What motion would a member propose to reduce the time for debate?

The motion to limit or extend the limits of debate is the most appropriate choice for proposing a reduction in the time allotted for discussion during a meeting. This motion specifically addresses the duration of debate on a particular issue, allowing members to directly modify the rules governing how long discussions can last.

When a member moves to limit debate, they can specify a new time frame, thus streamlining the decision-making process and ensuring that meetings remain efficient. This function is particularly important in organizations where time constraints are present or when a discussion seems to be dragging on without reaching a conclusion.

The other options do not effectively serve the purpose of reducing debate time. For instance, postponing indefinitely does not alter debate time but delays the discussion altogether. The amendment motion involves changing a main motion, which could indirectly affect debate but does not specifically target the time for discussion. Commit or refer motions direct the issue to another committee for further consideration and likewise do not directly address the debate time. Therefore, limiting or extending the limits of debate is the correct approach when seeking to alter debate duration.