Tuber crops are biologically highly efficient converters of energy into consumable produce. Their yields on a per-day-per-unit-area basis are higher than other food crops. Some of the tubers also score over key staple cereals in terms of dietary nutrition (energy). Many of them, such as cassava (tapioca), sweet potato, yams, taro (colocasia or arvi) and arrowroot are among the cheapest sources of energy, albeit in the form of carbohydrates and are, thus, often hailed as “calorie density” foods.
Yet the consumption of most tubers – barring potato – is gradually dwindling thanks, chiefly, to the easy availability of highly subsidised rice and wheat. However, these cereals may not be able to wholly displace tubers from the food chain or undermine their role as providers of nutrition and livelihood security to resource-poor farmers and undernourished people. Efforts are afoot by the Thiruvananthapuram-based Central Tuber Crops Research Institute (CTCRI) to rehabilitate and, more importantly, promote tuber farming. The two-pronged strategy adopted for this purpose involves: breeding improved crop varieties to lower the cultivation cost of tubers and developing technologies for the industrial-scale production of value-added and nutrition-rich tuber products.
With the use of new varieties, yields of some of the tuber crops have spurted handsomely. The average productivity of cassava in India, for instance, has shot up to around 35 tonnes a hectare — which is nearly three times the global average of 11 to 12 tonnes per hectare.
Thus, tuber crops seem to transforming into commercial crops. Such a makeover can be expected to spur the emergence of small, medium and big tuber processing units to produce tubers-based nutritious foods. The CTCRI has developed several technologies over the past few years to manufacture utility and health foods from cassava and sweet potato — some of these have been passed on to prospective entrepreneurs for commercialisation. Consequently, over 800 industrial units, including some in the cooperative sector, have come up in the Salem district of Tamil Nadu alone for producing sago (also called sagodana) and its value-added products from cassava. Such industries are also coming up in other states, notably in Kerala and Maharashtra.
Many units in Kerala are producing starch from cassava. Likewise, sweet potato has found many uses as snacks, convenient foods and nutrient supplements. Being rich in vitamin A, sweet potato, particularly the orange-coloured sweet potato, is believed to have enormous potential for combating vitamin-A malnutrition, which is widespread among children and women in India and poor countries in Africa. A study published last week in the reputed, “Journal of Nutrition”, provided conclusive evidence of alleviation of vitamin-A deficiency in Uganda and Mozambique. Orange-hued sweet potato was introduced in the diets of people in these countries under a joint project by international research institutes (“HarvestPlus” institutes) being run by the Consultative Group on International Agricultural Research (CGIAR).
This apart, the low glycaemic content of the products made from orange sweet potato and some other tuber crops make them suitable for consumption for even diabetics whose number is fast swelling in India. CTCRI Director S K Chakrabarti maintains that more research and development work can help fabricate several kinds of low glycaemic foods from these tubers with therapeutic and prophylactic properties for the benefit of people suffering from ailments like diabetes, cancer, cardiovascular problems and general malnutrition. The inclusion of tuber products in the mid-day meal programme, too, can help improve the nutritional profile of school-going children.
He also feels that the tuber crops can potentially be used for making ethanol (biofuel), though at the current costs and prices, such ethanol may not be able to compete with the one made from molasses, a by-product of sugar production. Technological refinement, it is hoped, may improve the competitiveness of tuber-based ethanol.
At present, the cultivation of tuber crops, other than potato, is confined largely to the peninsular and north-eastern states. The CTCRI is making efforts to introduce these crops elsewhere as well, especially in the agriculturally-progressive areas in the north. It is collaborating with the Ludhiana-based Punjab Agricultural University to try out cassava cultivation in Punjab. Indications are that these efforts may yield positive results, paving the way for the introduction of cassava as a summer crop for harvest before planting wheat in winter.
