摘要:

Modified Olsen (MO) and N KC1 are the extractans used in Costa Rica to diagnose soil fertility. Our laboratory used Universal Soil Extractants to speed analysis and to obtain the best correlations between relative yield and nutrient level in the soils. We evaluated the aforementioned, Mehlich 3 (M3), Modified Morgan (MM) and Ammonium Acetate (AA) in four soil orders (Ultisols, Vertisols, Inceptisols, and Andisols). For calcium (Ca), all reagents gave highly significant correlations and in some cases AA, M3, and KCl showed an essentially one‐to‐one relation. The regression slope of 0.9 was for KCl‐Ca and M3‐Ca when all soils were considered as a population. KCl‐Ca and MM‐Ca regression gave an average slope of 0.94. When KC1 and M3 extractable magnesium (Mg) were regressed, we obtained highly significant correlations in all orders. The same behaviour was found for KCl‐Mg and AA‐Mg. MM showed poor correlations with the other extractants. All reagents gave highly significant correlations for potassium (K). The regression between MO‐K and M3‐K showed a perfect one‐to‐one relation. The average regression slope indicated that MM extracts 55% less K than MO. AA extracted 13% more than MO in these soils. We concluded that M3 can be used instead of KCl and MO in Costa Rican soils without exception for the extraction of cations.

ISSN:0010-3624    

DOI:10.1080/00103629409369102

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Iron (Fe) index was studied in 19 cultivars of muskmelon (Cucumis meloL.) throughout a growth period. All cultivars were grown under greenhouse conditions and were sampled each 15 days. Leaf material was analyzed in order to determine total and hydrochloric acid (HCl)‐extractable micronutrient concentrations in leaves. Total iron (Fe) content was particularly high in cv. Galia and low in cv. Amarillo Canario. Cultivar Cantaloupe showed the highest levels of total manganese (Mn) and zinc (Zn) while lowest of total Mn were recorded in cv. Arava, and lowest total Zn content in cv. Alma. Cultivar Gold‐King showed the highest foliar levels of total copper (Cu), and this micronutrient was lowest in cv. Hum. 2627. Greater differences between cultivars were noted in terms of HCl‐extractable micronutrients. Bayon and Num. 1213 showed very low values for total Fe index, which was highest in Amarillo Canario. Optimal nutritional ranges in the cultivars analyzed were variable but generally high for micronutrients as well as total and soluble Fe index. The evolution of these indices, conditioned by the number and size of sink (fruit), was similar in all cultivars.

ISSN:0010-3624    

DOI:10.1080/00103629409369103

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Soil and plant analyses are useful diagnostic tools only if they supply adequate information about the current state and can predict effects of different types of management. The prerequisites for reproducibility and consistency may not be met with boron which is not distributed homogeneously in plants. It accumulates in marginal areas and between veins, is transported with the transpiration stream and accumulates at terminal places of transpiration. The boron concentration within the same leaf may vary 100‐fold and foliar analyses represent an average value only. Moreover, the boron content increases with the age of leaves, and there is no indication of a homeostatic control of foliar boron contents. Accurate, representative sampling may thus be difficult and critical. An extreme case is shown where toxicity occurs in old leaves and deficiency in new growth. The rate of transpiration greatly affects boron transport into leaves and its distribution. Predictions must thus take water relations into account.

ISSN:0010-3624    

DOI:10.1080/00103629409369104

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Commonly used methods of arsenic (As) determination in plant material require dissolution of tissue in strong acids prior to analysis. Progress in the graphite furnace atomic absorption spectrometry (GFAAS) technique has made the determination of metals in solid samples possible. This study was undertaken to evaluate the possibility of As determination directly in ground plant tissue using GFAAS. The Perkin‐Elmer Model 4100 ZL atomic absorption spectrometer with Zeeman background correction and AS‐70 autosampler has been used for analysis. Spinach (Spinacia oleracea) and com (Zea mays L.) tissues samples containing various As levels were used as test materials. Before injection of the plant slurry into the furnace, the ultrasonic agitator was used to mix the slurry in the autosampler cup to assure uniform distribution of plant powder in the whole volume of liquid. The furnace program contained a pyrolysis step using palladium as the modifier. The GFAAS method was compared with the hydride generation method performed on plant tissue digested with nitric‐perchloric acid mixture. Results show that slurry sampling As values agreed very closely with the standard wet digestion and hydride generation method values.GFAAS is an accurate method, eliminating the time and labor of the plant digestion step.

ISSN:0010-3624    

DOI:10.1080/00103629409369105

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103629409369071

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor