The Impact of Climate Change on Maize Phenophase and Crop Water Requirement in the Heihe River Basin, Northwestern China

Climate change is likely to change crop phonological characteristics, which will then affect crop water requirement. The identification of phenophase change and its impact on crop water demand has become a key factor in agricultural water resources management and confronting climate change. The study adopts climatic tendency rate method, active accumulated temperature threshold method and synthetic estimate method recommended by FAO to determine the phenophase and water requirement change for springwheat and spring maize in Heihe River Basin. The study shows that: a) climate change advances the phenology of wheat and maize for all growth stages in Heihe River Basin, and the entire growth period of the crops is reduced by 7 days; b) water requirement for entire growth period impacted by climate change (without consideration of phenology) is demonstrated by the increase of 26.1mm, 6.0% up for wheat and the increase of 5.6mm, 0.7% up for maize; c) water requirement in entire growth period impacted by climate change (with consideration of phenology) is featured in the decrease of 50mm, 11.5% down for wheat and the decrease of 13.4mm, 1.8% down for maize.