Physiological Response and Leaf Production of Two C4 grasses after Small Rainfall Events

The response of plant water status and leaf production of sideoats grama (Bouteloua curtipendula Michx.) and curly mesquite (Hilaria belangeri Steud.) to application of 10 mm of water were studied in 6 continuous weighing lysimeters near Sonora, Texas, USA.: Transpiration, stomata! conductance, xylem water potentials and leaf production were measured foe both species. Soil water content was monitored in each lysimeter. The 10-mm simulated rainfall events improved plant water status regardless of prior soil water· content.' The transpiration rate for both species was similar. Stomata! conductance' of B. c1irtipe11d11/a responded faster after the simulated rainfall events. More favorable xylem water potentials and the absence of midday depression of stomatal conductance indicated B. c11rtipe11d11la was heller able 10 access water within the lysimeters. B. curtipe11dula produced more biomass through leaf extension than H. belangeri when total soil moisture content exceeded 15%, and greater total leaf production when total soil moisture content exceeded 25%.