Root development and water uptake in winter wheat under different irrigation methods and scheduling for North China

A field experiment was conducted on winter wheat (Triticum aestivum L.) during 2013-2014 and 2014-2015 to study the root distribution profile and soil water dynamics under the main currently used irrigation methods in the North China Plain (NCP). The WinRHIZO system and the HYDRUS-1D model were used to identify a promising irrigation schedule. In this two-factor experiment, three irrigation methods, i.e., sprinkler irrigation (SI), surface drip irrigation (SDI) and surface flooding (SF), were scheduled to irrigate the crop as soon as the soil water content decreased to 70%, 60% and 50% of the field capacity. The results showed that both the irrigation method and irrigation schedule influenced root development, the profile root distribution pattern and the profile root water uptake (RWU). The soil surface temperature fluctuated very rapidly depending on the irrigation method and scheduling system used, whereas profile soil temperature fluctuations became more consistent with depth. The RWU was higher in the upper soil layer (0-60 cm) for all irrigation methods for frequently irrigated treatments, and the maximum was observed in SDI compared to SI and SF due to the higher root length density (RLD) in the top soil under SDI. On the other hand, the RWU was higher in SF at a deep soil profile below 60 cm, where it had a higher RLD compared to that of SI and SDI. SDI at 60% of FC not only improved water uptake but also resulted in better water productivity and produced the highest grain yield (9.53 t/ha). The simulated RWU and soil water dynamics presented in this paper will be helpful to improve winter wheat production in the NCP and can be used as a reference for further research on water management practices.