photoperiod, and temperature were automatically controlled and monitored in a growth chamber modified for the collection of plant volatiles. The lipoxygenase pathway products (Z)-3-hexenal, (Z)-3-hexenol, and (Z)-3-hexenyl acetate were emitted by lettuce plants after the transition from the light period to the dark period. The volatile collection system developed in this study enabled measurements of volatiles emitted by intact plants, from planting to harvest, under controlled environmental conditions.
Polyamines in Chloride-stressed Citrus Plants: Alleviation of Stress by Nitrate Supplementation via Irrigation Water
Authors: Bar Yoel , Apelbaum Akiva , Kafkafi Uzi , Goren Raphael
Published: January 2019

A study was conducted to elucidate the effects of chloride in the irrigation water on growth and development of two citrus rootstocks. `Cleopatra' mandarin (Citrus reshni Hort. ex Tan) is salt tolerant and `Troyer' citrange (Poncirus Citrus sinensis) is salt sensitive. Increasing chloride from 2 to 48 mm in the irrigation water resulted in increased leaf chloride levels, more severe damage of the leaves, and reduced branch growth. High chloride in the irrigation water also caused increased putrescine (PUT) and decreased spermine (SPM) contents of the leaves. These effects were slight in `Cleopatra' but highly apparent in `Troyer'. The symptoms caused by high chloride were associated with high PUT and low SPM levels in the leaves. PUT may be involved in the development of chloride toxic symptoms, and SPM may protect or have no effect on chloride plant injury. The leaf polyamine profiles of `Troyer' and `Cleopatra' under nonstress chloride conditions were different. In `Troyer' leaves, PUT level was 9-fold higher than in `Cleopatra'; in `Cleopatra' leaves, SPM level was 25-fold higher than in `Troyer'. Nitrate supplement to saline water reduced chloride accumulation in the leaves and reduced the increase in PUT. The possible connection between ethylene production and PUT and SPM levels in the leaves of stressed plants is discussed.
Prestorage Heat Treatments Influence Free Sterols and Flavor Volatiles of Tomatoes Stored at Chilling Temperature
Authors: McDonald R.E. , McCollum T.G. , Baldwin E.A.
Published: January 2019

The objective of this study was to determine the effects of prestorage heat treatments on chilling tolerance of tomatoes. Mature-green `Agriset' tomato fruit (Lycopersicon esculentum Mill.), either C2H4-treated or not, were immersed in 42C water for 60 min, held in 38C air for 48 hours, or not treated, and then stored at either 2C (chilled) or 13C (nonchilled) for 14 days before ripening at 20C. Heat-treated fruit stored at 2C and transferred to 20C ripened normally while nonheated fruit decayed before reaching red ripe. Color (a*/b* ratio), lycopene content, and internal quality characteristics of fruit were similar at the red-ripe stage irrespective of method of heat treatment. In red-ripe heat-treated fruit, free sterol levels were significantly higher in chilled fruit than in nonchilled fruit. Heating fruit in 38C air resulted in significantly higher levels of some free sterols compared with heating fruit in 42C water. Of the 15 flavor volatiles analyzed, six showed significantly decreased concentrations as a result of C2H4-treatment and seven showed decreased concentrations when stored at 2C before ripening. Some volatiles were decreased by the heat treatments. Prestorage short- and long-term heat treatments could allow for storage of mature-green tomatoes at lower temperatures with little loss of their ability to ripen normally.
Factors Influencing Ethylene-induced Isocoumarin Formation and Increased Respiration in Carrots
Authors: Lafuente Ma. Teresa , López-Gálvez Gloria , Cantwell Marita , Yang Shang Fa
Published: January 2019

