A microcosm was assembled to physically separate soil from roots and was used to study both the impact of living roots on the soil–plant system during early stages of growth and plant responses to abiotic stress. Oat (Avena sativa L.) seedlings were grown in the microcosm unit for 44 days. Twenty-three days after planting, 0.154 mg CdSO4/g dry soil was added. Plants grown in Cd-treated microcosms showed considerable inhibition of shoot growth rates, and leaf chlorophyll content. Soil microbial biomass C and respiration increased with plant age, and most of the measured biochemical indicators decreased with increasing distance from the soil–root interface, thus demonstrating the rhizosphere effect, likely due to the quick assimilation of rhizodeposits by rhizosphere microflora. On the other hand, short-term Cd contamination sometimes had an inhibitory effect on soil respiration, qCO2, ATP content, and phosphatase activity, while stimulating microbial biomass, mainly at the rhizosphere level. The decrease in rhizosphere microbial activity observed after Cd application to soil may be due to a synergic effect of the metal directly on microbial cells and indirectly on plants, which reduced shoot growth rate and chlorophyll content, resulting in decreased availability of root exudates.
|Numero di pagine||10|
|Rivista||Australian Journal of Soil Research|
|Stato di pubblicazione||Published - 2011|
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