bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil Organisms Influence Fine Root Lifespan in Peach
Authors: Wells Christina , Eissenstat David , Glenn Michael
Published: January 2019

Damage to the root system by soil insects and pathogenic fungi is difficult to assess and often goes unnoticed until a tree exhibits significant decline above ground. In this study, below-ground imaging technology was used to quantify fine root turnover in peach and to determine what percentage of root death may be caused by soil pests in an apparently healthy orchard. The study was conducted on six 15-year-old `Loring' peach trees on Halford rootstock in Kearneysville, W.Va. Five root observation tubes were placed in the soil beneath each tree in Apr. 1996. Each tube was randomly assigned one of five soil drench treatments: Lorsban 4E insecticide, Ridomil 2E fungicide, a combination of both pesticides, 1/10th strength Hoagland's solution, or water. A portable VCR and camera system were used to record images of fine roots (<1 mm diameter) growing along the tubes at biweekly intervals from May 1996 through Nov. 1997. The images were used to construct a database of life history information for more than 1500 individual roots. Peach root survivorship was influenced by root diameter and pesticide treatment. Fine roots on tubes receiving either of the pesticide treatments had higher survivorship than roots on control tubes for all diameter classes. The effect was most pronounced for white roots <0.5 mm in diameter, whose survivorship during the growing season was increased by 45% when both insecticide and fungicide were applied. These results suggest that a substantial fraction of fine root death may be caused by interactions with the soil fauna.
Mapping of Five Morphological Markers (dgs, blu, rnd, Ib, and asp) in a Molecular Linkage Map of Common Bean
Authors: Beltran Gino , Jung Geunhwa , Bassett Mark , Nienhuis James
Published: January 2019

The classical genetic linkage map of common bean contains only a fraction of the total genes that has been reported. These genes can be mapped in a molecular linkage map so that genetic relationship among diferent genes can be better understood. The objective of this study was to identify RAPD markers linked to genes for five morphological traits using bulked segregant analysis and to map the markers to a molecular linkage map previously constructed in common bean. Five segregating populations were evaluated. Three BC2F2 populations with dgs (dark green savoy leaf), blu (blue flower), and rnd (round leaf), respectively, were developed with a Florida breeding line 7-1404 and 5-593 as the recurrent parent. One BC3F2 population with the asp (dull seed coat) was developed from a BC2F2 5-593 line and 5-593 as the recurrent parent. Finally, an F2 segregating population for Ib (flat pod) was developed from `Hialeah' flat pod mutant × `Hialeah'. The linked RAPD markers were mapped in a molecular linkage map previously constructed using recombinant inbred population of the cross PC-50 × XAN-159. The results of this study indicate that integrating morphological and molecular merkers can result in a more complete genetic linkage map in common bean.
Monitoring Nitrates in Ground Water of an Apple Orchard
Authors: Toselli Moreno , Perry Ronald L.
Published: January 2019

Nitrate (NO3–) pollution is of high interest in modern agriculture. Although the amount of nitrogen (N) usually supplied to an apple orchard is lower than other crops, it could become a factor of pollution because of the lower tree root density and of the low nitrogen use efficiency. In this study we monitored the concentration of nitrate in soil water solution in a 3-year old apple orchard located near Grand Rapids (Mich.) during 1996 and 1997. The orchard had no history of fertilization, but alfalfa crop was previously planted for several years. Eight lysimeters, 1.8 m tall and 1.8 m of diameter, were installed in 1995 in the orchard site without changing the soil profile. One tree was planted in each lysimeter in spring 1996. Leached soil solution was collected bi-weekly in a connected 143-L storage container. Additionally, three soil suction tubes (SST) were placed inside and outside the lysimeters at a depth of 0.6, 1.05 and 1.55 m, in order to collect water solution to evaluate the level of nitrate at different soil layers. Daily water (L/ha) and nitrate (kg/ha) flow rate were linearly correlated with an R2 of 0.9. Nitrate flow rates were highest and during the wet spring and winter periods. The variation of NO –3 flow rate during the year is a result of root and bacteria activity. All year long, the nitrate concentration in the SST inside the lysimeters was higher than those outside. These results show that the application rate for N could be different from orchard to orchard and it must be necessary to know the soil N background, cropping history and N-NO –3 availability, in order to maximize productivity and avoid environmental risks.
Coconut Coir Medium for Tomato Transplant Production
Authors: Arenas Mireia , Vavrina C.S.
Published: January 2019

Peat [70% peat + 30% vermiculite (v/v/)] has long been the primary growing medium in standard vegetable transplant production. However, interest has increased in the use of coir (coconut pith) as an alternative vegetable transplant medium because of favorable physico-chemical properties such us high water holding capacity, low bulk density and high potassium content. Sixteen different transplant media formulations (v/v) were tested in a mixture component experiment with tomato, using coir and peat as organic components and vermiculite and perlite as inorganic components. Transplant growth was evaluated after 4, 5, and 6 weeks by growth analysis and at 6 weeks transplant quality parameters (e.g. shoot/root dry weight, leaf area, stem diameter, height, etc.) were collected. Coir grown tomato plants showed a delay in leaf production exhibiting lower leaf area values over the total transplant growth period. Shoot and root growth was maximized in media containing peat as the major organic component. However, plants grown in a 50% peat/50% vermiculite medium were too tall for commercial acceptance. Plants grown in all sixteen-transplant media pulled easily. However, medium loss when transplants were pulled was unacceptable in medium high in perlite content (50% by total volume). Coir-medium compared well with the standard peat/vermiculite medium based on the transplant quality parameters of stem diameter, root growth and height when used in the following mixtures: 50% peat/25% coir/25% vermiculite and 50% peat/25% coir/25% perlite.
Uniformity of Photosynthetic Photon Flux and Growth of `Poin-sett' Cucumber Plants under Metal Halide and Microwave-powered Solar-1000 Lamps
Authors: Krizek Donald T. , Mirecki Roman M. , Bailey William A.
Published: January 2019