Ethylene-induced formation of isocoumarin was characterized in relation to ethylene-enhanced respiration in whole or cut carrots (Daucus carota L.). Ethylene concentrations (0.1 to 5 ppm) and temperatures (1 to 15C) that increased respiration also favored a more rapid formation of isocoumarin (8-hydroxy-3-methyl-6-methoxy-3,4-dihydro-isocoumarin). Exposing mature carrots to 0.5 ppm C2H4 for 14 days at 1 or 5C resulted in isocoumarin contents of 20 and 40 mg/100 g peel, respectively. These levels were easily detected as a bitter flavor in the intact carrot roots. Immature carrots formed higher levels of isocoumarin than mature carrots; 180 mg/100 g peel were detected in young carrots stored 14 days at 5C in air containing 0.5 ppm C2H4. Freshly harvested carrots exposed to 5 ppm C2H4 accumulated 4-fold higher isocoumarin levels than those formed by carrots stored 30 days at 5C before exposure to C2H4. An atmosphere of 100% O2 potentiated the effect of C2H4 on isocoumarin formation, resulting in a 5-fold increase over that found in carrots treated with C2H4 in air. A storage atmosphere of 0.5 ppm C2H4 in 1% O2 resulted in isocoumarin levels about one-half those attained in 0.5 ppm C2H4 in air. Sliced, cut, or dropped carrots exposed to C2H4 showed greater isocoumarin accumulation rates than intact uninjured carrots. Peeled baby carrots, however, had little capacity to form isocoumarin. In general, the more rapid the respiratory rise in response to C2H4, the more rapidly isocoumarin accumulated. The greater the respiratory response to ethylene, the higher the level of isocoumarin formed.
Changes in Lipids and Electrolyte Leakage during Nonnetted Muskmelon Ripening
Authors: Lacan Dominique , Baccou J.C.
Published: January 2019

Respiration, C2H4 production, lipid composition, and electrolyte leakage were monitored during ripening of two nonnetted muskmelon (Cucumis melo L.) varieties differing in their storage life: `Clipper' (a long-storage-life variety) and `Jerac', which was used as a control. Respiration rates were comparable in both varieties. Although `Jerac' exhibited normal climacteric C2H4 production, `Clipper' continued to produce significant amounts of C2H4 until senescence. Electrolyte leakage increased with ripening and was always higher in `Jerac'. The loss of membrane integrity seems to be related to changes in the lipid composition due to a breakdown of phospholipids, an increase of sterol synthesis, and an increase in fatty acid saturation. On the contrary, in `Clipper', the absence of a major change in sterol and phospholipids content and the high level of fatty acid unsaturation suggest that membrane permeability is not greatly affected during ripening. This is consistent with the low loss of solutes measured and may delay senescence in `Clipper' fruit.
Identifying Yield-optimizing Environments for Two Cowpea Breeding Lines by Manipulating Photoperiod and Harvest Scenario
Authors: Ohler Tracy A. , Mitchell Cary A.
Published: January 2019

Photoperiod and harvest scenario of cowpea (Vigna unguiculata L. Walp) canopies were manipulated to optimize productivity for use in future controlled ecological life-support systems. Productivity was measured by edible yield rate (EYR: g·m-2·day-1), shoot harvest index (SHI: g edible biomass·[g total shoot dry weight]), and yield-efficiency rate (YER: g edible biomass·m-2·day-1per [g nonedible shoot dry weight]). Breeding lines `IT84S-2246' (S-2246) and `IT82D-889' (D-889) were grown in a greenhouse under 8-, 12-, or 24-h photoperiods. S-2246 was short-day and D-889 was day-neutral for flowering. Under each photoperiod, cowpeas were harvested either for leaves only, seeds only, or leaves plus seeds (mixed harvest). Photoperiod did not affect EYR of either breeding line for any harvest scenario tested. Averaged over both breeding lines, seed harvest gave the highest EYR at 6.7 g·m-2·day-1. The highest SHI (65%) and YER (94 mg·m-2·day-1·g-1) were achieved for leaf-only harvest of D-889 under an 8-h photoperiod. For leaf-only harvest of S-2246, both SHI and YER increased with increasing photoperiod, but declined for seed-only and mixed harvests. However, photoperiod had no effect on SHI or YER for D-889 for any harvest scenario. A second experiment utilized the short-day cowpea breeding line `IT89KD-288' (D-288) and the day-neutral breeding line `IT87D-941-1' (D-941) to compare yield parameters using photoperiod extension under differing lamp types. This experiment confirmed the photoperiod responses of D-889 and S-2246 to a mixed-harvest scenario and indicated that daylength extension with higher irradiance from high pressure sodium lamps further suppressed EYR, SHI, and YER of the short-day breeding line D-288.
Monitoring the Spread of Xanthomonas Campestris pv. Dieffenbachiae Introduced from Symptomless Anthurium Cuttings into Production Fields
Authors: Norman David J. , Alvarez Anne M.
Published: January 2019

