bluuebunny/crossref_metadata_2025 huggingface dataset:
THE GENUS CARYA IN NORTH AMERICA.
Authors: Grauke L. J.
Published: April 2024

The genus Carya is represented in North America by two Sections, with 14 species. Section Apocarya includes 4 U.S. and 1 Mexican species, all of which are diploid (n=16). The only commercially important Apocarya species is pecan, Carya illinoinensis (Wangenh.) K. Koch. Utilization and possible dissemination of pecan by man is evident in the archeological record to 6000 B.C. Patterns of genetic diversity in pecan in relation to geographic origin will be discussed for both native and cultivated trees. Other species of section Apocarya will be introduced and their potential role as rootstocks or for cultivar development through interspecific hybridization will be discussed. Section Carya includes 9 species, some of which are diploid (n=16) and some tetraploid (n=32). Horticultural selection has been greatest in the diploid species of the section [C. ovata (Mill.) K. Koch and C. laciniosa (F. Michx.) Nutt.]. Native species distributions and prominent cultivars will be discussed, along with problems associated with commercial culture of hickories.
MANAGEMENT TOOLS FOR TREE NUT CROPS: WHAT ABOUT THE SOUTHERN OSCILLATION?
Authors: Wood Bruce W.
Published: April 2024

Worldwide weather is closely associated with a cyclic oscillation in atmospheric pressure in the equatorial Pacific Ocean. This Southern Oscillation event affects regional weather via atmospheric teleconnections in both the Northern and Southern Hemispheres. When these episodes exceed certain thresholds, sunlight, temperature and precipitation in orchards strongly deviate and potentially cause severe biotic and abiotic stress-related problems. Such events therefore influence management strategies, marketing, and revenues.

Analysis of weather in the `Georgia Pecan Belt' indicates that patterns exist and that such patterns are predictable and appear to be regulated by the Southern Oscillation. Periods of exceptionally excessive rainfall and lack of rainfall are associated with these oscillations; therefore, disease, water, and sunlight management strategies and harvesting strategies are subject to alteration based on events transpiring several months previously. These data indicate that Oscillation events have the potential to be utilized as a tool to enable orchard managers to better protect orchards against weather anomalies.
TEACHING MENDELIAN GENETICS WITH TOMATO SEEDLING MUTANTS
Authors: Tigchelaar E.C.
Published: April 2024

The tomato rivals the fruit fly as a convenient species for genetic research. As an important and familiar food crop, the tomato is also a useful species to demonstrate application of the principles of genetics for crop improvement.

Fifteen unique seedling mutants which are expressed during the first 2-3 weeks of seedling growth have been selected to illustrate genetic variation and to demonstrate the common principles of genetics. Appropriate markers have been used in crosses to demonstrate segregation, lethal genes, independent assortment, repulsion and coupling phase linkage, epistasis, and random chromosome and chromatid segregation). F2 populations segregating for as many as seven marker genes have been developed to illustrate gene interaction and to demonstrate the remarkable variation possible even with a small number of segregating gene pairs. Unknown populations may also be used to challenge students to independently analyze an unknown population for two or more of the 15 seedling marker genes chosen. A small greenhouse or laboratory bench with growing lights will provide adequate space for each exercise.
ORCHARD GROUND COVER MANAGEMENT AFFECTS TREE FRUIT PRODUCTION
Authors: Skroch Walter A.
Published: April 2024

Studies indicate that growth of apple and peach trees and yield of apple fruit is affected by ground cover management. Living ground covers compete with trees for water and nutrients, but bare ground (clean culture) results in soil compaction, increased runoff and erosion, and poor maneuverability of equipment. Competition between orchard trees and living ground covers is a factor in tree growth, timing of the first crop year, and fruit yield and quality. Certain grasses tend to be more competitive than broadleaf ground covers. Cool-season grasses (bluegrass, orchardgrass, tall fescue) under Red Delicious and Golden Delicious apples were shown to reduce soil moisture levels, reduce fruit yield and size, and delay fruit maturity. Various vegetative ground cover systems (strip cover, cover crop, herbicide no-till) and ground cover types can be utilized to reduce soil erosion and maintain soil structure, while at the same time reduce competition with trees and optimize crop yield and quality.
MAP OF BLUEBERRY FRUIT: EFFECT OF TEMPERATURE AND CO2 ON PACKAGE O2 AND THE RQ BREAKPOINT
Authors: Beaudry Randolph M.
Published: April 2024

The respiratory behavior of blueberry (Vaccinium corymbosum L. `Bluecrop') fruit was determined under a variety of conditions using a modified-atmosphere packaging (MAP) approach. In each case, O2 and CO2 partial pressure gradients across the film were used to calculate rates of O2 uptake, CO2 production and the respiratory quotient (RQ). The effects of temperature and O2 partial pressure on O2 uptake, CO2 production and the RQ were characterized. The steady state O2 partial pressure at which the fruit began to exhibit anaerobic CO2 production (the RQ breakpoint) increased with increasing temperature from approximately 2 kPa O2 at 0C to 4.5 kPa O2 at 25C. It was determined that the energy of activation of O2 permeability for a film needed to be approximately 60 kPa to maintain O2 levels at or above the RQ breakpoint across this temperature range. RQ was also dependent on CO2 levels. As CO2 partial pressure increased, the RQ breakpoint increased. The lower O2 limit was estimated to be 6, 7, 11 and 23 kPa O2 for 5, 20, 40 and 60 kPa CO2, respectively, at 15C.
RECLAIMED WATER FOR CITRUS: EFFECTS OF IRRIGATION RATE ON TREE GROWTH AND YIELD.
Authors: Wheaton T. Adair , Parsons Larry R.
Published: April 2024

