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- Author or Editor: S.J. Browning x
A computerized relational database is an efficient and powerful way to store, retrieve, query, and manipulate data. Databases have been prevalent in the scientific community for several years but, recently, have become more immediately available. Personal computers and local area networks (LAN) have revolutionized the accessibility of shared data. At the USDA-ARS Sugarcane Field Station, a database has been created to streamline the entry and recovery of data for the breeding program using Microsoft (MS) Access 2000, a readily available and inexpensive product, which makes it highly adaptable to a variety of breeding programs. Data collection from the sugarcane breeding program has previously consisted of field books and separate computer files. This method of documentation can lead to errors and lost data, therefore a multi-user database was needed to avoid continued problems in data handling. Data entry is performed though a series of self-explanatory forms. Once entered, data can be accessed through the LAN and easily sorted or grouped as desired or queried for items of interest. Reports can then be output as a means of storing important hard copy records. Data from stage I and stage II (the first two clonally propagated selection stages) of the breeding program have currently been included in the database, as well as the seedling stage (true seed planting). Future plans are to incorporate data from stage III and IV (the final two clonally propagated selection stages). The database also handles the Canal Point breeding collection inventory, crossing information, seed (fuzz) inventory, and pedigree tracking. This type of database has widely applicable properties that can be implemented to handle data for any crop, either agronomic or horticultural.
A barrier system for pest control consisting of insect-exclusionary cages covered with three types of mesh material was placed over columnar apple (Malus domestica Borkh.) trees. This system has been shown to provide arthropod control equivalent to insecticides. Light intensity, evaporation, and air and soil temperature were reduced inside the cages. Shoot elongation of columnar apple trees grown inside insect-exclusionary cages was significantly greater than that of trees grown outside the cages. However, this increased shoot growth was not due to etiolation. Tree performance was unaffected by insect-exclusionary cages. Fruit set and fruit soluble solids concentration were not reduced by the cages; however, fruit color intensity was reduced as the degree of shading from the mesh increased. These findings, in conjunction with high levels of arthropod control by insect-exclusionary cages, may allow insect-exclusionary cages to be used for evaluating integrated pest management thresholds, predator-prey relationships, and apple production without insecticides.
Buffalograss [Buchloë dactyloides (Nutt.) Engelm] is a drought-resistant, dioecious species, native to the Central Great Plains, which shows excellent potential as a low-maintenance turfgrass. Although buffalograss can be propagated vegetatively, there is a need for seeded turf-type cultivars. To assist in developing seeded cultivars, heritabilities of turf characteristics were estimated. Heritabilities from maternal half-sib analyses ranged from h2 = 0.04 ± 0.03 for the 1988 uniformity rating to h2 = 0.62 ± 0.26 for the 1989 spring color rating. Heritability estimates calculated from offspring-parent regression were also variable and generally lower than maternal half-sib analysis. The results suggest that some turf characteristics are highly heritable and that growing conditions markedly affect heritability estimates.
For the past several years, many college horticulture programs have experienced a decline in undergraduate enrollment, resulting in the elimination of some degrees. In this study, we compared postsecondary U.S. horticulture program availability from a survey completed in 1997 with offerings existing in 2012 and 2017. In 1997, 446 U.S. postsecondary institutions offered degrees and/or certificates in horticulture. In 2012, this number had decreased by 43% to 253 institutions, which included 98 with 4-year degrees, 215 with 2-year degrees, and 138 with certificate programs. In 2017, the total number of institutions offering horticulture-related degrees and/or certificates decreased to 209, representing a 53% decrease over the 20 years from 1997 to 2017 and a 17% decrease during the 5-year period between 2012 and 2017. In 2017, 85 institutions offered 4-year degrees, 133 offered 2-year degrees, and 98 offered certificate programs, which over this 5-year period represents decreases of 13%, 38%, and 29%, respectively. “Horticulture” was the most common program title in both 2012 and 2017, and the percentage of programs with this name increased during the 5-year period for all program types. In 2017, 28 horticulture programs not identified in the 1997 survey were found, but only two of these were confirmed to have been created since 1997. Overall, these data suggest a trajectory toward elimination of 2-year and certificate programs, and continued consolidation for 4-year degrees. If it continues, this trend is not favorable for the continued vitality of postsecondary horticulture programs in the United States and may impact progress negatively for the field of horticulture as a whole.
