The primary planting material used for yam propagation is tuber pieces, called setts. Yams are generally propagated vegetatively, meaning new plants are started from parts of an existing tuber rather than from botanical seed. A sett that contains a viable bud can sprout, produce vines and roots, and later form a new tuber. This makes vegetative propagation dependable and well suited to yam cultivation.

Setts are also practical because they contain stored food reserves that help the young plant establish early in the season. That gives yam propagation an advantage over methods like seed planting, which is not the normal field practice for cultivated yams. Stem cuttings and root cuttings are also not the standard planting material in most yam systems. For both biological and practical reasons, tuber pieces are the correct answer.

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The recommended size for yam setts is 50-100 grams because pieces in this range are usually large enough to establish well while still using planting material efficiently. A sett needs enough stored food to support sprouting, early root growth, and initial vine development before the plant becomes fully established. If it is too small, it may dry out, rot, or produce weak growth.

Using very large pieces can also be inefficient because it consumes more tuber than necessary for each planting spot. Farmers often aim for a size that balances strong emergence with economical seed use, and 50-100 grams is a commonly recommended range for that purpose. It provides enough reserve tissue and usually enough viable bud area to produce a healthy plant. That is why option D is correct.

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Fungicide dusting or dipping is commonly used on yam setts before planting because cutting tubers into setts exposes fresh surfaces that are vulnerable to infection. Those wounds can allow fungi to enter and cause rot, especially in warm, moist soils. A protective treatment helps reduce early losses and improves the chance that the sett will survive long enough to sprout and establish.

This is an example of preventive crop management: farmers protect the planting material before it goes into the ground rather than waiting for disease to appear later. The other options are unsuitable because boiling, freezing, or excessive sun exposure would damage living tissue instead of protecting it. Since the goal is to reduce rot and disease in freshly cut planting pieces, fungicide dusting or dipping is the correct answer.

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In yam cultivation, “milking” means harvesting a tuber while leaving the root system or enough of the plant intact so it can continue growing and possibly produce another harvest. It is a special harvesting technique rather than a planting or processing method. The key idea is partial removal: the farmer takes the marketable tuber but does not completely destroy the plant’s ability to continue growing.

This explains why the term fits so well. Like the word suggests, something useful is taken while the source remains alive. It is not related to extracting sap or using milk in irrigation. In practical terms, milking is a careful management practice that aims to extend production from a single plant under suitable conditions. Because option C describes that process accurately, it is the correct answer.

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The optimal planting depth for yam setts is about 5-10 cm because this gives a good balance between protection and emergence. At this depth, the sett is covered enough to stay moist and stable in the soil, but it is not buried so deeply that the sprout struggles to reach the surface. Good early establishment depends on that balance.

Planting too shallowly can expose the sett to drying, heat, or physical damage, while planting too deeply can delay emergence and weaken the young shoot. Since yam setts rely on stored food reserves to get started, wasting too much energy on pushing upward is not ideal. In practice, moderate depth gives better stand establishment and more uniform growth. That is why 5-10 cm is the correct answer.

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Tissue culture and minisett technology are used to produce clean planting material for yams because they help generate larger quantities of healthier, more uniform seed stock. Tissue culture can produce plants from carefully selected material under controlled conditions, reducing the chance that important diseases are carried forward. Minisett technology then allows many planting pieces to be produced efficiently from healthy source tubers.

This matters because yams are usually propagated vegetatively, so pests and diseases can easily move from one generation to the next if infected tubers are used as seed. Farmers and seed programs benefit when the planting material is both clean and available in sufficient quantity. The other options do not solve that problem. For improving sanitation and multiplication at the same time, tissue culture and minisett technology are the correct answer.

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The recommended spacing between yam mounds or ridges in traditional cultivation is about 1 meter by 1 meter. This gives each yam plant enough space for proper tuber development below ground and enough room above ground for vine growth, staking, weeding, and general field management. Because yams are vigorous and long-season plants, overcrowding can reduce performance.

Spacing that is too close increases competition for light, nutrients, and moisture, and it makes the field harder to manage. Spacing that is too wide wastes land and can reduce the number of plants per area without clear benefit. In practice, 1 m by 1 m is a useful compromise that supports both plant growth and efficient field operations. That is why option A is the correct answer.

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Stake or trellis systems are used to maximize yam yield in small spaces because yam vines are naturally climbing plants. By training the vines upward, growers use vertical space efficiently instead of letting the canopy spread across the ground. This improves access to sunlight and often supports better photosynthesis, which ultimately helps tuber development.

There are practical benefits too. Supported vines are easier to manage, less tangled, and often better ventilated, which can make weeding and crop care easier. In small plots especially, staking or trellising helps the grower fit the crop into a limited area without sacrificing plant performance. The other options do not address the yam plant’s natural growth habit. For efficient space use and better crop management, option C is the correct answer.

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The preferred part of the yam tuber for planting is the head, or proximal portion, because it typically has the strongest bud activity and the greatest likelihood of sprouting well. In vegetative propagation, the presence and vigor of buds are crucial, since the new plant must emerge from them. Choosing a section with strong bud potential improves the chances of rapid and uniform establishment.

The head portion is also practical because it combines viable buds with enough stored tissue to support the young sprout before the plant becomes fully established. Other sections of the tuber may sometimes be used, but they are usually less preferred if reliability is the goal. The skin alone would not be enough. Because the head portion best supports successful propagation, option B is the correct answer.

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The characteristic that shows yam setts are suitable for planting is the presence of viable buds or sprouts. Yams are propagated vegetatively, so a new plant must grow from living bud tissue on the sett. If the bud is active, the sett can produce a shoot, establish roots, and begin the crop cycle. That makes bud viability one of the most important indicators of good planting material.

By contrast, soft texture, mold, decay, or complete dehydration are warning signs that the sett is damaged or dying. Such pieces are much less likely to establish well in the field. Farmers therefore prefer firm, healthy setts with visible bud activity or sprouting. Because viable buds directly indicate that the planting material can grow, option D is the correct answer.

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Pre-sprouting yam setts before field planting is done to identify viable planting material and promote uniform emergence. When setts are allowed to sprout first, the grower can tell which pieces are alive and capable of establishing well. That helps avoid planting dead or weak material, reducing gaps in the field.

Uniform emergence also makes crop management easier. A yam field that comes up at roughly the same time is easier to weed, stake, monitor, and harvest than one with widely uneven growth. Pre-sprouting is therefore a practical way to improve stand quality before planting even begins. It is not intended to shrink tubers, stop flowering, or change plant sex. Because it helps select viable setts and synchronize establishment, option A is the correct answer.

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