Rhizosphere microflora of winter wheat plants cultivated under elevated CO2

• Published in: Plant and soil Vol. 197; no. 2; pp. 251 - 259
• Main Authors: ELHOTTOVA, D, TRISKA, J, SANTRUCKOVA, H, KVETON, J, SANTRUCEK, J, SIMKOVA, M
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer 01.12.1997; Springer Nature B.V
• Subjects: Agronomy. Soil science and plant productions; Biochemistry and biology; Biological and medical sciences; Carbon dioxide; Chemical, physicochemical, biochemical and biological properties; Cultivation; Fractionation; Fundamental and applied biological sciences. Psychology; Grain cultivation; Hydroponics; Lipids; Microbiology; Microorganisms; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Plant growth; Retention time; Rhizosphere; Sand; Silica; Soil science; Winter wheat; SOIL BIOLOGY; Monocotyledones; Microbiology; Cultivated soil; Carbon dioxide; Environmental factor; Microflora; Cereal crop; Trophic group; Medium enrichment; Controlled environment study; Gramineae; Hydroponic cultivation; Angiospermae; Bacteria; Method study; Analytical chemistry; Nutrition; Soilless study; Coupled method; Vegetal microorganism relation; Butyrate(hydroxy)polymer; Microbial biomass; Carbon; Gas chromatography; Rhizosphere; Analysis method; Rhizobacteria; Winter crops; Concentration effect; Environment; Spermatophyta; Microorganism; Soil plant relation; Mass spectrometry; Triticum aestivum
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1023/A:1004220514167

We studied an effect of elevated atmospheric CO^sub 2^ on rhizosphere microorganisms in a hydroponics system where young wheat plants provided the only source of C for microorganisms. Plants were cultivated in mineral solution in sterile silica sand and exposed to control (ambient) and elevated (double) CO^sub 2^ concentrations for periods of 13, 20, 25 and 34 days. Microbial biomass C (C content in fraction of size 0.3-2.7 µm) was not affected by the elevated CO^sub 2^ concentration during the first 25 days of plant growth and was increased after 34 days of plant growth. A content of poly-β-hydroxybutyrate (PHB) reserve compounds (measured as derivatized product of 3-hydroxy-butyric acid and N-tert-butyldimethylsilyl-N-methyltrifluoracetamide using GC-MS) was lowered significantly (p<0.001) in the elevated CO^sub 2^ after 25 and 34 days. It was accompanied with a shift of bacterial distribution towards the nutritional groups utilising more complex organic material (number of CFUs on media with different sources of C and N). A coincidence of several events connected with plant and microbial carbon economy (decrease of an assimilation rate and relative growth rate of plants, small increase of microbial biomass, PHB decrease and suppression within the bacterial nutritional group requiring the most readily available source of C and energy) was observed in the system under elevated CO^sub 2^ on the 25th day. A modification of the GC-MS method for the detection of low levels of PHB compounds in natural samples was developed. We excluded the lipids fractionation step and we used EI MS/MS detection of the main fragment ions of the derivatized compound. This guarantees that the ion profiles have high signal-to-noise ratio at correct retention time. The detection limit is then about 30 pg g^sup -1^ of sand or soil. The rhizosphere microflora responded very sensitively to the short-term changes in C partitioning in plants caused by the elevated CO^sub 2^.[PUBLICATION ABSTRACT]