Intra-specific variation of wheat grain quality in response to elevated [CO2] at two sowing times under rain-fed and irrigation treatments

In order to investigate the intra-specific variation of wheat grain quality response to elevated atmospheric CO₂ concentration (eCO₂]), eight wheat (Triticum aestivum L.)cultivars were grown at two CO₂ concentrations (CO₂]) (current atmospheric, 389 CO₂ μmol mol⁻¹vs. eCO₂], FACE (Free-Air CO₂ Enrichment), 550  ±  10% CO₂ μmol mol⁻¹), at two water levels (rain-fed vs. irrigated) and at two times of sowing (TOS₁, vs. TOS₂). The TOS treatment was mainly imposed to understand whether eCO₂] could modify the effects of timing of higher grain filling temperatures on grain quality. When plants were grown at TOS₁, TKW (thousand kernel weight), grain test weight, hardness index, P, Ca, Na and phytate were not significantly changed under eCO₂]. On the other hand, eCO₂] increased TKW (16%), hardness index (9%), kernel diameter (6%), test weight (2%) but decreased grain protein (10%) and grain phytate (11%) at TOS₂. In regard to grain Zn, Mn and Cu concentrations and some flour rheological properties, cultivar specific responses to eCO₂] were observed at both sowing times. Observed genetic variability in response to eCO₂] in terms of grain minerals and flour rheological properties could be easily incorporated into future wheat breeding programs to enable adaptation to climate change.