No-Tillage Promotes Wheat Seedling Growth and Grain Yield Compared with Plow-Rotary Tillage in a Rice-Wheat Rotation in the High Rainfall Region in China

Optimizing soil properties to match ecological conditions can alleviate stress damage and promote crop growth. However, the suitable soil conditions for wheat growth in an integrated rice-wheat breeding scheme under high rainfall and the mechanisms that affect yield production are not well known. Field experiments were carried out at two sites, which were all located in Jiangsu Province, China, a subtropical monsoon climate zone during two wheat growing seasons, to assess the effects of plow tillage followed by rotary tillage (PR) and no-tillage (NT) on soil physical and chemical properties, wheat seedling growth, grain yield, and spike amounts and quality. The finding indicates that with the reduction in soil mixing, soil bulk density was higher in NT than in PR, which helped to maintain moisture in dry soil. In soils with high water content, in NT, when the wheat field was subjected to waterlogging stress, the drainage decreased to deeper soil possibly due to reduced infiltration and a higher evaporation of surface water. The diurnal variation in soil temperature decreased in NT, and when the soil was cold, NT helped to insulate soils at 0-25 cm. Compared with PR, the contents of available nitrogen and phosphorus increased at 0-20 cm in NT. Root biomass and root activity of wheat seedlings at 0-20 cm were also greater in NT than in PR. Compared with PR, wheat also had more culms at the beginning of the overwintering stage, more spikes, and higher grain yield in NT, but the differences were not significant under excessive soil moisture. Therefore, the soil hydrothermal environment and spatial distributions of nutrients in NT promoted shallow root growth and tiller development in the early phase of wheat growth, which led to higher amounts of spikes per plant that resulted in high-yielding wheat crops.