Question

Topophysis is the position on the stock plant that impacts on the growth orientation of the propagule; however, in some plant, scion grows like branches instead of its normal growth orientation and such growth is termed as _______

• A. Orthotropic growth
• B. Plagiotropic growth
• C. Epicormic growth
• D. Apical dominance

Hint:

To avoid plagiotropic growth in tree propagation, always collect scions or cuttings from vertical, orthotropic terminal leaders rather than lateral branches.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Topophysis is a physiological phenomenon where a vegetatively propagated cutting or graft retains the growth form and orientation of the parent branch from which it was collected.

Step 2: Detailed Explanation:
- Forest tree growth can be divided into:
1. Orthotropic growth: Upright, vertical growth typical of main stem leaders.
2. Plagiotropic growth: Horizontal, lateral branch-like growth.
- When cuttings or scions are collected from lateral branches of certain species (such as conifers, Araucaria, or Coffea), they sometimes continue to grow horizontally like a branch rather than producing an upright trunk.
- This lateral growth behavior is called plagiotropic growth.
- Epicormic growth refers to shoots arising from dormant buds on the trunk, and apical dominance is the control of lateral bud growth by the terminal bud.

Step 3: Final Answer:
The lateral branch-like growth retained by a propagule is termed plagiotropic growth.