Response of Root and Shoot Growth of Three Grass Species to Decreases in Soil Water Potential

Abstract

Native grass species show differences in leaf and root growth response to soil water potential. Soil water potential developed by blue grama at the time of leaf growth stoppage ranged from < -80.0 bars at 5 cm depths to -8.4 bars at 35 cm depths, while corresponding values for little bluestem were -24.3 and -3.0 bars, and -30.0 and -15.3 bars for western wheatgrass. Soil water potentials at the time of root growth cessation were somewhat lower with a minimum of -16.6 bars at the 5 cm depth of blue grama and a maximum of -5.0 bars at the 25 cm and 35 cm depths of little bluestem. The R2 values indicate a lower level of correlation between soil water potential and root growth than between soil water potential and leaf growth. In ranking the three mixed prairie grass species as to their growth tolerance to decreasing soil water potential, blue grama ranks the highest followed by western wheatgrass and little bluestem, respectively.