Abstracts
Kirsch, A., Franken and M.M. Blanke, 2000: Field measurement of substrate-induced respiration. Zeitschrift Pflanzenernährung Bodenkunde 163, 165-171
Measurement of substrate-induced respiration in the field
A new technique has been developed at Bonn university for the comparison of soils at different sites and estimation of soil fertility. So far, a discrepancy existed between soil respiration rates obtained from laboratory measurements of sieved soil and field "in-situ" measurements. Additionally, the substrate-induced respiration (SIR) measurement was restricted to the laboratory.
The new technique based on the PP Systems Soil Respiration System enables soil respiration measurements "in-situ" in the field. Sugar solutions are added as substrate for soil microbes and field measurements conducted over time and a range of sugar concentrations. This is to determine both the time and the sugar concentration when the soil microbes are saturated in terms of respiratory substrate before multiplication commences. Once, the saturating sugar concentration is established for a particular soil, the resulting double sigmoidal respiration curves are analysed using a commercial biokinetics program from Bristol, UK. Within this biokinetics program, the kinetic model of Hanes and the so-called non-parametric kinetic model gave good agreement and were found appropriate for substrate-induced soil respiration. They provide the user with the calculated maximum soil respiration, Vmax, and the substrate concentration at half maximum soil respiration, Km (Michaelis-Menten-constant) and the initial rate Vo. These three parameters enable a description of the substrate situation of a particular soil.
The study also established a correlation of r2= 0.81 between field and laboratory soil respiration measurements with 59% larger soil respiration rates in the laboratory compared to field measurements.
Environmental and Experimental Botany, Vol. 34, No 4, p.385-391. 1994
Copyright © 1994 Elsevier Science Ltd.
DIURNAL CO2 FLUCTUATIONS IN AN APPLE ORCHARD
MARIA HAMACHER, MICHAEL M. BLANKE* and FRITZ LENZ
Institut für Obstbau und Gemüsebau, Auf dem Hügel 6, D-53121 Bonn, Germany
(Received 14 April 1994; accepted in revised form 2 ]une 1994)
Hamacher M., Blanke M. M. and Lenz F. Diurnal CO2 fluctuations in an apple orchard. Environmental and Experimental Botany 34, 385-391, 1994.-Diurnal CO2 fluctuations were recorded in an apple orchard at Bonn, Germany. The CO2 concentration was measured continuously for 24-hr periods with a portable, batterv-driven infrared gas analyser with combined datalogger at 0.60, 1.20 and 1.80 m heights within an apple tree canopy and 1.50 m above the grass between tree rows. Measurements were conducted on typical sunny or cloudy days during the vegetation period in 1992.
The largest diurnal variations on sunny summer days were ca 300 ppm CO2 i.e. between 328 and 632 ppm CO2. On these days, CO2 concentrations declined to 328 ppm in the afternoon between 1400 and 1600 hr and reached a maximum of either 466 ppm during warm or 632 ppm during hot nights between 200 and 400 hr in the lower part of the apple tree canopy 0.60 m above ground. The low afternoon CO2 concentrations in the canopy may be a result of tree photosynthesis during the day, whereas the large CO2 concentrations were attributed to lack of wind or turbulence and considerable dark respiration of the apple trees and grass and soil as dependent on night temperature.
On cloudy and overcast summer days, in contrast, the CO2 concentrations during the day remained constant around 340-350 ppm CO2 with a slight increase to 370-380 ppm CO2 during the night.
Key words: CO2, leaf, photosynthesis, radiation, respiration, soil, temperature, tree.
*Author to whom correspondance should be addressed.
