Intraspecific Variation in the Yield Response of Winter Wheat to Elevated CO2 Concentrations: A 3-Year Free-Air CO2 Enrichment Experiment.

Although wheat is known as a global staple for human an animal nutrition, there is few studies evaluated intra-specific yield response to projected rising in atmospheric carbon dioxide (CO2) in a filed. We examined 12 contrasting winter wheat cultivars over 3-year period under ambient (400 ¦Ìmol mol-1) and elevated CO2 (550 ¦Ìmol mol-1) at the free-air CO2 enrichment (FACE) facility in a semi-arid region in northern China. The four cultivars out of 12 cultivars are taller, with greater variation in tiller production, smaller spike, while the other eight cultivars produces fewer tillers and has larger spike. Irrespective of the cultivars, grain yield was increased by 10.8% under elevated CO2. Significant CO2 and cultivar interactions was observed, as a results of an increased percentage of tillers for the larger spike cultivars relative to the smaller spike cultivars at elevated CO2. This greater increase in tiller number per plants also resulted in a significant increase in harvest index for larger spike cultivars as CO2 increased. These results indicate that grain yield response to elevated CO2 may be determined by the availability of reproductive sink capacity to assimilate additional carbon. This study provides implications for breeders to explore adaptive cultivars with higher sink capacity in a CO2-rich future.