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Production of tapioca crop varieties in Kerala
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Friday, 01 April, 2016, 08 : 00 AM [IST]
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Pooja Rawat, Pawan Kumar Singh and Vipin Kumar
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fiogf49gjkf0d fiogf49gjkf0d Cassava (Manihot esculanta Crantz; family Euphorbiaceae) is the most important starchy food crop grown in the tropics. Common names of cassava are tapioca, manioc, manihot and yucca. Cassava originated in Latin America and was later introduced into Asia and Africa. It is well adapted to varied soil and environmental conditions, tolerant to low soil fertility and biotic stresses. It is a highly efficient carbohydrate compared to other food crops and therefore consumed as staple food. In India, Kerala and Tamil Nadu are the two major tapioca growing states, together accounting for about 98 per cent of total tapioca growing area. Kerala holds the key position in cassava cultivation where it is widely grown as a food crop, while in Tamil Nadu, it is grown mainly for industrial purposes.
Nutritional Content
The nutritive contents of cassava depends on numerous factors, such as variety, plant age, geographical location and other environmental conditions. The leaves and roots are considered as nutritionally valuable and constitute 50% and 6% of the mature cassava plant, respectively. However, nutritional value of cassava root is highly important as it is consumed in most of the developing countries, including India. Cassava root is a good source of energy but protein, fat and other essential nutrients are in low quantity (Table 1)
Edible and non-edible varieties
Several edible and non-edible varieties of cassava are commercially cultivated worldwide. M-4 is considered one of the best edible variety with superior culinary qualities. Cooked roots of this variety are soft, highly delicious and contains negligible cyanogen content. The other edible varieties are Sree Visakham, Sree Sathya, Sree Jaya, Sree Vijaya, Sree Rekha and Sree Prabha (2). Many hybrid varieties such as H-97, H-165, H-226 have been developed by extensive inter-varietal hybridisation by Central Tuber Crop Research Institute (CTCRI), Kerala (3). Besides these, about 125 local varieties have also been recorded which are the result of farmer selection of clones, chance hybrids or mutation occurring over the centuries. Starch, the prime nutritive component of cassava, varies from one variety to another (Table 2)
Due to presence of cyanogenic glycosides, processing (peeling, slicing and cooking) should be done with utmost care while using tapioca as a food. Cyanogenic glycosides are present in many edible plants and seeds, when fresh plant material is macerated/chewed, it associates with enzymes and releases hydrogen cyanide. Tapioca cultivars are characterised as "sweet" (below 10mg/100g of fresh weight) and "bitter" cultivars (above 20mg/100g fresh weight), depending upon the presence of cyanogenic glycosides quantity. "Sweet" types may be eaten raw or cooked after boiling whereas "bitter" varieties are not commercially traded and traditionally processed by peeling, grating, fermenting, dehydrating, sun drying, frying or boiling. (5).
Morphological characteristics of roots
Cassava roots may vary from 15 to 100 cm in length and 0.5 to 2.0 kg in weight. The roots mature to harvest during 8 to 24 months of plantation, which also depend on the cultivar and climate. Anatomically, the cassava roots can be divided into three main areas viz. periderm (outermost layer), cortex (middle layer) and starchy flesh (central portion) (6).
Production and yield of cassava in India
Marginal reduction in production of cassava has been observed from 2009 to 2014, which correlates with the decrease in the cultivation area (7) (Table 1). The reason for observed decline in cassava production in India specifically in Kerala is due to prominence gained by plantation crops like rubber, black pepper, and coffee, which provide more cash income to the farmers (3). Globally, after maize, rice, wheat and potato, cassava ranks fifth in terms of production and sixth in terms of area cultivated. In India, it is mainly cultivated in southern peninsular region including Tamil Nadu and parts of Kerala, Andhra Pradesh, Nagaland, Assam and Meghalaya. India exports several forms of tapioca products like raw tapioca tubers, starch, sago and sago pith. The export of tapioca and its value-added products has slightly decreased from 152.4 million (2012-13) to 145.1 million (April-December 2013-14) (8).
Price trend of cassava
An analysis over the period from January 1999 to June 2011 revealed that the peak phase for cassava prices in Kerala is in the months of March and April (9). This is the result of increasing demand from the industries involved in starch production since the quality of starch manufactured during the dry summer days is good. The observed rise in prices of cassava in Kerala during the period of September to November is due to poor market arrival (Figure 1).
Post-harvest uses of cassava
Food: The leaves are known to contain up to 25 per cent protein on a dry matter basis, and are rich in calcium, iron, vitamin A and C. The essential amino acid content of leaf protein is similar to that found in a hen’s egg. Roots are the main part which are processed and consumed as a food in various forms. Several value-added edible products of cassava such as sago, starch, chips, flour, wafer, papad are commercially available throughout Kerala and India.
Animal feed: The roots and leaves are used to prepare animal and poultry feed at commercial scale. Consumption of fresh leaves is generally avoided due to their high cyanide content. Traditional processing techniques such as sun drying and ensiling is carried out to release cyanide before using them as feed for animals.
Industrial uses: Various valuable modified starch-based products are made out of cassava for their application in food products and feedstock such as sweeteners, fructose, alcohol and monosodium glutamate. Modified starch is also used in the manufacture of paper, textiles and plywood. Cassava is also being used for production of biofuel (ethanol), which can be blended with gasoline to produce “gasohol” containing different percentage of ethanol (11).
Raw material standardisation
Owing to increased uses of tapioca starch especially in food and pharma, quality control is an essential requisite to ensure consistent delivery of high-end products. Traditional chemical methods employed for identification of starch are time as well as money consuming and are not adequate for rapid analysis. Nowadays, modern identification tools (FT-IR) are being used and proposed for rapid, non-invasive, chemical-free and cost-efficient analysis (12).