The uniformity of photosynthetic photon flux (PPF) and vegetative growth of Cucumis sativa L. (`Poinsett' cucumber) were examined using growth chambers equipped with either six 400W metal halide (MH) lamps or with a single 1000W microwave-powered (MP) Solar-1000 lamp. PPF levels in the center of each growth chamber were set initially at 500 mmol·m–2·s–1. Plants were grown in 7.6-cm-diameter white plastic pots filled with a peat-vermiculite mix and fertilized 1–2X daily with complete nutrient solution. Pots were placed at equal distances from one another in 10 columns of six rows each (n = 60). Growth measurements were only taken on the center six columns of plants (n = 36) with border plants on each side. The uniformity of PPF was greater in the MP than in the MH chamber for both the 36-pot (495.9 ± 3.7 vs. 459.4 ± 11.5 μmol·m–2·s–1, respectively) and for the 60-pot arrangement (489.3 ± 3.3 vs. 496.6 ± 9.6 mmol·m–2·s–1, respectively). However, growth measurements showed greater uniformity in the MH than in the MP chamber, e.g., 492.2 ± 8.9 vs. 629.9 ± 12.7 mg dry weight of tops. Plants grown for 14 days under MP lamps had significantly greater leaf number, stem and petiole elongation, leaf expansion, and biomass of leaves, petioles, stems, and roots than those grown under MH lamps. These findings demonstrate the efficacy of using MP lamps for increasing seedling production and combined with spectroradiometric measurements, suggest that additional levels of UV-A (320–400 nm) radiation and/or reduced red and far-red radiation may be needed to provide the most compact seedlings when using these lamps. These results should be of interest to growers and researchers involved in protected cultivation. These new MP lamps should also afford a useful tool for photobiologists interested in studying the photocontrol of stem and petiole elongation.
Using Nutrient Uptake Patterns to Develop Efficient N Management Strategies for Vegetables
Authors: Sanchez C.A.
Published: January 2019

Nitrogen in a soil that is not immediately taken up by a crop is subject to leaching, denitrification, and other mechanisms of loss. Generally, split applications of N throughout the growing season reduce the potential for N loss compared to a single preplant application. Timing of N application should account for the characteristic N uptake patterns of the crop and the lag time between application of fertilizers and plant availability. N uptake studies allow one to identify total amount of N accumulated by the crop and periods of peak nitrogen demand. This information can then be used to devise management strategies aimed at supplying N preceding anticipated N uptake. Split sidedress N application, fertigation, and the use of controlled-release fertilizers are all viable options, depending on the crop production scenario and available infrastructure.
Evaluating Tree Canopy Color Using Computerized Microdensitometry
Authors: Headley David B. , Mower Robert G.
Published: January 2019

The color of a tree's canopy can provide much information about the tree's physiological status as well as its aesthetic function. We present a system for the qualitative and quantitative analysis of tree canopy color, based on a previously published algorithm. This algorithm determines (with a known accuracy) the Munsell hue, value, and chroma of a color using densitometric readings obtained through the use of color separation filters. This method was adapted for use with black-and-white video images. Combining the Rib algorithm with the techniques of photography, video imagery, scanning microdensitometry, and batch data computer processing, a semi-automated system was devised for the pixel-by-pixel color evaluation of a 512 × 512-pixel image. Based on a sample of 251 color chips, the following accuracies were obtained: Munsell hue—86%, Munsell value—93%, Munsell chroma—70%, and Munsell color—62%. An example is provided that demonstrates how this system may be used to determine tree canopy color. By employing this technique, an estimation may be made of the colors and their relative quantities that are displayed by a tree's canopy.
Antitranspirant Reduces Water Use by Peach Trees Following Harvest
Authors: Steinberg Susan L. , McFarland Marshall J. , Worthington Josiah W.
Published: January 2019

The potential for reducing water use of peach [Prunus persica (L.) Batsch] trees with antitranspirants following fruit harvest was investigated using matched peach trees planted in an outdoor twin weighing lysimeter facility. A 10% solution of the antitranspirant Wilt Pruf NCF was applied to one of the two trees on 7 July 1986. Immediately after application, water use of the treated tree was reduced by 40%. One month after treatment, the water use was reduced 30% and, by the termination of the experiment (85 days after treatment), water use was reduced 12% as compared to control. The average reduction in tree water use for the entire period was 30%. Fully expanded, sunlit leaves (nodes 10 to 20 from the terminal end) from the treated tree exhibited the greatest reduction in water loss compared with immature or inner canopy, shaded leaves. Use of the antitranspirant did not prevent the development of water stress once a critical level of soil moisture was reached. The change in tree water use induced by the antitranspirant did not significantly reduce shoot length, new leaf production, or individual leaf size on actively growing, current-season branches. Fruit and leaf bud initiation, as measured the following spring, were not affected: however. flower bud maturation could not be evaluated due to freeze damage. Chemical name used: di-1-p-menthene (Wilt Pruf NCF).
Sweet Potato Canopy Architecture: Branching Pattern
Authors: Somda Zana C. , Kays Stanley J.
Published: January 2019

The effect of the plant density (15, 30, 45 × 96-cm spacing) on the branching pattern `Jewel' sweet potato [Ipomoea batatas (L.) Lam.] was determined bi-weekly for 18 weeks. Plant density effects were significant for the number of branches formed and timing of branch formation. Plant density did not affect the type of branches formed (e.g., primary, secondary, and tertiary), but did alter the timing of induction during the growing season. By the end of the growing period, the ratios for the number of primary to secondary branches were 1.5:1, 1.3:1, and 0.6:1 at the 15-, 30-, and 45-cm spacing, respectively. Few tertiary branches were formed, but were present on some plants at each spacing. Tertiary branches most commonly occurred on plants at the widest spacing. While the number of branches per plant was highly plastic and inversely related to plant density, nodes per branch and internode length were not significantly affected. Average internode length per branch decreased with descending branch hierarchy (i,e., main stem < primary branch < secondary branch). `Jewel' sweet potato responded to increased space available largely through production of additional branches with the modification of branching pattern increasing as the season progressed.
Fall Performance and Post-dormancy Growth of `Midiron' Bermudagrass in Response to Nitrogen, Iron, and Benzyladenine
Authors: White Richard H. , Schmidt Richard E.
Published: January 2019

Field research was conducted to determine the effects of N, Fe, and benzyladenine (BA) on fall performance, post-dormancy recovery, and storage nonstructural carbohydrate composition of `Midiron' bermudagrass [Cy - nodon dactylon (L.) Pers.]. Fall green color retention and turf quality were superior for 48 than for 24 kg N/ha per month. Nitrogen level did not affect post-dormancy recovery or nonstructural carbohydrate levels in stolons and rhizomes measured in Sept. and Nov. 1983 and 1984. Iron level did not influence turf color and quality during summer months. Biweekly application of 0.6 kg Fe/ha produced better retention of greenness and turf quality during Fall 1983 and 1984 and superior turf color in Spring 1985 than the 0 kg Fe/ha treatment. Better green turf coverage was obtained with the biweekly than the monthly Fe (1.2 kg-ha-l) treatment during Fall 1983. In contrast, monthly Fe produced color and turf quality similar to that of the biweekly Fe treatment during Fall 1984. Nonstructural carbohydrates were similar among Fe levels in 1983 and 1984. The effects of Fe on turf color and quality were similar at each level of N and BA. BA level did not consistently influence turf color or quality and did not affect storage carbohydrate levels. When used in conjunction with moderate summer N fertilization, foliar-applied Fe can extend bermudagrass quality during fall without adversely affecting postdormancy recovery. Chemical name used: N- (phenylmethyl)-lH-purin-6-amine (benzyladenine, BA).
Growth, Yield, and Fruit Quality of Eight Lemon Cultivars in Arizona
Authors: Fallahi Esmaeil , Rodney D. Ross , Mousavi Zahra
Published: January 2019

Tree growth, yield, and fruit quality of eight lemon cultivars [Citrus limon (L.) Burro. f.] on macrophylla (Alemow) (C. macrophylla Wester) rootstock were compared when grown in sandy soil in the arid climate of south-western Arizona. `Foothill Lisbon' had higher cumulative yield and titratable acids than `Monroe Lisbon', `Prior Lisbon', `Eureka', and `Villafranca', and had larger fruit than other `Lisbon' cultivars. `Prior Lisbon' produced a larger tree canopy with lower yield efficiency than all other cultivars and did not show any decline due to sieve tube necrosis 12 years after planting. Overall, `Eureka' cultivars and `Villafranca' had lower relative cumulative yields, canopy volumes, total soluble solids content, titratable acids, and seed content, but higher tree decline than `Lisbon' cultivars. Overall, `Foothill Lisbon', in spite of carrying exocortis viroid, produced good yields and fruit quality and `Prior Lisbon' had a satisfactory growth-performance.
An Irrigation Scheduling Model for Snap Bean
Authors: Smittle Doyle A. , Dickens W. Lamar , Stansell James R.
Published: January 2019

An irrigation scheduling model for snap bean (Phaseolus vulgaris L.) was developed and validated. The irrigation scheduling model is represented by the equation: 12.7(i - 4) × 0.5ASW = Di-1 + [E(0.31 + 0.01i) - P - I]i, where crop age is i; effective root depth is 12.7(i - 4) with a maximum of 400 mm; usable water (cm3·cm-3 of soil) is 0.5 ASW, deficit on the previous day is Di-1; evapotranspiration is pan evaporation (E) times 0.31 + 0.01i; rainfall (mm) is P, and irrigation (mm) is I. The model was validated using a line source irrigation system with irrigation depths ranging from 3% to 145% of tbe model rate in 1985 and from 4% to 180% of the model rate in 1986. Nitrogen fertilization rates ranged from 50% to 150% of the recommended rate both years. Marketable pod yields increased as irrigation rate increased in 1985. Irrigation at 4%, 44%, 65%, 80%, 150%, and 180% of the model rate produced yields that were 4%, 39%, 71%, 85%, 92%, and 55% as great as yields with the model rate in 1986. Marketable pod yields increased as N rate increased when irrigation was applied at 80%, 100%, or 150% of the model rate in 1986, but pod yields varied less with N rate when irrigation was applied at 4%, 44%, 65%, or 180% of the model.
Seedling Establishment of Direct-seeded Guayule
Authors: Mihail J.D. , Alcorn S.M.
Published: January 2019

