Combating Vitamin A Deficiency
Vitamin A deficiency (VAD) is a public health problem in South Africa. A recent national survey showed that 43.6% of 1-5 year-old children and 27% of women at childbearing age suffer from VAD.
Vitamin A is important for normal vision and for immune response (fighting infection). Vitamin A deficiency is the result of insufficient intake of foods rich in vitamin A.
Consumption of provitamin A rich vegetables such as orange-fleshed sweet potato, is a long term strategy promoted by the Agricultural Research Council (ARC) to reduce this deficiency. Orange-fleshed sweet potato is a very useful food for school feeding.
Orange Fleshed Sweet Potato - Nutritious and Easy-to-Grow Crop
Sweet potato is an excellent source of energy, while containing substantial quantities of vitamin C and also contribute B vitamins and minerals such as magnesium, zinc and iron to the human diet.
It provides abundant quantities of provitamin A in the form of beta-carotene. Most of the beta-carotene is retained during boiling and the efficacy of orange-fleshed sweet potato to improve the vitamin A status has been proven by the South African Medical Research Council.
This crop has been used in large-scale provitamin A interventions in Mozambique and Uganda with great success. The ARC has developed orange-fleshed varieties with pleasant taste, high yield and dry texture containing high quantities of beta-carotene.
Variety BOPHELO contains 7700 µg/100 g boiled root (or 640 µg/100 g) retinol activity equivalents (RAE). A 100 g boiled portion of this orange-fleshed sweet potato provides in the dietary requirement of most age groups.
Production Practices
The crop is sensitive to frost, and this affects the planting season: Area Light to mild frost Heavy frost Frost-free Winter rainfall Months for Planting Middle Oct to Dec Middle Nov to beginning Dec Aug to March Nov to Dec Farmers can use staggered planting to lengthen the availability during the year by planting every month as from October to January in order to harvest as from February until August the following year.
Sweet potatoes are established by means of cuttings; 20-30 cm long, planted with 3-4 nodes underground. The spacing between rows can be 0,75 – 1 m with an in-row spacing of 25-30 cm. Planting on ridges is recommended since it will increase marketable yield with less damage to the sweet potatoes during harvesting.
Harvest sweet potato after 4½ months (warm areas) to 5 months (moderate areas) after planting. Various products can be made such as chips, juice, doughnuts.
Availability of Planting Material
Cuttings are disseminated from Sweet Potato Vine Growers Association (SPVGA) growers in bags (large orders) or bundles (small orders). The ARC supplies the vine growers with cuttings of disease-tested source, ensure effective managed of the nursery block in terms of disease and pest control in order to disseminate good quality, healthy cuttings for production.
The vine growers are required to comply to set production standards. The nursery blocks are inspected and approved by officials of the ARC before cuttings may be disseminated. Large quantities of cuttings of new ARC cultivars can be obtained from August till April.
By Louise Brodie