Mango (Mangifera indica L.) germplasm can be classified by origin with the primary groups being cultivars selected from the centers of diversity for the species, India and Southeast Asia, and those selected in Florida and other tropical and subtropical locations. Accessions have also been classified by horticultural type: cultivars that produce monoembryonic seed vs. cultivars that produce polyembryonic seed. In this study we used 25 microsatellite loci to estimate genetic diversity among 203 unique mangos (M. indica), two M. griffithii Hook. f., and three M. odorata Griff. accessions maintained at the National Germplasm Repository and by Fairchild Tropical Botanic Garden in Miami, Fla. The 25 microsatellite loci had an average of 6.96 alleles per locus and an average polymorphism information content (PIC) value of 0.552 for the M. indica population. The total propagation error in the collection (i.e., plants that had been incorrectly labeled or grafted) was estimated to be 6.13%. When compared by origin, the Florida cultivars were more closely related to Indian than to Southeast Asian cultivars. Unbiased gene diversity (Hnb) of 0.600 and 0.582 was found for Indian and Southeast Asian cultivars, respectively, and both were higher than Hnb among Florida cultivars (0.538). When compared by horticultural type, Hnb was higher among the polyembryonic types (0.596) than in the monoembryonic types (0.571). Parentage analysis of the Florida cultivars was accomplished using a multistage process based on introduction dates of cultivars into Florida and selection dates of Florida cultivars. In total, 64 Florida cultivars were evaluated over four generations. Microsatellite marker evidence suggests that as few as four Indian cultivars, and the land race known as `Turpentine', were involved in the early cultivar selections. Florida may not represent a secondary center of diversity; however, the Florida group is a unique set of cultivars selected under similar conditions offering production stability in a wide range of environments.
Commercial production of cacao in Hawaii is increasing, and this trend is expected to continue over the next several years. The increased acreages are being planted with seedlings from introduced and uncharacterized cacao populations from at least three initial introductions of cacao into the islands. Productive seedlings have been selected from a planting at Waialua, Oahu. The parents of these selections were believed to be the population at the Hawaii Agriculture Research Center (HARC) at Kunia; however, potential parental populations also exist at Univ. of Hawaii research stations at Waimanalo and Malama Ki. Using microsatellite markers, we analyzed the potential parental populations to identify the parents and determine the genetic background for 99 productive and 50 unproductive seedlings from the Waialua site. Based on 19 polymorphic microsatellite loci the parental population was identified as trees from Waimanalo and not trees from Malama Ki or Kunia. The Kunia and Malama Ki populations were very similar with low allelic diversity (A = 1.92) and low unbiased gene diversity (Hnb) of 0.311 and 0.329, respectively, and were determined to be Trinitario in type. The Waimanalo, productive seedling, and unproductive seedling populations had much higher levels of genetic diversity with Hnb of 0.699, 0.686, and 0.686, respectively, and were determined to be upper Amazon Forastero hybridized with Trinitario in type. An additional 46 microsatellite markers were amplified and analyzed in the Waimanalo parents, productive, and unproductive seedlings for a total of 65 loci. Seventeen loci contained alleles that were significantly associated with productive seedlings as determined by Armitage's trend test. Of these, 13 loci (76.4%) co-located with previously reported quantitative trait loci for productivity traits. These markers may prove useful for marker assisted selection and demonstrate the potential of association genetic studies in perennial tree crops such as cacao.
