Abstract
Perennial rye-grass plants were grown at 15°C in microcosms containing soil sampled from field plots that had been maintained at constant pH for the last 30 years. Six soil pH values were tested in the experiment, with pH ranging from 4.3–6.5. After 3 weeks growth in the microcosms, plant shoots were exposed to a pulse of 14C-CO2. The fate of this label was determined by monitoring 14C-CO2 respired by the plant roots/soil and by the shoots. The 14C remaining in plant roots and shoots was determined when the plants were harvested 7 days after receiving the pulse label. The amount of 14C (expressed as a percentage of the total 14C fixed by the plant) lost from the plant roots increased from 12.3 to 30.6% with increasing soil pH from 4.3 to 6. Although a greater percentage of the fixed 14C was respired by the root/soil as soil pH increased, plant biomass was greater with increasing soil pH. Possible reasons for observed changes in the pattern of 14C distribution are discussed and, it is suggested that changes in the soil microbial biomass and in plant nitrogen nutrition may, in particular be key factors which led to increased loss of carbon from plant roots with increasing soil pH.
Similar content being viewed by others
References
Adams T McM and Adams S N 1983 The effects of liming and soil pH on carbon and nitrogen contained in the soil biomass. J. Agri. Sci. 101, 553–558.
Ames R N, Ingham E R and Reid C P P 1982 Ultraviolet induced autofluorescence of arbuscular root infections: An alternative to clearing and staining methods of assessing infections. Can. J. Microbiol. 28, 350–355.
Bowen G D 1969 Nutrient status effects on loss of amides and amino acids from pine roots. Plant and Soil 30, 139–142.
Carter M R 1986 Microbial biomass and mineralizable nitrogen in solonetizic soils: Influence of gypsum and lime amendments. Soil Biol. Biochem. 18, 531–537.
Curl E A and Truelove B 1986 The Rhizosphere. Chapter 2, pp 9–54, Springer-Verlag, Berlin.
Dalal R C 1979 Simple procedure for the determination of total carbon and its radioactivity in soils and plant materials. Analyst 104, 151–154.
Frenzel B 1960 Aetiology of the accumulation of amino acids and amides in the root zone of Helianthus annuus L.: Contribution to the clarification of problems of the rhizosphere. Planta 55, 169–207.
Hansen G K and Jensen C R 1977 Growth and maintenance respiration in whole plants, tops, and roots of Lolium multiflorum. Physiol. Plant. 39, 155–164.
Higashida S and Takao K 1986 Relationship between soil microbial activity and soil properties in grassland. Soil Sci. Plant Nutr. 32, 587–597.
Hojito M, Higashida S, Nishimune A and Takao K 1987 Effects of liming on grass growth, soil solution composition, and microbial activities. Soil Sci. Plant Nutr. 33, 177–185.
Jenkinson D S and Powlson D S 1976 The effects of biocidal treatments on metabolism in soil. V. A method for measuring soil biomass. Soil Biol. Biochem. 8, 209–213.
Killham K 1987 A new perfusion system for the measurement and characterization of potential rates of soil nitrification. Plant and Soil, 97, 267–272.
Kraffczyk I, Trolldenier G and Beringer H 1984 Soluble root exudates of maize: Influence of potassium supply and rhizosphere micro-organisms. Soil Biol. and Biochem. 16, 315–322.
Kucey R M N and Paul E A 1982 Carbon flow, photosynthesis, and N2 fixation in mycorrhizal and nodulated faba beans (Vicia faba L.). Soil Biol. Biochem. 14, 407–412.
Lambers H 1979 Efficiency of root respiration in relation to growth rate, morphology and soil composition. Physiol. Plant. 46, 194–202.
Lee K J and Gaskins M H 1982 Increased root exudation of 14C-compounds by sorghum seedlings inoculated with nitrogen-fixing bacteria. Plant and Soil 69, 391–399.
Lundegradh H and Stenlid G 1944 On exudation of nucleotides and flavanone from living roots. Arkiv Botanik 31, 1–27.
Marschner H, Romheld V, Horst W J and Martin P 1986 Root-induced changes in the rhizosphere: Importance for the mineral nutrition of plants. Z. Pflanzenernaehr. Bodenkd. 149, 441–456.
Martin J K 1977 Factors influencing the loss of organic carbon from wheat roots. Soil Biol. Biochem. 9, 1–7.
Martin J K and Kemp J R 1986 The measurement of C transfers within the rhizosphere of wheat grown in field plots. Soil Biol. Biochem. 18, 103–107.
Meharg A A and Killham K 1988 Comparison of carbon flow from pre-labelled and pulse labelled plants. Plant and Soil 112, 225–231.
Merckz R, Hartog Aden and Veen J Avan 1985 Turnover of root-derived material and related microbial biomass formation in soils of different texture. Soil Biol. Biochem. 17, 565–569.
Pang E A and Paul E A 1980 Effects of vesicular-arbuscular mycorrhizoe on 14C and 15N distribution in nodulated faba beans. Can. J. Soil Sci. 60, 241–250.
Rovira A D 1969 Plant root exudates. Bot. Rev. 35, 35–57.
Rovira A D and Ridge E H 1973 Exudation of 14C-labelled compounds from wheat roots: Influence of nutrients micro-organisms and added organic compounds. New Phytol. 72, 1081–1087.
Shay F J and Hale M G 1973 Effect of low levels of calcium on exudation of sugars and sugar derivatives from intact peanut roots under axenic conditions. Plant Physiol. 51, 1061–1063.
Snellgrove R C, Splittstoesser W E, Stribley D P and Tinker P B 1982 The ditribution of carbon and the demand of the fungal symbiont in leek plants with vesicular-arbuscular mycorrhizae. New Phytol. 92, 75–87.
Wagatsuma T, Keneko M and Hayasaka Y 1987 Destructure process of plant root cells by aluminium. Soil Sci. Plant Nutr. 33, 161–175.
Wang G M A, Stribley D P, Tinker P B and Walker C 1985 Soil pH and vesicular-arbuscular mycorrhizas. In Ecological Interactions in Soil. Ed. A H Fitter. pp 219–224. Blackwell Scientific Publications, Oxford.
Whipps J M and Lynch J M 1983 Substrate flow and utilization in the rhizosphere of cereals. New Phytol. 95, 605–623.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Meharg, A.A., Killham, K. The effect of soil pH on rhizosphere carbon flow of Lolium perenne . Plant Soil 123, 1–7 (1990). https://doi.org/10.1007/BF00009920
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00009920