DMCA
Decomposer biomass in the rhizosphere to assess rhizodeposition (2007)
| Venue: | Oikos |
| Citations: | 5 - 0 self |
BibTeX
@ARTICLE{Christensen07decomposerbiomass,
author = {Søren Christensen and Lisa Bjørnlund},
title = {Decomposer biomass in the rhizosphere to assess rhizodeposition},
journal = {Oikos},
year = {2007},
pages = {65--74}
}
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OpenURL
Abstract
Quantification of the organic carbon released from plant roots is a challenge. These compounds of rhizodeposition are quickly transformed into CO2 and eventually bacterial biomass to be consumed by bacterivores (protozoa and nematodes). Microbes stimulate rhizodeposition several-fold so assays under sterile conditions give an unrealistic value. Quantifying bacterial production from 3H-thymidine incorporation falls short in the rhizosphere and the use of isotopes does not allow clear distinction between labeled CO2 released from roots or microbes. We reduced rhizodeposition in 35 week old barley with a 2 week leaf aphid attack and found that biomass of bacterivores but not bacteria in the rhizosphere correlated with plant-induced respiration activity belowground. This indicated top-down control of the bacteria. Moreover, at increasing density of aphids, bacterivore biomass in the rhizosphere decreased to the level in soil unaffected by roots. This suggests that difference in bacterivore biomass directly reflects variations in rhizodeposition. Rhizodeposition is estimated from plant-induced increases in bacterial and bacterivore biomass, and yield factors, maintenance requirements, and turnover rates from the literature. We use literature values that maximize requirements for organic carbon and still estimate the total organic rhizodeposition to be as little as 46 % of the plant-induced respiration belowground. During the growing season annual crop plants transport
Keyphrases
decomposer biomass organic carbon bacterivore biomass 3h-thymidine incorporation plant-induced increase week leaf plant-induced respiration activity belowground maintenance requirement clear distinction indicated top-down control plant-induced respiration belowground yield factor bacterial biomass unrealistic value bacterial production season annual crop plant sterile condition turnover rate total organic rhizodeposition literature value week old barley microbe stimulate rhizodeposition several-fold plant root