In field crops the origin and movement of bacterial inoculum is difficult to determine due to inadequate means of distinguishing strains of bacteria. In this study the introduction, establishment, and spread of Xanthomonas campestris pv. dieffenbachiae (McCulloch and Pirone) Dye into anthurium fields were examined by monitoring the distribution of serologically distinct strains recovered from propagation benches and production fields. One thousand Anthurium andraeanum Lind. plants were indexed for X. c. pv. dieffenbachiae and 962 were later introduced into a production field. Strains recovered from the propagative stock were serotyped using a panel of 10 monoclonal antibodies and serotypes were compared to serotypes of strains already prevalent in the production field. Four distinct serotypes were identified which were not characteristic of strains already prevalent in the production field. Two biotypes of X. c. pv. dieffenbachia were also identified, based on their ability to hydrolyze starch. Sensitivity to 500 ppm streptomycin sulfate also was used to characterize strains associated with introduced propagative stock. Of 248 strains isolated from field plants, 39% were streptomycin resistant, whereas none of the strains isolated from introduced cuttings at the initial indexing were resistant. Over a 3-year period, strains with serotypes associated with the propagation material became established in the field, but spread to other cultivars was limited. This paper demonstrates the utility of serological methods for epidemiological studies.
A Complex C Region Genotype [? R] that with G B vlae Produces Dark Seal-brown Seedcoat Color in Common Bean
Authors: Bassett Mark J.
Published: January 2019

Common bean (Phaseolus vulgaris L.) plant introduction 527829 (formerly Lamprecht M0048) has dark seal-brown (DSB) seedcoats and pink flowers. An investigation was conducted to determine the genotype of DSB seedcoat color. M0048 was crossed with Florida breeding line 5-593, which has genotype P [C r] D J G B V Rk. A series of crosses involving M0048, 5-593, and three genetic tester stocks (v BC2 5-593, cu BC2 5-593, and b v BC2 5-593) led to determination of the genotype. Data analysis indicated that M0048 has the genotype P [? R] J G B vlae, where DSB color is produced by the interaction of R with B. Crosses between [? R] and testers with [C r] always produced seedcoat mottling in F1, except where V masks the effect. The cross [? R] B v (DSB) × cu BC2 5-593 (cartridge buff seedcoat) produced marbled seedcoats (black/cartridge buff) with genotype [? R]/[cu?] B V. No way was found to determine whether the mottled or marbled seedcoat patterns were controlled at C or R; hence, the allelic ambiguity is indicated with a question mark. Illustrations are provided showing the difference between seedcoat mottling (a highly variable low-contrast patterning) and seedcoat marbling (a less variable high-contrast patterning, usually with cartridge buff as the background color). The development of a new genetic tester stock, [? R] b v BC3 5-593, was described, where [? R] b v gives unpatterned dominant red seedcoat color.
Phenotype, Inheritance, and Regulation of Expression of a New Virescent Mutant in Watermelon: Juvenile Albino
Authors: Zhang X.P. , Rhodes B.B. , Baird W.V. , Skorupska H.T. , Bridges W.C.
Published: January 2019

Juvenile albino, gene symbol ja, is a spontaneous virescent mutant, first observed in `Dixielee' and an F2 population of `G17AB' (msms) × `Dixielee' in 1992. Hypocotyls, new young leaves, shoot tips, tendrils and flowers on the main shoot of the ja mutant are all albino during early spring. The interior portions of albino leaves gradually become green, while the margins remain albino. Fruit rind color of the mutant is variegated. Growth of the ja mutant is severely impaired in the early spring. However, the mutant grows at a rate comparable to wild-type in the summer, and produces fruit of almost normal size. Genetic analysis of F1, F2, and BC1 populations derived from the ja mutant showed that the gene for the ja mutant is inherited as a single, recessive, nuclear gene. Segregation ratios in the F2 and BC1 progenies derived from the cross between the previously reported delayed green virescent mutant and the ja mutant indicate independent inheritance of the genes dg and ja. Temperature and red/far-red light had no differential effect on mutant and the wild-type plants. An increase of daylength from 8 to 15 hours increased fresh weight and chlorophyll content more in the ja mutant than in the wild-type. The mutant had a higher chlorophyll a: b ratio than the wild-type under long days. Chlorophyll synthesis or accumulation in the mutant is severely impaired under short days. This is the only virescent mutant in the family Cucurbitaceae whose expression is regulated by daylength.