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Yan Chen, Regina P. Bracy, Allen D. Owings and Donald J. Merhaut

weight of the shoots, rhizomes, and roots of ornamental and wetland plants grown for 10 weeks in a greenhouse nutrient recirculation system with total nitrogen and phosphorous concentrations of 11.29 and 3.1 mg·L −1 in three experiments conducted from

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Monica Ozores-Hampton, Francesco Di Gioia, Shinjiro Sato, Eric Simonne and Kelly Morgan

incorporated at bedding with 61 and 553 kg·ha −1 of P and K fertilizer, respectively. Phosphorous and K rates were selected based on the common commercial practices in the area. The soil was rototilled and the bottom mix including N, P, and K [prepared with a

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W.B. Evans and D.D. Warncke

Single-plant microplots of `Russet Norkotah' potatoes (Solanum tuberosum L.) were grown outdoors in a 5 × 5 factorial RCBD of indigenous phosphorous level (200, 325, 450, 575, 700 kg·ha-1 Bray-Kurtz Pl extractable; McBride sandy loam) and banded triple super phosphate (0, 50, 100, 150, 200 kg P2O5/ha). Disease in the low P soil that was used to create the four lower P soil blends completely confounds response of the plants across indigenous P levels and might have accentuated responses within levels. Plants responded to fertilizer P with tuber yield increases of 100, 70, 40, and 10 percent within the 200, 325, 450, and 575 indigenous P levels, respectively. Fertilizer P also increased marketable yield and tuber P concentration. Neither indigenous nor fertilizer P altered tuber specific gravity.

Companion studies compare the responses of corn (Zea mays L.) and potato to indigenous soil P levels and quantify P uptake among potato cultivars in solution culture.

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Lizzette Gonzalez*, Juan C. Vazquez and Maria del C. Libran

Municipal solid waste compost (MSW) can be used as an effective substrate for ornamental plant production as an alternative to peat. In a previous study a mix with peat, perlite, and vermiculite (1:1:1 per volume) was used along MSW compost at 1:1 per volume ratio as a growing substrate for Catharanthus roseus, providing nitrogen (N) for adequate plant growth. This study will focus in determining if MSW provides adequate amounts of N and Phosphorous (P) for Anthurium pot plant production, reducing the use of fertilizers and nutrient loss to the environment. Plants were fertilized at 0, 100, 150, and 200 ppm N using a 20-10-20 soluble fertilizer. Chemical characterization of leachates collected from plants grown in substrates with or without MSW, to determine possible nutrient run off. Tissue analysis for N and P content was conducted to determine absorption. Our results shows an increase in NH4 -N, NO3 -N and soluble P in leachates as the fertilizer level increased. Higher NO3 -N content in leachates was observed in treatments with MSW. Higher P concentrations were observed in leachates from substrate without MSW. Weeks after, 62% of the plants grown in MSW were dead; the surviving plants had less biomass, but similar N content in leaf and root tissues than plants grown without MSW. Higher P content in tissues was observed in fertilized plants grown without MSW. The MSW was a nutrient source for the plants, but further studies should be conducted for optimum use of MSW as a component of growing substrate.

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Andrés Olivos, Scott Johnson, Qin Xiaoqiong and Carlos H. Crisosto

N followed by fruit from the low P and K treatments, whereas fruit from the low N treatment had the least. Phosphorous concentrations in fruit were affected significantly by the nutrient deficit treatments with the low P treatment having the least P

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Arnon Dag, Ran Erel, Alon Ben-Gal, Isaac Zipori and Uri Yermiyahu

. Hort. Sci. 87:194–198. Haun, J.R. Cornell, P.W. 1951 Rooting response of geranium ( Pelargonium bortorum , Baily var. Richard) cuttings as influenced by nitrogen, phosphorous and potassium nutrition on the stock plant. Proc. Amer. Soc. Hort. Sci. 58

