LAUSR

Abstract During wetting-drying cycles, divergence is often found between the immediately improved soil water conditions after re-watering and the recovery of plant water status from stress, which ensues only gradually. Such an apparent hysteresis effect of water stress (HEWS) is usually neglected in simulating root-water-uptake (RWU) by empirical models. To consider HEWS in the empirical macroscopic RWU model of Feddes, a water stress recovery coefficient (δ) was introduced based on two lysimetric experiments under greenhouse and field conditions for winter wheat. The integrated effects of historical water stress events were investigated by assuming that the normalized influence weight of each past stress event declines with the increase of time interval before simulation as an exponential function of attenuation rate. Although δ could be described by an exponential function of an integrative index representing the general historical stress extent (R2 = 0.65, P