A study in the Journal of Physiology found that concentric actions involve a faster rate coding than eccentric actions.
This essentially means it builds up fast twitch fibers more effectively and allows for quick force production ( which is needed for a high vertical jump).
Perform some concentric-only lifting in your workouts.
This means starting from a deadstop on Deadlifts and DB Rows.
For presses and squats, this means starting from a deadstop out of the pins. Lifting in this manner ensures fast force production and recruitment of fast twitch fibers.