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partially explain the variability in published diagnostic guidelines. An alternative approach to developing foliar nutrient concentration guidelines is DRIS analysis ( Beaufils, 1973 ; Walworth and Sumner, 1987 ). In the DRIS approach, differences in foliar

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Laboratories (Camilla, GA) to perform a standard nutrient analysis. Based on the nutrient concentration in the hydroponic solution, the nutrient uptake efficiency of roots (milligrams nutrient per kilogram of root) was calculated for HLB-F and HLY-F trees using

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nutrient ranges ( Needham et al., 1990 ). Hartz et al. (1998) used DRIS analysis to calculate leaf nutrient norms for processing tomato ( Lycopersicon esculentum Mill.) and used those norms and the variance in nutrient concentrations among high

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breeding effort ( Sraffa, 2005 ; Willcox, 1954 ). Foliar nutrient analysis is a well-established method ( Munson and Nelson, 1990 ) to assist in the diagnosis of nutrient-related problems (deficiencies, toxicities, imbalances, etc.) of both annual and

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.0 kg/ha, respectively, among the orchards. In addition, the nutrient inputs from the chemical fertilizers were also quite different. Table 2. Application rate of N, P, and K. Analysis of the profits and losses of soil nutrients

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Abstract

Lettuce was grown in a complete nutrient solution, with Zn increased stepwise by a factor of 2 for 8 treatments from 1.6 to 200 μg/liter. Forty-seven days after imbibition the plants were harvested and separated into 6 parts for tissue analysis. The plants in the low Zn solutions were stunted in growth and showed a marginal purpling and a rupture of laticifers on the margins of the mature leaves. The symptoms progressed from an overall chlorosis to an interveinal necrosis; with the dark desiccated areas eventually coalescing to cover most of the leaf. The Zn nutrient status of the lettuce plant was best defined by determining the Zn concentration in the mature petiole (mid-rib). The critical level of Zn in the mature petiole is 9 ppm. Concentration of Zn in this tissue below 9 ppm indicates an unfavorable Zn nutrient status for the vegetative growth of lettuce.

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Abstract

The relationship between water extraction (1:1.5) values and nutrient uptake in geranium (Pelargonium × hortorum Bailey) growing in moss peat (peat), bark, or moss peat and soil media was investigated. Nitrogen, P, and K fertilizers were incorporated in increments in the starting media and applied again in solution, about at the crop midpoint. Desirable nutrient N(NH4 +-N + NO3 --N), P(H2PO4 --P) and K(K+) values (DV) from media analysis at the start of the experiments (MDV) and midway to flowering (FDV) also were calculated from regression equations on the basis of maximum growth rates, maximum dry weight production at midharvest, and final harvest. The relationships between plant uptake of N, P, and K and the water extract concentrations were generally very good, except for K in bark for both harvests and in peat at the first harvest, and an underestimated P uptake in peat + soil and in bark. The media DV obtained using growth data were broadly similar to those using plant dry weight data, although somewhat lower for N during the early growing period.

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. Literature Cited Bingham, F.T. 1961 Seasonal trends in nutrient composition of Hass avocado leaves Proc. Amer. Soc. Hort. Sci. 78 149 160 Bould, C. 1966 Leaf analysis of deciduous fruits, p. 651–684. In: Childers, N.F. (ed.). Temperate to tropical fruit

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will have minimal impacts on the environment ( USDA, 2000 ). Nutrient management for organic production requires attention and careful application to provide sufficient quantities of nutrients that are available for use by the crop at the appropriate

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Substrate solution testing is an essential management tool for greenhouse plug production. Current methods of plug solution extraction and testing can be confounded by subjective aspects of their techniques. The press extraction method (PEM) developed at North Carolina State University offers a convenient and timely method of solution extraction. The rooting substrate is brought to container capacity and after a period of one hour, pressing the plug surface with a finger or thumb is sufficient to expel the solution. This series of experiments serves to quantify possible variation that may occur in pH, Electrical conductivity (EC), and nutrient analysis from differing manual extraction forces. A modified press was designed to apply a range of force [53, 71, 89, 106, and 124 N (5.0, 6.7, 8.3, 10.0, and 11.6 lb/inch2)], and sampling protocol consistency was verified. For all three experiments, the range of extraction forces within a single fertilizer rate did not significantly affect solution pH or EC. When testing included a range of fertilizer rates, results were significantly different among the fertilizer rates, demonstrating the method's ability to detect changes in pH and EC resulting from increases in fertility levels. Nutrient analysis (NO3 -, NH4 +, P, K, Ca, Mg, Na, B, Cu, Fe, Mn, and Zn) of solution extracted from two different rooting substrates (peat-based and coir-based) showed no differences within substrates for the range of force treatments.

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