The establishment of stands from directly sown seed may be a way to reduce the current high costs associated with guayule (Parthenium argentatum Gray) cultivation. These field studies were conducted to examine the combined effects of shade and fungicides on the survival of guayule seedlings established from directly sown seed. Soil in the experimental plot was a loam of pH 7.25. The following fungicides: a) Terraclor Super X, b) Ridomil 5G, c) Ridomil PC llG, d) Tilt 3.6E, e) Terracoat, and f) Vitavax + PCNB were tested alone and in combination with the nonwoven polyester shadecloth, Reemay, to identify treatments enhancing seed germination and seedling establishment. In all cases, seedling emergence in microplots covered with Reemay was significantly higher than in noncovered microplots. Terraclor Super X, Ridomil 5G, and Ridomil PC 1 lG were effective only when used in combination with the shadecloth. The long-term survival of guayule seedlings was strongly affected by severe climatic events. Since Reemay-protected seedlings were larger and more robust, they were more likely to survive the climatic extremes than unprotected seedlings. Two new guayule seedling pathogens were recorded -pythium dissotocum Drechsler and P. paroecandrum Drechsler. Chemical names used: 5-ethoxy-3-(trichloromethyl)-1,2,4-thiadiazole (Terrazole) + pen. tachloronitrobenzene (PCNB); N-(2,6-dimethylphenyl)-N-(methoxyacetyl)-alamine methyl ester Ridomil + PCNB; 7. bromo-5-chloro-quinolin-8-yl-acrylate; Terrazole 5,6-dihydro-2-methyl-l,4 -oxathiin-3-carboxanilide + PCNB.
Relationship of Ethylene Production to Stress Alleviation in Seeds of Lettuce Cultivars
Authors: Prusinski Janusz , Khan Anwar A.
Published: January 2019

Seeds (intact or slit) of lettuce (Luctuca sativa L.) cultivars with greater ability to produce ethylene germinated better under stressful conditions. Highly significant correlations were found between ethylene production and germination in 0.1 m NaCI (- 0.49 MPa) solution at 25C (r = 0.95, intact seeds), in - 0.3 MPa PEG solution (r = 0.86, intact seeds; r = 0.81, slit seeds), and in water at 32C (r = 0.80, slit seeds) or 35C (r = 0.80, slit seeds). Slitting the seed coat increased the ethylene production and improved germination during osmotic restraint in most cultivars, particularly in `Mesa 659' and `Super 59'. The differing ability of cultivars to produce ethylene during stress generally corresponded with their ability to generate germination potential. Ethylene production and germination potential in untreated and ACC-treated `Mesa 659' seeds increased upon slitting under stressful conditions. Thus, the ability of seeds to produce ethylene and to generate high germination potential under stressful conditions may be used as criteria to select stress-tolerant lettuce cultivars. Chemical names used: polyethylene glycol 8000 (PEG), 1-aminocyclopropane-1-carboxylic acid (ACC), (2-chlorethyl) phosphoric acid (ethephon).
`Stayman' Fruit Cracking as Affected by Surfactants, Plant Growth Regulators, and Other Chemicals
Authors: Byers R.E. , Carbaugh D.H. , Presley C.N.
Published: January 2019

Submerging `Stayman' apples in nonionic and anionic surfactant-water solutions caused increased water uptake and fruit cracking. The primary sites of water uptake were lenticels and injured areas of the fruit cuticle. Fruit cracking caused by submerging fruit in 1.25 ml X-77/liter surfactant was used to predict the natural cracking potential of `Stayman' strains and apple cultivars in the field. Submerging apples in aqueous pesticide mixtures did not Increase fruit cracking or water uptake. Fruit cracking and uptake of surfactant-water were not correlated between apple cultivars. In a surfactant-water bath, `Starkrimson Delicious' absorbed more water than `Stayman', `York', `Jonathan', and `Golden Delicious'; no `Starkrimson Delicious' fruits cracked, but 32% to 80% of the other cultivars did. In field tests, four airblast spray applications of GA4+7 in July and Aug. 1987 reduced fruit cracking from 56% to 21%, and five applications In July, Aug., and Sept. 1988 reduced fruit cracking from 93% to 75%. In 1987, daminozide reduced cracking, but, in 1988, neither daminozide, NAA, nor Vapor Gard alone reduced cracking. However, in 1988, a combination treatment of GA4+7, daminozide, NAA, and Vapor Gard reduced fruit cracking from 93% to 22%. Also, two scorings of the trunk with a carpet knife reduced fruit cracking 22%. Chemical names used: alkylaryl polyoxyethylene alcohol glycol (X-77); butanedioic acid mono(2,2-dimethylhydrazide) (daminozide); naphthaleneacetic acid (NAA); di-1-p-methene (Vapor Gard); gibberellic acid (GA4+7).
Influence of Frequency and Dates of Plant Growth Regulator Applications to Centipedegrass on Seedhead Formation and Turf Quality
Authors: Johnson Billy J.
Published: January 2019

