Which of the following methods is appropriate for the cultivation of cassava?

Analyze the question: We're asked which method of propagation is appropriate for planting cassava (Manihot esculenta).

Explain the concept: Many crops are propagated vegetatively, meaning a part of the parent plant is used to grow a new plant. The part used differs from crop to crop:

• Stem cuttings: cassava, sugarcane
• Root/tuber parts (e.g. yam setts): yam, sweet potato (vines)
• Budding: citrus, rubber, cocoa (to join a bud from one plant onto another)
• Fragmentation: simple organisms such as Spirogyra and some flatworms

Step-by-step solution:

1. Cassava is grown for its tuberous roots, but those roots are the part we eat, not the part we plant.
2. Farmers in Nigeria cut mature cassava stems (about 20-30 cm long, with several nodes) and plant them in mounds or ridges.
3. The nodes on the stem produce roots and shoots, and the new plant develops.
4. Budding is used for tree crops such as citrus and rubber, not for cassava.
5. Fragmentation occurs in lower organisms, not in cassava farming.
6. Root cuttings are not used for cassava because the tuber doesn't have the nodes needed to sprout shoots. (Root cuttings work for plants like breadfruit.)

Answer: The correct option is D. Stem cutting.

Tip: Remember "Cassava = Cut stem." Also, sugarcane and cassava are both planted using stem pieces with nodes. If a question asks about the planting material for cassava, think "stem," not "root," even though the root is what we eat.