bluuebunny/crossref_metadata_2025 huggingface dataset:
Root Penetration in Heavily Compacted Soil Systems
Authors: Grabosky Jason , Bassuk Nina
Published: February 2019

In the development of a street tree planting medium for use as a sidewalk base, we have been testing a series of limestone gravel and soil media with varied amounts of clay loam suspended within the matrix voids. Tilia cordata and Quercus alba seedling roots quickly penetrated and grew in these systems when compacted to densities in excess of 2000 kg·m–3, while they were severely impeded in clay loam soil compacted to 1300 kg·m–3. Limestone mixes of the same design had variable, but consistently acceptable, California Bearing Ratios (>40) when compacted to similar densities; demonstrating their strength as a pavement base. Tilia root growth, based on the volume collected from total root excavations after two growing seasons, increased a minimum of 300% in the limestone mixes over the compacted clay loam control when the treatments were compacted to ≈80% Standard Proctor Optimum Density. Root penetration of Quercus increased >400% in the limestone mixes over compacted loam in a 6-month trial compacted to 95% Standard Proctor Optimum Density.
Chilling Affects Flowering of Fall-bearing Red Raspberries
Authors: Takeda F.
Published: February 2019

Tissue-cultured raspberry plants are not exposed to low temperatures during the propagation phase, yet the primocane that grows from the crown will flower terminally after developing 20 to 25 nodes. We studied the effect of duration of chilling (hours) (CH) on days to flower (DTF) in primocanes arising from root suckers of previously cropped fall-bearing `Heritage' and `'Summit' raspberries. Growth of `Heritage' plants with 0 or low CH was either short with rosetted leaves or indeterminate. Plants with 0 CH remained vegetative for >240 days, while plants with >750 CH flowered in <4 months when the primocane had 25 to 30 nodes. These results suggested that low-temperature exposure prior to shoot emergence was necessary for flower bud initiation in `Heritage' red raspberry. In contrast, all `Summit' flowered; DTF ranged from 120 days for 0 CH plants to <70 days for plants with 1000 CH. Low-temperature treatment affected flower bud development. Plants with 0 CH developed 15 flowering laterals, while plants with >750 CH had 25 flowering laterals. Although `Summit' needs no CH to flower, low temperature treatments definitely accelerated DTF and increased the number of fruiting laterals.
A Reevaluation of Mechanical Harvester vs. Hand-raking for Wild Blueberries
Authors: Yarborough David E.
Published: February 2019

Improvements in the Bragg harvester and the introduction of a new Nimco harvester warranted a reevaluation of new technologies. Four technologies: the Bragg harvester, a modified Bragg harvester, the Nimco prototype, and hand-harvesting were evaluated at two locations: a land-leveled field (T-19) and a field without land leveling (Deblois). The experimental design was a randomized complete block with eight replications. A 150-ft strip was harvested with each technology, with strips directly adjacent to each other to minimize field variability. Time to harvest and berry weights were measured. Poor maintenance, adjustment and skill of the operator contributed to a 69% recovery relative to hand-harvest by both the Bragg and modified Bragg harvesters. The Nimco harvester has great potential, but only if it is properly mounted to allow it to cover the fields at a speed similar to the Bragg harvesters. The land-leveled field allowed for greater recovery for the Bragg and Nimco harvester, indicating that smoother fields are more efficient for machine-harvesting.
Cover Crop Effects on Weed Control and Growth of First-year Grapevines
Authors: Bordelon Bruce P. , Weller Stephen C.
Published: February 2019

Four cover crops were evaluated for weed control and effects on first-year vine growth. Winter wheat (cv. Cardinal), rye (cv. Wheeler), oats (cv. Ogle), and hairy vetch (no cultivar name) were either fall- or spring-planted and compared to cultivated and weedy control plots. Cover crop and weed biomass dry weight was collected twice during the growing season. Vines (Vitis labrusca cv. Steuben) were planted in the spring and destructively sampled at the end of the growing season for analysis of leaf area, leaf number, shoot length., shoot number, top growth dry weight, and root system dry weight. None of the vines in cover crop treatments had growth as good as vines in the weed-free check. Vines in the best cover crop treatments had ≈70% as much leaf area, 75% as many leaves, 50% as much shoot dry weight, and 40% as much root dry weight as vines in the weed-free check. Cover crop biomass dry weight and vine growth was greater in fall-planted plots than in spring-planted plots. Despite low cover crop biomass dry weight, spring-planted plots had few weeds (low weed biomass dry weight). However, vine growth in spring-planted plots was not significantly different than vine growth in the weedy check.
Effects of Nutrient and Growth Regulator Treatments on Growth and Development of Zinnias
Authors: Clardy Arvazena E. , Garton Stephen
Published: February 2019

Two cultivars of Zinnia elegans, `Big Red' and `Sunrise Red', were grown hydroponically in two different nutrient solutions. The experiment was implemented in the greenhouse to assess affects of growth regulator treatments on growth and development of the plants. Heights of seedlings germinated in peat pellets were measured prior to placement in the hydroponic units. Plants were sprayed with five rates of either paclobutrazol or uniconazole. The experiment was laid out as a randomized complete-block design with four replicates of the treatments, which were factorial combinations of variables. Days to first flower were recorded for each plant. After 90 days, measurements were made of plant heights, flower bud numbers, and dry weights of shoot and root systems. Nutrient treatments affected all parameters observed. Growth regulator treatments affected plant heights. `Sunrise Red' produced more flower buds and earlier flowers than `Big Red'.
Differential Effect of Population Density on Shape and Size of Cylindrical Red Beet Genotypes
Authors: Goldman I.L.
Published: February 2019