Two separate experiments (one and two applications and dates of treatment) were conducted on plant growth regulator (PGR) injury and seedhead suppression of centipedegrass [Eremochloa ophiuroides (Munro) Hack.]. Mefluidide caused less injury to centipedegrass than either imazethapyr or flurprimidol + mefluidide. Mefluidide applied at 0.56 kg·ha-1 in each of two applications at 2-week intervals suppressed seedheads of centipedegrass for 10 weeks. A single 0.56-kg·ha-1 application of the mefluidide failed to suppress seedheads when applied any time from mid-June until late July. A single treatment with flurprimidol + mefluidide severely injured centipedegrass, and seedhead suppression was poor regardless of date of treatment. Centipedegrass was severely injured when flurprimidol + mefluidide was applied at 1.68 + 0.28 kg·ha-1 in each of two applications, but seedheads were suppressed for 10 weeks. Imazethapyr applied at 0.30 and followed by 0.15 kg·ha-1 suppressed seedheads 10 weeks after treatment in 1987 and 6 weeks after treatment in 1988 without reducing turf density. When this PGR was applied as a single treatment at 0.30 kg·ha-1, seedhead suppression was generally greater for 8 weeks when applied mid- to late July than mid- to late June. Chemical names used: N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl]amino]phenyl]acetamide (mefluidide); α -(1-methylethyl)- α -[4-(trifluoromethoxy)phenyl]-5-pyrimidinemethanol (flurprimidol); and (±)-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-ethyl-3-pyridinecarboxlic acid (imazethapyr).
Evaluation of Preemergent Herbicide Phytotoxicity to Tissue, Culture-propagated `Heritage' Red Raspberry
Authors: Neal Joseph C. , Pritts Marvin P. , Senesac Andrew F.
Published: January 2019

Five greenhouse and two Geld experiments were conducted to evaluate tissue culture-propagated (TC) raspberry (Rubus idaeus cv. Heritage) sensitivity to preemergent herbicides. Plant performance was measured by plant vigor, above-ground fresh weight, root development, and primocane number. Simazine and oryzalin caused significant injury to newly planted TC raspberry plants in greenhouse and field experiments. The severity of injury was generally linear with respect to herbicide rate, but no appreciable differences in injury were observed between the granular and spray applications. Napropamide wettable powder caused some foliar injury, but plants recovered within one growing season and growth was equal or superior to the hand-weeded controls. The granular formulation of napropamide produced similar results, but did not cause the initial foliar burn. Pre-plant dipping of roots into a slurry of activated carbon did not prevent simazine or oryzalin injury, but injury was reduced when herbicide applications were delayed. Simazine applied 4 weeks after planting was not Injurious, and oqzalin applied 2 or 4 weeks after planting caused some foliar injury, hut no reduction in plant fresh weight. Delayed treatments of napropamide increased foliar injury. Herbicide tolerance of tissue-cultured plantlets appeared to be less than that of conventionally propagated plants. Chemical names used: N,N-diethyl-2-(1-napthalenyloxy)propanamide (napropamide), 4-(dipropylamino)-3,5-dinitrobenzenesulfonamide (oryzalin), 6-chloro-N,N'diethyl-1,3,5-triazine-2,4-diamine (simazine).
Physiological and Quality Responses of `Bartlett' Pears to Reduced O2 and Enhanced CO2 Levels and Storage Temperature
Authors: Ke Dangyang , van Gorsel Hendrik , Kader Adel A.
Published: January 2019

`Bartlett' pears (Pyrus communis L.) tolerated up to 10 days of exposure to atmospheres containing 1.0%, 0.5%, or 0.25% O2 at 0, 5, or 10C without any detrimental effects on their quality attributes. The fruits also tolerated 4 to 6 days of exposure to air enriched with 20%, 50%, or 80% CO2 at the three temperatures. The beneficial effects of exposures to the O2-reduced or CO2-enriched atmospheres included reduction of respiration and ethylene production rates and retardation of skin yellowing and flesh softening. While 1.0% or 0.5% O2 and 20% CO2 did not increase ethanol and acetaldehyde contents, 0.25% O2 slightly increased and 50% or 80% CO2 dramatically increased the contents of these two volatiles in juice of the fruits. The effects of low O2 or high CO2 on the above attributes generally became more pronounced at the higher temperatures. The low O2 or high CO2 treatments did not significantly affect either soluble solids content or titratable acidity. Low O2 did not influence, but high CO2 slightly increased pH of the fruits.
Storage Characteristics of Small Watermelon Cultivars
Authors: Risse L.A. , Brecht J.K. , Sargent S.A. , Locascio S.J. , Crall J.M. , Elmstrom G.W. , Maynard D.N.
Published: January 2019

Two newly released cultivars of small watermelons [Citrullus lunatus (Thumb.) Matsum and Naki], `Mickylee' and `Minilee', plus two other cultivars, Baby Fun and Sugar Baby, were stored at various temperatures from 1 to 21C for up to 4 weeks plus 1 week at 21C over two seasons. All cultivars were susceptible to chilling injury (CI) when stored below 7C; however, `Minilee' was less susceptible than the other cultivars tested. Chilling injury increased with storage length. Conditioning at 26C for 3 days before storage at 1C reduced CI and increased the percentage of marketable watermelons after storage. Decay percentage increased with storage time and was highest on fruit held at 1C where CI led to decay. The flesh of `Mickylee' and `Minilee' was firmer than that of the other cultivars tested and `Mickylee' and Minilee' retained their firmness better during storage. Total soluble solids concentration decreased with increased storage temperature. `Minilee' watermelons were superior to the other three cultivars in postharvest storage potential and exhibited the least CI and decay.
Inheritance of Resistance to Blotchy Ripening in Processing Tomatoes
Authors: Dick J.A. , Shattuck V.I.
Published: January 2019

Inheritance of resistance to blotchy ripening In tomato (Lycopersicon esculentum Mill.) cultivars intended for machine harvest was studied in two diallel crosses using the Hayman and Griffing analyses. Additive effects were most important as indicated by the high level of general combining ability compared with specific combining ability. Some hybrids performed better than the mid-parent mean; however, heterosis for resistance to blotch above the best inbred line was not evident. Epistasis occurred between recessive genes in two parents, resulting in reduced blotch. No significant interaction between the expression of blotch in diallel progeny and K availability was evident. Genotype-environment Interaction was significant, but relative variation in blotch between experiments only occurred in cultivars with an intermediate level of resistance.
Response of Ficus benjamina and Dracaena marginata to Iron Stress
Authors: Lang Harvey J. , Rosenfield Claire-Lise , Reed David Wm.
Published: January 2019

