We investigated that influence of percolation patterns on growth and yield ofrice plants and uptake of cadmium from polluted paddy flelds using soil dressing models. The experiment was conducted in the green house with open and closed system percolation models (M-1,M-2,M-3,M-4,MI5,M-6,MI7,M-8,M-9andM-10). Those models were consisted of stratified soil layers and two different percolation systems (open and closed system percolation) and operated by 12.5cm (M-1 to M-6),15cm (M-7 to M-8) and 20cm (M-9 to M-10) soil dressing with stratifled polluted paddy fields. The stratifled paddy field models were constructed in an iron box (30x50x70 cm)with three layers of soil; those were plow layer(layer I; 0-12.5 cm), plowsole (layer II;12.5-22.5cm), and subsoil(layer III,22.5-65cm)and constructed with Andosol or alluvial(layer I),Cd-polluted soil or Cd-polluted soil with alluvial (layer II) and gravel or Cd-polluted soil with gravel(III layer). In open system percolation models was planed in plowsole and subsoil but in the closed system percolation models, soil layers were planed under saturated condidon. The two percolation systems were applied to paddy field models by controlling the ground water level at 57.5 cm and 12.5 cm for the open system and closed system model, espectively, usinga subsurface drainage pipe.In open system percolation, the pressure head of the plowsole and subsoil werenegative but inclosed system showed positive pressure. In the open system percolation models, plowsole and subsoil temperature almost similar to the air temperature but in closed system percolation models were higher than the air temperature. The soil redox(Eh)value in plow layer of both percolations wasabout-190 mV. But in the plowsole and subsoil were in oxidative condition(650mV) in open system percolation models. On the other hand, in the plowsole and subsoil were in reducdon state(-200mV) in closed system percolation models. The average SPAD values in closed system percolation models were lower than the open system percolation models. In the harvesting period, the 14th leaf was dry about 78% in closed system percolation but 43% in open system percolation models; this result indicated that the difference of photosynthesis ability of rice plants in two systems during ripening time. Moreover, the plant length, number of stem, number and weight of pamicles, number and weight of grains were lower in open system percolation modelsthan the closed system percolation models. Accumuladon of cadmium in roots of each soil layer, stem and leaves and rice grain were higher in open system percolation than the closed system percolation models. In soil oxidation state, the insoluble cadmium metal in soil leading to soluble form with presence of oxygen which can be easily uptake by rice plants. As above mentioned, it was recogmized that percolation pattern in fluenced on the growth and yields of riceplants and uptake of cadmium.
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