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  • Author or Editor: D. E. Johnson x
  • Journal of the American Society for Horticultural Science x
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Abstract

Cold resistance of primary buds from grapevines (Vitis spp.) decreased with advancing phenological development. Morphological characteristics of canes produced during previous growing season had no effect on bud hardiness at a given stage of development or on development rate when cuttings were forced in the greenhouse. Cultivar differences were found to affect both the rate of bud development and the hardiness at a given stage of buds forced from stored cuttings.

Open Access

Floral morphology and differentiation of `Sharpblue' southern highbush blueberry (Vaccinium corymbosum L.) were studied under natural growing conditions. There was no rest period during floral development of `Sharpblue' blueberry in Louisiana. Basal florets were already present within a racemic inflorescence in early September. All floral and reproductive organs were clearly visible in early December. Microspores and pollen grains were observed in mid- and late-January, respectively. Megasporocytes, two-cell, four-cell, and seven-cell embryo sacs were found to be simultaneously present in developing ovules in late January, suggesting that megasporogenesis and megagametogenesis in `Sharpblue' blueberry are asynchronous.

Free access

Abstract

Equal volumes of peanut hulls, pine bark, and sphagnum peatmoss were combined into 5 media. Particle size distribution, total porosity, air space, easily available water, water buffering capacity, and bulk density were determined for each medium. Top dry weight, root dry weight, and percent growth of Rhododendron indicum (L.) Sweet cv. George L. Taber were measured 14 weeks after potting in 1-liter containers. Peanut hulls increased particle size, total porosity, and air space, and decreased easily available water, water buffering capacity, and bulk density of media. Peatmoss generally reduced total porosity and air space and increased easily available water, water buffering capacity, and bulk density regardless of other component combinations. Top dry weight, root dry weight, and percent growth were greater in peanut hull-containing media. Addition of peatmoss to the container media tended to produce less growth.

Open Access

Abstract

Marketable tomato yields were influenced more by applied N than by irrigation. Irrigation increased total marketable tomato yields only at the intermediate level. Average yields for the 3-year period by soil water regimes were about 58,300, 70,000, and 68,900 kg/ha for no, intermediate, and high irrigation, respectively. Applied N increased yields, but the increase was limited mainly to the lowest application rate (65 kg/ha) in 1971 and 1972, and to the 2 lowest rates (65 and 130 kg/ha) in 1973. Average yields for the test period by N application rates were about 53,500, 67,100, 69,900, 70,600 and 67,600 kg/ha for 0, 65, 130, 195, and 260 kg/ha rates, respectively. These data indicate that the best combination of N rate and soil water regime was 65 to 130 kg/ha of applied N and supplemental irrigation as needed to maintain 30% or more available water in 0 to 60 cm soil depth.

Open Access

Five-year old `Sharpblue' southern highbush blueberry plants (Vaccinium corymbosum L.) were self- and cross-pollinated (`O'Neal') to study peroxidase (POD) activity, isozyme patterns, and histological localization during fruit development. Cross-pollination resulted in larger and earlier-ripening fruit. Activities of soluble and bound POD were very high during fruit growth period I, with peaks at 10 and 20 days after self- and cross-pollination. Activity was much higher for cross-pollinated fruit. During fruit growth period II, POD activities were low in both pollination treatments. During ripening, soluble POD increased, then declined in both treatments. Bound POD activities increased during the color transition from blue to dark blue, with the increase greater in self-pollinated fruit. Banding patterns of soluble and bound POD isozymes and their histological localization varied by pollination treatment as well as fruit developmental stage. During fruit ripening, soluble POD activity appeared to be associated with color transition from light blue to blue, while bound POD activity appeared to be associated with color transition from blue to dark blue.

