{ "document_id": 15928, "page": 2, "width_pt": 603, "height_pt": 783, "rotation": 0, "pipeline_version": "paddleocr-vl-1.6+paul-48", "engine": "paddleocr_vl", "source_run_id": 16039, "item_count": 33, "counts_by_type": { "figure": 1, "footer": 6, "header": 3, "heading": 2, "text": 21 }, "build_ms": 10, "items": [ { "id": "p2.1", "order": 1, "type": "header", "bbox": { "l": 45.6591, "t": 775.3084, "r": 183.2794, "b": 761.6834 }, "text": "🛒 🎉 🎉 🎉", "attrs": { "block_label": "header" }, "level": 2 }, { "id": "p2.2", "order": 2, "type": "figure", "bbox": { "l": 295.8194, "t": 772.4516, "r": 306.7519, "b": 760.8044 }, "text": "", "attrs": { "role": "page_header", "block_label": "header_image" } }, { "id": "p2.3", "order": 3, "type": "header", "bbox": { "l": 419.7206, "t": 775.748, "r": 558.8415, "b": 761.9032 }, "text": "□", "attrs": { "block_label": "header" }, "level": 2 }, { "id": "p2.4", "order": 4, "type": "header", "bbox": { "l": 207.5023, "t": 738.6088, "r": 382.2073, "b": 727.6208 }, "text": "SOIL MANAGEMENT, FERTILIZATION, & IRRIGATION", "attrs": { "block_label": "header" }, "level": 2 }, { "id": "p2.5", "order": 5, "type": "text", "bbox": { "l": 65.8091, "t": 717.9514, "r": 213.0757, "b": 599.062 }, "text": "‘Rotundifolia’ holly (Ilex crenata Thunb.), leaf chlorophyll levels decreased with root-zone temperatures >30 °C (Ruter and Ingram, 1992). Some tree species do tolerate elevated root-zone temperatures. Root-zone temperatures as high as 36 °C did not reduce whole plant dry weight production in thornless honey locust (Gleditsia triacanthos L. var. inermis Willd.) compared to 25 °C (Klock et al., 1996). Increasing root-zone temperatures to enhance the early growth and development of container grown pawpaw seedlings has not been reported in the literature." }, { "id": "p2.6", "order": 6, "type": "text", "bbox": { "l": 65.8091, "t": 598.8423, "r": 213.5044, "b": 524.1243 }, "text": "Therefore, the objectives of this study were: 1) to compare the effects of several media and fertilizer regimes on germination and growth of container-grown pawpaw seedlings; and 2) to determine if an increased root-zone temperature would enhance early growth and development of container-grown pawpaw seedlings in the greenhouse." }, { "id": "p2.7", "order": 7, "type": "heading", "bbox": { "l": 98.6065, "t": 515.1142, "r": 180.9214, "b": 505.8844 }, "text": "Materials and Methods", "attrs": { "block_label": "paragraph_title" }, "level": 3 }, { "id": "p2.8", "order": 8, "type": "text", "bbox": { "l": 65.166, "t": 497.9731, "r": 214.5763, "b": 67.0264 }, "text": "Plant material. For all experiments, paw-\npaw seed was harvested from open-pollinated\nhalf-sibling trees at the Western Maryland\nResearch and Education Center in Keedysville,\nMd. Seed was stratified at 5 °C for 3 months\nand sown to a 3 cm depth in substrate in 5 × 6.4\n×25.4 cm (740 cm³) containers (Rootrainers;\nHummert Int., Earth City, Mo.). In all\nexperiments, Rootrainers were watered at\nleast weekly to runoff during germination.\nSeedlings were grown in a white-washed\ngreenhouse under a 16-h photoperiod\nsupplemented by high pressure sodium lights.\nPhotosynthetic photon flux was measured at\ncanopy level on a clear sunny representative\nday at 1200 HR at 1200 μmol·m⁻²·s⁻¹ by using\na LI-COR LI-185B photometer with a quant-\num sensor (LI-COR, Lincoln, Nebr.).\nExpt. 