This study was designed to determine the effects of different irrigation rates with reclaimed water on citrus tree growth and yield. High application rates (1270 and 2540 mm per year) of highly treated reclaimed water were compared to a recommended rate of 406 mm per year of reclaimed or well water. Greater irrigation significantly increased tree growth and fruit yield. Canopy volume at the 2540 mm rate was 55% greater than the 406 mm rate. With Hamlin orange and Orlando tangelo, fruit yields at the highest rate were 39 and 71% greater, respectively, than the lowest rate. Soluble solids were diluted at the higher irrigation rates, but total production of soluble solids per hectare was significantly greater at the high irrigation rates. Yield response was greatest at the high irrigation rate with Swingle citrumelo rootstock. On deep sands, high irrigation rates can improve tree growth and yield in a humid region.
PESTICIDES TOXICITY ON POLLEN GERMINATION OF `HADEN' MANGO (Mangifera indica L.)
Authors: Shu Zen-hong
Published: April 2024

It has been speculated for many years that crop yield diminution may be due to the possible adverse effects of pesticidal sprays during the blooming period on pollen germination and fruit set. To realize the toxicity of pesticides on the reproductive physiology of mango, pollen germination, both in vitro and in vivo, under the constrain of pesticides were conducted. The results showed that among all the pesticide tested, Lannate and Tamaron were the least toxic ones to mango pollens germinated on agar medium incorporated with pesticides. Pesticides when sprayed on the surface of germination medium had strong adverse effect on pollen germination. Except for Tamaron, the fertilization of mango flowers were extremely sensitive to pesticidal sprays 2 hours before or 4 hours after hand pollination. Fertilization and initial fruit set were not or less influenced by pesticides for flowers sprayed 24 hours after pollination.
LOSSES IN FRUIT YIELD DUE TO MANGO MALFORMATION.
Authors: Ibrahim M. , Anwar S.A. , Khan A.
Published: April 2024

Mango malformation is one of the major factors causing significant fruit loss in Pakistan. To investigate the role of malformation a long-term field experiment was established on 15 years old mango orchard. Malformation inflorescences were removed and counted in last week of April and fruit were harvested in July every year starting from 1989. Malformed inflorescence varied from plant to plant however, during 1990, 1991 and 1992 it decreased considerably over the control year (1989). The malformation was 77% during control year 1989, 57% during 1990, 57% during 1991 and 50% during 1992. Mango fruit yields were significantly decreased due to non-bearing malformed inflorescences. The mean yield decrease was 83 % during 1989 which relatively improved in later years and were 58% in 1990, 53% in 1991 and 54% in 1992.
SIMPLIFIED CONSTRUCTION AND PERFORMANCE OF A DEVICE FOR PARTICLE BOMBARDMENT
Authors: Gray D. J. , Hiebert E. , Compton M. E. , Lin C. M. , McColley D. W.
Published: April 2024

Design modification of a particle inflow-type gun for particle bombardment significantly simplifies construction and reduces fabrication time. The gun consists of a high-speed electric solenoid valve mounted on and through a vacuum jar. DNA-coated tungsten particles are placed on the support grid of a filter housing and accellerated by a burst of pressurized helium, which is controlled by a timer. Specimens are held between plastic screens and their distance from the particle support grid is adjusted with a miniature laboratory apparatus positioner. Transient expression of GUS in cantaloupe cotyledons and grape somatic embryos was equivalent to that obtained with a conventional particle inflow gun. The device was constructed with locally-available hardware in 40 minutes using a hand drill, some thread taps and a thread die.
CALLUS INDUCTION IN GARLIC, ALLIUM SATIVUM L., AND ITS IMPLICATION FOR TRANSFORMATION
Authors: Myers J. Michele , Simon Philipp W.
Published: April 2024

The effect of auxins and cytokinins on callus induction in garlic was investigated. Young basal plate leaf explants of one genotype were grown on a modified B5 medium supplemented with 50 hormone combinations in a complete factorial design. The best callus growth occurred on media supplemented with 2,4-D (compact-not friable) or picloram + 2iP (friable with some shoot production). These two hormonal treatments were applied to 5 different garlic genotypes. After 10 weeks, callus was transferred to the other hormonal treatment. The best induction of friable callus occurred when explants were initially cultured on media with 2,4-D and then subcultured on media with picloram + 2iP. This friable callus is being evaluated for developing suspension cultures and a genetic transformation system.
MYCORRHIZAE IN HIGHBUSH BLUEBERRIES: SURVEY RESULTS AND FIELD RESPONSE TO NITROGEN
Authors: Goulart B. L. , Demchak K. , Schroeder M. L. , Clark J.R.
Published: April 2024

The current state of knowledge regarding the role of mycorrhizae in Vaccinium spp. will be summarized. Survey data from Pennsylvania, New Jersey and Michigan indicate higher levels of mycorrhizae in both native and commercial plantings than have been previously reported for other locations in the U.S. However, level of infection was not correlated with soil ammonium, nitrate or organic matter. In a separate experiment, nitrogen supplied either as urea (67 kg actual N/Ha) or in a slow release formulation suppressed mycorrhizal development. Mycorrhizae infection level was highest in the fine feeder roots close to the crown, as compared to medial or apical portions of the root
INFLUENCE OF ORGANIC MULCHES AND DOUBLE CROPPING ON BELL PEPPER AND WINTER SQUASH YIELDS
Authors: Roe Nancy E. , Bryan Herbert H. , Stoffella Peter J.
Published: April 2024

