The cultivation of sweet potato has traditionally been confined to varying growing systems such as open land highland, rice fallow system, under shade, owita and homestead conditions. Sweet potato has remarkable ability to convert solar and soil energies into carbohydrates giving impressive yields under marginal and stress situations having low input requirements and little attention, wide adaptability, flexibility in crop management and non-seasonality make sweet potato a viable crop in all agroecological zones excluding high elevations.
Recommended Varieties
1. CARI-9 2. CARI-273 3.CARI-126
4. Wariyapola red 5. Wariyapola white 6. Ranabima
| Variety | Age (month) | Flesh colour | ||||
| CARI-9 | 3 1/2 - 4 | Light yellow | ||||
| CARI-273 | 3 1/2 - 4 | Light yellow | ||||
| Wariyapola-red | 3 1/2 | White | ||||
| Wariyapola-white | 3 1/2 | White | ||||
| Ranabima | 3 1/2 - 4 | Light yellow | ||||
| BW-8 (Shanthi) | 3 1/2 | White | ||||
| BW-21 (Chitra) | 3 1/2 | White | ||||
| Gannoruwa - Sudu | 3 1/2 - 4 | Light yellow | ||||
Variety Discription
CARI-9
Semi-vine plant type with entire to very slightly lobbed leaves. Root tubers have dark pinkish skin with highly variable tuber shapes which are fusiform.
CARI-273
Semi-vine plant type with entire leaves. The mature leaves are green in colour and the tender leaves are light green with purple at margin. Petioles are light green with purple at leaf end and petiole base. Root tubers are fusiform shape with purple coloured skin.
CARI-426
It is a polycross hybrid and maternal parent is a native variety Beli-batala. It has a bushy plant type with deeply cut leaf laminas. Vines and leaves are green in colour with purplish green tender leaves. Root tubers are highly uniform and fusiform in shape having pinkish orange skin.
Wariyapola red
It is a selection from the local sweet potato collection and planting material is available in all sweet potato growing areas. Semi-vine plant type with entire to very slightly lobbed leaves. Root tubers are highly uniform and fusiform in shape having purple skin.
Wariyapola white
Wariyapola white is a mutant, originated from the variety Wariyapola red. Semi-vine plant type with entire to very slightly lobbed leaves. Root tubers are highly uniform and fusiform in shape having white skin.
Ranabima
Semi-vine plant type, the leaves are entire to slightly lobbed, vines are yellowish green except tender vine apices are slightly pigmented. The root tubers are round elliptical shape with pink skin.
BW - 8 (Shanthi)
It is a natural selection from Kalutara district. BW - 8 is a semi-vine type plant with light green stems. Leaf type is moderately lobbed with purple colouration at the base of the leaf on the lower side. Tuber shape is egg shaped with tapering ends and skin colour is white.
BW - 21 (Chitra)
It is a natural selection from Galle district. Viny plant type with moderately lobbed leaves. Mature leaves are green while the young leaves are reddish brown in colour. It has conical shape root tubers with white skin.
Gannoruwa Sudu
It is a polycrose hybrid and material parent is recommended variety CARI-426. Semi-vine plant type with numerous major branches. Entire vines are green in colour except the very tender vine apices which are slightly pigmented with moderately lobbed leaves. The root tubers are round to elliptical shape, highly uniformed with white skin.
Field Establishment
Climate
Sweet potato is grown in the tropical, sub tropical and warm temperate regions of the world. Sweet potato is a sun loving crop. It requires considerable amount of rain during the growth period and a dry period during root formation. Warm sunnydays and cool nights are very much favourable for storage root formation in sweet potato. Tuber yields are reduced considerably if drought occurs within first six weeks after planting.
Soil
Sweet potato can be successfully grown in a variety of soils, however well drained sandy loam soils are best suited. On heavy clay soils shoots grow well, but yield of tubers will be poor with deformed tubers.
Land preparation
Till to a depth of 25cm. Soils must be well drained and well aerated for a successful tuber growth. Ridge and furrow method, mound method, narrow bed and broad bed method are practiced in sweet potato cultivation in different areas. Ridge and furrow method and narrow bed method are better than other methods.
Planting material requirement
Vine cuttings are suitable for planting. The vine tip cuttings are found to be best to get higher tuber yield from sweet potato. In some varieties recurrent use of vines as planting material for more than 5,6 seasons showed marked decrease in yield. For these varieties root tubers can be sprouted and get cuttings. About 55,000 - 60,000 cuttings are required to plant one hectare.
Time of planting
Under rainfed conditions, plant with the Yala and Maha rains. In the wet zone in both Yala and Maha and in the dry zone in Maha season only.
Under irrigated conditions, planting can be done at any time of the year.
Nursery preparation
To produce enough planting material a nursery can be prepared.
Planting and spacing
No of cuttings and method of planting depend on the method of bed preparation. Spacing between 2 plants is 20cm. In ridge and furrow method cuttings are planted at a spacing of 90cm x 20cm. Vines of 20-25cm length with at least 5 leaves are found to be ideal as planting material.
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