Table 1.

Trait list, abbreviations and description

Trait	Abbreviation++		Description
	Non-Stress	Stress	Unit
Root dry weight+	Rdwc	Rdws	mg	Roots were dried at 70 °C for 48 h and their weights were recorded using a weighing balance (Sartorius AC 1215, Germany).
Shoot dry weight+	Sdwc	Sdws	mg	Shoots were dried at 70 °C for 48 h and their weights were recorded using a weighing balance (Sartorius AC 1215, Germany).
Total plant biomass+	Byc	Bys	mg	Dry weights of shoots and roots were summed to get biomass/ biological yield of the seedlings.
Root to shoot ratio+	Rsc	Rss	ratio	It is measured as ratio of Root to Shoot dry weights.
Maximum root length+	Rlc	Rls	cm	Using scaled ruler maximum root lengths/ root length was measured.
Shoot length+	Slc	Sls	cm	Scaled ruler was used to record the shoot length of the seedlings.
Number of main roots	Nmrc	Nmrs	No.	Based on images of the scanned roots number of roots were recorded.
Average root thickness	Rthc	Rths	mm	Based on images of the scanned roots average root thickness were recorded.
Total root length	Trlc	Trls	mm	All roots were considered in recording the total root length based on images of the scanned roots.
Total root volume	Trvc	Trvs	mm3	All roots were considered in recording the total root volume based on images of the scanned roots.
Drought susceptibility index	DSI			It is calculated using the formula of Fisher and Maurer (1978) using Biological yield of control and stress see more details in Adel-Ghani et al. (2015).

⁺These traits were scored previously by Abdel-Ghani et al. (2015). ⁺⁺C and S denotes the control and stress treatments