How to grow sweet potato
Sweet potato
Scientific name: Ipomoea batatas L.
Family name: Convolvulaceae
Origin
Sweet potato originated from tropical Central America. Now it is an important tropical and sub-tropical crop worldwide.
Importance
1They are high in vitamin B6.
2. They are a good source of vitamin C.
3. They are a good source of vitamin D, which helps build healthy bones.
4. Sweet potatoes contain iron and support a healthy immune system.
5. Sweet potatoes are a good source of magnesium, which is the relaxation and anti-stress mineral.
6. They are a source of potassium.
7. Sweet potatoes do not cause blood sugar spikes.
8. Sweet potatoes help ward off cancer and protect against the effects of aging.
9. They are versatile.
Varieties
BARI SWEET POTATO-1 (TRIPTI)
BARI SWEET POTATO-4
BARI SWEET POTATO-5
BARI SWEET POTATO-6
BARI SWEET POTATO-7
BARI SWEET POTATO-9
BARI SWEET POTATO-10
BARI SWEET POTATO-11
BARI SWEET POTATO-12
BARI SWEET POTATO-13
Climatic requirement
Temperature
Because sweet potatoes are of tropical origin, they adapt well to warm climates and grow best during summer. Sweet potatoes are cold sensitive and should not be planted until all danger of frost is past. The optimum temperature to achieve the best growth of sweet potatoes is between 21 and 29 00 C, although they can tolerate temperatures as low as 18 00C and as high as 35 0 C. Storage roots are sensitive to changes in soil temperature, depending on the stage of root development.
Soil
A well-drained sandy loam is preferred and heavy clay soils should be avoided as they can retard root development, resulting in growth cracks and poor root shape. Soil pH should be adjusted to about 5.8-6.7
Preparation of cuttings
The cuttings should be 10-15 cm in length with 2-3 nodes and to be collected from matured vines aged 3 months and above. Dip the vine cuttings in a solution by mixing 400 g of Azospyrillum in sufficient quantity of water.
Planting time
Planting time is mainly determined by the climate of a location. Generally September-October in plains areas and June-July in hilly areas.
Spacing
Optimum plant density depends on cultivar, but is usually around 40 000 plants per hectare. Rows may vary from 1 to 1, 25 m apart; in-row spacing it is usually 25 to 30 cm.
Seeding rate
The number of cuttings required to plant 1 ha varies between 30 000 and 60 000, depending on the specific spacing used.
Application of fertilizers
100 kg Nitrogen (N)
90 kg Phosphorus (P)
200 kg Potassium (K)
200 kg Calcium (Ca)
All the phosphorus may be applied in the basal along with 50 kg of N and 50 kg of K. The remaining 50 kg N and 150 kg K should be divided into two side-dressings at 4 to 6 weeks and at 10 to 12 weeks from planting. Some calcium will be supplied by the lime or dolomite used to adjust the soil pH, and any additional calcium may be applied in the basal as gypsum.
Irrigation
Light irrigation is preferable. Newly planted crops should be irrigated on the 4th, 8th and 9th days. Excessive moisture early in the season delays storage root development and enlargement; late in the season, it induces cracking and/or rotting of roots.
Intercultural operation
Weeding
Weeds may be a problem early in crop growth before vigorous vine growth covers the beds as plants become established. So weeding should be done in early stage.
Vine Lifting
It is a special type of intercultural operation. Sweet potato are usually grown from vine cutting or stem cutting. 23 weeks after sowing the vines comes in contact to the soil surface adventitious root root system come from every node. As result roots are formed as carbohydrate produced in the plant. Then the vine lifting is done. The main purpose of vine lifting is to prevent water and nutrients supplied to these roots from developing in the nodes of the expanding vines which come in contact with the soil. Small, irregular roots may develop if nodes from vines come in contact with the soil surface, draining carbohydrates from the normal roots destined for market. Vines should not be turned over because this may cause rotting of the leaves in contact with the soil. 23 vine liftings may be necessary several days after irrigation when vine growth is vigorous, especially on moist, fertile soils. In practice, the benefit of vine lifting varies with the cultivar and weather conditions. It is very necessary to increase the yield of sweet potato.
Insects and Diseases Control
Insects: Sweet potato weevil, Giant termite, Leaf-feeding caterpillars etc. should be controlled by proper insecticides.
Diseases
Leaf spot; large brown spots appear on leavescontrolled by Dithane M – 45.
Black rot: It is primarily a storage rot of tubers but may also occur in the field, infested foliage become yellow and sticky in appearance and black canker are seen on the portion underground and grey black circular spots occur on fleshy roots.
Control measure: The seed tubers should be treated with mercuric chloride solution (1 in 1000) or 2.5 per cent borax solution.
Soft rot: Storage rot of tubers and their tissue become soft and stringy.
Control measure:
i) Avoiding brushing and injuring the tubers at harvesting is the best method of controlling this disease.
ii) The walls and floors of storage room should be disinfected before the storing tubers.
Harvesting
Regular field inspection is needed to determine when to harvest. Sweet potatoes can be harvested any time after a sufficient number of roots have reached marketable size. The price for uncured potatoes in late August and September may be high enough to justify sacrificing some yield to begin digging and marketing early. If the crop is to be stored, harvest before frost for maximum yields. If soil temperature falls below 55°F some damage to the quality, storability, and slip production of the roots will result. In cool weather, remove all dug potatoes from the field before nightfall. Prevent sunscald by removing or protecting harvested potatoes from the sun.
Curing
Sweet potatoes to be stored for later marketing or for seed stock must be cured immediately after harvest to minimize storage losses. Do not wash potatoes to be cured and stored. Curing involves controlling temperatures and relative humidity and providing ventilation for seven to ten days. Curing is a wound-healing process which occurs most rapidly at 80° to 90°F, a relative humidity of 85 to 90%, and good ventilation to remove carbon dioxide from the curing area. Wounds and bruises heal and a protective cork layer develops over the entire root surface. In addition, suberin, a waxy material, is deposited. The cork layer and suberin act as a barrier to decay-causing organisms and to moisture loss during storage.
Storage
Store sweet potatoes between 55° and 60°F. Do not allow temperature to fall below 55°F or chilling injury will result. Relative humidity should be maintained between 75 to 80% to prevent excessive water loss from the roots. Some ventilation should be provided to prevent carbon dioxide buildup.
Grading and Marketing
Whether marketed from the field or from storage, fresh market sweet potatoes are usually washed, graded, and often waxed before marketing. Poorly shaped, diseased, and damaged roots should be graded out to make a good looking pack. Buyer requirements for grade and size must be met for repeat sales.
Yield
40-50 ton/ha (BARI released variety)