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Timothy K. Broschat

Chinese hibiscus (Hibiscus rosa-chinensis), shooting star (Pseuderanthemum laxiflorum), downy jasmine (Jasminum multiflorum), areca palm (Dypsis lutescens), and `Jetty' spathiphyllum (Spathiphyllum) were grown in containers using Osmocote Plus 15-9-12 (15N-3.9P-10K), which provided phosphorus (two experiments), or resin-coated urea plus sulfur-coated potassium sulfate, which provided no phosphorus (one experiment). Plants were treated with water drenches (controls), drenches with metalaxyl fungicide only, drenches with phosphoric acid (PO4-P), drenches with metalaxyl plus phosphorus from phosphoric acid, drenches with PhytoFos 4-28-10 [4N-12.2P-8.3K, a fertilizer containing phosphorous acid (PO3-P), a known fungicidal compound], or a foliar spray with PhytoFos 4-28-10. Plants receiving soil drenches with equivalent amounts of P from PhytoFos 4-28-10, PO4-P, or PO4-P+metalaxyl generally had the greatest shoot and root dry weights and foliar PO4-P concentrations. There were no differences between the control and metalaxyl-treated plants, indicating that root rot diseases were not a factor. Therefore, responses from PhytoFos 4-28-10 were believed to be due to its nutrient content, rather than its fungicidal properties. Foliar-applied PhytoFos 4-29-10 produced plants that were generally similar in size to control plants or those receiving metalaxyl only drenches. Fertilizers containing PO3-P appear to be about as effective as PO4-P sources when applied to the soil, but are relatively ineffective as a P source when applied as a foliar spray. A distinct positive synergistic response for shoot and root dry weights and foliar PO4-P concentrations was observed for the PO4-P+metalaxyl treatment when no P was applied except as a treatment.

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Andrès A. Estrada-Luna and Fred T. Davies Jr.

Micropropagated cactus pear plantlets (Opuntia amyclaea Tenore) cv. Reyna were colonized with a Mexican endomycorrhiza isolate, ZAC-19 (containing Glomus etunicatum and two unknown Glomus spp.) and fertilized with two phosphorous levels (0 and 11 μg P/ml) to study their effect on plant growth and nutrient uptake. After 7 months of greenhouse culture, there was 100% survival of the micropropagated cactus pear plants. Evidence of mycorrhizal colonization was observed 5 days after inoculation, with the development of internal hyphae in root cortices. At the end of the study, high colonization occurred (48% to 54%) with no differences in P treatments. Plantlets transferred to soil began to actively grow with no lag phase. However, plant growth rate was significantly affected by treatments. Absence of P supply and lack of colonization resulted in lower dry mass and surface area of prickly pear cactus plants. In contrast, the combination of supplementary P and mycorrhizal colonization significantly increased plant growth.

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G.L. Miller, L.B. McCarty and I.R. Rodriguez

Establishment of an acceptable turfgrass quality on sand-based golf putting greens presents major agronomic and environmental challenges to turfgrass managers. The objective of this study was to evaluate of five N:P:K fertilizer ratios to aid in the establishment of bermudagrass on sand-peat (85:15 v/v). `Floradwarf' and `Tifdwarf' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burt-Davy] were sprigged in Aug. 1996 at the Envirogreen in Gainesville, Fla. `Tifeagle' and `Tifway' bermudagrass were sprigged in May 1999 at Clemson Univ. research green in Clemson, S.C. Treatments consisted of N:P2O5:K2O ratios of 1:0:1, 1:0:2, 1:1:1, 1:2:1, and 1:3:1 applied based on an N rate of 49 kg/ha per week. Treatments were applied weekly for 7 weeks. In Gainesville, the best growth rate was achieved from the 1:1:1 ratio of N:P2O5:K2O. While the 1:2:1 and 1:3:1 plots filled in well, they did not experience the same coverage rates as plots fertilized with the 1:1:1 ratio. In Clemson, similar growth was achieved with the 1:1:1, 1:2:1, and 1:3:1 treatments. The 1:0:1 and 1:0:2 plots were slow to establish at both locations. In general there were no differences in root and shoot dry weights of grasses grown in Clemson; whereas these weights were positively correlated to growth rates in Gainesville. These studies indicate that turf will respond to P fertilizer when it is grown in a P-deficit situation and that N or K cannot substitute for balanced nutrition.

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Joseph R. Heckman

Yield responses of `Blue Vantage' cabbage (Brassica oleracea L.) to P fertilizer and two commercially available biostimulants—ROOTS and ESSENTIAL-were evaluated on soils very high in P fertility. Head yield was not increased with P fertilizer when cabbage was transplanted into soil with Mehlich-3 soil test P indexes ≥ 112 ppm (112 mg·kg-1). Neither of the biostimlants applied as a root drench at transplanting influenced head yield or plant tissue nutrient analysis.