Dried sewage sludge (SS), municipal waste compost (MW), wood chips (WC), at 224 and 336 t·ha-1 and white polyethylene (WP) were applied as mulches on raised beds. `Tivoli' squash was direct seeded. Squash yields were 13.4, 11.9, 7.7, and 5.1 t·ha-1 from WC, MW, WP, and SS treatments, respectively, with WC and MW having significantly higher yields than WP and SS. Fruit weight per plant was significantly higher in WP and WC plots. Pepper plants (cv. `32008') were transplanted into the same plots, 5 months after squash harvest. Pepper yields, 4.7, 4.2, 2.9, and 2.6 t·ha-1 on WP, MW, WC, and SS treatments, respectively, were not significantly different. Fruit weights per plant were significantly different and varied in the order WP>MW>WC=SS. No yield differences occurred between rates of organic mulches in either crop. Diseased plants in WP plots resulted in lower total yields than organic-mulched plots, but individual plants on polyethylene yielded higher than others.
LETTUCE SEEDLING PRODUCTION FOR HYDROPONICS
Authors: Reiser Ramona A. , Langhans Robert W.
Published: April 2024

A production system for lettuce seedlings aimed at uniformity and repeatability for transplanting into a hydroponic system has been researched. Parameters for the initial 24 hr. germination period include low light levels (85 μmols), 20°C temperature to avoid thermodormancy, and no fertilizer in the media or nutrient solution to avoid imbibition and osmotic problems from salts. The 10 day nursery environment begins at 24 hrs. with 250 μmols of constant fluorescent light, 25°C and addition of 1/2 strength fertilizer. A sample size of 24 seedlings for dry weights at Day 7 and 11 (transplant) has established a growth curve for experimental comparison. Selection on Day 6 for uniformity at transplant eliminates small and large seedlings based on size and unfolding of first true leaf. Medias researched include oasis, rockwool, Metro Mix 360, peat-vermiculite and `rubber dirt'. Container type, cell size and transplanting techniques have proven plastic cells with peat-vermiculite optimum. Fertilizer has been incorporated into the media or added at 0, 24, 48 or 72 hrs. after germination with 24 hrs. proving optimum. Dry weights and growth chamber uniformity were compared.
QUALITY OF CUT FLOWER SNAPDRAGONS (ANTIRRHINUM MAJUS L.) AS INFLUENCED BY ROOT-ZONE HEAT AND NIGHT AIR TEMPERATURES.
Authors: Maqbool Muhammad , Newman Steven E.
Published: April 2024

Nine snapdragon cultivars of different response groups were transplanted into a double polyethylene greenhouse to determine the impact of no heat and 25C root-zone heat (RZH) and five night temperatures (NT) (10 to 26C at 4C increments) on plant growth and flower quality. Two weeks after transplanting, stem length was measured biweekly to compare growth rates under the existing conditions. Stems were tagged and the date recorded when the first floret showed color and harvested when the lower third of the florets were at anthesis. Flower quality was evaluated at harvest based upon stem length and fresh weight. Cultivars `Oakland', `Cheyenne', and `Montezuma' were the first to bloom under 26C NT regardless of RZH; whereas, `Potomac Pink' and `Oklahoma' were delayed. Similar trends were observed under each NT with days to anthesis increasing with decreasing NT. Flower quality was improved at the lower night temperatures.
INTERACTION BETWEEN PHOTOPERIOD, TEMPERATURE FLUCTUATIONS AND CYTOKININ ON PHARBITIS FLORAL INDUCTION.
Authors: Reese Cheryl L. , Erwin John E.
Published: April 2024

Etiolated seedlings of Pharbitis nil Chois. cv`Violet' were germinated and grown at 24C for 4 days and were then placed in controlled environment chambers (CEC) maintained at 12, 18, 24, 30 or 36C for flower induction. Seedlings were rotated among chambers to result in 25 day/night temperature (DT/NT) treatments. Photoperiod was 8, 12, or 16 hr (250 umols-1 m-2). N-6-benzyladenine (BA) (120 uM) was applied to half the seedlings in each treatment 1hr prior to the inductive night period. After the inductive night period, seedlings were placed in a CEC maintained at 24C under continuous light. Data were collected on percent flowering and flower number at anthesis. Flowering was a function of NT and photoperiod. Flowering increased as night length increased and as NT approached 30C. DT (30C) promoted flowering to a lesser extent than NT. Flowering did not occur on plants grown with a 8hr night length. Flowering occurred on plants grown with a 12hr night length when BA was applied and when plants were grown at 30/24 or 30/30C DT/NT. Seedlings flowered under the 16hr night length when NT was 30C without BA application; flowering occurred with 24 or 30C NT when BA was applied.
HORTICULTURAL CONSULTING FOR CHEMONICS--A PRIVATE TECHNICAL SERVICES AND PROJECT MANAGEMENT COMPANY
Authors: Lamb John E.
Published: April 2024

Chemonics has consulting experience with private enterprises, investment and trade promotion entities, research centers, universities, foreign assistance donors, and government and parastatal institutions in over 60 countries. A majority of this activity is financed by AID. Horticultural activities have emphasized all aspects of work with edible crops but consulting assignments have included cut flowers, ornamental plants, foliage, spice and nut crops. In recruiting long-term and short-term consultants, Chemonics considers quality and relevance of formal education, work experience, analytical and interpersonal skills, familiarity with applicable cultures and languages and demonstration of successful performance in appropriate activities.
RECLAIMED WATER AND IRRIGATION OF MATURE `REDBLUSH' GRAPEFRUIT TREES.
Authors: Maurer M.A. , Davies F.S.
Published: April 2024

