Fig. 3

Soybean grain yield (a, b, c) and WUE_-leaf (d, e, f) as affected by the interactive effects of drought and salinity stress as well as biochar addition. D-C = no drought stress; D-L = low drought stress; D-H = high drought stress. The bars indicate the standard error of the means (±SE). Different letters indicate significant differences according to the Fisher’s LSD test