The use of cylindrically shaped red beet cultivars for production of processing beets has increased in recent years. Yield and shape of globe-shaped red beet cultivars are determined in part by population density and within-row spacing; thus, it is thought cylindrical cultivars are similarly affected by these factors. The objective of this investigation was to evaluate the effects of population density on shape and size of cylindrical red beet cultivars. Two F1 hybrids and two open-pollinated cultivars were planted in replicated trials consisting of three population densities during 1993 and 1994. Ten traits were measured on a randomly selected sample of beets from each plot. Averaged over genotypes, significant differences among densities were found for percent harvestable beets per plot, length × width, harvest weight, length, and mid-width. Average over genotypes, greater harvest weight, higher percentage of harvestable beets, and greater length, mid-width, and length × width values were found at low density. Average over densities, open-pollinated cultivars exhibited a greater degree of straightness along with lower yield, harvest weight, and percent harvestable beets than their hybrid counterparts. These data demonstrate population density has a differential effect on shape and size of cylindrical beet genotypes.
Response of `Thompson Seedless' Grapevines to Sustainable Viticultural Practices
Authors: Striegler R.K. , Mayse M.A. , O'Keefe U. , Wineman D.R.
Published: February 2019

Consumer concerns about pesticide residues and environmental degradation are having a significant impact on the California grape industry. Growers are using a variety of practices, from integrated pest management to certified organic production, to reduce the amount of pesticides and other synthetic inputs used in vineyards. This experiment was established to test selected sustainable cultural practices in a mature `Thompson Seedless' vineyard. Treatments included in the experiment were row middle management (cultivated vs. perennial legume cover crop) and nitrogen fertilization (compost vs. synthetic). Vine nutritional status, yield, fruit composition, pruning weight, and population levels of the variegated leafhopper were monitored each season (1992–1994). In addition, efforts were expanded during the 1994 season to include assessment of spider, herbivorous mite, and beneficial arthropod densities. Conventional cultural practices (cultivation and synthetic fertilizer) produced the highest yields during the 1992 and 1993 seasons. This result may have been due to the nutritional status of vines, which was generally better for the cultivation and synthetic fertilizer treatment, especially in 1992. In 1994, significant treatment effects on yield were not observed, indicating that legume cover crop plots had become fully established. Sustainable cultural practices had little impact on growth, fruit composition, or insect pest pressure. `Thompson Seedless' grapes were grown for three seasons without the use of insecticides or herbicides. Vine diseases were managed by cultural practices and application of sulfur.
A Success Story of Commercialization of Pineapple in Pakistan
Authors: Aleemullah Mohammed
Published: February 2019

From 1950 until the 1980s, pineapple cultivation in Pakistan met with limited success because of a number of constraints. These included saline soils, brackish water, and a poor understanding of the requirements for nutrition, irrigation, growth and varietal adaptation, pest, disease, weather stress, overall crop management, and cultural practices. A new approach was attempted in late 1970 to the early 1980s, when a group of organizations in the Karachi metropolitan area developed a pot culture technique replacing local saline soils by river sand, and providing city city water instead of brackish underground irrigation. This pot culture system was limited by cost, unpredictable performance of survival, growth, and development, yield, and production of planting material. Thus, it could not be adapted on a commercial basis. These limitations were investigated in a 4-year study (1987–1990) at the Plant Introduction Centre, Karachi, of the Pakistan Agricultural Research Council, and technology was developed that led to the successful introduction, adaptation, and commercialization of pineapple production in Pakistan. Under the harsh arid conditions of Karachi, field trials were conducted with the pineapple var. Queen as an intercrop under a coconut canopy with trench and double-row system of planting. The best fertilizer management treatment consisted of the application of 4 kg gypsum and 5 kg cow manure on a per-plant basis, incorporated during land preparation and followed by the application of 56 g N and 60 g K per plant per annum in six split dosages. Fruit weighing 1000 g or more were harvested during 12 to 15 months following planting. Fruits were of high quality, with 13.6 % sugars, 1.5 % acidity, and TSS value of 4.7. Five suckers and slips were produced by each plant. The application of these soil amendments reduced soil pH from 8.5 to 6.9 and ECe by 80%. This regime enabled the use of slightly brackish underground water (ECe 2.7 mmhos) for irrigation. Weekly intervals of irrigation during summer and fortnightly intervals during winter were optimum. The crop was free of serious pest and disease. Mealy bugs and scale insects were controlled by Sumithion, rodents by Raccumin, while physical damage by squirrels and birds was avoided by covering the fruit with perforated paper bags. Through the development of this integrated production technology, Pakistan is now able to grow pineapples commercially.
Nitrogen Mineralizations as Affected by Container Substrate Temperatures
Authors: Taylor Helen H. , Mikkelsen Robert L. , Warren Stuart L.
Published: February 2019

The N release patterns of composted turkey litter, composted yard waste, and composted municipal waste amended pine bark substrates were measured under simulated diurnal temperature variations [25C, 45C, and 45/25C (14/10 h)] found in container substrates. Temperature regime, compost, and the interaction between temperature and compost affected the NH4 and NO3 availability and the total N released from the composted waste products over the 16-week experiment. Within each temperature regime, the composted turkey litter released greater amounts of NH4 and more total inorganic N than the municipal and yard wastes. The turkey litter yielded the highest NO3 concentrations at 25C, while the municipal waste produced the highest NO3 concentrations at the 45C and the 45/25C temperatures. Temperatures higher than 25C inhibited nitrification in the turkey litter-amended substrates; however, the 45C and the 45/25C treatments resulted in greater total N mineralization than the 25C treatment.
Isozyme Variability in Wild and Cultivated Carica papaya
Authors: Maimunah Morshidi , Manshardt R.M. , Zee Francis
Published: February 2019

