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Responses to Iron Limitation in Hordeum vulgare L. as Affected by the Atmospheric CO 2 Concentration
Author(s) -
Haase S.,
Rothe A.,
Kania A.,
Wasaki J.,
Römheld V.,
Engels C.,
Kandeler E.,
Neumann G.
Publication year - 2008
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2006.0136
Subject(s) - hydroponics , rhizosphere , hordeum vulgare , shoot , biomass (ecology) , horticulture , chemistry , iron deficiency , agronomy , plant physiology , biology , botany , bacteria , poaceae , medicine , genetics , anemia
Elevated atmospheric CO 2 treatments stimulated biomass production in Fe‐sufficient and Fe‐deficient barley plants, both in hydroponics and in soil culture. Root/shoot biomass ratio was increased in severely Fe‐deficient plants grown in hydroponics but not under moderate Fe limitation in soil culture. Significantly increased biomass production in high CO 2 treatments, even under severe Fe deficiency in hydroponic culture, indicates an improved internal Fe utilization. Iron deficiency‐induced secretion of PS in 0.5 to 2.5 cm sub‐apical root zones was increased by 74% in response to elevated CO 2 treatments of barley plants in hydroponics but no PS were detectable in root exudates collected from soil‐grown plants. This may be attributed to suppression of PS release by internal Fe concentrations above the critical level for Fe deficiency, determined at final harvest for soil‐grown barley plants, even without additional Fe supply. However, extremely low concentrations of easily plant‐available Fe in the investigated soil and low Fe seed reserves suggest a contribution of PS‐mediated Fe mobilization from sparingly soluble Fe sources to Fe acquisition of the soil‐grown barley plants during the preceding culture period. Higher Fe contents in shoots (+52%) of plants grown in soil culture without Fe supply under elevated atmospheric CO 2 concentrations may indicate an increased efficiency for Fe acquisition. No significant influence on diversity and function of rhizosphere‐bacterial communities was detectable in the outer rhizosphere soil (0–3 mm distance from the root surface) by DGGE of 16S rRNA gene fragments and analysis of marker enzyme activities for C‐, N‐, and P‐cycles.