Abstract:

Simulating on the atmosphere CO2 concentration in 2050 in a wheat field, investigating on the growth and yield response of winter wheat to elevated CO2, enable people to estimate the impacts of elevated CO2 on winter wheat in a CO2-rich world. Winter wheat (Triticum aestivum L. cv CA0493, high gluten wheat) was grown to maturity at ambient CO2 (415±16 μmol/mol) or elevated CO2 (550±17 μmol/mol) under 2 levels of N: normal N (NN, basal dressing N 118 kg/hm2+sidedressing N 70 kg/hm2) and low N (LN, basal dressing N 66 kg/hm2+sidedressing N 17 kg/hm2) at FACE (Free Air CO2 Enrichment) system, to investigate the effects of elevated CO2 (550 μmol/mol) and N fertilizer input on height, flag leaf area and the top three leaves area, tiller number seasonal changes, grain yield and yield components of winter wheat. Results showed that elevated CO2 increased wheat height by 5.12% at jointing stage, the scale of increasing was larger under normal N than low N input. Elevated CO2 increased flag leaf area and the top three leaves area by 14.87%, 10.02% at flowering stage, respectively. Increased leaf size under elevated CO2 was determined by longer leaf length (8.97%). Elevated CO2 tend to increase the tiller number under normal N input. Grain yield increased by 18.3% under elevated CO2 (P<0.05), with 6% in low N input and 31.4% in normal N input. Panicle number per square meter and grain number per panicle increased by 5.3% and 14.5% (P<0.05) under elevated CO2, and the increase amplitude was more in normal N than low N input. Infertile spikelet number decreased significantly by 11.12% at high CO2, while thousand grains weight showed no significant change under elevated CO2. Elevated CO2 reduced the degenerated spikelet number, thus increased grain number per panicle, which accounted for the yield increase under elevated CO2.