Populations of wild Carica papaya, previously designated as Carica peltata, were sampled from its native range on the Caribbean coast of Central America (Mexico, Belize, Guatemala, Honduras) and cultivated Carica papaya from both Central and South America were examined for isozyme variability. Thirteen loci from nine enzyme systems (Pgm, Pgi, Idh, Mdh, 6Pgd, Ugpp, Skdh, Aco, Tpi) were scored for all populations. Ten loci were polymorphic and a total of 31 alleles were detected. Isozyme genotypes as determined through segregation analysis were used in the genetic interpretation for eight loci and 18 alleles while six additional loci and 13 alleles were postulated on the basis of phenotypic variation found throughout the species. Nei's genetic identity, I, for both cultivated and wild Carica papaya was >0.9, which is consistent with conspecific populations. Wild papaya populations from different geographic areas appear more related to one another than to domesticates in the same geographic region.
Inheritance and Linkage Studies in Peach
Authors: Werner Dennis J. , Creller Michael A.
Published: February 2019

Inheritance of male sterility in peach [Prunus persica (L.) Batsch] Plant Introduction (PI) 240928 was investigated. Crosses of PI 240928 with five wild-type clones yielded all male-sterile offspring, indicating dominant gene action. Inheritance of the sweet kernel trait in peach was studied in F1 and F2 progeny of `Summer Beaut' nectarine (sweet kernel) × `Biscoe' peach (bitter kernel). All four F1 progeny were bitter. Segregation in an F2 of 80 progeny fit a ratio of 3 bitter: 1 sweet. We propose that the gene controlling the sweet kernel trait be designated sk. Sweet kernel (sk) was linked to nectarine (g) at a map distance of 17 cM. Evaluation of the peach PI collection showed that PI 129678 (`Stanwick' nectarine) and PI 34685 (`Quetta' nectarine) were the only clones with a sweet kernel. Crosses between `Davie II' and `Honeyglo' nectarine (dwdw) confirmed that the gene conferring the dwarf phenotype in progeny of `Davie II' is non-allelic to dw.
Biochemical Bases for Controlled-atmosphere Effects on Reducing Chilling Injury of `Hass' Avocado Fruit
Authors: Faubion Dana F. , Kader Adel A.
Published: February 2019

California-grown `Hass' avocado fruit were stored at 5C, in air or a controlled atmosphere (CA) of 2% oxygen and 5% carbon dioxide. Fruit were evaluated at 0, 2, 4, 6, 8, 10, and 12 weeks, both immediately upon removal from storage and after ripening at 20C. Severe chilling injury (flesh browning) developed in the airstored fruit after 6 weeks, while only moderate symptoms were observed in CA-stored avocado fruit after 12 weeks. Lipid peroxidation breakdown products increased during storage and ripening in both air and CA treatments. Sterols, steryl esters, steryl glycosides, glycolipids, and phospholipids were analyzed. Quantity of acylated steryl glycoside in ripe fruit changed from 34 nmoles initially, to 51 or 27 nmoles after 6 weeks at 5C in air or CA, respectively. Glycolipid fatty acid unsaturation in air-stored fruit decreased with the development of chilling injury. Fatty acid unsaturation in phospholipids (phosphatidylinositol, phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine) of air-stored avocados decreased with the development of chilling injury. CA storage delayed the development of chilling injury and the loss of fatty acid unsaturation.
Growth Analysis of Tomatoes Grown in Black Polyethylene and Hairy Vetch Mulches
Authors: Teasdale John R. , Abdul-Baki Aref A. , Potts William J.E.
Published: February 2019

Dry weight and leaf area of tomato (Lycopersicon esculentum Mill.) plants grown on raised beds with black polyethylene (BP) or hairy vetch (Vicia villosa Roth) (HV) mulches were measured at weekly intervals during 1993 and 1994. Leaf area and foliage, fruit, and total weight of tomato plants grown in BP were greater early in the season, but less later in the season than plants grown in HV. The relative growth rate of tomatoes in HV was higher throughout most of each year than that in BP. There was little difference between treatments in unit leaf rate (rate of weight gain per unit leaf area). The growth rate of fruit per unit of tomato foliage was greater in BP than HV, whereas the leaf area to weight ratio was greater in HV than BP. These results suggest that tomatoes grown in BP produce greater early yield because of greater early foliage growth and greater partitioning to fruit than HV. However, tomatoes grown in HV eventually outgrow and outyield those in BP because of greater partitioning to and maintenance of leaf area throughout the season.
Studies on the Fruit and Vegetable Handling System at Farmers' Market in Hawaii
Authors: Smith-Kayode O. , Thompson Richard , Yamauchi Yoshiko
Published: February 2019