A field study was conducted near Vero Beach, Fla. on poorly drained (flatwoods) soil to determine the effects of reclaimed water on the growth and development of mature `Redblush' grapefruit trees (Citrus paradisi Macf.) on sour orange (Citrus aurantium L.) rootstock. Treatments consisted of a control (canal water), and reclaimed water applied at 2.31, 3.07 and 3.86 cm/wk. For the first two years after treatments were implemented there were no significant differences among treatments in yields, trunk diameter, fruit growth rates or fruit quality (fruit and juice weight, total soluble solids, acids or solids:acid ratio), and leaf nutrient levels. Moreover, although reclaimed water increased leaf B, Na and Cl levels over control values, no toxicity symptoms were observed. Soil moisture content was always well above field capacity for the reclaimed water treatments; however, soil redox potentials rarely were in the anaerobic range. The reclaimed water treatment receiving 3.86 cm/wk also provided about 80 kg/ha of N which is ⅔ of the yearly N requirement. All reclaimed water treatments caused significantly greater weed growth than control treatments.
GENETIC MAPPING AND QTL ANALYSIS OF A RECOMBINANT INBRED TOMATO POPULATION USING MOLECULAR MARKERS
Authors: Paran I. , Zamir D. , Goldman I.L.
Published: April 2024

Recombinant inbred (RI) populations are a valuable genetic resource for mapping traits. An RI population composed of 100 F8 lines was developed from a cross of the cultivated tomato and a related wild species L cheesmanii. RI lines were grown in field trials in 1991 and 1992, and were evaluated for soluble solids, fruit weight, pH, and other parameters. Lines were genotyped for 130 RFLP and RAPD markers. A genetic map of the RI population was constructed, revealing large increases in recombination frequency between linked markers (as compared to F2 data) which is characteristic of RI populations. Percent heterozygosity was greater than expected for F8 lines. Segregation at most marker loci was skewed toward esculentum alleles. Quantitative trait locus (QTL) analysis revealed significant associations between selected marker loci and each of the traits measured, many of which were consistent with associations observed in this cross in the F2, thus confirming the chromosomal location of important QTL in processing tomato.
NITROGEN CONCENTRATIONS TO MAXIMIZE YIELD AND DECREASE LEACHATE-N IN PEPPERS GROWN IN ROCKWOOL.
Authors: Schon M.K. , Compton M.S. , Burns I. , Bell E.
Published: April 2024

Many nutrient recommendations for greenhouse production of vegetable crops were developed in northern climates and may not be optimum for Florida production. Experiments were designed to determine nitrogen (N) levels that would maximize yield of rockwool-grown peppers (Capsicum annuum `Midal') in Florida, while reducing nitrate leaching. Treatment 1 plants were fed 60, 90, and 120 ppm N during vegetative, early fruit, and late fruit stages, respectively. Plants in Treatments 2 and 3 were grown at 120 and 175 ppm N, respectively, throughout their entire growth cycle.

In Trial 1, increasing N did not affect the number of marketable fruit produced, but increased fruit size. Marketable fruit weight was significantly greater for plants in Treatment 3 compared to Treatment 1. However, there was not a significant difference in marketable yield between plants grown at 120 ppm N and 175 ppm N. Excess N provided by the 175 ppm N treatment caused a 10% increase in total water use and a 250% increase in nitrate-N in the leachate compared to the 120 ppm N treatment. Nitrogen level did not affect blossom end rot (BER) occurrence. Early results of Trial 2 indicate higher occurrence of BER with increasing N concentration and are again showing that 120 ppm N will maximize yield and reduce environmental impact of greenhouse pepper production in Florida.
FOLIAR NUTRITION OF TOMATOES UNDER SUSTAINABLE SYSTEMS USING PLANT MULCHES AND LOW-N INPUT
Authors: Korcak R. F. , Abdul-Baki A. , Teasdale J.
Published: April 2024

Tomato (Lycopersicon esculentum Mill., cv. Sunny) plants were grown in a sustainable agricultural system of mulches: black plastic, paper, hairy vetch, crimson clover, and hairy vetch + rye. Total yields were highest with hairy vetch (85.8 t ha-1) and lowest with paper mulch (30.0 t ha-1). The low fertilizer input hairy vetch, crimson clover and hairy vetch + rye treatments received one-half the N-P-K fertigation that was applied to other treatments. Immediately before mowing the cover crops, samples were analyzed. Five weeks after transplanting the tomatoes and at the end of 12 weeks, leaf samples were analyzed for macro- and micro-nutrients. Results of the cover crop analyses indicated minimal differences in N, P, K, Ca, Mg, Mn, B, and Fe concentrations. Tomato leaf analyses at 5 weeks after field planting showed that, among the macro-nutrients, only K was significantly higher in the hairy vetch, hairy vetch + rye, crimson clover, and black plastic treatments than in bare soil and paper mulch. End-of-season leaf analyses showed that significantly higher K was found in the vetch + rye treatment compared to all other treatments.
FIELD CHLOROPHYLL AND PETIOLE SAP NITRATE INDICATE THE NITROGEN STATUS OF POTATO VARIETIES
Authors: Minotti Peter L. , Halseth Donald E.
Published: April 2024

We report field experiments, under N limiting conditions, where applied N was varied between 0 and 252 Kg/ha. Two varieties (Castile and Allegheny) were planted in 1990 and 3 varieties (Katahdin, Monona and Superior) were planted in 1991. A curvilinear tuber yield response to N rate was obtained both years for all varieties with maximum yields at about 168 Kg/ha of N. Weekly field measurements with a hand-held chlorophyll meter (Minolta SPAD 502) were highly correlated to yield, to fresh petiole sap nitrate, to dry petiole nitrate and to the total N of whole leaves, all of which were generally highly correlated to each other and markedly affected by applied N. As plants matured the chlorophyll readings, and concentrations of nitrate and N decreased. In general variety differences or variety × N rate interactions were not significant which encourages the use of such tests to avoid unnecessary N sidedressings.
THE EFFECT OF VARIOUS RATES OF N AND S ON THE ASCORBIC ACID CONTENT OF LEAF LETTUCE
Authors: McCluskey Melinda McVey , Paparozzi Ellen T. , Albrecht Julie A.
Published: April 2024

Research previously conducted on leaf lettuce has shown that altering the amount of N and S applied had an effect on plant growth, color, N content and S content. The amount of N and S applied to the plant also affected consumer acceptance of leaf lettuce.

