High yields of wheat are mainly obtained through a high level of nitrogen and irrigation supplementation.  However, excessive nitrogen and irrigation supplication increase the risk of lodging.  The main objectives of this work were to clarify the capacity of lodging resistance of wheat in response to nitrogen and irrigation, as well as to explore the effective ways of improving lodging resistance in a high-yield wheat cultivar. In this study, field experiments were conducted in the 2015–2016 and 2016–2017 growing seasons.  A wheat cultivar Jimai 22 (JM22), which is widely planted in the northern of Huang-Huai winter wheat region, was grown at Tai’an, Shandong Province, under three nitrogen rates and four irrigation treatments.  The lodging risk was increased with increased nitrogen rate, as indicated by increasing lodging index (LI) and lodging rate across both growing seasons.  With nitrogen increasing, the plant height, the basal internode length and the center of gravity height, which were positively correlated with LI, increased significantly.  While the density of the basal 2nd internode (for culm and leaf sheath) and cell wall component contents, which were negatively correlated with LI, decreased conspicuous along with nitrogen increased.  Increasing irrigation supplementation increased the 2nd internode culm wall thickness, breaking strength and leaf sheath density within limits which increased stem strength.  Among the treatments, nitrogen application at a rate of 240 kg ha^–1 and irrigation application at 600 m3 ha^–1 at both the jointing and anthesis stages resulted in the highest yield and strongest stem.  A suitable plant height ensures sufficient biomass for high yield, and higher stem stiffness, which was primarily attributed to thicker culm wall, greater density of the culm and leaf sheaths and higher cell wall component contents are the characteristics that should be taken into account to improving wheat lodging resistance.

   Straw return is an important management tool for tackling and promoting soil nutrient conservation and improving crop yield in Huang-Huai-Hai Plain, China. Although the incorporation of maize straw with deep plowing and rotary tillage practices are widespread in the region, only few studies have focused on rotation tillage. To determine the effects of maize straw return on the nitrogen (N) efficiency and grain yield of winter wheat (Triticum aestivum L.), we conducted experiments in this region for 3 years. Five treatments were tested: (i) rotary tillage without straw return (RT); (ii) deep plowing tillage without straw return (DT); (iii) rotary tillage with total straw return (RS); (iv) deep plowing tillage with total straw return (DS); (v) rotary tillage of 2 years and deep plowing tillage in the 3rd year with total straw return (TS). Treatments with straw return increased kernels no. ear^–1, thousand-kernel weight (TKW), grain yields, ratio of dry matter accumulation post-anthesis, and nitrogen (N) efficiency whereas reduced the ears no. ha^–1 in the 2011–2012 and 2012–2013 growing seasons. Compared with the rotary tillage, deep plowing tillage significantly increased the grain yield, yield components, total dry matter accumulation, and N efficiency in 2013–2014. RS had significantly higher straw N distribution, soil inorganic nitrogen content, and soil enzymes activities in the 0–10 cm soil layer compared with the DS and TS. However, significantly lower values were observed in the 10–20 and 20–30 cm soil layers. TS obtained approximately equal grain yield as DS, and it also reduced the resource costs. Therefore, we conclude that TS is the most economical method for increasing grain yield and N efficiency of winter wheat in Huang-Huai-Hai Plain.