1, substrate study. The growth and development of pawpaw seedlings was compared in a factorial experiment in the greenhouse using three fertilizer treatments and four potting substrates: ProMix ‘BX’, 6 pine bark : 1 sand (v/v), 1 sand : 1 sphagnum peat, and 4 pine bark : 1 sand : 1 sphagnum peat. Fertilizer treatments were 0, 50, and 100 mg·L ⁻¹ N as Peters (Scotts Co., Marysville, Ohio) 20N–8.6P–16.6K water-soluble fertilizer plus soluble trace elements. Experimental treatments were in a split-plot arrangement in three replicated blocks (main plot: fertilizer level, subplot: potting substrate) on three benches in the greenhouse. There were 10 replicate seedlings in each subplot. Blocks were arranged along the long, east-west axis of the greenhouse. The greenhouse air temperature was measured every 30 min during the experiment using TEMP HOBO sensors (Onset Computer Corp., Pocasset, Mass.). Average greenhouse air temperatures were 29.1 ± 0.7 °C and 21.2 ± 0.1 °C, at 1200 HR and 300 HR, respectively (± SE), during the experiment. In early March, stratified pawpaw seed were sown in 740-mL Rootrainers containing the substrate treatments. ProMix ‘BX’ (Premier Horticulture, Red Hill, Penn.) was purchased, whereas the other substrates were made by combining aged, but not composted, pine bark (GSO America, Columbus, Ohio), mason sand (Quikrete All Purpose Sand, Atlanta, Ga) or sphagnum peat (Southern Importers, Greensboro, N.C.)." }, { "id": "p2.9", "order": 9, "type": "text", "bbox": { "l": 220.364, "t": 717.9514, "r": 368.7025, "b": 672.0219 }, "text": "made by combining aged, but not composted, pine bark (GSO America, Columbus, Ohio), mason sand (Quikrete All Purpose Sand, Atlanta, Ga) or sphagnum peat (Southern Importers, Greensboro, N.C.)." }, { "id": "p2.10", "order": 10, "type": "text", "bbox": { "l": 220.5784, "t": 671.5824, "r": 368.7025, "b": 507.4227 }, "text": "Substrate bulk density was determined for three replicates for each substrate after heating for 24 h at 50 °C. Substrate pH was measured using 250 mL substrate and distilled water (1:1 v/v). Water holding capacity for each was determined by weighing 250 mL of substrate in 250-mL beakers before and after saturating the substrate and allowing it to drain from inverted beakers. Substrate analysis (Division of Regulatory Services, Univ. of Kentucky, Lexington) was performed on samples of all the substrate used in the experiment for electrical conductivity (EC), as well as N-nitrate, P, K, Ca, and Mg concentration. Cation exchange capacity (CEC) for each medium was determined by using an ammonia substitution method (A&L Analytical Laboratories, Memphis, Tenn.)." }, { "id": "p2.11", "order": 11, "type": "text", "bbox": { "l": 221.0071, "t": 506.7634, "r": 368.9168, "b": 342.6037 }, "text": "Plant height and seed germination percentage were determined in each medium at the 2 to 3 leaf stage. Weekly fertilization treatments were also initiated at this time by saturating media with the appropriate liquid fertilizer. Plants were watered daily. Fertilizer treatments were prepared from a stock solution and applied by hand to the growing media; water used for preparation of the treatments had a total N content ([p2.11.1] and[p2.11.2]) of[p2.11.3] mg·L[p2.11.4] and a Ca concentration of 35 mg·L[p2.11.5] (Scott Laboratories, Allentown, Pa.). The number of leaves per plant and seedling height were determined 70 d after imposition of fertilizer treatments, which was 140 d after sowing. Immediately thereafter, stems, leaves, and roots were oven-dried at 70 °C for 48 h and weighed.", "children": [ { "id": "p2.11.1", "order": 12, "type": "text", "bbox": { "l": 221.0071, "t": 506.7634, "r": 368.9168, "b": 342.6037 }, "text": "NO₃", "attrs": { "inline": true, "text_offset": 422, "text_span": 9, "bbox_estimated": true } }, { "id": "p2.11.2", "order": 13, "type": "text", "bbox": { "l": 221.0071, "t": 506.7634, "r": 368.9168, "b": 342.6037 }, "text": "NH₄", "attrs": { "inline": true, "text_offset": 435, "text_span": 9, "bbox_estimated": true } }, { "id": "p2.11.3", "order": 14, "type": "text", "bbox": { "l": 221.0071, "t": 506.7634, "r": 368.9168, "b": 342.6037 }, "text": "≈ 0.7", "attrs": { "inline": true, "text_offset": 448, "text_span": 9, "bbox_estimated": true } }, { "id": "p2.11.4", "order": 15, "type": "text", "bbox": { "l": 