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  • Author or Editor: John J. Sloan x
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Irrigation of sand-based golf greens with ozonated water may affect grass growth and chemical processes in the root zone. The objective of this study was to evaluate the effects of ozonated and aerated water on bentgrass growth and root zone chemistry in sand-based greens over a 12-month period. Creeping bentgrass (Agrostis stolonifera) cores [10 cm diameter × 12 cm depth (3.9 × 4.7 inches)] were collected from a sand-based bentgrass nursery and placed in columns designed to collect leachate water. Cores were placed in a greenhouse and irrigated with 1) municipal tap water [6 to 8 mg·L-1 (ppm) dissolved oxygen (DO)], 2) aerated tap water (12 mg·L-1 DO), or 3) ozonated tap water (aerated plus 0.8 mg·L-1 ozone). Leachate was periodically collected and analyzed for pH, electrolytic conductivity (EC), and nutrients. Grass clippings were weighed and analyzed for total nitrogen (N) and phosphorus (P). Roots were periodically collected from selected cores to determine root distribution. At 40 and 90 days after initiating water treatments, bentgrass irrigated with ozonated water had a higher chlorophyll index than bentgrass irrigated with tap water. After 128 and 157 days, bentgrass clipping weights were significantly greater for the cores irrigated with ozonated water and, to a lesser extent, aerated water. At 61 and 149 days, nitrate (NO3-N) and EC levels were elevated in leachate from aerated and ozonated samples, suggesting increased mineralization of organic matter in those bentgrass cores. Ozonated water increased bentgrass crown weights, but had no effect on root mass. Ozonated water did not affect bentgrass tissue N and P concentrations. Statistically significant effects from ozonated water occurred within the first few months, but sustained benefits were negligible.

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Greenhouse rose (Rosa × spp. L.) production is facing the use of poor-quality irrigation waters and regulatory pressures to recycle runoff and drainage effluents. Two experiments (were conducted to evaluate the yield and quality and ion accumulation responses of roses grafted on various rootstocks to increasing salinity stress. In Expt. 1, the scion ‘Bridal White’ grafted on ‘Manetti’, R. odorata (Andr.), ‘Natal Briar’, and ‘Dr. Huey’ were irrigated over four flowering cycles with complete nutrient solutions supplemented with NaCl at 0, 5, and 30 mm. In Expt. 2, plants of ‘Red France’ on ‘Manetti’ and ‘Natal Briar’ were irrigated over six flowering cycles with complete nutrient solutions supplemented with NaCl + CaCl2 (2:1 m ratio) at 0, 1.5, 3, 6, 12, and 24 mm. Salt concentration increases significantly and negatively affected the biomass, cut flower production, and foliage quality of the roses in both experiments, but the responses were modulated by rootstock selection. ‘Manetti’ plants in general sustained better absolute and relative biomass and flower yields, accumulated less Na+ and Cl in its tissues, and showed less toxicity symptoms with increasing salinity than the others. ‘Natal Briar’ also had similar absolute productivity responses as ‘Manetti’ but were afflicted by a significantly different mineral nutrient profile, including higher accumulations and toxicities with Na+ and Cl that led to lower foliage visual ratings. Conversely, the relative yields of plants on ‘Dr. Huey’ and R. odorata were similarly reduced by increasing salinity, but the former had lower Na+ and Cl concentrations in its tissues and better visual scores than the latter, which fared as the worst. A combined analysis of the results suggests that on a productivity basis (biomass and flower yields), greenhouse roses could withstand overall maximum electrical conductivities (i.e., osmotic effects) of applied fertigation solutions of 3.0 ± 0.5 dS·m−1. On the other hand, and considering the aesthetic responses (visual scores) of on-plant and harvested foliage (cut flower shoots), greenhouse rose tolerance to applied Na+ and Cl concentrations (ion-specific effects) could range up to 10 ± 2 mm.

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Excessive soil moisture in clay soils can cause poor aeration and adversely affect plant growth. Small [1 to 3 mm (0.039 to 0.118 inches)] and large [3 to 6 mm (0.118 to 0.354 inches)] diameter expanded shales (ExSh), quartz sand, sphagnum peatmoss (SPM), and cottonseed hulls (CH) were evaluated as soil amendments for Austin silty clay soil. A 3-inch (7.6-cm) layer of each amendment was incorporated to a depth of 6 inches (15.2 cm), resulting in a 1:1 mixture by volume. Pansies (Viola × wittrockiana `Crown Azure Blue') were grown from December to June, followed by scaevola (Scaevola aemula `New Wonder') from June to November for two growing seasons. Foliage quality and extent of flowering were evaluated biweekly. Pansy root weights and above-ground biomass were quantified at the end of each growing season. None of the amendments significantly affected pansy foliage quality or the number of blooms per plant. Small diameter ExSh and SPM decreased pansy nitrogen content the first year after application, but not the second. During the first growing season, when soils were frequently saturated due to excessive rainfall, pansy root weights were significantly higher in soils amended with the small and large diameter ExSh. Large diameter ExSh treatments significantly increased the survival rate of transplanted scaevola plants and also the quality of foliage and percent blossom coverage during both growing seasons. Cottonseed hulls also increased scaevola survival for both growing seasons, but did not consistently improve scaevola foliage quality or bloom coverage. Of the five amendments tested, large diameter ExSh consistently improved overall plant performance more than the other amendments.

