不同降水量分配下黄土高原旱地小麦根系深扎优化水分吸收机理探索

降水量少而分配不均是制约黄土高原旱地小麦产量的主要因素。针对黄土高原表土低水多变、深层土壤含水较为稳定的环境特点，虽然提出通过促进旱地小麦根系深扎提高对深层土壤水分吸收利用。但目前对于不同土壤水分条件下旱地小麦根系深扎与土壤水分分布交互影响根系水分吸收缺乏深入研究，根系深扎如何优化水分吸收尚缺乏明确结论。本研究拟采用遮雨棚和自流灌溉系统人工控制降水量分配，通过大田试验的研究方法，结合氢氧同位素示踪技术，重点回答：不同降水量分配下旱地小麦根区土壤水分的数量与分布规律；小麦根系深扎对不同降水量分配的响应机理；根系深扎与不同降水量分配交互影响下根系吸收土壤水分格局等关键科学问题。据此，揭示不同降水量分配下小麦根系深扎优化根系水分吸收途径与机理，提出旱地小麦根系深扎与水分高效利用的最优调控方案。研究结果为黄土高原旱地小麦根系性状选育与合理用水以提高小麦生产力提供理论参考。

Both limited amount and uneven distribution of annual precipitation are the major threats to enhance dryland wheat productivity in the Loess Plateau. Considering the low and variable soil water storage in top-soil and sub-soil layers in this area, it has been proposed to improve the absorption and utilization of deep soil water storage by promoting the deep rooting of dryland wheat. However, the interaction between wheat deep-rooting and soil water distribution is not well understood, and the deep-rooting associated breeding measures have not got the clear results. This study intends to use canopy and gravity irrigation system to manually control precipitation distribution, through the field experiments combined with hydrogen and oxygen isotope tracing technique, the key answers we want to clarify are as follows: 1) the amount and distribution of soil water in root zone of dryland wheat in response to different precipitation distribution; 2) the response mechanism of wheat deep rooting under different precipitation distribution and 3) the main scientific factors affecting root water absorption and water use pattern of root system by the interactions of wheat deep rooting and precipitation distribution. According to these, we will reveal the mechanism for optimizing water uptake by wheat deep rooting, and put forward the optimal regulation scheme of wheat root architecture and water uptake and utilization under different precipitation distribution. The results would provide a theoretical reference for the selection of root traits and rational water use in order to improve the productivity of dryland wheat in the Loess Plateau.