The effects of temporal variation in soil carbon inputs on resource allocation in an annual plant

Hagai Shemesh, Uri Ben-Yosef, Stav Livne, Ofer Ovadia

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Aims: Resource allocation in plants can be strongly affected by competition. Besides plant-plant interactions, terrestrial plants compete with the soil bacterial community over nutrients. Since the bacterial communities cannot synthesize their own energy sources, they are dependent on external carbon sources. Unlike the effect of overall amounts of carbon (added to the soil) on plant performance, the effect of fine scale temporal variation in soil carbon inputs on the bacterial biomass and its cascading effects on plant growth are largely unknown. We hypothesize that continuous carbon supply (small temporal variance) will result in a relatively constant bacterial biomass that will effectively compete with plants for nutrients. On the other hand, carbon pulses (large temporal variance) are expected to cause oscillations in bacterial biomass, enabling plants temporal escape from competition and possibly enabling increased growth. We thus predicted that continuous carbon supply would increase root allocation at the expense of decreased reproductive output. We also expected this effect to be noticeable only when sufficient nutrients were present in the soil. Methods: Wheat plants were grown for 64 days in pots containing either sterilized or inoculated soils, with or without slow-release fertilizer, subjected to one of the following six carbon treatments: daily (1.5mg glucose), every other day (3mg glucose), 4 days (6mg glucose), 8 days (12mg glucose), 16 days (24mg glucose) and no carbon control. Important Findings: Remarkably, carbon pulses (every 2-16 days) led to increased reproductive allocation at the expense of decreased root allocation in plants growing in inoculated soils. Consistent with our prediction, these effects were noticeable only when sufficient nutrients were present in the soil. Furthermore, soil inoculation in plants subjected to low nutrient availability resulted in decreased total plant biomass. We interpret this to mean that when the amount of available nutrients is low, these nutrients are mainly used by the bacterial community. Our results show that temporal variation in soil carbon inputs may play an important role in aboveground-belowground interactions, affecting plant resource allocation.

Original languageEnglish
Pages (from-to)30-39
Number of pages10
JournalJournal of Plant Ecology
Volume9
Issue number1
DOIs
StatePublished - 1 Feb 2015

Keywords

  • Triticum
  • immobilization
  • microbial loop
  • resource allocation
  • soil carbon inputs
  • temporal variation

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Plant Science

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