{ "document_id": 15924, "page": 7, "width_pt": 830.88, "height_pt": 606.24, "rotation": 90, "pipeline_version": "paddleocr-vl-1.6+paul-48", "engine": "paddleocr_vl", "source_run_id": 16038, "item_count": 13, "counts_by_type": { "header": 4, "heading": 1, "text": 8 }, "build_ms": 3, "items": [ { "id": "p7.1", "order": 1, "type": "header", "bbox": { "l": 63.36, "t": 578.64, "r": 80.64, "b": 569.76 }, "text": "360", "attrs": { "block_label": "number" }, "level": 2 }, { "id": "p7.2", "order": 2, "type": "header", "bbox": { "l": 282.96, "t": 583.92, "r": 391.92, "b": 573.84 }, "text": "K. POMPER AND D. LAYNE", "attrs": { "block_label": "header" }, "level": 2 }, { "id": "p7.3", "order": 3, "type": "header", "bbox": { "l": 460.8, "t": 577.92, "r": 738.72, "b": 565.2 }, "text": "7. THE NORTH AMERICAN PAWPAW: BOTANY AND HORTICULTURE", "attrs": { "block_label": "header" }, "level": 2 }, { "id": "p7.4", "order": 4, "type": "header", "bbox": { "l": 772.08, "t": 577.44, "r": 788.88, "b": 569.28 }, "text": "361", "attrs": { "block_label": "number" }, "level": 2 }, { "id": "p7.5", "order": 5, "type": "text", "bbox": { "l": 62.64, "t": 558, "r": 392.16, "b": 516 }, "text": "pawpaw cultivars (Huang et al. 1997). Urban encroachment and the resulting destruction of native pawpaw patches may also be leading to a reduction in genetic diversity in the wild." }, { "id": "p7.6", "order": 6, "type": "text", "bbox": { "l": 63.36, "t": 521.28, "r": 394.8, "b": 384.24 }, "text": "In 1981, R. Neal Peterson and Harry Swartz began a long-term breeding project that aimed to develop improved pawpaw cultivars (Peterson 1986, 1991, 2003). A collection of about 1500 accessions of open-pollinated seedlings was assembled at the University of Maryland Experiment Stations at Queenstown and Keedysville, Maryland. The seed for this germplasm collection was obtained from pawpaw trees that remained at the sites of the historic collections of Buckman, Zimmerman, and the Blandy Experimental Farm, as well as those of Hershey (Downington, Pennsylvania), Allard (Arlington, Virginia), Ray Schlaans-tine (West Chester, Pennsylvania), and open-pollinated seed from some modern cultivars." }, { "id": "p7.7", "order": 7, "type": "text", "bbox": { "l": 66.24, "t": 389.28, "r": 397.92, "b": 156.96 }, "text": "In 1993, the PPF and KSU embarked on a joint venture to test 10 commercially available pawpaw cultivars and 18 of PPF's advanced selections from the Maryland orchards in a Pawpaw Regional Variety Trial (PRVT) (Layne 1996; Pomper et al. 1999; Pomper et al. 2003d). From 1996 to 1999, 13 universities or private cooperators have established or have attempted to establish PRVT demonstration orchards (Wapello, Iowa; Frankfort and Princeton, Kentucky; Baton Rouge, Louisiana; Keedysville, Maryland; Jackson, Michigan; Lincoln, Nebraska.; Ithaca, New York; Raleigh, North Carolina; Piketon, Ohio; Corvallis, Oregon; West Lafayette, Indiana; and Clemson, South Carolina). Named cultivars that were secured for testing include: 'Middletown' (selected in Ohio), 'Mitchell' (Illinois), 'NC-1' (Ontario, Canada), 'Overleese' (Indiana), 'PA-Golden' (New York), 'Sunflower' (Kansas), 'Taylor' (Michigan), 'Taytwo' (Michigan), 'Wells' (Indiana), and 'Wilson' (Kentucky). The \"advanced selections\" were chosen based on superior horticultural traits including fruit size and taste, flesh-to-seed ratio, resistance to pests and diseases, and overall productivity on a year-to-year basis. Regional recommendations have not yet been made because more years of performance evaluation are needed." }, { "id": "p7.8", "order": 8, "type": "text", "bbox": { "l": 68.64, "t": 161.76, "r": 400.32, "b": 35.04 }, "text": "In 1994, KSU was designated as a satellite repository for Asimina preservation in the U.S. Department of Agriculture (USDA), National Plant Germplasm System (NPGS). As a result, germplasm evaluation, preservation, and dissemination are a