Silicon Accumulation and 13C Composition as Indices of Water-Use Efficiency in Barley Cultivars

Abstract

Barley cultivars were examined for silicon accumulation in dry matter as a possible indicator of water-use efficiency (W), and for their organic 13C composition, whose discrimination from the 13C composition of atmospheric CO2 (Δ) is an accepted indicator of W. Silicon concentration was found to correlate with 13C discrimination more strongly in the field than in the glasshouse experiments. We suggest that, under mild glasshouse conditions, plants actively accumulate Si whereas, under higher evaporative demand in the field, Si accumulates passively on the transpiration stream. We find that Si may be used as a corroborative indicator of water-use efficiency in normal field circumstances.