221.0071, "t": 506.7634, "r": 368.9168, "b": 342.6037 }, "text": "⁻¹", "attrs": { "inline": true, "text_offset": 462, "text_span": 9, "bbox_estimated": true } }, { "id": "p2.11.5", "order": 16, "type": "text", "bbox": { "l": 221.0071, "t": 506.7634, "r": 368.9168, "b": 342.6037 }, "text": "⁻¹", "attrs": { "inline": true, "text_offset": 505, "text_span": 9, "bbox_estimated": true } } ] }, { "id": "p2.12", "order": 17, "type": "text", "bbox": { "l": 220.364, "t": 342.6037, "r": 368.9168, "b": 66.8066 }, "text": "Expt. 2, root-zone heating study. A greenhouse experiment was conducted with treatments that included two levels of root-zone temperature, ambient (24 ± 0.2 °C) and bottom-heat (32 ± 0.3 °C), to determine the influence of elevated soil temperature on early growth and development of container-grown pawpaw seedlings. Treatments were arranged on greenhouse benches in three replicated blocks, with 10 seedlings per treatment in each block. Seeds were sown in early September in Rootrainer cells containing ProMix. All Rootrainers were placed on sheets of Dow foam insulation (10 × 20 × 2 cm) on the bench. For the bottom-heat treatments only, the heat mat was placed directly on the foam sheet. In addition, the four sides of the Rootrainers were enclosed using the same insulation. Sides went from the bench to the top of the Rootrainer. A greenhouse temperature regime of 27 ± 0.8 °C day and 21 ± 0.2 °C night was maintained and was confirmed on a representative clear day and night. Soil temperature was elevated using ProGro propagation mats (Hummert Int., Earth City, Mo.). Average mean soil temperature was determined over a 5-d period in adjacent cells in the same zone within treatment blocks by using a soil temperature probe (Digi-Sense model 8525-00; Cole Parmer Inst. Co., Niles, Ill.) inserted to a depth of 8 cm.\n\nA delivery rate of 50 mg·L⁻¹ N as Peters 20N–8.6P–16.6K water-soluble fertilizer was applied twice weekly after seedling emergence until substrate saturation, using a Gewa proportioner (Hummert Int.). Fertilizer delivery rates were confirmed by solution analysis (Scott Laboratories, Allentown, Pa.). The fertilizer solution had a pH of 6.2 and EC was 1.56 dS·m⁻¹." }, { "id": "p2.13", "order": 18, "type": "text", "bbox": { "l": 375.3477, "t": 635.1024, "r": 524.1148, "b": 516.4328 }, "text": "The number of days from sowing to seedling emergence from the substrate was evaluated. Following seedling emergence, seedlings were rogued based on size to a total of 30 seedlings per treatment. When seedlings produced three unfolded leaves, fertilization treatments began, and plant height and unfolded leaf number were measured weekly for all plants. After 114 d, shoot and taproot length, leaf number, and total leaf area (using model CI-203 area meter; C.I.C., Vancouver, Wash.) were determined. Stems, leaves, and roots were ovendried at[p2.13.1] for 48 h and weighed.", "children": [ { "id": "p2.13.1", "order": 19, "type": "text", "bbox": { "l": 375.3477, "t": 635.1024, "r": 524.1148, "b": 516.4328 }, "text": "70 °C", "attrs": { "inline": true, "text_offset": 542, "text_span": 9, "bbox_estimated": true } } ] }, { "id": "p2.14", "order": 20, "type": "text", "bbox": { "l": 375.562, "t": 515.9933, "r": 523.9005, "b": 397.9829 }, "text": "Chlorophyll determination. Immediately prior to destructive harvest, four discs (0.32 cm² each) were obtained from apical, medial and basal expanded leaves using a paper hole punch. Leaf discs were extracted for at least 24h in the dark using N,N-dimethylformamide (Sigma, St. Louis). Extract absorbance was read at 625, 647, and 664 nm using a UV-VIS spectrophotometer (Beckman Instruments, Fullerton, Calif.). Chlorophyll (chl) a, b, and protochlorophyll (chl p) concentrations were determined according to the method of Moran (1982)." }, { "id": "p2.15", "order": 