The effect of different post-anthesis water supply on the carbon isotope discrimination of winter wheat grain

Abstract

Isotopic carbon discrimination (Δ13C) of winter wheat grain grown under different water and nitrogen supplies was determined. In two field experiments during years 2004-2007 (A) and 2008-2013 (B), a water shortage was induced from the flowering stage on with a mobile shelter (S), while an optimal water supply was ensured with drip irrigation (I), and a rain-fed crop served as the control treatment (R). Water supply had a statistically significant effect on grain Δ13C values in both experiments (P < 0.01). The average values of grain Δ13C in treatments I, R and S were 19.43, 18.68 and 17.70‰ (A); and 20.36, 19.60 and 18.13‰ (B). Grain Δ13C was in a significant linear relationship (P < 0.01) with the amount of water supplied by precipitation or irrigation. The regressions suggested that grain Δ13C increased by 1.14‰ and 1.16‰ (A), and 0.98‰ or 0.96‰ (B) for every 100 mm of water from January and March, respectively, until the early dough stage (r = 0.79-0.74, P < 0.05). Pooled data for the whole period 2004-2013 showed increases of 1.06‰ and 1.08‰ (r = 0.91 and 0.82, P < 0.05) for 100 mm of water, respectively. The results of the experiment confirmed the stable and predictable effect of water supply on wheat grain Δ13C.

Keywords

• triticum aestivum l.
• rainfall
• evapotranspiration
• water stress
• nitrogen fertilization