Growth and Mineral Composition of Rice at Various Soil Moisture Tensions and Oxygen Levels
1976
Patrick, W. H. | Fontenot, W. J.
The better growth of rice in a flooded soil as compared to an upland soil has been attributed to the reducing conditions caused by submergence. No study has been carried out, however, in which the effects of the soil moisture status has been separated from the effect of the oxidation-reduction conditions of the soil. In the study reported here, the effect of soil oxidation-reduction conditions on early growth and mineral composition of lowland rice (Oryza sativa L. ‘Saturn’) was determined by growing plants in artificially packed soil columns maintained under different soil moisture tension and oxygen conditions. Since soil aeration is largely governed by the moisture status of the soil, this study was designed to separate these effects by subjecting the rice plant to different aeration conditions while at the same time attempting not to limit moisture supply. In one experiment different redox conditions were established by maintaining soil columns at soil moisture tensions ranging from 0 to 80 cm during growth of the plants. In a second experiment plants were grown at soil oxygen levels of 0, 3, 8, and 12% while soil moisture was maintained at 10 cm moisture tension. Vegetative growth of rice was greater under reduced conditions than under oxidized conditions in both experiments. The P concentration of the plant was much higher under reduced conditions than under oxidized conditions. Reduced conditions increased the solubility of P, Fe, and Mn in the soil although no consistent effect of reducing conditions on plant uptake of Fe and Mn was observed.
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