A simulation study of the effect of soil water balance and water stress on winter wheat production under different climate change scenarios

The effect of water balance parameters and water stress on winter wheat production in a specified environment and under different climate change scenarios using the CERES (Crop Environment REsource Synthesis)-Wheat model is presented. For our study, two test sites with similar climatic conditions and soil water storage potential but with (site B) and without (site A) groundwater impact in a semi-arid agricultural area in central Europe (southeast of the Czech Republic and northeast of Austria) were chosen. For the current climatic conditions, the impact of groundwater to the rooting zone at site B caused a rain-fed yield level close to the potential yield (6772 kg ha(-1)), whereas at site A the rain-fed yield reached only 49% of the potential yield level of 6552 kg ha(-1). Although potential yields also increased at both sites in the range of 17-24%, rain-fed yields came closer to potential yields under all applied climate scenarios (47-61% of potential yield at site A and 55-75% of potential yield at site B, depending on the climate scenario). The most yield-sensitive simulated growing stage at both sites was found during the grain filling period. Despite higher yield levels, crop transpiration and water stress dropped significantly compared with current conditions through the simulated increase in water use efficiency and reduced total potential evapotranspiration (caused by shortened growing period) under the applied 2 x CO2 climate scenarios. Up to 42% (194 mm.) of evapotranspiration was provided by groundwater at site B under present climate and only 126 mm was used for the worst case scenario ECHAM. For both locations, however, the availability and management of soil water reserves will remain an important influence on the attainment of the potential yield level of winter wheat under climate change scenarios, especially when extreme events such as droughts occur more frequently and annual soil and groundwater recharge decrease. (C) 2003 Elsevier Science B.V. All rights reserved.