摘要:

A high performance liquid chromatography apparatus with a resin based anion exchange column and a conductivity detector were used to develop a method for borate separation and quantification in extracts of gypsiferous soils. An eluant containing 5 mMNaOH and 0.5 mMNa‐benzoate was found to produce satisfactory chromato‐grams. Calibration curves were linear in the range l to 7 mg B/L. The recovery of ? in spiked samples had a mean and coefficient of variation of 99.6 and 2.2 percent, respectively. The presence of divalent cations caused baseline instability that was remedied by exchange with H+using Dowex 50–8X. The presence of sulfate extended analysis time and was removed by precipitation with BaCl2. Coloration by organic matter does not interfere with ? determination by this method, but individual simple organic acids may mask the borate peak

ISSN:0010-3624    

DOI:10.1080/00103628909368095

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Field data from Florida and Georgia were combined with a simulation model to evaluate the effect of applied ? and split ? application on bahiagrass production. Seasonal dry matter distribution, total yield and ? removal were all analyzed. Early spring growth is enhanced by a single application in April, while split applications spread out the growth. Total yield and ? removal are nearly the same. Equations are given which relate total yield and ? concentration to applied N. This work quantitatively describes the relationship of forage production to ? fertilization.

ISSN:0010-3624    

DOI:10.1080/00103628909368096

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

An equation was developed which relates average annual nitrogen concentration of Pensacola bahiagrass to applied nitrogen and harvest interval. The equation incorporates linear decrease with harvest interval (up to 7 weeks) and exponential increase with applied nitrogen. Regression analysis of field data from five studies in Georgia, Florida and Alabama allowed evaluation of the four coefficients in the equation. An attempt was made to interpret the significance of the coefficients. These results are relevant to forage production and environmental quality

ISSN:0010-3624    

DOI:10.1080/00103628909368097

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The growth dynamics and Ca content of apple fruit were investigated over three growing seasons for the cultivar Spartan and two seasons for the cultivar McIntosh. Calcium content per fruit increased from fertilization to harvest, with some fluctuations during the season. The final Ca content ranged from 8 to 11 mg per fruit. Calcium concentration diminished markedly as a function of dilution during the first few weeks of growth after which it decreased less rapidly until reaching minimum values at 100 and 110 days after bloom for Mclntosh and Spartan respectively

ISSN:0010-3624    

DOI:10.1080/00103628909368098

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Quick, and reliable tissue testing is important in a soil fertility program to ensure adequate yields for profitability. However, commonly used tissue tests for elements require from 2 to 6 hours for digestion and extraction of samples. A rapid digestion procedure for ? and certain cations that requires only an analytical balance and volumetric glassware was therefore developed to assay plant tissues by inductively‐coupled plasma emission spectroscopy. The method is based on the oxidation and solubilization of plant organic matter created by the heat of solution when 30% hydrogen peroxide (H2O2) is added to concentrated sulfuric acid (H2SO4). This step requires about 30 minutes for 40 samples. No further wet‐digestion is requiredfor sample preparation because the high temperature of the plasma converts all complexes and organics in the digest to elemental forms. For the determination of ? by the colorimetric molybdate‐blue method, an additional heating is required to eliminate unreacted peroxide. Results of the proposed procedure compared well with certified values from the National Bureau of Standards plant materials and with results from a nitric acid and a Kjeldahl digestion procedures. Elemental concentrations found with the proposed method also compared well with the two conventional methods for different plant species and plant parts. While recoveries with the proposed procedure for P, K, Ca, Mg, Zn, Cu, and Mn appeared to be within the sensitivities needed for nutritional diagnostic purposes, recoveries of Fe and Al were low. The ease and rapidity of the procedure could make it useful for routine analysis, or for early‐season tissue analysis where correction of ? and certain cation deficiencies could result in increased profits. The method should be especially useful for screening small numbers of samples

ISSN:0010-3624    

DOI:10.1080/00103628909368099

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The formation of a colored indophenol complex is commonly used as a quantitative measure of the ammonium content of soil extracts. The potential interference with ammonium determination from co‐extracted amino acids was examined. The extent of color development was examined for 22 amino acids by subjecting pure solutions to ammonium determination by both the indophenol method and steam distillation. Apparent detection of amino acid as ammonium ranged from 0 to 94 % of total nitrogen for the indophenol procedure, whereas steam distillation resulted in little apparent ammonium recovery. With the exception of threonine, the extent of color development was inversely related to amino acid molecular weight. The range in recoveries for the indophenol procedure suggests both size and composition of the co‐extracted amino acid pool is important in determining the extent of interference.