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Planting depth during container production may influence plant growth, establishment, and subsequent landscape value. A lack of knowledge about the effects of common transplanting practices may lead to suboptimal performance of planted landscape trees. Planting depth, i.e., location of the root collar relative to soil grade, is of particular concern for posttransplant tree growth both when transplanted to larger containers during production and after transplanting into the landscape. It is unknown whether negative effects of poor planting practices are compounded during the production phases and affect subsequent landscape establishment. This study investigated effects of planting depth during two successive phases of container production (10.8 L and 36.6 L) and eventual landscape establishment using lacebark elm (Ulmus parvifolia Jacq.). Tree growth was greater when planted at grade during the initial container (10.8 L) production phase and was reduced when planted 5 cm below grade. In the second container production phase (36.6 L), trees planted above grade had reduced growth compared with trees planted at grade or below grade. For landscape establishment, transplanting at grade to slightly below or above grade produced trees with greater height on average when compared with planting below grade or substantially above grade, whereas there was no effect on trunk diameter. Correlations between initial growth and final growth in the field suggested that substantial deviations of the original root to shoot transition from at-grade planting was more of a factor in initial establishment of lacebark elm than the up-canning practices associated with planting depth during container production.

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Tree transplanting practices influence plant survival, establishment, and subsequent landscape value. However, transplanting practices vary substantially within the horticultural industry. Of particular importance is the location of the root collar relative to soil grade at transplant. The objective of this study was to determine the effects of factorial combinations of planting depths, root collar at grade or 7.6 cm either above or below grade, and soil amendments on container-grown (11 L) Quercus virginiana Mill. Soil treatments included a tilled native soil (heavy clay loam, Zack Series, Zack-urban land complex, fine, montmorillonitic, thermic, udic paleustalfs), native soils amended with 7.6 cm of coarse blasting sand or peat that were then tilled to a depth of 23 cm, or raised beds containing 20 cm of sandy loam soil (Silawa fine sandy loam, siliceous, thermic, ultic haplustalfs). A significant (P ≤ 0.05) block by soil amendment interaction occurred for photosynthetic activity. Incorporation of peat significantly decreased the bulk density of the native soil. Planting depth had no significant effect on photosynthetic activity or stem xylem water potential at 3 months after transplant. Soil water potentials did not statistically differ among treatments.

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Organic and inorganic amendments are often used to improve chemical and physical properties of soils. The objective of this study was to determine how the inclusion of light-weight expanded shale in various organic matter blends would affect plant performance. Four basic blends of organic growing media were prepared using traditional or alternative organic materials: 1) 75% pine bark (PB) + 25% sphagnum peatmoss (PM), 2) 50% PB + 50% wastewater biosolids (BS), 3) 100% municipal yard waste compost (compost), and 4) 65% PB + 35% cottonseed hulls (CH). Light-weight expanded shale was then blended with each of these mixtures at rates of 0%, 15%, 30%, and 60% (v/v). Vinca (Catharanthus roseus), verbena (Verbena hybrida), and shantung maple (Acer truncatum) were planted into the growing media after they were transferred into greenhouse pots. Vinca growth was monitored for 3 months before harvesting aboveground plant tissue to determine total biomass yield and elemental composition. Verbena growth was monitored for 6 months, during which time aboveground plant tissue was harvested twice to determine total biomass yield. Additionally, aboveground vinca plant tissue was analyzed for nutrients and heavy metal concentrations. In the absence of expanded shale, verbena and shantung maple trees produced more aboveground biomass in the 50-PB/50-BS blends, whereas vinca grew more biomass in the pure compost blends. Inclusion of expanded shale in the various organic matter blends generally had a negative effect on plant growth, with the exception of shantung maple growth in the 65-PB/35-CH blend. Reduced plant growth was probably due to a lower concentration of nutrients in the growing media. Macro- and micronutrient uptake was generally reduced by addition of expanded shale to the organic growing media. Results suggest that organic materials that have been stabilized through prior decomposition, such as compost or PM, are safe and reliable growing media, but expanded shale offers few benefits to a container growing medium except in cases where additional porosity is needed.

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