Homestead and organic farming systems are the main sources of commodities sold at farmers' markets in Hawaii. Consumers are attracted because the products are generally accepted as safe and of premium nutritional quality. Markets were frequented by many groups, including senior citizens. Two models were studied in urban and rural Hawaii, respectively, to determine the support systems that make then function properly with special attention to the postharvest technology component of operations. Innovative preparation, presentation, and display methods were observed for bananas, ethnic vegetables, and herbs. Homestead and organic farmers work in the mornings and strict use of shade is significant in maintaining freshness from produce temperature standpoint. Hawaiian fresh produce distribution models that emphasize grower participation as found in this study could rapidly expand the horticultural industry and reduce postharvest losses significantly if adopted by developing countries.
Transfer of the Long-lived Postharvest Keeping Characteristic from a long-lived Inbred line of Antirrhinum majus (L.) to a Short-lived Line through the Inbred Backcross Method
Authors: Schroeder Kenneth R. , Stimart Dennis P.
Published: February 2019

In an effort to reduce chemical usage to prolong postharvest keeping time of cut flowers, a cross was made between a long-lived (vase life, 10.9 days) inbred line of Antirrhinum majus and a short-lived (vase life, 5.0 days) inbred line. The F1 hybrid was backcrossed to the short-lived parent. Sixty plants of the BC1 generation were carried on through three generations of selfing by single-seed descent. Eight replications each of 60 BC1S3 families, the parents, and the F1 hybrid were grown in the greenhouse, harvested with 40-cm stems when five florets opened, and placed in distilled water for vase life evaluation. Stems were discarded when 50% of the florets on a spike wilted, browned, or dried. Three families proved not significantly different from the long-lived inbred parent. Results indicate that inbred backcross breeding shows potential to increase the postharvest keeping time of short-lived Antirrhinum majus inbred lines.
Changes in Pectins in Apple Fruit during Development and Ripening
Authors: Chun Jong-Pil , Lee Jae-Chang , Hwang Yong-Soo
Published: February 2019

Pectins isolated from three cultivars with different maturity were compared to find a potential role of pectin modification on the fruit softening during fruit development and ripening. There was an increase of total pectins in developing fruit and no significant decrease of pectins was confirmed even after storage in `Tusgaru' (30 days) and `Fuji' (120 days), whereas soluble pectins, except NaOH-soluble ones, gradually increased in all cultivars. Gel-filtration profile and ion exchange chromatographic evidence of soluble pectins revealed that pectin degradation in apple fruit may not be associated with softening. However, a degree of esterification probably has an important role on softening of fruits. Further results will be discussed in the presentation.
Effect of Heat Treatment on the Development of Superficial Scald in `Red Delicious' Apples
Authors: Murr D.P. , Hustwit K. , Tschanz R. , Rao M.V. , Paliyath G.
Published: February 2019

Heat treatment of apples (Malus domestica Borkh cvs. Red Delicious, Starkrimson) and its effect on scald development have been investigated. Several parameters indicative of scald, such as ethanol and acetaldehyde content, UV-absorbing components from skin, and fruit quality parameters, such as fruit firmness and soluble solids content, were monitored after exposing apples to heat therapy at 40C for 24 h, followed by storing them at room temperature in polyethylene bags. In general, heat-treated apples possessed higher ethanol and acetaldehyde levels. As well, heat-exposed apples appeared to possess a lower degree of scald. The content of soluble solids did not appear to be affected by heat treatment. The degree of firmness, however, was maintained in heat-treated apples. Effect of heat treatment on several other physiological and biochemical parameters will be presented.
Storage Studies with Virus-infected Blueberries
Authors: Ahmedullah M. , Bristow P.
Published: February 2019

Concord blueberries treated with biocontrol fungi (Trichoderma and Gliocaladium) both at 1 and 2x rates and with fungicides benlate + captan + B 1956 and Tween for controlling botrytis flower blight were stored at 32F. Trichoderma (2x)-treated fruit was 71% without infection; Gliocaladium (2x)-treated fruit 69%, compared to 57% from untreated control. Momentum Transfer Generator (MTG) readings indicating fruit firmness ranged from 474 to 494 for the above treatments, indicating that fruit firmness was not affected by the treatments. Concord blueberries from bushes infected with blueberry scorch carla virus showed no difference in fruit firmness compared to healthy berries either before or after 7 weeks of storage at 32F.
Effect of Harvest Maturity, Storage, and Cultivar on Strawberry Fruit Aroma Volatiles
Authors: Forney Charles F. , Jordan Michael A.
Published: February 2019

`Annapolis', `Cavendish', `Honeoye', `Kent', and `Micmac' strawberry fruit (Fragaria ×ananassa Duch.) were harvested underripe (75% to 90% red) or fully ripe. Fruit were stored at 0C for 5 days followed by 2 days at 15C. Volatiles were trapped onto Tenax-GR from the headspace over fruit before and after storage and analyzed using GC-MS. Volatile esters identified in headspace included methyl and ethyl butanoate, methyl and ethyl hexanoate, methyl and ethyl 3-methylbutanoate, 3-methylbutyl acetate, hexyl acetate, and methyl 2-methylbutanoate. Headspace concentrations of volatile esters over freshly harvested strawberries averaged 1.3 and 6.8 μmol·m–3 for underripe and ripe fruit, respectively. After 7 days of storage, volatile concentrations increased in both underripe and ripe fruit to 6.3 and 12.2 μmol·m–3, respectively. There were quantitative and qualitative differences between cultivars. Total volatile concentrations were 16.0, 8.1, 5.7, 2.4, and 0.9 μmol·m–3 in the headspace over `Annapolis', `Kent', `Micmac', `Cavendish', and `Honeoye', respectively. `Annapolis' had the highest concentrations of methyl and ethyl butanoate, while `Micmac' had the highest concentrations of methyl and ethyl hexanoate. Volatile concentrations at harvest increased 5.7, 1.9, 1.7, 1.4, and 1.3 times during storage in `Kent', `Annapolis', `Micmac', `Cavendish', and `Honeoye', respectively. Results indicate that strawberry fruit continue to produce aroma volatiles after harvest.
Protocol for Developing Weed-tolerant Crops
Authors: McGiffen Milton E. , Ogbuchiekwe E.J. , Saharan B.S.
Published: February 2019