21, "type": "text", "bbox": { "l": 375.7764, "t": 397.3236, "r": 524.3292, "b": 296.2346 }, "text": "Statistical analysis. Data for leaves per plant, seedling height, total shoot, root, and plant dry weight, leaf area, average plant specific leaf dry weight (SLW), root: shoot ratio, chl concentration, and chl a:b ratio in relation to treatments were subjected to GLM analysis of variance using the statistical program Costat (CoHort Software, Monterey, Calif.). Treatment means were separated based on the least significant difference (LSD) or independent t tests." }, { "id": "p2.16", "order": 22, "type": "heading", "bbox": { "l": 436.2264, "t": 286.5653, "r": 463.8791, "b": 276.8959 }, "text": "Results", "attrs": { "block_label": "paragraph_title" }, "level": 3 }, { "id": "p2.17", "order": 23, "type": "text", "bbox": { "l": 375.1333, "t": 269.6438, "r": 524.5435, "b": 66.5869 }, "text": "Expt. 1, substrate study. The container substrates differed significantly in bulk density, pH, water retention, water holding capacity, EC, and CEC (Table 1). ProMix had the lowest density, whereas 1 sand : 1 sphagnum peat had the greatest density, almost 7 times that of ProMix. Substrate pH ranged from 5.1 for 6 pine bark : 1 sand (v/v) to 5.8 for 4 pine bark : 1 sand : 1 sphagnum peat. Water holding capacity of ProMix was almost 8 times greater than that of other substrates. The EC of 6 pine bark : 1 sand (v/v) was about half that of ProMix, and values for 6 pine bark : 1 sand (v/v) and 4 pine bark : 1 sand : 1 sphagnum peat were only about one-quarter that of ProMix. On a weight basis, the CEC of ProMix was [p2.17.1]10-fold greater than that of the other substrates. On a volume basis, the CEC of ProMix was [p2.17.2]2-fold greater than 1 sand : 1 sphagnum peat or 4 pine bark : 1 sand : 1 sphagnum peat, and [p2.17.3]4-fold greater than 6 pine bark : 1 sand (v/v). The Ca concentration", "children": [ { "id": "p2.17.1", "order": 24, "type": "text", "bbox": { "l": 375.1333, "t": 269.6438, "r": 524.5435, "b": 66.5869 }, "text": "≈", "attrs": { "inline": true, "text_offset": 720, "text_span": 9, "bbox_estimated": true } }, { "id": "p2.17.2", "order": 25, "type": "text", "bbox": { "l": 375.1333, "t": 269.6438, "r": 524.5435, "b": 66.5869 }, "text": "≈", "attrs": { "inline": true, "text_offset": 821, "text_span": 9, "bbox_estimated": true } }, { "id": "p2.17.3", "order": 26, "type": "text", "bbox": { "l": 375.1333, "t": 269.6438, "r": 524.5435, "b": 66.5869 }, "text": "≈", "attrs": { "inline": true, "text_offset": 922, "text_span": 9, "bbox_estimated": true } } ] }, { "id": "p2.18", "order": 27, "type": "text", "bbox": { "l": 386.2801, "t": 59.5546, "r": 523.4717, "b": 48.3469 }, "text": "HORTSCIENCE, VOL. 37(2), APRIL 2002" }, { "id": "p2.19", "order": 28, "type": "footer", "bbox": { "l": 66.6665, "t": 59.1151, "r": 82.7437, "b": 49.4457 }, "text": "330", "attrs": { "block_label": "footer" } }, { "id": "p2.20", "order": 29, "type": "footer", "bbox": { "l": 7.0739, "t": 28.7884, "r": 24.6516, "b": 21.5363 }, "text": "——", "attrs": { "block_label": "footer" } }, { "id": "p2.21", "order": 30, "type": "footer", "bbox": { "l": 43.5155, "t": 26.5908, "r": 86.3878, "b": 18.6795 }, "text": "6807, p. 329-333", "attrs": { "block_label": "footer" } }, { "id": "p2.22", "order": 31, "type": "footer", "bbox": { "l": 156.0555, "t": 26.371, "r": 167.2023, "b": 18.8992 }, "text": "330", "attrs": { "block_label": "number" } }, { "id": "p2.23", "order": 32, "type": "footer", "bbox": { "l": 296.2481, "t": 22.4154, "r": 306.1088, "b": 11.2077 }, "text": "", "attrs": { "block_label": "footer_image" } }, { "id": "p2.24", "order": 33, "type": "footer", "bbox": { "l": 362.7003, "t": 27.2501, "r": 406.0014, "b": 18.8992 }, "text": "3/15/02, 2:24 PM", "attrs": { "block_label": "footer" } } ], "excluded_furniture": { "first": [], "last": [] } }