Soil CO2 venting as one of the mechanisms for tolerance of Zn deficiency by rice in flooded soils |
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Authors: | Marie‐Cecile Affholder Dominik J Weiss Matthias Wissuwa Sarah E Johnson‐Beebout Guy JD Kirk |
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Institution: | 1. School of Water, Energy and Environment, Cranfield University, Cranfield, UK;2. Department of Earth Science and Engineering, Imperial College London, London, UK;3. Crop Production and Environment Division, Japan International Research Center for Agricultural Sciences, Ibaraki, Japan;4. Crop and Environmental Sciences Division, International Rice Research Institute, Metro Manila, Philippines |
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Abstract: | We sought to explain rice (Oryza sativa) genotype differences in tolerance of zinc (Zn) deficiency in flooded paddy soils and the counter‐intuitive observation, made in earlier field experiments, that Zn uptake per plant increases with increasing planting density. We grew tolerant and intolerant genotypes in a Zn‐deficient flooded soil at high and low planting densities and found (a) plant Zn concentrations and growth increased with planting density and more so in the tolerant genotype, whereas the concentrations of other nutrients decreased, indicating a specific effect on Zn uptake; (b) the effects of planting density and genotype on Zn uptake could only be explained if the plants induced changes in the soil to make Zn more soluble; and (c) the genotype and planting density effects were both associated with decreases in dissolved CO2 in the rhizosphere soil solution and resulting increases in pH. We suggest that the increases in pH caused solubilization of soil Zn by dissolution of alkali‐soluble, Zn‐complexing organic ligands from soil organic matter. We conclude that differences in venting of soil CO2 through root aerenchyma were responsible for the genotype and planting density effects. |
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Keywords: | dissolved CO2 genotype nutrient uptake differences rhizosphere pH zinc solubilization |
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