No-tillage with total green manure mulching increases maize yield through improved soil moisture and temperature environment and enhanced maize root structure and photosynthetic capacity

1、 No-tillage with total green manure (GM) mulching (NTG) can optimize maize root structure by improving soil water content (SWC) and soil temperature (ST) environment. 2、 NTG increased maize photosynthetic capacity and grain yield (GY). 3、 The relationship between SWC, ST, root length (RL), photosynthetic characteristics and GY was expounded. Wheat-maize rotation is a widely used planting pattern in oasis irrigated areas in northwest China. Although this planting pattern has the advantage of breaking the barrier of continuous cropping to some extent, it also has some problems such as large evaporation and prominent soil degradation during fallow period, which seriously restricts the improvement of crop yield. Planting green manure (GM) after wheat and returning it to field can effectively improve soil physicochemical properties, regulate photosynthetic characteristics of subsequent crops and promote crop yield. However, the photosynthetic physiological mechanism of crop yield improvement under different green manure return methods (GMRM) is still unclear. Therefore, by exploring the relationships among soil moisture and temperature environment, maize root structure, photosynthetic characteristics, fluorescence characteristics and yield under different GMRM, this study aims to provide theoretical basis for clarifying the photosynthetic physiological mechanism of GMRM to improve maize yield. A three-year field experiment was conducted at a research station in the Shiyang River Basin (Gansu, China). Five treatments were involved in this study: (i) conventional tillage without GM (CT), (ii) no-tillage with total GM mulching (NTG), (iii) no-tillage with removal of aboveground GM (NT), (iv) tillage with total GM incorporation (TG), and (v) tillage with only root incorporation (T). Results showed that the NTG and TG significantly increased soil water content (SWC) in 0-110 cm soil layer, soil temperature (ST) of maize seedling (V3) to jointing stage (V6), canopy cover (CC), leaf stay-greenness (SG), root length (RL), net photosynthetic rate ( P n ), transpiration rate ( T r ), actual photochemical efficiency of PSII (ՓPSII), maize biomass and grain yield (GY) compared with CT. In addition, NTG and TG significantly decreased ST of maize big trumpet stage (V12) to blister stage (R2), and dissipation of excess energy (NPQ) compared with CT. The GM return to field could improve root structure and canopy coverage of maize mainly by improving soil water content. The optimization of maize root structure and canopy coverage increased maize chlorophyll content (SPAD) value and promoted P n . The increase of P n inhibits the increase of NPQ, thus promoting ՓPSII. The increase of ՓPSII promoted the increase of maize biomass, and finally realized the increase of maize GY. 1