While there are published reports of varietal differences in competitiveness with weeds, no crop varieties have been specifically developed for tolerance to weed interference. We explored several methods that mechanistically compare potential sources of tomato varietal tolerance to purslane, velvetleaf, and black night-shade: 1) The influence of canopy structure and development was studied with a wide range of crop and weed germplasm with different growth habits. Leaf expansion rate and other morphological characters were used to select crop genotypes for more-detailed study. 2) Replacement series experiments with selected cultivars found that purslane and other species can adapt to avoid competition. The greatest varietal differences in competitiveness were with nightshade species that had a canopy structure similar to tomatoes. 3) Field measurements of canopy development and light interception found that competitive advantage shifted over time as height and leaf area of weeds and crops changed. 4) A systems analysis method, sensitivity analysis, found that changes in plant architecture over time were more important than initial or final crop characteristics in determining competitive outcomes.
Construction of a Genetic Linkage Map and Locations of Common Blight, Rust, and Web Blight Resistance Loci in Phaseolus vulgaris L. Using Random Amplified Polymorphic DNA (RAPD) Markers
Authors: Jung Geunhwa , Coyne Dermot P. , Skroch Paul W. , Nienhuis James , Arnaud-Santana E. , Bokosi James , Ariyarathne H.M. , Steadman James , Beaver James S.
Published: February 2019

Common blight, web blight, and rust, incited by the bacterial pathogen Xanthomonas campestris pv. phaseoli (Smith) Dye (Xcp) and the fungal pathogens Thanatephorus cucumeris (Frank) Donk (Tc) and Uromyces appendiculatus (Pers.:Pers) Unger, respectively, are important diseases of common beans (Phaseolus vulgaris L.). The objectives of were to construct a linkage map, and to locate CBB, rust, and WB resistances and plant architecture traits using RAPDs. Ten linkage groups were identified. Eighty-nine RAPD markers and rust resistance were mapped in 128 RI lines of the cross BAC-6 and HT-7719. Regression analysis and interval mapping using MAPMAKER/QTL were used to identify genomic regions involved in the genetic control of the traits. One, two, two, and three putative QTLs were identified for leaf, seed, and pod reactions to Xcp, and foliar reaction to Tc. These regions accounted for 11%, 9%, 32%, and 30% of the phenotypic variation in the resistances. Two, two, and three regions were identified for plant uprightness, branch density, and pod distribution. These regions accounted for 27%, 13%, and 16% of the phenotypic variation. Unassigned marker G17d influenced some of the phenotypic variation in all three traits. A rust resistance gene controlling pustule size on primary leaves was located in linkage group 1.
Resistance of 25 Melon Cultigens to Race 1 and Race 2 of Fusarium Wilt under Two Soil Fumigation Treatments
Authors: Ng Timothy J , Kantzes James G.
Published: February 2019

Twenty-five melon (Cucumis melo L.) cultigens were screened for resistance to fusarium wilt in a field infested with race 1 and race 2 of Fusarium oxysporum f.sp. melonis in 1993 and 1994. Plants were grown on clear plastic mulch using commercial production recommendations. The soil was fumigated with methyl isothiocyanate at a broadcast rate of 340 liters·ha–1 in 1993, and with dichloropropene at a broadcast rate of 136 liters·ha–1 in 1994. Resistance was determined by the percentage of plants surviving 8 weeks after transplanting. In general, highly resistant cultigens (>90% survival) and highly susceptible cultigens (<20% survival) performed consistently in the two experiments. However, differences in performance between the two years were noted for cultigens with intermediate resistance, and their performance may have contributed to the significant cultigen × year interaction in this study.
Genetic Variation and Selection for Carotene Content in Carrots
Authors: Simon Philipp
Published: February 2019

A six-parent diallel which included carrot inbreds with a range of carotene content from 80 to 490 ppm was evaluated over 2 years. General combining ability accounted for most of the variation observed. Phenotypic mass selection was exercised for high carotene content in three carrot populations. Response to selection continued to be high in one population, HCM, after 11 cycles of selection. In contrast, after three generations of selection, little progress was able to be made in a population derived from primarily Nantes-type open-pollinated cultivars. Realized heritability estimates varied from 15% to 49%. Environment contributed significantly to variation in carotene content.
An Unstable Mutation Affecting Tomato Reproductive Development
Authors: Poysa V.
Published: February 2019

Somatic sectors possessing mutations affecting flower and fruit development were found at a high frequency in an F4 tomato plot. Over the past 4 years, this population has manifested a range of variant phenotypes, including conversion of calyx to leaflets; flecking, striping of sectoring of fruit; and development of “prolific callus” (PC) fruit, characterized by the green fruit bursting open, with new flowering shoots developing from the internal tissue. The variant phenotypes were not stably inherited. The majority of plants having sectors with abnormal flowers, abnormal fruit, or PC fruit developed phenotypically distinct somatic sectors. The aberrant phenotype ratios, the very high frequency of somatic reversions toward normal development, and the range of traits affecting tomato reproductive development indicate this could involve a transposable element interacting with control genes involved in tomato reproduction, with the phenotype partly dependent on the timing of the transposition event.
Fruit Characteristics of Hybrid Triploid Melons
Authors: Nugent Perry E. , Adelberg Jeffrey
Published: February 2019