The leaf lettuce cultivar `Grand Rapids' was grown hydroponically at 8 different treatment combinations consisting of four N levels (30, 60, 120, and 240 ppm) and three S levels (7.5, 15, and 120 ppm). Ascorbic acid content was determined immediately after harvest using the 2,6-dichloroindophenol method. Color was measured with a chromometer.

Results indicate that differences in ascorbic acid content could be detected between the various treatments. Plants which were darker green in color contained more ascorbic acid than plants yellow-green in color. Nitrogen applied had a significant effect on the ascorbic acid content while sulfur applied had no effect on ascorbic acid content of fresh leaf lettuce.
Growth and Stomatal Conductance of `Amate' Schefflera Using Exterior Retractable Shading
Authors: Svenson Sven E. , Johnston Diane L.
Published: April 2024

Growth and stomatal conductance of Schefflera actinophylla (Endl.) Harms `Amate' was studied in response to production shading environment. During two different growing seasons, plants grown under stationary shading (50% shade) had more shoot dry weight, were taller, and had larger stem diameters 2, 3, 4 and 5 months after potting, compared to plants grown without shading. Similarly, plants grown under retractable shading (50% shade) had more shoot dry weight, were taller, and had larger stem diameters than plants grown under stationary shading. There were no differences between plants grown under stationary or retractable shading after 5 months. Stomatal conductance of canopy-shaded foliage did not differ between plants grown under stationary or retractable shading when shading was extended or retracted. The increasing amount of foliage that becomes shaded by the canopy as the plant grows may limit the advantages of using exterior retractable shading.
EFFECT OF PERFORATED FILM PACKAGES ON STORAGE OF ASPARAGUS
Authors: Herner Robert C.
Published: April 2024

Some horticultural crops have very high respiration rates which makes it difficult to develop modified atmosphere packages that will prevent the product from being injured by high CO2 or from injury by low O2' or anaerobic conditions. Asparagus has a very high respiration rate and responds well to relatively high CO2. Oxygen concentration is less important providing that the asparagus does not go anaerobic.

This investigation reports the results of holding asparagus at 0 C in packages of 3 film thicknesses (1, 2 or 3 mil LDPE) and varying the number of holes from 0 to 16 per package. Five hundred grams of asparagus was held up to 4 weeks. Carbon dioxide and oxygen inside the packages was monitored as well as the quality of the asparagus.
INTRODUCTION TO COMPUTER MODELLING
Authors: McGiffen Milton E.
Published: April 2024

Computer modelling uses mathematical relationships to characterize a complex system. There are several reasons for using mathematical modelling in crop production: 1) Models serve as a framework to bring together and order our concepts of an agricultural system, 2) Many processes are so dynamic that they cannot be adequately measured in the field, but can be examined with models, 3) Once a model has been built, it can be used as a tool to study problems that would be difficult to approach experimentally, and 4) Computer modelling often results in software that can be made interactive and user-friendly for wide distribution. Different methods of computer modelling include regression, simulation, and the systems-oriented approach. Regression is the most widely used approach, and is good for developing simple relationships from experimental data. However, regression models are often oversimplified and may not transfer well. Simulation models are built from many subroutines of individual processes that are linked to simulate a complex problem, such as the physiology of crop growth. A systems approach uses a variety of techniques to help users meet predetermined management goals.
BIOECONOMIC WEED MANAGEMENT MODELS
Authors: Forcella Frank , King Robert , Wiles Lori , Buhler Douglas , Swinton Scott , Gunsolus Jeffrey , Maxwell Bruce
Published: April 2024

Bioeconomic weed management models integrate the complex interactions of the biology of crops and weeds, efficacies and costs of chemical and mechanical weed control options, and commodity prices of crops. These models enable producers to customize weed management strategies so that weed control and crop yields are optimized while net economic returns are maximized. A prototype model, WEEDSIM, was developed (Swinton & King) for corn and soybean production. It was field-tested for two years in Minnesota. WEEDSIM's recommendations were agronomically equivalent to standard farmer practices, but they increased net financial returns and reduced chemical release to the environment. A new bioeconomic modeling “shell” has been developed (Wiles & King) to increase adaptability to new crops, weeds, control options, and production regions.
DRIP IRRIGATION OF VEGETABLE CROPS IN THE SOUTHWEST
Authors: Hartz T.K.
Published: April 2024

The use of drip irrigation in the production of vegetable crops has expanded rapidly in the Southwest in the last decade. The factors contributing to this conversion are: a) water availability and cost, b) improved design and production of drip irrigation products which has dramatically improved performance and reliability, c) reduced cost of drip irrigation in relation to other crop production costs, and d) development of integrated management practices which maximize crop productivity and system performance. Regionally, more than 30,000 ha of vegetable crops are produced annually using drip irrigation, the majority of which is in California; major commodities are tomato, pepper, melons and salad crops. Many different types of drip installations have been evaluated. The trend in new installations is toward buried systems in semipermanent beds, with multiple crops being produced before system renovation. Specialized management practices are evolving which make such systems highly efficient.
DRIP IRRIGATION USAGE IN THE MIDWESTERN UNITED STATES
Authors: Lamont W. J.
Published: April 2024

Drip irrigation used in conjunction with plastic mulches and other intensive production technologies continues to expand in the Midwestern states. The vegetable crops being produced on the greatest acreages using drip irrigation/plastic mulch are tomatoes, peppers, muskmelons and watermelons. Summer squash, eggplant, cucumbers and some cole crops are also grown using drip irrigation and plastic mulches but to a much lesser extent. The estimated acreage for drip irrigation in the Midwest is 43,209 acres which includes both vegetable and fruit crops.

