Biomass allocation in an agropyron Smithii-glomus symbiosis
- Argonne National Lab., IL (USA)
The type of response the steppe grass Agropyron smithii Rydb. exhibits to mycorrhizal fungi is dependent upon where along the resource gradient the experiment is conducted. At the lower end of a soil-phosphorus (P) gradient (2 {mu}g P g{sup {minus}1} soil) mycorrhizal A. smithii biomass was 35% greater than its nonmycorrhizal counterpart; while at the high end of the gradient (20 {mu}g P g{sup {minus}1} soil) no difference in host biomass production was evident. Mycorrhizal plants were shorter in stature and produced more tillers than nonmycorrhizal plants. The stature and tiller response was more pronounced at the high end of the soil-P gradient. The partitioning of the mycorrhizal fungus was influenced by the soil-P gradient. At the lower end of the gradient the majority of the fungus was produced extramatrically, where over 5,000 cm of hyphae per plant were encountered after 10 wk growth. While at the high end of the gradient, the majority of fungus was produced internally. The highest mycorrhizal dependency values were measured at the lower end of the soil-P gradient where cost to the host (as measured by fungus biomass expressed as a percentage of the root system) was also highest. Increasing shoot and root-P concentrations were correlated with decreasing external fungus biomass. A positive association between tiler production and internal fungus biomass also existed.
- DOE Contract Number:
- W-31-109-ENG-38
- OSTI ID:
- 6942823
- Journal Information:
- American Journal of Botany; (USA), Vol. 74:1; ISSN 0002-9122
- Country of Publication:
- United States
- Language:
- English
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