Thirteen triploid lines of melon (Cucumis melo L.) were derived from crosses involving five tetraploid and seven diploid lines. Fruit characters were assessed. When allowed to open pollinate in field plots with adjacent diploid pollinators, eight triploid genotypes were sterile or nearly sterile (<1% viable seed). Five triploid genotypes were partially fertile, indicating viable pollen grains were present. Cytological analysis performed on progeny of a partially fertile triploid plant fertilized by open pollination indicated euploid female gametes were common. Triploid hybrids between tetraploid `Miniloup' and several other diploid parents had vegetative and fruit characteristics intermediate to the parents. Most triploid genotypes yielded round fruit in contrast to their diploid parent whose fruit were oval to oblong and the tetraploid parent that had oblate fruit. Sugar levels of some triploid hybrids were as high as diploid parents.
Heritability Estimates of the Pungency and Single-center Traits in Onion
Authors: Wall Marisa M. , Mohammad Ayaz , Corgan Joe N.
Published: February 2019

Heritabilities of the pungency and single-center traits were estimated in onion breeding lines using selection response and half-sib family analyses. Pungency was determined by measuring enzymatically produced pyruvic acid in individual bulbs. After one generation of selection, pungency was lowered by 0.37 and 0.42 μmol pyruvic acid/gram fresh weight in the breeding lines 90-61-1 and 89-69-8, respectively, and realized heritabilities of 0.21 and 0.51 were estimated. Heritability estimates calculated through half-sib progeny analysis were 0.53, 0.48, and 0.25 for pungency in the breeding lines 90-61-1, 90-62, and 89-69-8, respectively. The number of single-centered onions was increased by 19% and 22% in the lines 90-62 and 89-69-8, respectively, after one generation of selection, and the realized heritability estimates were 0.37 and 0.34, respectively.
Ultrastructural Changes in Chloroplasts in Harvested Broccoli Flower Buds During Senescence
Authors: Terai Hirofumi , Tsuchida Hironobu , Mizuno Masashi , Fukui Yumi
Published: February 2019

Green broccoli (Brassica oleracea L. Italica Group) flower heads were stored in perforated polyethylene bags at 20C. Green color of sepals in broccoli flower buds changed to yellow and individual flower buds wilted gradually during storage. Chlorophyllase activity in flower buds tended to increase and chlorophyll content decreased during senescence. Optical and scanning electron microscopic observations were conducted to elucidate the structural changes of chloroplasts in sepals of broccoli flower buds through the senescence. The chloroplasts observed with optical microscope were fine and green when the stage of broccoli flower buds was all green. However, at half-yellow stage, the shapes of chloroplasts obscured and the green color faded. After this stage, colored small particles appeared in the cells and the number of particles tended to increase as yellowing of the flower buds progressed through the senescence. Scanning electron micrographs indicated that the small particles were formed in the chloroplasts and come out from them with senescence followed by aggregation with each other.
Calcium Application Increases Potato Tuber Medularry Tissue Calcium Concentration and May Reduce the Incidence and Severity of Soft Rot Due to Erwinia carotovora pv. atroseptica
Authors: Kleinhenz Matthew D. , James R. Vaughan , Stevenson Walter R. , Palta Jiwan P.
Published: February 2019

Plots set up on a commercial seed farm were supplemented with 0 or 168 Ca/ha supplied from liquid calcium nitrate at 3 and 6 weeks after hilling (84 kg Ca/ha per application). Paired measurements of tuber medullary tissue Ca concentration and decay severity after inoculation with Erwinia carotovora pv. atroseptica (Eca.) were taken on identical tubers from these separate plots of `Atlantic', `Superior', `Red Norland', and `Russet Burbank'. Fresh-cut seed pieces sprayed with a suspension of Eca. (108 cfu/ml) were planted in separate 1-liter containers filled with field soil maintained under two soil moisture regimes: 1) air-dry days 1–5, saturation days 6–10, field moisture capacity (FMC) days 11–18, or 2) FMC days 1–18. Containers were placed at 22C constant air temperature at the Univ. of Wisconsin–Madison Biotron. Decay severity (percent volume seed piece decay) and decay incidence (percent tubers with any decay) were rated after 18 days. Eight seed pieces per treatment were evaluated. The mean tuber Ca concentration was higher in plots receiving calcium compared to nonsupplemented plots. Mean medullary Ca concentration varied among cultivars as `Russet Burbank' > `Atlantic' > `Superior' > `Red Norland'. The influence of cultivar on decay showed an incidence and severity pattern `Atlantic' = `Russet Burbank' > `Superior' = `Red Norland'. Decay incidence and severity were greatest in seed pieces kept in temporarily saturated soil compared with those in soil maintained at FMC. Decay incidence and severity were ≈6% lower in tubers produced on Ca-supplemented soil. A scatter plot of decay severity × Ca concentration for seed pieces held at FMC suggests that a threshold of Ca concentration exists above which little or no decay occurs.
Coating Waxes on Pepper Fruits cv. Caribbean and Quality on Different Storage Conditions
Authors: Manzano-Méndex Juan E. , Zambrano Judith
Published: February 2019

