Effect of PEG-6000 induced water stress on seed Germination (a) and on Relative Water Content (RWC); (b) of controls (B. napus, B. rapa) and hybrids seedlings (DHBKZ, DHBKY). Data are means ± SD bars of three experiments (n = 20 seeds per experiment), measured in triplicate. The same letter indicates no significant difference and the different letters indicate a significant difference (Fisher’s LSD, P <  0.05).