Table 5.
Pearson correlation coefficient of the relationship between stable carbon isotope composition in mature grains (δ13Cgrains) and the combination of the δ13C from the peduncle and the awns (δ13Cpeduncle+δ13Cawns) in the water-soluble fraction (WSF)
‘Peduncle (%)’ represents the relative contribution of the culm (i.e. the whole plant below the ear) to grain filling as a percentage and ‘awns (%)’ represents the relative contribution of the awns to grain filling as a percentage. The individual values of δ13Cawn and δ13Cpeduncle used in the linear regression belong to δ13C in the WSF before and after irrigation during the 2012 crop season. After irrigation for samples that were not frozen with liquid nitrogen a correction factor of 0.4‰ in the values of the δ13C in the WSF was applied (see ‘Materials and methods’ and Supplementary Table S1). The six genotypes and three replications per genotype were considered, accounting for a total of 18 plots per sampling date. For each plot the relative weight assigned to the δ13C of each of the two organs depended on the water status of the plot assessed by its δ13Cgrains based on Sanchez-Bragado et al. (2014b). Level of significance: ***, P<0.001.
| Interval δ 13 C grain (‰) | Awns (%) | Peduncle (%) | R2 | |||
|---|---|---|---|---|---|---|
| Before irrigation | ||||||
| [−25.2, −25.8] | 75 | 25 | ||||
| [−25.8, −26.4] | 50 | 50 | ||||
| [−26.4, −27.0] | 25 | 75 | ||||
| δ13Cgrain | vs | [δ13Cawns*(%) | + | δ13Cpeduncle*(%)] | 0.61*** | |
| After irrigation | ||||||
| [−25.2, −25.8] | 100 | 0 | ||||
| [−25.8, −26.4] | 80 | 20 | ||||
| [−26.4, −27.0] | 66 | 33 | ||||
| δ13Cgrain | vs | [δ13Cawns*(%) | + | δ13Cpeduncle*(%)] | 0.70*** |