Table 2. The primary and secondary drought indices used in the safflower experiment conducted at PPV, Horsham.

Drought index	Formula	Reference
Yield index (YI)	$\frac{Ys}{Yp}$	[43]
Geometric mean productivity (GMP)	$\sqrt{Yp\times Ys}$	[46]
Mean productivity (MP)	$\frac{Yp+Ys}{2}$	[45]
Tolerance index (TOL)	Yp − Ys	[45]
Stress tolerance index (STI)	$\frac{Yp\times Ys}{{\left(\stackrel{-}{Yp}\right)}^2}$	[46]
Branch number index (BrNI)	$BrNI=1-\left(\frac{{\text{X}}_t}{{\text{X}}_{c\left(mean\right)}}\right)$	This manuscript
Bud number index (BdNI)	$BdNI=1-\left(\frac{{\text{X}}_t}{{\text{X}}_{c\left(mean\right)}}\right)$	This manuscript
Plant height index (PHI)	$PHNI=1-\left(\frac{{\text{X}}_t}{{\text{X}}_{c\left(mean\right)}}\right)$	This manuscript
Dry biomass index (DBI)	$DBNI=1-\left(\frac{{\text{X}}_t}{{\text{X}}_{c\left(mean\right)}}\right)$	This manuscript
Seed number index (SNI)	$SNI=1-\left(\frac{{\text{X}}_t}{{\text{X}}_{c\left(mean\right)}}\right)$	This manuscript
Estimated shoot biomass index (ESBI)	$ESBI=1-\left(\frac{{\text{X}}_t}{{\text{X}}_{c\left(mean\right)}}\right)$	This manuscript

Where Yp and Ys are yields at control and stress respectively; $\stackrel{-}{Yp}$ mean yields of all genotypes under control treatment; X_t is the mean value for the respective trait for all genotypes under a particular stress treatment, and X_{c (mean)} is the mean value for the respective trait for of all genotypes under control treatment.