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Silicon accumulation and water uptake by wheat
H.F. MAYLAND, J.L. WRIGHT and R.E. SOJKA
Plant and Soil
Vol. 137, No. 2 (November (II), 1991), pp. 191-199
Published by: Springer
Stable URL: http://www.jstor.org/stable/42937191
Page Count: 9
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Silicon (Si) content in cereal plants and soil-Si solubility may be used to estimate transpiration, assuming passive Si uptake. The hypothesis for passive-Si uptake by the transpiration stream was tested in wheat (Triticum aestivum cv. Stephens) grown on the irrigated Portneuf silt loam soil (Durixerollic calciorthid) near Twin Falls, Idaho. Treatments consisted of 5 levels of plant-available soil water ranging from 244 to 776 mm provided primarily by a line-source sprinkler irrigation system. Evapotranspiration was determined by the water-balance method and water uptake was calculated from evapotranspiration, shading, and duration of wet-surface soil. Water extraction occurred from the 0 to 150-cm zone in which equilibrium Si solubility (20°C) was 15 mg Si L⁻¹ in the Ap and Bk (0-58 cm depth) and 23 mg Si L⁻¹ in the Bkq (58-165 cm depth). At plant maturity, total Si uptake ranged from 10 to 32 g m⁻², above-ground dry matter from 1200 to 2100 g m⁻² and transpiration from 227 to 546 kg m⁻². Silicon uptake was correlated with transpiration (Siup = -0.7 + .06T, r² = 0.85) and dry matter yield with evapotranspiration (Y = 119 + 3.3ET, r² = 0.96). Actual Si uptake was 2.4 to 4.7 times that accounted for by passive uptake, supporting designation of wheat as a Si accumulator. The ratio of Si uptake to water uptake increased with soil moisture. The confirmation of active Si uptake precludes using Si uptake to estimate water use by wheat.
Plant and Soil © 1991 Springer