Ficus benjamina L. and Dracaena marginata Lam. were grown in a modified Hoagland's nutrient solution containing either 0, 0.22 or 5.52 mg Fe3+/liter (HEEDTA or EDTA). F. benjamina grew well at all Fe levels and showed mild chlorosis only at 0 mg Fe/liter. For D. marginata, growth decreased and chlorosis increased as solution Fe level decreased. F. benjamina exhibited a high capacity for Fe3+ reduction, which increased as Fe level decreased, reaching a maximum below 0.06 mg·liter-1 D. marginata exhibited a low capacity for Fe3+ reduction, which was slightly enhanced at 0.1 to 0.15 mg·liter-1. In both species, reduction occurred in the presence of roots, with minimal reduction in their absence. This result indicates that Fe3+ is reduced at the root surface and not by reductants released into the solution. F. benjamina increasingly lowered pH as solution Fe decreased, and always lowered pH more than D. marginata at all Fe levels. Total and extractable Fe concentration of leaves did not correlate well with chlorosis, whereas total Fe content per plant correlated highly with chlorosis. Chemical names used: N-hydroxyethyl-ethylenediamine-triacetic acid (HEEDTA), ethylenediamine tetraacetic acid (EDTA).
Effect of Acremonium Endophytes on Four Species of Billbug Found on New Jersey Turfgrasses
Authors: Johnson-Cicalese Jennifer M. , White R.H.
Published: January 2019

Laboratory studies were conducted to determine the effects of Acremonium endophytes on four species of billbug (Coleoptera:Curculionidae: Sphenophorus parvulus Gyllenhal, S. venatus (Say), S. inaequalis Say, and S. minimus Hart) found damaging cool-season turfgrasses in New Jersey. Billbug adults feeding on potted tall fescue (Festuca arundinacea Schreb.) plants infected with Acremonium coenophialum Morgan-Jones and Gams showed significantly greater mortality than billbugs feeding on endophyte-free tall fescue. Little difference was observed in amount of feeding. In petri dish preference tests, billbug adults were given a choice and, again, no significant difference was observed in the amount of feeding on endophyte-free versus endophyte-infected tall fescue tillers. In a third experiment, billbug adults were placed in petri dishes with either tall fescue with or without A. coenophialum or perennial ryegrass (Lolium perenne L.) with or without Acremonium lolii Latch, Christensen, and Samuels. Only small differences were seen in number of eggs laid and amount of feeding. Mortality of all four billbug species, however, was greater on both grasses when endophyte-infected.
Additional Host Plants of Four Species of Billbug Found on New Jersey Turfgrasses
Authors: Johnson-Cicalese Jennifer M. , Funk C.R.
Published: January 2019

Studies were conducted on the host plants of four billbug species (Coleoptera:Curculionidae: Sphenophorus parvulus Gyllenhal, S. venatus Chitt., S. inaequalis Say, and S. minimus Hart) found on New Jersey turfgrasses. A collection of 4803 adults from pure stands of various turfgrasses revealed all four billbugs on Kentucky bluegrass (Poa pratensis L.), tall fescue (Festuca arundinacea Schreb.), and perennial ryegrass (Lolium perenne L.), and S. parvulus, S. venatus, and S. minimus on Chewings fescue (F. rubra L. ssp. commutata Gaud.). Since the presence of larvae, pupae, or teneral adults more accurately indicates the host status of a grass species, immature billbugs were collected from plugs of the various grass species and reared to adults for identification. All four species were reared from immature billbugs found in Kentucky bluegrass turf; immatures of S. venatus, S. inaequalis, and S. minimus were found in tall fescue; S. venatus and S. minimus in perennial ryegrass; and S. inaequalis in strong creeping red fescue (F. rubra L. ssp. rubra). A laboratory experiment was also conducted in which billbug adults were confined in petri dishes with either Kentucky bluegrass, perennial ryegrass, tall fescue, or bermudagrass (Cynodon dactylon Pers.). Only minor differences were found between the four grasses in billbug survival, number of eggs laid, and amount of feeding. In general, bermudagrass was the least favored host and the other grasses were equally adequate hosts. The results of this study indicate a need for updating host-plant lists of these four billbug species.
Temperature Effects on Lily Development Rate and Morphology from the Visible Bud Stage until Anthesis
Authors: Erwin John E. , Heins Royal D.
Published: January 2019

Day (DT) and night temperatures (NT) influenced Lilium longiflorum Thunb. `Nellie White' stem elongation and development rate from the visible bud stage (VB) until anthesis. Plant height increase after VB was a function of the difference (DIF) between DT and NT (DT-NT). Plant height increased 90% as DIF increased from - 16 to 16C. A cubic model described bud development rate as a function of temperature from 14 to 30C. A linear model adequately described bud development rate as a function of average daily temperature from 14 to 21C. Based on the linear model, bud development rate increased 0.05 per day for each 1C increase in average daily temperature. The base temperature for bud development, i.e., the temperature at which bud development rate was 0, was calculated as 3.5C.
Osmotic and Turgor Adjustment in Rosa Foliage Drought-stressed under Varying Irradiance
Authors: Augé Robert M. , Stodola Ann J.W. , Pennell Brian D.
Published: January 2019

