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James S. Owen Jr, Stuart L. Warren, Ted E. Bilderback, and Joseph P. Albano

growing medium. This management strategy needs to be reconsidered as a result of economic and environmental concerns surrounding current production practices. Phosphorus losses are being investigated because P leaching or runoff can contribute to

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Jeff B. Million, Thomas H. Yeager, and Joseph P. Albano

release of nutrients from CRF during this period ( Huett and Gogel, 2003 ). In contrast, temperatures at the end of 2004 were decreasing and nutrient release would be expected to decrease as well. Fig. 7. Weekly amounts of nitrogen (N), phosphorus (P), and

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Matthew D. Taylor, Paul V. Nelson, and Jonathan M. Frantz

Sudden pH decline (SPD) describes the situation where crops growing at an appropriate pH rapidly (within 1–2 weeks) cause the substrate pH to shift downward one to two units. Phosphorus (P) deficiency has been shown to cause plants to acidify

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Aaron Heinrich, Richard Smith, and Michael Cahn

characteristics and total nitrogen (N), phosphorus (P), and potassium (K) uptake, and N in residue and soil for commercial spinach fields sampled in 2011 in the Salinas Valley and San Juan Valley of California. Fig. 1. Uptake in aboveground spinach biomass of (A

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Timothy K. Broschat

( Ogden et al., 1987 ). Controlled-release fertilizers (CRFs) have been very effective in supplying plant nutrient needs and minimizing the loss of environmentally problematic ions such as nitrate nitrogen (NO 3 -N) and phosphate phosphorus (PO 4 -P

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George C. Martin, Chic Nishijima, and John M. Labavitch

Abstract

A method was devised for quantitation of methylated indoleacetic (MeIAA) using a nitrogen-phosphorus (N-P) detector gas chromatograph with sensitivity greater than 5 pg MeIAA. Parameters are described for use conditions of the N-P detector.

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T. Greidanus and M. N. Dana

Abstract

Phosphorus stress caused a general restriction of growth, pinkish tips and purplish leaves and was associated with low tissue P concn. Phosphorus concn for severe deficiency ranged from 0.034 to 0.08%, hidden hunger occurred from 0.09 to 0.11%, and sufficiency 0.12 to 0.27%. Phosphorus removed from the nutrient solutions was recovered in the plants. Soil test P at 50-70 kg/ha did not limit growth.

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Kristian Borch, Carter Miller, Kathleen M. Brown, and Jonathan P. Lynch

A series of experiments was conducted to investigate the response to drought stress of marigold (Tagetes patula L. `Janie Tangerine') plants grown with reduced phosphorus. Plants were grown with convention al phosphorus fertilization (1 mm, control) or one of two levels of alumina-buffered phosphorus (Al-P), 21 or 5 μm. Plants supplied with 21 μm Al-P produced plants with equal total dry weight, more flowers and reduced leaf area compared to control plants. Whole-plant photosynthetic CO2 assimilation expressed on a leaf area basis was nearly twice as high in 21 μm Al-P plants as in controls, probably as a result of reduced intraplant shading. In plants supplied with 21 μm Al-P, smaller leaf area resulted in reduced whole-plant transpiration. Moreover, the relative water content of the growing medium was significantly lower at wilting with 21 μm Al-P than for control or 5 μm Al-P regimes. The improved water acquisition with 21 μm Al-P could be explained by increased root proliferation via longer main roots and less densely distributed lateral roots. The results indicate that optimizing phosphorus nutrition with solid-phase buffered-phosphorus fertilizer improves drought tolerance by reducing transpiration and increasing water acquisition from the medium.

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John M. Smagula

Liquid phosphorus (23% phosphoric acid) was applied preemergence at 0, 22.4, 44.8, 67.2, or 89.6 kg·ha-1 to 9 fields: 3 commercial blueberry fields having plants with very low (<.111%), 3 low (.111-.125%), and 3 adequate (>.125%) leaf phosphorus concentrations. Years of application ('89,'89+'91,'89 + '91 + '93) were assigned in a split-block RCB design with 4 replications at each location. A linear increase in leaf phosphorus concentration with increasing rates of P application was found in both 1989 and 1991. Differences in response were found among locations. A second application in 1991 was effective in raising leaf P levels at most locations to higher levels than the application in 1989. Also, there were higher levels of leaf P in treatment plots that only received P fertilizer in 1989 compared to controls, indicating a carry over effect.

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Richard T. Poole and Charles A. Conover

Abstract

Grade and color of the bromeliad, Aechmea fasciata, improved with increased N. Increased K fertilization increased grade but decreased color. Phosphorus had no effect. Placement of the fertilizer solution and water in the vase of the bromeliad was not essential for the production of quality bromeliads under greenhouse conditions.