Step 1: Understanding plant growth pattern.
Plant growth follows a characteristic sigmoid or S-shaped curve, showing phases of slow growth, rapid growth, and maturation.
Step 2: Contribution of Sachs.
Julius von Sachs described the overall growth period of plants and termed it the ``Grand period of growth''.
Step 3: Eliminating other options.
F.W. Went is associated with auxin discovery.
Kurosawa worked on gibberellins.
Gane is not related to this concept.
Step 4: Conclusion.
Hence, the term ``Grand period of growth'' was given by Sachs.