The influence of irradiance and drought on osmotic and turgor adjustment was examined in leaves of rose (Rosa hybrida L. `Samantha'). Plants cultured under full ambient light in the greenhouse were placed in shade chambers and, after 2 weeks of acclimation, exposed to drought for 21 days. Treatments consisted of a water stress factor (well-watered and drought-stressed) and an irradiance factor (100%, 70%, and 30% of ambient irradiance). Pressure-volume analyses of leaves indicated that osmotic potentials at full turgor were decreased 0.42, 0.36, and 0.23 MPa by drought in the 100%, 70%, and 30% irradiance treatments, respectively. Plants stressed under 100% and 70% irradiance exhibited similar osmotic adjustments. Plants under 30% irradiance had higher osmotic potentials at full turgor under well-watered conditions than plants in the other two irradiance treatments and showed only 55% as much adjustment to drought. In each irradiance treatment, drought induced an increase in elastic modulus and a decrease in relative water content at zero turgor. Turgor pressures were higher across a range of relative water contents in plants in the two higher irradiance treatments under both soil moisture treatments. Turgor also was higher at any particular water potential at 100% and 70% irradiance than 30% irradiance, within each soil moisture treatment. Heavy, but not mild, shading inhibited osmotic and turgor adjustments in leaves during drought.
Inheritance of Prostrate Growth Habit in Tomato
Authors: Ozminkowski Richard H. , Gardner Randolph G. , Moll Robert H. , Henderson Warren R.
Published: January 2019

Prostrate growth habit (PGH) in tomato (Lycopersicon esculentum Mill.) lines derived from breeding material developed at the Agriculture Canada Research Station, Beaverlodge, Alberta, was the subject of a quantitative inheritance study. Plants with PGH have an increased lateral branch angle, relative to upright plants, and crown-set fruit supported above the soil surface making hand harvest easier. Genetic parameters were estimated in two families (20G and 53G), each containing PGH and upright-habit parental lines, F1, F2, and backcrosses to each parent. Field-grown plants were subjectively rated twice during the growing season. Broad-sense heritability of PGH in family 20G was estimated to be 0.65 and 0.71 for ratings of plant growth habit 6 and 9 weeks after transplanting, respectively, and 0.71 and 0.68 for those of family 53G. Narrow-sense heritability was estimated to be 0.83 and 1.05 for the two ratings in the 20G family and 0.77 and 0.78 in the 53G family. F1 and F2 means were not different from mid-parent values. The genetic variance was entirely additive and expression was influenced by the environment. The data did not support the hypothesis that PGH was controlled by a single gene.
Feasibility Studies Using β -Glucuronidase as a Gene Fusion Marker in Apple, Peach, and Radish
Authors: Martin G.C. , Miller A.N. , Castle L.A. , Morris J.W. , Morris R.O. , Dandekar A.M.
Published: January 2019

The udiA gene encoding the enzyme β -glucuronidase (GUS) appears promising as a genetic marker for early confirmation of successful plant cell transformation. Two strains of Agrobacterium rhizogenes and eight strains of A. tumefaciens were selected as hosts to carry a binary plasmid (pBI121) containing the marker gene encoding the GUS marker that is controlled by the CaMV35S promoter. Presence of plasmid pBI121 in the bacteria was confirmed by resistance to kanamycin, plasmid re-isolation, and restriction enzyme analysis. When the GUS enzyme was expressed in transformed plant cells, reaction with the histochemical substrate 5-bromo-4-chloro-3-indolylglucuronide (X-gluc) lead to blue pigment development. Expression of GUS in viable bacteria that had not been eliminated from transformed tissue caused problems with the early transformation detection in radish, peach, and apple stem sections by also producing a positive X-gluc color reaction. Putative transformation of apple xylem parenchyma callus was accomplished, as judged by resistance to kanamycin, opine analysis, GUS marker gene expression, and presence of the APH(3')11 enzyme. In this system, elimination of bacterial contamination was accomplished during multiple culture transfers on selective media. To be more useful as a marker, the GUS gene should be coupled with a promoter that will not be expressed by Agrobacterium. Parenchyma callus may serve as a primary screen to provide an efficient way of determining the ideal strain for transformation of deciduous tree fruit genera. In our studies, strain A281 consistently proved to be a vector superior to others tested.
Surface Chemical Differences Between Sweetpotato Lines with Varying Levels of Resistance to the Sweetpotato Weevil
Authors: Son Ki-Cheol , Severson Ray F. , Arrendale Richard F. , Kays Stanley J.
Published: January 2019

Methodology was developed for the extraction of surface components of sweetpotato [Ipomoea batatas (L.) Lam.] storage roots. Surface components of storage roots were quantitatively extracted with methylene chloride using 8-minute ultrasonication. After removal of the solvent, the extract was treated with 3 Tri Sil-Z:1 trimethylsilylimidazol (v/v) to convert components with hydroxyl moieties to silyl ethers and then separated on a SE-54 fused silica capillary column. Distinctly different gas chromatography profiles were found between lines displaying moderate levels of resistance (`Resisto', `Regal', `Jewel') to the sweetpotato weevil [Cylas formicarius elgantulus (summers)] and weevil-susceptible lines (`Centennial', SC 1149-19, W-115), indicating a possible role of surface components in insect response. Chromatographic fractionation techniques were developed for separation of major components or groups of components. The results will allow subsequent bioassaying for the presence of an ovipositional stimulant(s) and other weevil behavior-modulating compounds and their chemical characterization.
Identification of the Developmental Phases in Poinsettia
Authors: Siraj Ali Yusef S. , Tayama Harry K. , Prince Thomas L. , Carver Stephen A.
Published: January 2019

