W Stepniewski

Effects of Soil Compaction and Transient Oxygen Deficiency on Growth, Water Use and Stomatal Resistance of Maize

Abstract The effect of various bulk densities and transient increase of soil matric potential from -420 hPa to -10 hPa on the root and shoot growth, water use and stomatal behaviour of maize was evaluated in a growth chamber experiment. A topsoil of silty loam texture was passed through a 4 mm mesh sieve and compacted to bulk densities of 1.28 Mg m−3 (L), 1.42 Mg m−3 (MC) and 1.58 Mg m−3 (SC) in 0.008 m3 containers. Root length, rooting depth, plant height, leaf area, stem diameter and water uptake decreased as soil compaction increased, whereas water used per g of dry shoot, stomatal resistance and its variation with time decreased. In all treatments final stomatal resistances were higher than the initial ones although soil matric potentials were similar. The stomatal resistance was significantly higher in lower than upper leaves when measured at highest soil matric potential. Water used per g of dry shoot was lowest in L and highest in SC. The highest root:shoot ratios (on dry weight basis) and the lowe...