Leaf cuttings from 6-week-old potato plants were planted into the Astroculture flight unit for the STS-73 shuttle flight in Oct. 1995. Tubers developed in the axils of the five leaf cuttings during the 16-days in microgravity. The flight unit had a closed growth chamber maintained at 22°C, 82% relative humidity, 150 μmol·m–2·s–1 photosynthetic photon flux, and with carbon dioxide controlled during the light period to ≈400 μmol·mol–1 and exceeding 4000 μmol·mol–1 during the dark period. A controlled delivery system using a porous tube system in arcillite medium provided water to the cuttings. A camera mounted in the top of the chamber provided video images of the plants at 2-day intervals. The cuttings maintained good vitality for the first 12 days of the flight followed by senescence of the leaves. Tubers 1.5 cm in diameter and weighing 1.7 g were produced. The shape and size of the tubers, the internal cell arrangement, and the size range of the starch grains, were similar on cuttings developed in a control experiment on the ground. Also the concentrations of starch, sucrose, fructose, glucose, and total soluble protein in the cuttings from space were similar to the cuttings developed on the ground. The challenges in scheduling experiments in a space flight and in conducting comparison control experiments on the ground are discussed. Environment control variations associated with cabin pressure changes, venting requirements, and air sampling are reviewed.
Optimum shoot development of Epiphyllum chrysocardium Alexand. stem cutting was obtained on a modified half-strength Murashige and Skoog (MS) medium supplemented with 0.1 mg/liter benzylamino purine (BA). Best rooting occurred after subculturing excised shoots on half-strength MS supplemented with 0.01 mg/liter indolebutyric acid (IBA).
The ability of two tomato cultivars, Lycopersicon esculentum cv. VFNTCherry (chill sensitive) and L. esculentum × L. pimpinellifollim cv. New York 280 (chill tolerant) to acclimate to low temperature storage at 2 °C were compared following prior temperature preconditioning. The activities of catalase, peroxidase, and superoxide dismutase and electrolyte leakage were monitored during a 15-day preconditioning period. Low temperature preconditioning reduced membrane damage in both fruit. In contrast, high temperature preconditioning accelerated the rate of leakage in VFNT, while fruit of NY 280 remained relatively undamaged. Low temperature preconditioning stimulated a 4-fold increase in catalase and peroxidase activities in fruit of NY280. High-temperature preconditioning appeared only to benefit fruit of NY280. Regardless of pretreatment, no significant change in superoxide dismutase activities were observed for either cultivar. These findings suggest that the ability to acclimate to low temperature stress may correlate with increased levels of catalase and peroxidase.
Three horticultural races of avocado (Persea americana Mill.) are known: Guatemalan, Mexican, and West Indian. Each race has unique characteristics and current commercial varieties have been selected from within the races or from interracial hybrids. Using 14 microsatellite loci we investigated the genetic variation among 224 accessions (394 plants) maintained at the National Germplasm Repository (NGR) in Miami, Fla., and a set of 34 clones from the University of California South Coast Field Station (SCFS) located in Irvine, Calif. The 14 microsatellite loci had an average of 18.8 alleles per locus and average unbiased genetic diversity was 0.83. The total propagation error in the collection, i.e., plants that had been incorrectly labeled or grafted, was estimated to be 7.0%. Although many unique alleles did exist, no useful race-specific markers were found. A general concordance between the horticultural race and the clusters obtained from molecular data was observed. Principal Coordinate Analysis (PCA) grouped the Guatemalan and Mexican races into two distinct clusters. The West Indian also grouped into a unique major cluster but with an outlying group. Using the PCA a change in the racial designation or interracial hybrid status for 50 accessions (19.7%) is proposed. The unbiased gene diversity estimate was highest in the Mexican and Guatemalan races and lower in the West Indian group. This demonstrates the need to collect more of the West Indian germplasm to broaden the genetic diversity and to emphasize the identification of individuals conferring resistance to Phytophthora Root Rot (PRR).