Experiments were conducted with poinsettia [Euphorbia pulcherrima (Willd. ex. Klotzsch)] to determine the 1) existence of developmental phases from seedling establishment to flower induction and 2) characteristics that may be used to delineate the phases. The characteristics evaluated were flowering and rooting ability, heterophylly and other leaf characteristics, phyllotaxy, and internode characteristics. Two developmental phases, juvenility and maturity, were identified. The transition between these phases occurred in poinsettias that were 6 to 8 weeks old, following establishment. Mean values for flowering ability, rooting ability, phyllotaxy, and heterophylly differed for the two developmental phases, rendering them the most useful of the characteristics evaluated for identifying developmental phases in poinsettia.
Distinction Between Infectious and Noninfectious Corky Root of Lettuce in Relation to Nitrogen Fertilizer
Authors: van Bruggen Ariena H.C. , Brown Philip R. , Greathead Art
Published: January 2019

In growth chamber experiments with five concentrations of NH4NO3 and inoculation of lettuce (Lactuca sativa L.) cv. Salinas with Rhizomonas suberifaciens, the causal agent of corky root (CR), symptoms of noninfectious corky root induced by high rates of N were distinct from those of infectious corky root (ICR). Nitrogen toxicity was observed at 350 kg·ha-1 and above, and was not affected by inoculation with R. suberifaciens. There was a curvilinear relationship between concentration of NH4NO3 applied and ICR severity with a maximum at 525 kg·ha-1. In a similar growth chamber experiment with NH4NO3 plus urea, ICR severity decreased and N toxicity increased at increasing N levels (N at 160 to 650 kg·ha-1). In microplots at Davis, Calif., sidedressing with NH4NO3 (N at 170 kg·ha-1) increased ICR severity on `Salinas' lettuce over the nonfertilized control. There was a significant interaction between N fertilization and soil-infestation with R. suberifaciens with respect to head fresh weight: sidedressing with NH4NO3 increased head weight in noninfested plots, but decreased head weight in infested plots. In four field experiments at Salinas, Calif., sidedressing with N at 78 to 213 kg·ha-1, with N as (NH4)1SO4, NH4NO3, urea, or Ca(NO3)2, increased ICR over the control, but there were no significant differences between the forms of N. Head fresh and dry weights were either increased or unaffected by sidedressing with N fertilizers, depending on the residual concentrations of N in the soil. The increase in ICR was likely related to concentrations of soil NO3 rather than NH4.
Absorption, Translocation, and Metabolism of Chlorsulfuron in Kentucky Bluegrass and Tall Fescue
Authors: Goatley J.M. , Powell A.J. , Barrett M. , Witt W.W.
Published: January 2019

Laboratory studies were conducted to determine the basis for chlorsulfuron selectivity between Kentucky bluegrass (Poa pratensis L. cv. Kenblue) and tall fescue (Festuca arundinacea Schreb. cv. Rebel). Tall fescue absorbed and translocated more foliar-applied [14C]-labeled chlorsulfuron from the treated leaf than Kentucky bluegrass. The two species absorbed similar amounts of chlorsulfuron from nutrient solution into the roots, but tall fescue translocated more of the absorbed radioactivity to the shoots. Tall fescue metabolized chlorsulfuron in the shoots slightly more slowly than Kentucky bluegrass. Allof these factors apparently contributed to the higher tolerance of Kentucky bluegrass than of tall fescue to chlorsulfuron. Chemical name used: (2-chloro-N-[[4-methoxy-6-methyl-1,3,5 -triazin-2-yl)amino]-carbonyl] benzenesulfonamide) (chlorsulfuron).
Changes in Respiration Rate and Energy of Activation after Chilling and Forcing Dormant Apple Trees
Authors: Young Eric
Published: January 2019

Dormant apple trees (Malus domestics Borkh., cv. MM. 111) were chilled at SC for O, 500, 1000, or 1500 hours and then forced at 10, 20, or 30C for 21 days. Budbreak and root growth were recorded after forcing, and shoot and root respiration was measured at 5, 10, 20, and 30C to determine Q10 and energy of activation values. Budbreak, root growth, and respiration generally increased with chilling and forcing temperature. The Q10 of shoot respiration increased significantly with increasing chilling when measured before forcing; however, after forcing, Q10 decreased with chilling. Root respiration Q10 was not as influenced as shoot respiration by chilling either before or after forcing. Energy of activation for shoot and root respiration decreased significantly with chilling after forcing at each temperature.
Quantitative Genetic Analysis of Fruit Quality in Pear
Authors: Bell R.L. , Janick Jules
Published: January 2019

Narrow-sense heritability estimates were computed for five fruit quality characteristics and their weighted total index. Grit content and skin russeting were moderately heritable traits, while flesh texture, flavor, appearance, and the weighted total score were of relatively low heritability. Within sub-populations of crosses, defined by the species ancestry of the parents, the relative magnitudes of heritabilities for each trait varied, but were in general agreement with those for the entire population. The general combining ability variances were 4.5 to 12.0 times those for specific combining ability, although both were statistically significant for all traits and the weighted quality index. The species ancestry of a parent had no effect on its general combining ability rank. While selection of individual seedlings on the basis of their own phenotype will result in genetic improvement for grit and russet, selection based on a combination of full-sib family means and individual phenotypes is recommended for flavor, texture, appearance, and overall fruit quality.