Pepper fruits (Capsicum annum L. c.v. Caribbean) were treated with two commercial was coatings, Primafresh and Prolong. Fruits were sprayed with Primafresh (original concentration) and Prolong at 0.5% and 1.5% (w/v) concentration. Fruit samples were taken for analysis each of 5 days during 20 days from storage rooms at 1, 5, 10, and 15C. Parameters TSS, titratable acidity, pH, fresh fruit weight loss, texture, and dry matter content were analyzed. TSS and dry matter decreased with the storage time. Titratable acidity increased until 10 days after storage and decreased when fruit were stored for a longer time. The lowest texture deformation was observed at 1 and 5C. Coating treatments reduced the rate of fresh fruit weight loss of peppers compared to uncoated ones.
Ethylene Production Rate and Postharvest Shelf-life Diversity in Melon (Cucumis melo L.) Germplasm
Authors: Wolff David W. , Dunlap James R.
Published: February 2019

Cucumis melo varieties show a great diversity of ripening and abscission phenotype, ethylene production, and postharvest keeping quality. As a preliminary step in the development of melons with improved shelf-life and modified ripening, we surveyed 100 genotypes of melons with diverse ripening characteristics for ethylene production rate and shelf-life. Genotypes representing seven melon types (Western shipper cantaloupes, Eastern cantaloupes, Long shelf life cantaloupes [LSL], Charenteis, Galias, Honeydews, Casabas) were planted in the field in a randomized complete block with three replications. C. melo var. reticulatus and C. melo var. inodorus were harvested 40 and 50 days post-anthesis, respectively, and brought in the lab for ethylene production measurement. Fruit at horticultural maturity were also harvested and stored at room temperature. After 7 days, a postharvest decay rating (1 = complete rot and collapse–5 = no softening or decay) was taken to determine relative shelf-life of the genotypes. Average ethylene production rate ranged from 44.44 to 0.64 nl·h–1·g–1 for Eastern cantaloupes and Casaba melons, respectively. A negative linear relationship was observed between ethylene production rate and postharvest decay rating. LSL cantaloupes had the lowest ethylene production rate of the netted, orange flesh types. The relationship between ethylene production rate and polymorphism for ACC oxidase (pMEL1) and ACC synthase (pMEACS1) cDNA probes is being investigated.
Differential Reaction of Melon (Cucumis melo L.) Germplasm to Monosproascus Vine Decline
Authors: Wolff David W.
Published: February 2019

We conducted a field screen of 130 melon cultigens to identify potential sources of host-plant resistance to Monosporascus cannonballus. Seed were sown in Speedling trays with inoculated or non-inoculated media. Plants were transplanted into a field known to be highly infested with Monosporascus cannonballus. Noninoculated plots were planted in rows that were fumigated with Telone II. Cultigens were arranged in a randomized complete block with three replications in each treatment (fumigated, nonfumigated). A disease symptom rating (1 = complete death to 5 = no symptoms) was taken at 78 and 90 days post-transplanting. Disease symptoms were most severe and occurred earliest in the inoculated, nonfumigated plots. Natural infection by Monosporascus occurred in the fumigated plots as over 95% of root samples collected contained perithecia. At the second rating date, 108 of the 130 cultigens tested were classified as moderately to highly susceptible (rating < 2.5). The four most resistant genotypes had a second rating equal or close to 4.0 (`Galia', `Deltex', `Rocky Sweet', and `Charlynne'). A group of 14 genotypes showed moderate resistance with a second rating of 3.0. Included in this group were `Morning Ice', `Doublon', `Israeli', `MR-1', `Santa Clause', and `Primo'. The physiological stress of a concentrated fruit set increases severity of vine decline symptoms.
Potential of Plant Cystatins for the Production of Transgenic Strawberry Plants Resistant to the Black Vine Weevil
Authors: Michaud Dominique , Vrain Thierry C. , Daubeny Hugh A.
Published: February 2019

Transformation of plant genomes with cysteine proteinase inhibitor (cystatin) genes represents an attractive option for the biological control of insect pests. However, this strategy must be carefully considered, because the transgenic plant endogenous proteinases may represent potential target enzymes for the exogenous inhibitors produced. For example, we are considering the transformation of strawberry (Fragaria ×ananassa) with cystatin cDNA clones, to control the Coleoptera pest black vine weevil (BVW; Otiorynchus sulcatus). Electrophoretic analyses of adult BVW proteinases have revealed the involvement of at least five proteinase forms for protein digestion, and the major form was strongly inhibited by oryzacystatins (OCI and OCII), two cystatins isolated from rice seeds. A similar analysis of proteinases showed the existence of OC-sensitive proteinase activity in the leaves of strawberry, suggesting a possible risk of interference of the inhibitors in the transformed plants. In addition, the two rice inhibitors were rapidly hydrolyzed at 25C when incubated with proteinase extracts from either young, mature or senescent leaves. An efficient control of BVW by plant cystatin-expressing transgenic strawberry plants is therefore potentially possible, but the correct targeting of the inhibitors in the plant cells using appropriate signal peptides could be necessary.
Native Sand-prairie Plants That are Poor Hosts for Pratylenchus penetrans
Authors: McKeown Alan W. , Potter John W. , Gartshore Mary , Carson Peter
Published: February 2019