Diseases and pests
The cassava farmers bear huge losses in the yield due to attack and infestation of insects and pests, with high incidence in the areas where cultivation is done round the year (13). Some of the important pest and disease are:
Bacterial blights: Bacterial blight is caused by Xanthomonas axonopodis and is transmitted by infected planting material and farm tools. It can be controlled by using tolerant varieties, hot water treatment of stakes, sterilisation, and intercropping.
Viral diseases: Cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) are the common viral diseases. CMD, caused by Gemini viruses is the most serious issue in Kerala. The diseased plants show the symptoms of reduced leaf size, stunted growth, leaf curling and mosaic resulting in reduced yield. Routine sanitation of cultivation field, use of disease-free planting stem and tolerant varieties, vector control are recommended by experts for reduced disease incidence.
Tuber rot: Phytophthora dreschleri is a causal organism of tuber rot of cassava, which leads to discolouration and rotting of tissues. Immersing the stakes in Trichoderma viride suspension protects against soil-borne phyto-pathogenic fungi.
Mites: Spider mites (Tetranychus cinnabarinus, T. neocaledonicus Eutetranychus orientalis and Oligonychus biharensis) attack during dry season which causes chlorosis, withering and curling. Mites may be controlled with spray of neem oil or chemicals.
Scale insect: Anoidomytllus albus attack results in drying of the cassava plant and can be controlled with insecticides.
Termites and white grubs: Termite, Odontotermes obesus and white grub, Leucopholis coneophora infests the plants which results in complete drying.
Application of modern molecular tools
Modern molecular tools are being utilised for early and fast detection of viruses in the plant (14). In Kerala, molecular characterisation tools are being used for cassava variety characterisation which enables to protect the breeders and farmers’ right. (15). These techniques also equip to characterise the spontaneous mutations in the cassava varieties and transfer desirable traits for production of novel varieties for commercial exploitation (16). Studies are also being focussed to reduce the cyanogen content in the roots through mutation breeding.
Future scope
A report released by The International Food Policy Research Institute (IFPRI) in 1999, had projected an increase in global demand of cassava by 68% by year 2020 (17). In order to meet this challenge, development of short duration varieties is the need of the hour especially for the low-lying areas. CMD infestation is the major factor of crop-loss and therefore its eradication will be very useful in enhancing the cassava production in Kerala and also worldwide. Wild varieties of cassava which exhibit vast array of genetic variation, viral resistance, shade tolerance, low cyanogen content, protein enrichment in roots and high vigour must also be exploited for variety improvement.
References
1. Montagnac, Julie A., et al. Nutritional value of cassava for use as a staple food and recent advances for improvement. Comprehensive Reviews in Food Science and Food Safety. 8 (3), 2009: 181-194.
2. Varmudy, V. Cassava cultivation and export: Vast scope in India. Facts for you. 2014: 22-25
3. Abraham, K., et al. Cassava breeding and varietal Dissemination in India-Major achievements during the past 25-30 years. In Cassava’s Potential in the 21st Century: Present Situation and Future Research and Development Needs. Proc. 6th Regional Workshop, held in Ho Chi Minh city, Vietnam. 2000: 174-184
4. http://www.kissankerala.net/ kissan/ kissancontents/tapioca.htm
5. Cyanogenic glycosides in cassava and bamboo shoots. A Human Health Risk Assessment Technical report series no. 28. Food Standards Australia New Zealand. 2004
6. http://www.fao.org/ docrep/x5415e/ x5415e01.htm
7. Agriculture statistics at a glance 2014. Government of India, Ministry of Agriculture
8. Press Note - Currently sown tapioca to fetch a good price at harvest by Tamil Nadu Agricultural University, Coimbatore. 2014
9. Domestic and Export Market Intelligence Cell (DEMIC). Centre for Agricultural and Rural Development studies, Tamil Nadu Agricultural University, Coimbatore
10. Jayasree, K., et al. Price behaviour of cassava in Kerala: An Econometric Analysis. Journal of Root Crops. 38(2), 2013: 168
11. Howeler, R.H., et al. Save and Grow: Cassava: a guide to sustainable production intensification. Food and Agriculture Organization of the United Nations. 2013: 89-108
12. Sacithraa, R. et al. Quantitative Analysis of Tapioca Starch using FT-IR Spectroscopy and Partial Least Squares. International Journal of Computer Applications (0975 – 8887) 29-33
13. http://www.fao.org /ag/save-and-grow/ cassava/en/6/index.html
14. Standardization and implementation of the RT-PCR methodology for the diagnostic of cassava virus. XXXII Colombian congress of phytopathology, Colombia. July 15-17, 2015
15. Aiemnaka, et al. Molecular characterization of a spontaneous waxy starch mutation in cassava. Crop Science. 52(5), 2012: 2121-2130
16. Sree Lekha, S. DNA analysis as a tool for Genetic Studies and Molecular Breeding in Cassava (Manihot esculenta Crantz). 2013
17. Scott, Gregory J. Roots and Tubers in the Global Food System: A Vision Statement to the Year 2020: Report to the Technical Advisory Committee (TAC) of the Consultative Group on International Agricultural Research (CGIAR). Iita, 2000 m
(Singh is innovation officer/scientist; Kumar is director and chief innovation officer; and Rawat is fellow. The authors are from National Innovation Foundation India, an autonomous body of department of science and technology, Govt of India, Gujarat. They can be contacted at pawan@nifindia.org)
(The authors are grateful to Prof. Anil Gupta, executive vice-chair, National Innovation Foundation India, Prof, IIM, Ahmedabad, for guidance)
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