That doesn't really look all that bad for bass. There's no super serious decay that extends past the chart, so that's a good start. The upper end is not bad at all... and the lower end really can't be controlled too easily with acoustic treatments. Maybe some seriously large corner traps might get you down below 100Hz. If you have a means of electronic EQ, it possible you could smooth out the response a little, depending on what is handling your bass and what kind of headroom you have.
Tell us more about your equipment... maybe add it all to your profile. Then room size and placement of the speaker you measured.