Special consideration in using drip irrigation in this region of the country are high pH of the water, amounts of calcium salts, and iron levels in the water.
ETHICAL AND SOCIAL ISSUES OF INTELLECTUAL PROPERTY RIGHTS PROTECTION OF PLANT MATERIALS
Authors: Ryder Edward J.
Published: April 2024

In January 1993, a workshop on intellectual property rights as applied to plants was held. One topic of discussion was the question of ethical and social issues that may apply to the protection of plant materials. Seven issues were identified that appeared to have ethical and social implications in such protection. These were: 1) criteria for access to germplasm, 2) the effects on global biodiversity and developing nations, 3) plants as private property, 4) effects on agricultural social structures and sustainability, 5) survival of public sector research, 6) the rights of farmers to save and sell seed, and 7) the need for education of students and the public to understand the concepts of plant protection and its ramifications. Six recommendations to clarify these questions were derived. These propose: to provide education, revise the applicable laws, support public research in plant breeding, maintain the research exemption in the use of protected materials, set up an arbitration system over disputes, and consider means of compensating developing nations for use of germplasm within their borders.

In addition, the definition, applicability, and consequences of intellectual property rights protection for plants will be discussed. In particular, the impact on the public sector and public/private sector relationships will be examined.
FIELD EMERGENCE OF SHRUNKEN-2 CORN PREDICTED BY SINGLE AND MULTIPLE VIGOR LABORATORY TESTS
Authors: Parera Carlos A. , Cantliffe Daniel J.
Published: April 2024

A rapid and reliable predictor of sweet corn seed field emergence is required to produce high-quality, uniform crops. Field emergence of seven sh2 sweet corn cultivars grown at 3 geographic locations in Florida over 2 planting periods (fall and spring) was correlated with laboratory vigor tests. Factor analysis was used to separate non-collinear vigor tests for subsequent multiple regression models. The best single predictor test (R2=0.93***) was an index based on conductivity of the leachate and germination percentage after complex stressing vigor test incubated at 15°C. Leakage conductivity after 3 h soaking at 25 or 30°C (R2=0.90***), cold test in soil (R2=0.90***), mean alternate temperature stress conductivity test (R2=0.88***), standard germination test incubated at 30°C (R2=0.88***), and the index incubated at 25°C (R2=0.88***) were also good predictors of field emergence. Non-collinear tests including the towel germination test at 25°C and an alternate temperature stress conductivity test generated the highest most significant two factor predictor (R2=0.89***), and with glutamic acid decarboxylase activity (GADA) the best three factor predictor (r2=0.93***). The index of conductivity and complex stressing vigor test (ICS) proposed as a predictor of seed emergence considered two main factors affecting emergence in sh2 sweet corn: the condition of the membrane of the seeds and potential pathogen infection.
CO2 AND TEMPERATURE INTERACTION ON STARCH AND MINERAL CONCENTRATIONS IN POTATO LEAVES
Authors: Cao W. , Tibbitts T.W.
Published: April 2024

Foliar concentrations of starch and nutrients (N, K, Ca, Mg, P and S) were determined in three potato (Solanum tuberosum L.) cvs Denali, Norland and Russet Burbank grown for 35 days under 500, 1000, 1500 and 2000 ppm CO2 at each of 16 and 20C. The plants were grown in 8-liter plastic pots containing commercial peat-vermiculite mix under controlled environments with 450 μmol m-2 s-1 PPF for 12 h photoperiod. The average starch concentrations in three cultivars increased from 4.4% to 18.5% d.w. with increased CO2 and decreased temperature. The starch concentrations were linearly related to specific leaf weight with a R2 of 0.97. With or without starch correction, the concentrations of N, Ca, Mg, P and S on dry weight basis tended to decrease with elevated CO2, and reduced temperature whereas the concentration of K did not change with the CO2 levels and was higher at 16C than at 20C. Combined mineral concentrations of N, Ca, Mg, P and S, before or after starch correction, were negatively related to the starch concentrations up to 14%, and then changed only slightly with higher starch concentrations. These results will be discussed in terms of potential growth enhancement from CO2 supplementation.
CHILLING INJURY ON GRAPEFRUIT IS RELATED TO GAS PERMEABILITY OF THE PEEL
Authors: McDonald Roy E. , McCollum T. Gregory
Published: April 2024

Differences in chilling injury (CI) susceptibility of `Marsh' grapefruit (Citrus paradisi Macf.) from interior and exterior tree canopy positions were used to determine the effects of temperature conditioning (7 days at 21C), application of squalene (10% in hexane), and high oxygen (42%) atmospheres on CI development during low temperature storage. Chilling injury was significantly lower on interior tree canopy, temperature conditioned, squalene treated, and fruit stored in ambient oxygen atmospheres compared with exterior tree canopy, nontemperature conditioned, and fruit stored in high oxygen atmospheres. Greater air flux was observed through exterior canopy compared with interior canopy fruit, and through the sun-exposed surface compared with the shaded surface of exterior canopy fruit. Rate of oxygen diffusion through the peel of exterior canopy was greater than interior canopy fruit, and through the sun-exposed surface compared with the shaded surface of exterior canopy fruit. Permeability of grapefruit peel to air and oxygen may influence the expression of CI.
EFFECT OF SUPPLEMENTAL AND PHOTOPERIODIC LIGHTING ON FLOWERING OF SATIN FLOWER
Authors: Anderson Robert G. , Jia Wenwei
Published: April 2024