high priority. The repository orchards currently contain over 1700 accessions collected from the wild in 17 states and more than 40 cultivars. One of the goals of the repository is to assess levels of genetic diversity in native populations, in the repository collection, and in commercially available cultivars. Another goal is to acquire unique germplasm to add to the collection that could be useful in future pawpaw breeding efforts." }, { "id": "p7.9", "order": 9, "type": "heading", "bbox": { "l": 461.04, "t": 543.6, "r": 562.08, "b": 531.12 }, "text": "D. Genetic Diversity", "attrs": { "block_label": "paragraph_title" }, "level": 3 }, { "id": "p7.10", "order": 10, "type": "text", "bbox": { "l": 460.32, "t": 528, "r": 790.8, "b": 381.6 }, "text": "A range of molecular markers has been utilized in attempts to evaluate genetic diversity in pawpaw. Rogstad et al. (1991) used a minisatellite probe, M13, to determine the genetic variation in pawpaw collected in five states. Using data from one to 22 samples per population, these authors examined genetic variation at 16 sites both within and among populations. They determined that genetic variation is very low within populations, but moderate genetic variation occurred between populations. They concluded that the low level of genetic variation within populations might be due to clonality of pawpaw patches or inbreeding. However, inbreeding is considered to be rare in pawpaw's reproductive biology, because it is most likely self-incompatible and therefore may require out-crossing (Peterson 1991; Norman et al. 1992)." }, { "id": "p7.11", "order": 11, "type": "text", "bbox": { "l": 460.8, "t": 383.52, "r": 791.04, "b": 225.84 }, "text": "Huang et al. (1997) used isozymes to evaluate the genetic diversity represented in 32 pawpaw cultivars and advanced selections from the breeding program of R. Neal Peterson of the PPF. These authors determined that the isozyme marker variation in cultivated pawpaw is comparable to those of other long-lived temperate woody perennials of widespread geographic range with insect-pollinated outcrossing breeding systems, secondary asexual reproduction and animal-dispersed seed, thus having a higher level of genetic diversity than Rogstad et al. (1991) had reported (Table 7.3). Huang et al. (1997) acknowledged that the results may have been impacted by non-random selection because several of the trees studied may have been purposely selected by pawpaw enthusiasts for desirable characteristics such as large fruit size or good growth vigor." }, { "id": "p7.12", "order": 12, "type": "text", "bbox": { "l": 461.04, "t": 228.72, "r": 791.04, "b": 142.32 }, "text": "Using isozymes, Huang et al. (1998) assessed the level of genetic diversity within wild collected pawpaw accessions at KSU and examined genetic diversity between pawpaw populations from different geographical locations. Isozymes were used to score 23 loci using 25 to 50 trees from each of nine populations. The level of genetic variation found in the KSU repository accessions was similar to that found in cultivated pawpaws (Huang et al. 1997)." }, { "id": "p7.13", "order": 13, "type": "text", "bbox": { "l": 461.52, "t": 145.44, "r": 791.76, "b": 32.88 }, "text": "Using 12 randomly amplified polymorphic DNA (RAPD) primers, Huang et al. (2000) identified 21 Mendelian markers and determined that the level of genetic diversity in six populations in the KSU repository collection was higher than determined for pawpaw by the same authors using isozymes (Huang et al. 1997, 1998). Huang et al. (2003) have also used additional RAPD markers for fingerprinting pawpaw cultivars. They reported similar levels of genetic diversity in cultivated pawpaw, in terms of Nei's genetic diversity constant (He) and percent polymorphic loci (P), to that reported for wild pawpaw populations by Huang et al." } ], "excluded_furniture": { "first": [], "last": [] } }