J. Plant Physiol. Vol. 150. pp. 247-250 (1997)
Bioenergetics, Maintenance Respiration and Transpiration of Pepper Fruits
MICHAEL M. BLANK1* and PETER A. HOLTHE2
1 Institut für Obstbau und Gemüsebau, Auf dem Hügel 6, D-53121 Bonn, Germany
2 San Joaquin Gourmet Produce Company, 21878 Road 254, Lindsay, California 93247, USA
Received May 9, 1996. Accepted August 2, 1996
Summary
Structure and function of chile pepper Capsicum annuum var. annuum L. fruit tissues were examined by SEM, GC and porometry. Stomata were absent from the inner (endocarp) and outer (exocarp) epidermis of mature chile pepper fruits of cvs. Serrano, Jalapeño, Hungarian Wax, Anaheim and MexiBell. Fruit transpiration of 0.4 to 2.4 mmol H2O m-² s-¹ was hence attributed solely to cuticular transpiration. Chlorophyll contents of mature fruits ranged from 4.1 µg g-¹ to 76 µg g-¹ fresh weight with chlorophyll a: b ratios of 1.68:1 to 2.35:1. Locular space volumes and CO2 concentrations ranged respectively from 22 % to 52 % (v/v) and from 0.6 to 2.1 % CO2 with concomitant locular oxygen concentrations from 18.4 to 20.6 % O2 and RQ of between 0.89 to 1.81. Immature seeds and placenta were the primary sources of accumulated CO2, while respiration of the endocarp was comparatively low. The large maintenance respiration from 0.81 to 2 mg CO2 [g dwt day]-¹ and 0.54 to 1.3 mg glucose [g dwt day]-¹ provided 0.05 to 1.3 kjoule fruit-¹ h-¹ for biochemical conversions.
Key words. Bioenergetics, Capsicum annuum var. annuum L., carbon, CO2, fruit, pepper quality, maintenance respiration, transpiration, water loss.
Annals of Botany 78 599-604, 1996
Ammonium Nutrition Enhances Chlorophyll and Glaucousness in Kohlrabi*
MICHAEL M. BLANKE+, WOLFGANG BACHERT+, RICHARD J. PRINGT++and EDWARD A. BAKER++
+ Institut für Obstbau und Gemüsebau, Auf dem Hügel 6, D-53121 Bonn, Germany
and ++ IACR-Long Ashton Research Station, Department of Agricultural Sciences, University of Bristol, Long Ashton, Bristol BS18 9AF, UK
Received: 10 October 1995 Accepted: 11 May 1996
Kohlrabi (Brassica oleracea var. gongylodes) plants were grown in the greenhouse under autumn conditions and fertilized either with pellets containing nitrogen as 40 % ammonium sulphate and 60 % urea or with nutrient solution containing nitrogen predominantly as nitrate. Plants given nitrogen as ammonium ions developed glaucous leaves compared to those supplied with nitrate which formed glossy leaves. Ammonium-induced glaucousness was the result of a two-fold increase in the amount of epicuticular wax and a markedly altered fine structure. Leaves from ammonium fertilized kohlrabi plants also showed a 21 % increase in chlorophyll content together with a reduction in the chlorophyll a:b ratio and decreased ground state fluorescence compared to plants supplied with nitrate. Photosynthesis and stomatal transpiration were unaffected by the form of supplied nitrogen.
© 1996 Annals of Botany Company
Key words: Brassica oleracea, chlorophyll, chlorophyll fluorescence, epicuticular wax, glaucousness, photosynthesis,
transpiration.
Journal of Applied Ecology(1981),18, 221-228
AN IMPROVED METHOD FOR MEASURING SOIL RESPIRATION IN THE FIELD
BY K. J. PARKINSON
Physics Department, Rothamsted Experimental Station, Harpenden, Herts AL5 2JQ
SUMMARY
(1) Soil respiration is commonly determined by measuring the rate of increase in the CO2, concentration within a chamber placed on the soil surface, with an opening to the soil.
(2) In the present method the errors associated with the technique have been minimized by careful design of the chamber and the sampling system, and by the use of a sensitive infra-red gas analyser for the analysis of the CO2 concentration.
(3) Small (5 cm³) samples of the chamber air are taken at 1 min intervals over a 4 min period. From the measured CO2 concentrations, the respiration rate is determined, using a graphical technique, to an accuracy of 2% and with a precision of 10%.
References
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