Satin flower (Clarkia amoena ssp. whitneyi; syn. Godetia whitneyi) is a cool temperature plant grown as a cutflower in Japan, Europe and California with great market potential for Christmas and Valentine's Day markets. Sequential crops of 4-week-old plugs of `Grace Rose Pink,'`Grace Salmon,' `Grace Red' and `Satin White' were planted 24 Sept, 15 Oct and 5 Nov 1993. Plants were placed immediately in the following supplemental and photoperiodic lighting treatments: ambient light; incandescent light 1800 to 2400 HR, 8 μmol s-1m-2 HPS; HID light 1800 to 2400 HR, 40 μmol s-1m-2 HPS; HID light 1800 to 2400 HR, 150 μmol s-1m-2 HPS. The node number and days to flower for satin flower plants in the ambient light treatment were significantly different from lighting treatments in each crop. Node number and days to flower were similar in the three lighting treatments for the first crop. Node number was similar for the lighting treatments for the second and third crop but days to flower was significantly different between the lighting treatments.
ACCELERATING GROWTH OF GERANIUMS IN PLUGS WITH LIGHT AND CARBON DIOXIDE.
Authors: Kaczperski Mark P. , Armitage Allan M.
Published: April 2024

Seeds of Pelargonium × hortorum `Scarlet Elite' were germinated in #406 plug trays under fluorescent lights using an irradiance of 100 μmol s-1 m-2 and 18 hr photoperiod and ambient CO2. Upon emergence seedlings were exposed to irradiances of 100, 225 or 350 μmol s-1 m-2 and CO2 levels of 500, 1000, or 1500 μl l-1 for 7 to 35 days after which they were transplanted in 10 cm pots and grown to flower under greenhouse conditions. Seedling height decreased as irradiance increased, and increased as CO2 increased. Seedling quality increased with increasing irradiance and CO2. Elevated CO2 at any irradiance during the seedling stage decreased days to flower during the growing on stage.
VARIATIONS IN BRANCHING OF CHRYSANTHEMUM CULTIVARS AS INFLUENCED BY SEASON, TEMPERATURE, AND IRRADIANCE.
Authors: Schoellhorn Richard Kent , Barrett James E. , Nell Terril A.
Published: April 2024

Effects of irradiance and temperature on bud break and elongation in chrysanthemum (Dendranthema grandiflora × Ramat.) were studied. Expt. 1 - 2 growth chambers were maintained at air temperatures of 25C and 30C and within each chamber root-zone temperatures were maintained in relationship to air temperature (+ 5C, 0C, -5C). At 15C/20C and 30C/25C root-zone/air temperatures, lateral number was reduced up to 50%. Variation in response was seen between cultivars `Tara' and `Limelight'. Expt. 2 - A study of the interaction of temperature, irradiance and cultivar on lateral number showed increasing irradiance fro m 400 to 1400μmol m-2s-1 increased lateral numbers by up to 40% depending on cultivar. Cultivars `Limelight', `Tara' and `Improved Mefo' were used. Temperature had no effect on lateral number.
CARBOHYDRATE COMPOSITION OF PLANT ORGANS AND LEAF DIURNAL CARBOHYDRATE FLUCTUATION IN SNAPDRAGON
Authors: Campos Ricardo , Miller William B.
Published: April 2024

The objective of this work was to determine the carbohydrate composition of snapdragon (Anthirrinum majus L.) organs, and the diurnal carbohydrate fluctuation in leaves. Particular interest was in mannitol, a polyol that occurs in snapdragon. Mannitol was present in all organs; its concentration was highest in shoot tips (68 mg/g dw) and lowest in roots (12 mg/g dw). Mature flowers had the highest soluble carbohydrate concentration (328 mg/g dw) and roots the least (45 mg/g dw). Starch concentration varied from 15 to 60 mg/g dw. An undetermined sugar was found in all organs. In the diurnal study, conducted in the greenhouse, the undetermined sugar had the highest concentration at midnight and the lowest at noon. In vegetative plants, total soluble carbohydrates and starch were highest at 9 and 6 pm, respectively; whereas in reproductive plants, they were highest at midnight and 9 pm, respectively.
SUPPLEMENTAL SUCROSE INCREASES LONGEVITY OF MINIATURE POTTED ROSE FLOWERS
Authors: Monteiro José A. , Nell Terril A. , Barrett James E.
Published: April 2024

Potted `Orange Sunblaze' miniature roses, were grown under long days by night interruption from 2200 to 0200 HR. Flowering plants were moved to interior conditions (12 μmol s–1 m–2 from cool white fluorescent lights for 12 hr daily and 21 ± 1C) when buds were showing color and sepals were beginning to unfold. A needle connected to a reservoir containing either water or a 3% sucrose solution was inserted into stems. One flower bud was selected on each plant and other buds and open flowers were removed. Flower longevity and amount of solution/water uptake were recorded. Flowers of plants receiving sucrose lasted 2 days longer than flowers receiving water (P=0.015) with longevities of 15 and 13 days for sucrose and water, respectively. Research is being completed to relate solution uptake to respiration and flower longevity. These data show that supplemental sucrose increases flower longevity in potted plants, similar to results with cut flowers.
INHIBITION OF ETHYLENE BIOSYNTHESIS AND ACTION IN CUT CARNATION FLOWERS BY AMINOTRIAZOLE
Authors: Altman Steven A. , Solomos Theophanes
Published: April 2024

Treatment of carnation flowers (Dianthus caryophyllus I., cv Elliot's White) with 50 or 100 mM aminotriazole (ATA) for 4 days postharvest results in suppression of the respiratory climacteric and significant extension of vase life. ATA inhibited ethylene evolution and the ethylene climacteric via inhibition of the biosynthesis of ACC synthase. The inhibitory effects of ATA increased with time of exposure and concentration. Flowers treated with 50 or 100 mM ATA for 2 days exhibited a dose dependent climacteric increase in ethylene evolution and increased respiratory activity, in response to application of 10 μL/L exogenous ethylene. Senescence associated morphological changes, increased ACC synthase activity, ACC content, and ethylene evolution were completely inhibited in flowers treated for 4 days with 100 mM ATA. Although treatment with 50 mM ATA for 4 days did not completely inhibit components of the ethylene biosynthetic pathway, applicationof 10 μL/L exogenous ethylene failed to elicit any responses typically associated with carnation senescence, indicating that prolonged ATA treatment inhibited ethylene action. ATA may therefore serve as a useful tool in identifying molecular species involved in the perception or transduction of ethylene action.
DEVELOPMENT OF A COMPUTERIZED AGRICULTURAL WEATHER PROGRAM INCLUDING A FREEZE ALERT AND CHILLING ADVISORY
Authors: Powell Arlie A. , Getz Roger R. , Simpson Eugene H.
Published: April 2024

An initial effort began in 1987 to provide limited freeze forecast information to the fruit industry using a computerized program. This initial thrust at providing timely weather information to county agents and growers resulted in development of a sophisticated, user friendly program presently providing over 900 weather files daily to users. This program operates with a 420 Sun Server that automatically downloads files from the NWS office across the AU campus and makes them instantly available to county agent (CEA) offices via the Extension Network (Acenet). Growers may obtain information from CEAS or use their personal computers to access a “Weather Board” which provides the same weather products. Chilling models have been developed to provide growers information and predict guides for applying chemicals needed during mild winters. A very helpful freeze alert program is in place which includes four separate products which provide freeze predict forecasts and a commentary to supplement this information.
FOLIAR DISEASES OF THE GROUND COVER, VINCA MINOR L., DURING NURSERY PRODUCTION
Authors: Koelsch Mary C. , von Broembson Sharon L. , Cole Janet C.
Published: April 2024

The production of Vinca minor, a shade tolerant ground cover, has declined in recent years due to foliar diseases. Two fungal pathogens, Colletotrichum gloeosporioides and Phoma exigua var. inoxydabilis, were consistently observed on infected plant material from Oklahoma nurseries. Symptoms caused by C. gloeosporioides included severe anthracnose and stem dieback, while P. exigua caused leaf and stem lesions. The pathogenicity of two isolates of C. gloeosporioides and one isolate of P. exigua was evaluated on the native species and the cultivar `Bowles' of V. minor to determine relative disease resistance of these plants. Specific environmental conditions for infection were determined by C. gloeosporioides. Infection was greatest at 28±1°C with high humidity and a light intensity of 126 μmol m-2-sec-1. Five concentrations of eight fungicides (chlorothalonil, cupric hydroxide, mancozeb. propiconazole, San 619, thiophanate methyl, thiophanate methyl/mancozeb, and triforine) were used to test mycelial growth inhibition of the three isolates on amended agar. San 619 completely inhibited mycelial growth of P. exigua, and propiconazole inhibited growth of all three isolates at all concentrations tested.
ENHANCED CONVERSION OF 14C-GLUCOSE INTO SORBITOL UNDER WATER STRESS IN MATURE APPLE LEAVES
Authors: Wang Zhongchun , Quebedeaux Bruno , Stutte Gary
Published: April 2024

Studies were conducted to determine whether water stress stimulates the conversion of glucose (glu) to sorbitol (sor) in leaves. 14C-glu or 14C-sor was introduced through the cut stem of detached apple (Malus domestica Borhk.) shoots which previously experienced either water stress or no stress before excision. When shoots were labelled with 14C-glu, the 14C sugars in mature leaves were partitioned as follows: 38% glu, 20% fructose (fru), 24% sucrose (suc), 18% sor in well-watered (CK) shoots and 30% glu, 22% fru, 18% suc, 30% sor in water-stressed (WS) shoots. Water stress enhanced the conversion of 14C-glu to sor but reduced the conversion to suc and starch. When labelled with 14C-sor, the 14C sugars in mature leaves were partitioned as follows: 94% sor, 1% suc, 3% fru, 2% glu in CK shoots and 90% sor, 4% suc, 3% fru, 3% glu in WS shoots. Young expanding leaves and stems had lower 14C-sor, but higher 14C-suc, 14C-glu and 14C-fru levels than mature leaves. Our 14C data support the hypothesis that water stress stimulates the conversion of glu to sor.
SOIL MOISTURE RESPONSES AND RESULTANT CROP WATER STRESS INDEX FOR PEACHES IRRIGATED BY A WATER BALANCE COMPUTER MODEL
Authors: Worthington J.W. , Lasswell J.L.
Published: April 2024

Irrigation water applications were made to `Majestic' and `Redskin' peaches using micro-irrigation. Scheduling was done with a water balance computer model. Predicted application rates called for irrigation at 10%, 30%, and 50% depletion of available moisture in the wetted area. Neutron probe and tensiometers indicated that moisture levels were maintained at predicted levels. The crop water stress index as measured with an infrared thermometer were negatively correlated with soil moisture levels in the wetted area. Yields and fruit size increased with irrigation. Soluble solids and titratable acidity for irrigated and non-irrigated fruit were measured and data will be presented.