Sweet potato plant propagation techniques

Plant propagation is the art, science, and business of multiplying plants.

Plant propagation is the method to increase the number of outstanding fruit and crop varieties in order to perpetuate their desirable qualities such as high production, large fruits, and excellent eating quality—those that command better market prices.

Ways to propagate plants:

1. Sexual: through the use of seeds (for papaya, mangosteen, and for root stocks for asexual propagation).
2. Asexual: through the use of plant parts other than seeds. This does not involve the exchange of genetic material, so the process almost always produces plants that are identical to the parent.

Advantage of asexual propagation:

1. Plants are true-to-type.
2. More rapid means of producing planting materials for crops such as cassava, sweet potato, and other root crops.
3. Plants start fruiting in a shorter time than normal, and mature into smaller trees; hence they are easy to manage (e.g., grafted fruit trees).

Asexual propagation methods for root crops:

1. Divisions: Specialized or modified stems and roots are cut into pieces or sections, each with a growing point or bud.
2. Micropropagation or tissue culture: A tiny piece of bud, leaf or stem can produce incredible numbers of new plants in a small space over a short time period with the use of technical advances, specialized equipment, and sterile laboratory conditions.
3. Cuttings: Regeneration of structural parts in detached vegetative parts such as stem cuttings, leaf cuttings, root cuttings, softwood, and hardwood cuttings.

Stem cuttings for sweet potato:

Sweet potato (Ipomoea batatas L. [Lam.]) is a dicotyledonous plant that belongs to the family Convolvulaceae. It has large, starchy, sweet-tasting tuberous roots that are cooked and processed into human food such as starch, flour substitute, and other delicacies. Its industrial uses include the production of alcohol and animal feed. Its young leaves and shoots are also eaten as greens.

Besides containing simple starches, sweet potatoes are rich in complex carbohydrates, dietary fiber, beta carotene (Vitamin A equivalent nutrient), Vitamin C, and Vitamin B6.

Sweet potatoes are perennial vines that are propagated vegetatively, either by shoots/vine cuttings or from tubes. They are not grown from seeds. To propagate with the use of cuttings, collect 25 - 30 centimeter (cm)-long vine cuttings from insect- and disease-free plants. Use cuttings as soon as possible, but in case they need to be stored, keep vines moist for 2 - 3 days in a cool and shaded place.

Environmental requirements: Sweet potatoes need full sunlight, well-drained soil (preferably sandy loam), and plenty of room to thrive. They are not heavy feeders but require a good balance of nitrogen, potassium, and phosphorus.

Nursery establishment: Establish a nursery to propagate selected sweet potato plants more rapidly.

Land preparation: Plow and harrow the soil once when using a tractor. When using an animal drawn implement, plow once and harrow twice. Make furrows at 75cm distances.

Planting:

1. Plant the vine cuttings vertically or at a slight incline to the soil.
2. Plant in ridges during the rainy season and in furrows during the dry season; maintain a spacing of 30cm between hills.
3. Replant missing hills 1 - 2 weeks after planting.

Fertilization:

1. Apply well decomposed manure or compost at the rate of 10 - 15 bags per hectare, if necessary.
2. Apply six bags of complete fertilizer (14-14-14) per hectare along rows and cover with a thin layer of soil before cuttings are planted.

Irrigation:

1. Water the field just after planting if the soil is dry.
2. During the dry season, water the plants regularly or during the first 2 months after planting and when needed.
3. Provide drainage because sweet potato is sensitive to water logging.

Weeding/cultivation:

1. Control weeds, especially Ipomoea triloba (‘kamokamotehan’) during the first 2 months after planting.
2. Off-bar 3 - 4 weeks after planting and hill-up 2 - 4 weeks later.

Insect pest and disease management:

1. Sweet potato weevil is a major problem in tuber production during the dry season. It attacks both the vine and fleshy roots.
2. Plant early to avoid the peak of the weevil population during summer.
3. Choose sandy loam soil and avoid clayey soil which develops cracks through which weevils enter.
4. Use clean or uninfested planting materials.
5. Dip planting materials in insecticide before planting to reduce infestation.
6. Practice crop rotation or the planting of two other crops, one after the other, following sweet potato.
7. Use sex pheromone traps to attract males and reduce we evil population. Use chemicals only as a last resort.

The sweet potato vines will be ready for gathering 3 - 4 months after planting.