The effects of micro-organisms upon plant growth
Phytotoxins developed during heat-sterilization of soil were removed by 40 per cent of the fungi and ten per cent of the bacteria isolated from inoculated heat-sterilized soil. Detoxication by the fungi was not necessarily associated with marked proliferation in sterile soil,Trichoderma viride was an active colonizer of sterile soil but quite ineffective as a detoxicating agent.
The phytotoxins could be readily leached out and their effects transmitted to sterile sand and irradiated soil. Results indicate that the toxicity is not due to changes in pH, soluble manganese or ammonia but is probably due to the formation of toxic organic materials.
Primary root growth of subterranean clover is markedly stunted by toxins formed during heat-sterilization of soil and could provide an extremely sensitive bioassay for toxicity.
Detoxication by micro-organisms may have been misinterpreted in the past as a direct stimulation of plant growth and caution is required in studies of the effects of micro-organisms upon plant growth.
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- 1.Bowen, G. D. and Rovira, A. D., Plant growth in irradiated soil. Nature191, 936–937 (1961).Google Scholar
- 2.Bowen, G. D. and Rovira, A. D., The effects of micro-organisms on plant growth. I. Development of roots and root hairs in sand and agar. Plant and Soil15, 166–188 (1961).Google Scholar
- 3.David, D. J., The application of atomic absorption to chemical analysis (A review). The Analyst85, 779–791 (1960)Google Scholar
- 4.Evans, E., Survival and recolonization by fungi in soil treated with formalin or carbon di-sulphide. Trans. Brit. Mycol. Soc.38, 335–346 (1955).Google Scholar
- 5.Greweling, T. and Peech, M., Chemical soil tests. Cornell Univ. Agr. Exp. Sta. Bull.960, 1–54 (1960).Google Scholar
- 6.Johnson, J., The influence of heated soils on seed germination and plant growth. Soil Sci.7, 1–104 (1919).Google Scholar
- 7.Lawrence, W. J. C. and Newell, J., Seedling growth in partially sterilized soil. Sci. Hort.4, 165–177 (1936).Google Scholar
- 8.Ludwig, R. A. and Henry, A. W., Studies on the microbiology of recontaminated sterilized soil in relation to its infestation withOphiobolus graminis Sacc.. Canad. J. Research C.21, 343–350 (1943).Google Scholar
- 9.Robinson, R., Inhibitory plant growth factors in partially sterilized soils. J. Am. Soc. Agron.36, 726–739 (1944).Google Scholar
- 10.Russell, E. J. and Petherbridge, F. R., On the growth of plants in partially sterilized soils. J. Agr. Sci.5, 248–287 (1913).Google Scholar
- 11.Samuel, G. and Piper, C. S., Grey speck (manganese deficiency) disease of oats. J. Agric. South Australia31, 789–799 (1928).Google Scholar
- 12.Warcup, J. H., Effect of partial sterilization by steam or formalin on damping-off of Sitka spruce. Trans. Brit. Mycol. Soc.35, 249–262 (1952).Google Scholar
- 13.Warcup, J. H., Chemical and biological aspects of soil sterilization. Soils and Fertilizers20, 1–5 (1957).Google Scholar
- 14.Wright, Joyce M., Biological control of soil-bornePythium infection by seed inoculation. Plant and Soil8, 132–140 (1956).Google Scholar