Interactive effects of different warming levels and tillage managements on winter wheat growth, physiological processes, grain yield and quality in the North China Plain

The interactive effects mechanisms of different warming levels and tillage managements on crop development, growth, physiological processes, and subsequently grain yield and quality are essential to accelerate understanding of climate change impact and adaptation for crop production system, however have not been well-understood. Here, a full growth season open-field infrared warming experiment was conducted for winter wheat in the North China Plain from 2018 to 2019. The experiment had three warming treatments (Control: no warming, Tl: warming 1.4 degrees C & T2: warming 2.3 degrees C above ambient temperature) and two tillage treatments (CT: conventional tillage & NT: no-tillage). The results showed that experimental warming reduced the durations from sowing to anthesis by 7-15 days, however had little effect on the duration from anthesis to maturity. Warming significantly increased leaf area index (LAI), leaf Chlorophyll content, net photosynthetic rate (P-n), maximum rates of electron transport (J(max)), and maximum rates of carboxylation of Rubisco (V-cmax) before anthesis, and consequently increased biomass, harvest index, and grain yield. However, it accelerated leaf senescence, increased the number of sterile spikelets, and inhibited photosynthetic capacity at grain-filling stage. As a result, wheat biomass, yield, and thousand kernel weights were increased by 6.5 % (4.8 %), 8.5 % (11.9 %), and 9.5 % (10.5 %), respectively, under T1 (T2) treatments with conventional tillage; in contrast, by 40 %, 39.3 %, and 4.9 %, respectively, under T1 treatment with no-tillage. Warming could significantly improve nitrogen (N), protein, and carbon (C) contents, while reduce the C/N ratio, the contents of crude fibers and total amino acids in grain. There was a non-linear relationship between warming levels and contents of microelements (Mn, Zn, Cu). Our findings gain new insights into the interactive effects mechanisms of different warming levels and tillage managements on crop growth, physiological and grain yield formation processes.