Table 1.

Drought indices calculated from grain yield and from traits with a significant positive correlation (p < 0.001) with grain yield (GY) under FDS and FNS conditions.

Drought indices	Formula (equation)	References
Drought susceptibility index (DSI)	[1-(GY_FDS/GY_FNS)]/[1–(${\overline{Y}}_{\text{FDS}}/{\overline{Y}}_{\text{FNS}}$)]	Fischer and Maurer, 1978
Relative drought index (RDI)	(GY_FDS/GY_FNS)/(${\overline{Y}}_{\text{FDS}}/{\overline{Y}}_{\text{FNS}}$)	Fischer et al., 1998
Stress tolerance index (STI)	(GY_FDS × GY_FNS)/(${\overline{Y}}_{\text{FNS}}^2$)	Fernandez, 1992
Geometric mean productivity (GMP)	$\sqrt{\text{GY}\_\text{FDS }\times \text{ GY}\_\text{FNS}}$	Ramirez-Vallejo and Kelly, 1998
Tolerance (TOL)	GY_FDS-GY_FNS	Rosielle and Hamblin, 1981
Yield stability index (YSI)	GY_FDS/GY_FNS	Bouslama and Schapaugh, 1984

GY_FDS and GY_FNS, grain yield lsmean under FDS and FNS conditions for each genotype, respectively. ${\overline{Y}}_{FDS}$ and ${\overline{Y}}_{FNS}$, grain yield lsmean under FDS and FNS conditions for all genotypes, respectively.