Free access

Ovule abortion occurred between 5 and 10 days after pollination (DAP) in self- and cross-pollinated `Sharpblue' blueberry (Vaccinium corymbosum L.) fruit. More ovule abortion occurred with self-pollination (35%) than with cross-pollination (22% for `Sharpblue' × `O'Neal' and 29% for `Sharpblue' × `Gulfcoast'), and there were more poorly developed ovules with self-pollination (88.1%) than with cross-pollination (× `O'Neal', 33.6%; × `Gulfcoast' 50.8%). The increase in ovule area correlated exponentially with fruit growth during early developmental stages, regardless of pollination treatment. However, cross-pollination resulted in significantly greater ovule area and fruit mass during early fruit development as well as at ripening. Ovule area was maximum at 25 to 30 DAP for both pollination treatments, followed by exponential fruit growth (stage III). Cross-pollination resulted in greater fruit growth and a shorter stage III. At 10 DAP, ovules from cross-pollination were larger than those from self-pollination, suggesting that cross-pollination initiated ovule growth immediately after fertilization. This research suggests that southern highbush blueberry fruit growth and development is intimately associated with ovule growth and development, which is affected by pollen sources.

Free access

Continued reduction in limited natural resources worldwide increasingly necessitates the incorporation of low-maintenance and low-input plant materials into urban landscapes. Some fine-leaved Festuca grass species have been used in formal gardens and native urban landscapes because of their inherent tolerance to abiotic stresses, but native, ornamental types (tall and non-spreading with multicolored culms and panicles) are not common in landscapes of the western United States. A native fine-leaved Festuca collection made in Montana (designated FEID 9025897) by the U.S. Natural Resources Conservation Services possesses such ornamental characteristics but has not been evaluated for its horticultural potential. Therefore, a study was designed to assess its phenotypic and genotypic attributes by cloning 270 FEID 9025897 plants and evaluating them along with native F. idahoensis and F. ovina PIs (five) and commercial checks (five) for genetic diversity and plant morphology for 2 years (2010–11). Plant genetic constitution was determined using amplified fragment length polymorphism (AFLP) analysis. Plant height, width, biomass, relative vigor (visual rating of 0 = dead to 5 = green, abundant growth), persistence (number of plants alive per plot), and regrowth after clipping (visual rating of 0 = none to 5 = most) were estimated by evaluation of plants under replication at Hyde Park, UT. Based on AFLP-based coancestry analysis, FEID 9025897 plants possessed considerable genetic affinities with F. idahoensis. Morphological traits as averaged over both years varied in height (13.9 to 105.0 cm), width (9.9 to 66.2 cm), biomass (0 to 170.4 g), vigor (0.2 to 4.7), persistence (0 to 3.9), and regrowth (0 to 4.0). Based on these differences, 19 (7%) FEID 9025897 plants were identified for their ornamental potential that possessed multicolored (red, orange, and yellow) culms and varied in morphology with 2-year means of height (79.8 cm), width (45.2 cm), biomass (88.5 g), vigor (2.9), persistence (1.8), and regrowth (3.7).

Free access

Abstract

Experiments were conducted to evaluate precision planting of single uncoated and spherically (clay) coated single seeds at 2 (uncoated only), 3, 4, 6, and 12 inches in the row. Three planters were used and compared to the conventional Planet Junior at accepted seeding rates. Sprinklers were compared with furrow irrigation. Seed emergence was superior with sprinkler irrigation. Coated seed and 6-inch spacing was not satisfactory with furrow irrigation, but was considered comparable to commercial stands with the sprinkler method (87.5% stand). In planting to a stand with a single seed every 12 inches (thus eliminating the thinning requirement), 84.4% of the desired stand was obtained with uncoated seed and sprinklers. Commercial stands most often range from 80 to 90% of the theoretical 12-inch spacing. Theoretical machine thinning of 3-inch plantings resulted in 8.6 single plants/10 ft of row indicating promise for this innovation.

Open Access

Abstract

This study was designed to determine the effect of pest control intensity on net returns in multiple cropping systems. The study is tempered with an evaluation of risk. The cropping system encompasses: turnip greens (Brassica rapa L.) for processing, field corn (Zea mays L.), and southern peas [Vigna unguiculata (L.) Walp. ssp. unguiculata] for processing. Within the ranges of pest control intensities studied, less intensive control resulted in higher net returns. Further, the level of greatest pest control intensity consistently yielded negative net returns. This level, however, was less risky in terms of gross returns. Risk did not differ significantly between the other levels of pest control.

Open Access