Question

Which among the following rootstock of apple is not vigorous in ture ?

• A. M-2
• B. M-13
• C. Merton-793
• D. MM-106

Hint:

Key Malling-Merton Rootstocks:
- M-9 = Dwarf
- MM-106 = Semi-Dwarf (Woolly Aphid resistant)
- Merton-793 = Vigorous (Woolly Aphid resistant)
- M-13 = Very Vigorous

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question asks to identify the apple (Malus domestica) rootstock from the given choices that does NOT belong to the vigorous or very vigorous vigor categories (i.e., it is a semi-dwarf rootstock).

Step 2: Classification of Apple Rootstocks by Vigor:

• Ultra Dwarf: M-27.

• Dwarf: M-9, M-26.

• Semi-Dwarf: MM-106, M-7.

• Vigorous Semi-Vigorous: M-2, Merton-793.

• Very Vigorous: M-13, M-25, MM-109, Seedling rootstocks.

Step 3: Detailed Explation:

• M-13: Classified as a very vigorous rootstock that produces large trees and is tolerant to wet soils.

• Merton-793: A vigorous clol rootstock developed by crossing M-2 with Northern Spy, known for resistance to woolly apple aphid (Eriosoma lanigerum).

• M-2: A semi-vigorous to vigorous rootstock widely utilized historically in traditiol high-canopy orchards.

• MM-106 (Mallling-Merton 106): Classified specifically as a semi-dwarf rootstock. It restricts tree size to approximately $50--60\%$ of a standard seedling tree and induces early bearing (precocity).

• Thus, among the given options, MM-106 is semi-dwarf and not vigorous in ture.

Step 4: Fil Answer:
MM-106 is a semi-dwarf rootstock and is not vigorous in ture. Hence, option (D) is the correct answer.