Tillage practices effect on root distribution and water use efficiency of winter wheat under rain-fed condition in the North China Plain

Abstract

Water shortage has limited the agricultural sustainable development of North China Plain (NCP), where winter wheat (Triticum aestivum L.) is the major irrigated crop that consumes 60–80% of available deep groundwater for agriculture production, leading to the significant decline in groundwater resource. The protection of water resources is important for the sustainable development of agriculture in NCP. The objective of this study was to evaluate the effect of plow-tillage (PT), rotary-tillage (RT) and no-tillage (NT) on root growth, water consumption characteristics, grain yield, water use and water use efficiency (WUE) under rain-fed condition conducted in a field with 20-year of rotary tillage history. Findings of this research show that plow-tillage (PT) and rotary-tillage (RT) decreased the soil bulk density in the 0–20cm soil depth and the penetration resistance in the 0–30cm soil depth. During two growth seasons, PT had greater root weight density (RWD), root length density (RLD) and root surface density (RSD) than those under NT across the 0–110cm soil profile at the tillering stage and in the 0–40cm soil profile at the flowering stage, respectively. However, RWD, RLD and RSD of PT were lower than NT at 0–10cm soil depth and greater at 10–20cm soil depth at the ripening stage. Similar trends were observed under RT compared with NT. Soil water content (SWC) under PT and RT were lower compared with NT from tillering to flowering stage across 0–110cm, but higher than under NT in 0–20cm soil profile at ripening stage. Evapotranspiration (ET) values under PT were higher than under NT from sowing to flowering stages, but significantly lower at the ripening stage. Moreover, tillage practices had no notable influences on pre-planting soil water storage and total ET under rain-fed condition during two growing season, but PT significantly enhanced grain yield through higher spike number and grain weight compared with NT, which led to higher WUE under PT. The findings of this study show that PT practice can reduce soil bulk density and penetration resistance at the tillage zone, which can lead to greater RWD, RLD and RSD and greater ET from tillering to flowering stage. This can increase plant population and cause greater WUE and grain yield under rain-fed condition.