Root lesion nematodes (Pratylenchus penetrans Cobb) are well-adapted to sandy soils and have a host range including most agronomic, horticultural, and wild species grown in Ontario. As native climax sand-prairie species have coexisted with the nematode for millennia, resistance or tolerance may have developed. We have screened using the Baermann pan technique, soil samples taken from a private collection of sand-prairie species collected from local prairie remnants. Several species [Liatris cylindracea Michx., Monarda punctata L., Pycnanthemum virginianum L., Echinacea purpurea (L.) Moench] proved to be excellent hosts (>500/kg of soil) of root lesion nematode, confirming the presence of this nematode in the soil. Over two seasons, we determined that 10 plant species belonging to the families Asclepiadaceae, Compositae, Graminae, and Leguminosae to support very low numbers of P. penetrans. Brown-eyed susan (Rudbeckia hirta L.) had no root lesion nematodes throughout both seasons, Butterfly weed (Asclepias tuberosa L.) very low counts, while Switch grass (Panicum virgatum L.) and Indian grass [Sorghastrum nutans (L.) Nash] had detectable root lesion nematodes on only one sampling date each year. Big Bluestem (Andropogon gerardii Vitman), Little Bluestem [Schizachyrium scoparium (Michx) Nash], Sand Dropseed [Sporobolus cryptandrus (Torr.) Gray], Side-oats Grama [Bouteloua curtipendula (Michx.)) Torr], Broomsedge (Andropogon virginicus L.), Bush clover [Lespedeza capitata (Michx] also are poor hosts. These species have potential as cover or rotation crops useful for nematode management.
`Black Ruby', a Japanese-type Plum Adapted to the Humid Southeastern United States
Authors: Okie W.R.
Published: February 2019

`Black Ruby' is the newest plum released by the USDA stone fruit breeding program at Byron. This variety has large, firm fruit that ripens in early July, about 1 week after `Santa Rosa'. Fruit has reddish-black skin and yellow flesh. Eating quality is very good. `Black Ruby' has an upright tree similar to `Santa Rosa', except that tree health and vigor are much better than `Santa Rosa'. USDA has been breeding plums for the humid Southeast for 30 years. Goals are to combine large, firm, high-quality fruit with a disease-resistant tree that will live 8 to 10 years. Most plum varieties are short-lived in our area due to disease caused by Xanthomonas, Pseudomonas, and Xylella. Most existing varieties adapted to our climate have fruit unsuitable for commercial production. Previous USDA releases include “green plum” types `Robusto' (1980) and `Segundo' (1984); a yellow plum, `Byrongold' (1985); a black shipping plum, `Explorer' (1980); and the blood-fleshed, high-quality `Rubysweet' (1989).
`Platonivs'ka': A New Scab-resistant and Cold-hardy Pear Cultivar
Authors: Kucher Anatoliy , Granger Raymond L.
Published: February 2019

`Platonivs'ka' has been released as a new autumn pear cultivar that combines scab (Venturia pirina Aderh.) resistance and cold hardiness under Ukrainian climate and soil conditions, selected from a cross of `Hybrid 1931' (`Oleksandrivka' × `Dekanka du Comice') × Beurré Bosk. The trees grow vigorously, are adequately winter-hardy, and resistant to both leaf and fruit scab. Very good tree productivity has been observed when `Platonivs'ka was grafted on Limonska Oleksandrivka, Wild Forest Pear, Quince A, or BA-29 rootstocks. The fruit attains its picking ripeness between 10 and 20 Sept. (2 weeks after `Bartlett') and eating ripeness between the beginning and end of October in Ukraine. Its storage life at 0 to 2C lasts until the end of January. The average weight per fruit ranges between 180 and 200 g (70–75 mm in diameter). The fruit eating quality is excellent; its juicy and pleasant sugar/acid ratio makes it a very good dessert pear. Fruits are ovatepyriform in shape. Their skin color is light grayish-green and their finish is glossy at harvest. Flesh texture is moderately find and buttery. At harvest, grit cells are small and evenly distributed in the flesh and they become inconspicuous when the fruit is held at 20C for a week. `Platonivs'ka' is recommended for both home and commercial orchards.
Identification of a RAPD Marker Linked to Eastern Filbert Blight Resistance in Hazelnut
Authors: Davis Joel W. , Mehlenbacher Shawn A.
Published: February 2019

Eastern filbert blight (EFB) is a serious disease of hazelnut and threatens crop production in the Willamette Valley of Oregon. We have employed the use of the bulk segregant analysis method to screen RAPD primers for identification of a marker linked to a disease-resistance gene for this pathogen. Using 100 progeny from a modified backcross population segregating for resistance to the disease, two pooled DNA samples from 10 individuals of each phenotype were constructed. One-hundred 10-mer PCR primers were screened for bands present in the resistant pool, but absent in the susceptible pool. We identified one primer that produces a marker cosegregating with resistance and appears to be linked to the resistance gene (frequency of recombination = 0.17). This marker proved to be easily scoreable and reliably reproduced, even under varying amplification profiles. From these results, we have determined that this method may be suitable for identification of markers more closely linked to the resistance gene. Such a marker would be useful for early selection of seedlings having resistance to EFB.
Rubus Genetic Resources in Bolivia
Authors: Ballington James R. , Messinger Wes , Williams David F. , Garcia Emilia
Published: February 2019

Intermountain valleys in the Andean region of Bolivia are rich in diversity of Rubus species. Species in both subgenus Orobatus and subgenus Rubus occur in this region. These species include Rubus betonicifolius, R. bogotensis, R. Boliviensis, R. briaceus, R. holtenii, R. imperialis, R. macrocarpus, R. megalococcus, R. nubigenus, and R. roseus. Rubus macrocarpus and R. roseus have previously been determined to be worthy of domestication and commercialization as new crops in tropical highlands. The potential of the other species as new bramble crops and for use in breeding will be discussed.