ISSN:0010-3624    

DOI:10.1080/00103628909368100

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

‘Centennial’ and ‘Jewel’ sweet potato [Ipomoea batatas(L.) Lam.] plants were grown in hydroponic sand culture in either 3.5 or 15 mM nitrogen solutions for 65 days. Petioles, leaf blades, stems, fibrous roots, and fleshy roots were analyzed for dry weight and Kjeldahl nitrogen (N) determinations. Whole plant dry weights of ‘Centennial’ and ‘Jewel’ plants averaged 81.4 and 38.8 g plant‐1, respectively, when grown in 15 mM nitrogen solutions. High ? fertility was associated with a 60 and 48% reduction of fleshy storage root dry weight in ‘Centennial’ and ‘Jewel’, respectively. Total ? concentrations in blades, stems, and fleshy roots were greater for both cultivars when grown in 15 mM nitrogen solutions. Total ? contents of ‘Centennial’ and ‘Jewel’ plants grown in 15 mM nitrogen solutions were 2473 and 1186 mg N plant‐1respectively. These results demonstrate that intraspecific variability for ? absorption and utilization efficiency exists within sweet potato.

ISSN:0010-3624    

DOI:10.1080/00103628909368101

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This study examined the influence of turnip mosaic virus (TuMV) on rutabaga (Brassica napusssp. rapifera (Metzg.) Sinsk) root yield, mineral composition and storability from plants infected during the late stages of first year growth. TuMV‐infected plants from four commercial fields in Ontario, Canada were sampled when one‐sixth to one‐fourth of the plant foliage displayed TuMV symptoms. TuMV was detected in the roots of infected plants but at. low levels. Root yield, root dry matter percentage and the elemental composition of roots were similar from TuMV non‐infected and infected plants in the same field. Nitrogen, ?, ?n and Zn contents in the root tissues were observed to vary among the fields. There was no obvious differences in storability between TuMV non‐infected and infected roots after 5 months at 1°C and 87% humidity

ISSN:0010-3624    

DOI:10.1080/00103628909368102

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In Morocco,response of dryland wheat (Triticum aestivuro) to ? has not been related to soil ? availability index. The objectives of the experiments reported were to determine the critical NaHCO3‐extractable ? level in soils of Settat Province in Morocco and to compare the effect o‐f banding with broadcasting of concentrated superphosphate (CSP) for wheat, crops. Eighteen ?‐P factorial experiments were conducted on three different soil types (Rendolls, Caloixerolls and Chromoxererts) with different ? availability indexes and lime levels in 1985–86 and 1986–87. The ? rates were 0, 9, and 18 in 1985–86 and an additional 36 kg P/ha rate in 1986–87. The rainfall levels were 300 mm with an excellent distribution and 220 mm with a poor distribution in the above years, respectively. In the latter year, a P placement study was conducted on a Rendoll with a NaHCO3‐P level of 4.5 mg/kg. For the placement study the rates were 0, 9, 18, 36, and 54 kg P/ha. The grain yield response to ? averaged 8% in the wet year and 40% in the drier year. The maximum yields obtained were close to 3 and 1 Mg/ha for the above years, respectively. A critical level of 5 mg/kg of NaHCO3‐P was obtained, separating responsive from nonresponsive soils for a relative yield of 90%. The ? placement study showed that yield response to broadcast ? reached a plateau at 9 kg P/ha, but the response to banded ? continued up to the highest rate. This shows that the banding effect of CSP is more than a simple ? nutrition effect

ISSN:0010-3624    

DOI:10.1080/00103628909368103

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Periodic nitrate tissue tests are used to determine nitrogen (N) fertility status of a variety of crops. Data on the importance of plant part selection, sample handling techniques, grinding criteria and extraction conditions in N03‐N analysis of wheat tissue are essential if the procedure is to achieve widespread adoption and use. Detailed partitioning of field grown durum spring wheat (Triticum durum) plants at the Feekes 2 (3–4 leaf), 6 (joint) and 10 (boot) growth stages was conducted to document which plant part exhibits the greatest accumulation of NO3‐N. Sample handling, fineness of tissue grinding, different tissue: extractant ratios and extraction times were examined to determine their effects on NO3‐N recovery. Partitioning data confirmed previous findings which identified the basal stem between ground level and the seed prior to jointing and the 5 cm of stem just above ground level thereafter as the plant parts showing the greatest accumulation of NO3‐N. Therefore, these plant parts have the greatest potential as indicators of the ? nutritional status of durum spring wheat. Optimal recovery of tissue NO3‐N was obtained when stem tissue was separated immediately in the field and dried within 8 hours of sampling, ground to pass a 0.55 mm mesh screen, and extracted for at least 30 minutes when using a sample size of 0.1000 g in conjunction with 25 ml of extractant (i.e. 1: 250 plant tissue to extractant ratio)

ISSN:0010-3624    

DOI:10.1080/00103628909368104

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor