eChapters

Annual plants complete their life cycle within the space of one year are called annuals. They have multipurpose uses like as cut flowers, a wealth of bloom through out the summer and early autumn months; as component in herbaceous border, to make colour scheme, for window boxes and porches, as pot plants in green house or conservatory, for edging, for drying and herbal medicines.

Rose
Rose is a perennial erect shrub, climber or trailing plant  belonging to the genus Rosa within the  family Rosaceae. The plants bear large and showy flowers of white, yellow, red, pink, orange and various shades. Most of the species are native to Asia.

Valuable Genetic Resources

India is bestowed with diverse agroclimatic zones which aids in the cultivation of large number of commercial flowers like rose, gladiolus, chrysanthemum, tuberose, jasmine, marigolds, orchids, lavender, lily, anthurium, gerbera, potted plants, cut foliages, bedding plants etc. In floriculture trade, value addition takes place at every step to create a novel product and to cater the demand of heterogeneous consumers. In the international floriculture trade, besides floriculture and pot plants, many other value added products include artificial colouring of the flowers to create novelty, aqua-packing for better presentation and attraction, three dimensional window packing of flowers for greater visibility, garland, venis, bouquets, flower arrangements etc.

The world’s population is increasing exponentially. Projected totals for the year 2050 vary but it is acknowledged that access to sufficient quality and quantity of food, water and living space and other natural resources will be limiting factors for the human population. The environmental impact of this huge population and its everyday activities will be significant and possibly irreversible. There is urgency therefore, in addressing issues of sustainable food production, water and land use for the coming decades. Endemic hunger (due to carbohydrate-protein malnutrition), hidden hunger (induced by deficiencies of vitamins and minerals) and transient hunger (caused by natural calamities such as drought, flood, earthquake, tsunami etc.) can be overcome only by integrated strategy with sustainable and equitable use of agricultural biodiversity.

In tropics, many crops are grown for their edible roots or tubers. Broad group of “tuber crops” encompasses a wide range of starchy food crops, some of which are true botanical roots and some others are stem tubers or corms. In global scenario, they are in a neglected state mainly due to their negative image as poor people’s food. They are highly perishable and are normally consumed locally in fresh or home processed state. It is time to bring out the positive attributes of these important foods and the increased contribution they can make to the nutritional welfare, food security and economic wellbeing of people, especially in developing countries.

After attaining a rich experience over a period of time, our forefathers have developed very pertinent primitive knowledge in a wide variety of fields (Rohilla et al., 1999). These location specific wisdom are known as indigenous traditional knowleges (ITKs). Indigenous traditional knowledge are the upshots of the pragmatic approach by our sons of the soil. As such, there are many ITKs emerged due to the incremental and cumulative learning among societies living in close connection with nature. The traditional communities are often called as indigenous or local or ethinic people. They have accumulated lots of empirical knowledge gained from the day-to-day life. The variations in availability of raw materials and environmental conditions clubbed with time tested traditional knowledge and wisdom, have made people of different regions of the North Eastern hill states to formulate, develop and perpetuate consumption of a wide range of traditional foods and beverages unique to its places since ages (Savitri and Bhalla, 2007).

Tropical root and tuber crops are important staples for food security for about a fifth of the world population. Tropical root and tuber crops like cassava, sweet potato, yams and aroids [taro and elephant foot yam] come under tropical root and tuber crops. Sweet potato, yams and colocasia are processed mainly as fresh vegetable, whereas 75% of the cassava in Africa, 75-80% in Asia and 65% in Latin America are processed either as fermented foods and feeds or as food additives such as starch, starch based sweeteners (glucose and fructose syrups), organic acids (acetic, lactic, glutamic and gluconic), mono-sodium glutamate and microbial polysaccharides (xanthan, pullulan, scleroglucan, etc).

Tuber crops grown in India include Cassava, Sweet potato, Dioscorea, Colocasia, Amorphophallus and minor tuber crops like Chinese potato, Arrowroot, Canna, Yam bean etc. Biotechnology can contribute solution to the major problems and realize greater benefits for tuber crops. Traditional breeding in tuber crops is difficult due to their heterozygous nature, low fertility, out crossing coupled with strong inbreeding depression. Many of the agronomic traits are polygenic and/or recessive which make breeding for such characteristics complicated. Biotechnology is a powerful tool to complement traditional breeding. Developments in the field of tuber crops biotechnology are discussed below.

Tuber crops are rated as one of the richest sources of energy, besides being a treasure house of vitamins and minerals. The highest rate of dry matter production per day per unit area makes tuber crops important in the food economy, especially in meeting rural feed security. The tuber crop produce can also be processed into various food products to suit the taste and need of the urban, semi-urban and rural folk as well. Better post harvest management and diversification for production of value added products is one of the dependable methods to make tuber crops lucrative to both farmers and entrepreneurs.

1. Tuber crops Starches

Tropical root and tuber crops are rich sources of starch (Ghosh et al., 1988; Chadha and Nair, 1994; Moorthy, 1994) besides many vitamins, minerals etc (Table 1). In addition to food applications, they have important industrial uses; especially, cassava in view of the considerable starch content. Cereals form the major source of commercial starches in most developed countries, but cassava (Manihot esculenta Crantz) and to a lesser extent, sweet potato (Ipomoea batatas Lam.) tubers are used for starch extraction in India, Brazil, Thailand, Indonesia, Philippines and China.

The North Eastern region stretches from 21°25' to 29° 28' N and 80° 4' to 97°25' E and covers a total geographical area of 2.55 lakh square kilometer sharing about 8 percent of the country’s geographical area. The NE states, otherwise known as eight jewels, which are Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Tripura and Sikkim. This region is characterized by inaccessibility, marginality, fragility, cultural heterogeneity, ethnicity, rich bio-diversity, low livestock and crop productivity. These states are the reservoirs for genetic diversity of tuber crops like Colocasia, Xanthosoma, Alocasia, elephant foot yam, Dioscorea and other minor tuber crops. The annual precipitation in the region is about 2450mm and maximum rainfall is received from South West monsoon.

The major tuber crops cultivated in tropical countries are: cassava (Manihot esculenta Crantz), sweet potato (Ipomoea batatas L.), yams (Dioscorea sp.), aroids (Amorphophallus, Alocasia, Xanthosoma, Colocasia ), Canna edulis, arrowroot, Chinese potato, winged bean and yam bean. In addition to this, there are a number of under exploited and under utilized tuber crops grown as wild cultivars having medicinal and pharmaceutical applications. Processing and utilization of tuber crops as food are traditional with both primitive as well as modern equipments being in use (Nanda and Kurup, 1994). One of the oldest traditional processing tools is a stone pounder for making poi from taro in Hawaii.

Tropical tuber and root crops are subjected to the depredation of a number of insect and non insect pests. Comprehensive studies revealed that cassava is attacked by a wide range of arthropod and rodent pests. An exhaustive global account of cassava pests and their management was given by Anon (1978), Bellotti and Schoonhoven (1978) and Bellotti et al. (1999). Lal and Pillai (1982); Pillai and Palaniswami (1984), Pillai (1994) and Palaniswami (1999) reviewed the pests of cassava in India. Anon (1978), Sutherland (1986) and Jansson and Raman (1991) covered world sweet potato pests. Palaniswami (1999) detailed the pests attacking sweet potato in India. Pests of edible aroids, yams and chinese potato were comprehensively reported by Anon (1978); Mitchell and Maddison (1983) and Palaniswami (1994, 1999). In India about 34 species of insects and non-insect pests infest cassava, 80 species attack sweet potato, 46 species on edible aroids, 21 on yams and 10 on chinese potato. One of the main factors for the low productivity of these crops in India is attributed to the pest complex attacking them (Chadha, 2001).

Application of manures and adoption of proper cultivation practices have profound influence in yield and quality of tubers. There crops also need macro nutrients (N,P,K which are primary nutrients and Ca, Mg and S which are secondary nutrients) and micro nutrients (Fe, Mn, Zn, Cu, Mo, B) for their maximum yield potenial.

the package of practices vary with crop and again with soil, climate, edaphic and topographic factors, especially with reference to tropical tuber and root crops. The yield can be maximized through good agronomical practice and by adoption of proven recommended production technologies. Soils, climate, topographic and edaphic factors suitable for each crop alongwith salient cultivation practices and production technologies are enunciated for important tuber and root crops in various parts of India.

In enhancing  the food production there appears to be two solutions, viz., horizontal or vertical increase in production.  In the vertical expansion of production varieties are important. High yielding, high starch and value added varieties suitable to each region/ cropping system play vital role in enhancing vertical production.  Therefore varieties especially value added consumer preferred ecologically adaptable ones hold the key and is very much true in tuber and root crops which have a significant role in supplementing the food and nutritional requirement in rural and semi urban population of India.

A broad class of polypeptides and proteins occur in plants and other life forms, which inhibit the action of proteolytic enzymes and are known therefore as proteinase inhibitors and this includes those which specifically inhibit the important digestive enzyme trypsin. Others inhibit a related enzyme chymotrypsin. The subject of proteinase inhibitors was reviewed by Ryan (1981). The occurrence of these inhibitors has nutritional implications for human and animal feeding as they are found in many important food plants eaten both raw and cooked. The first known plant proteinase inhibitor was the trypsin inhibitor crystallized from soybeans (Kunitz, 1945). Other proteinase inhibitors have since been described in a variety of plants, especially the Graminae, Leguminosae and Solanaceae families. The exact physiological function of proteinase inhibitors in plants is thought to be in plant protection by inhibiting digestive enzymes of invading insect pests or pathogens (Ryan, 1981).

The dry matter production is maximum in cassava (3.0 m t ha^-1) and is followed by yams (2.4 m t ha^-1) and sweet potato (2.1 m t ha^-1) and are higher than rice, wheat, maize and banana (1.3 to 1.9 m t ha^-1). The energy production is maximum in yams (182 M J ha^-1 day^-1) and it is followed by sweet potato (152 M J ha^-1 day^-1) and cassava (121 M J ha^-1 day^-1) (Horton and Fano, 1985).

1. Sweet Potato

Both sweet potato roots and tops are nutritious foods which could be used to advantage in combating nutritional deficiencies in parts of the developing world if means could be found to overcome resistance to their increased consumption. The roots are used primarly as human food and are eaten boiled, steamed, fried or baked. They are not only a moderately good energy source, but also contain significant quantities of the water-soluble vitamins viz., ascorbic acid and thiamin, besides supplying part of the daily requirement for riboflavin and niacin. Their contents of pyridoxine, folic acid and pantothenic acid may be relatively high. Raw leaves and tender tips are also excellent sources of ascorbic acid and some of the B-vitamins, especially riboflavin which is deficient in many Asian diets. However, high percentages of water-soluble vitamins are lost on cooking (Woolfe, 1992).

Plant biodiversity, in particular, is arguably the single greatest resource that humankind has garnered from nature during our long cultural development. Nowhere is the value of biodiversity more evident than in our food supply. Roughly one third of all plant species have edible fruits, tubers, nuts, seeds, leaves, roots, or stems. The World Health Organization estimates that 3.5 billion people in developing countries rely on plant-based medicine for their primary health care, in which tuber crops also play a major role (Tuxill, 1999). There are 25 hot spots of biodiversity of which Western Ghats and Eastern Himalayan are the most important ones in India. About 7% of world flora and 6.5% of world fauna are in India. Indo-Burma region is one of the eight hottest hot spots of the world, and is the centre of origin of tuber crops like Dioscorea, Colocasia, Amorphophallus and Alocasia.

Among angiosperms, there are about 18 families which have more than 30 genera which produce tubers. Most genera have many species which are tuberizing, most of which are unknown to man even now. The history, origin and distribution of only a few species which are economically important root and tuber crops and which are commonly used by men for edible as well as medicinal purpose are elucidated in this chapter.

1. Sweet Potato

Exact centre of origin of sweet potato (Ipomoea batatas), and the routes and times for its dispersal to some of its present locations, are still in dispute and are likely to remain so until further archaeological or ethnobotanical evidence is available (O’Brien, 1972).

As per the projection of International Food Policy Research Institute, Washington, there is likelihood of shortfall of 41% in food production in India by 2020 and need to produce 300mt of food by 2020. India is the seventh largest country in the world with a population of more than 1.03 billion and with 1.93 population growth rate. To overcome such problems we have to go for horizontal or vertical increase in production. As the cultivable area and water resources are limited to bring under cropping, except by way of increasing the cropping intensity/cropping system, horizontal increase has little scope. While the vertical increase in production has tremendous scope with better value added varieties and farmer friendly sustainable management and production technologies.