Affholder Marie-Cecile, Weiss Dominik J, Wissuwa Matthias, Johnson-Beebout Sarah E, Kirk Guy J D
School of Water, Energy and Environment, Cranfield University, Cranfield, MK43 0AL, UK.
Department of Earth Science and Engineering, Imperial College London, London, SW7 2AZ, UK.
Plant Cell Environ. 2017 Dec;40(12):3018-3030. doi: 10.1111/pce.13069. Epub 2017 Nov 10.
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 CO 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 CO through root aerenchyma were responsible for the genotype and planting density effects.
我们试图解释水稻（Oryza sativa）基因型在淹水水稻土中对锌（Zn）缺乏耐受性的差异，以及早期田间试验中得出的与直觉相悖的观察结果，即单株锌吸收量随种植密度增加而增加。我们在高、低种植密度下，于缺锌的淹水土壤中种植耐受性和不耐受性基因型水稻，发现：（a）植株锌浓度和生长随种植密度增加，耐受性基因型增加得更多，而其他养分浓度降低，表明对锌吸收有特定影响；（b）只有当植物引起土壤变化使锌更易溶解时，种植密度和基因型对锌吸收的影响才能得到解释；（c）基因型和种植密度效应均与根际土壤溶液中溶解的二氧化碳减少以及由此导致的pH值升高有关。我们认为，pH值升高通过溶解土壤有机质中碱溶性、络合锌的有机配体导致土壤锌溶解。我们得出结论，通过根通气组织排出土壤二氧化碳的差异是造成基因型和种植密度效应的原因。
