1 Introduction

      There are an estimated 7000 plant species that have been used as crop plants at some point in human history (FAO, 1998). However, today only 150 plant species are cultivated; just 12 of these provide approximately 75% of the world’s food and four produce over 50% of the world’s food (Bermejo and León, 1994). Prescott-Allen and Prescott-Allen (1990) state that common figures range from seven plant species providing 75% of human nutrition to 30 plant species providing 95% of human nutrition. These commonly utilized crops are intensively cultivated and require farm mechanization and increased inputs in the form of labour, high-yielding varieties, chemical fertilizers and pesticides (Bhargava et al., 2008, 2012). These accelerated inputs have resulted in intolerable pressure on fragile agroecosystems. Modern agriculture has increased homogeneity and mono-crop cultivation, resulting in loss of agrobiodiversity and frequent crop losses due to infestation by pathogens. The need of present times is a gradual shift from input-intensive to environmentally sound sustainable agriculture. Modelling of traditional farming systems to modern needs with increased organic linkages might be a good option for sustainability of the agricultural production system and maintenance of agroecological stability (Bhargava et al., 2008). This would also require a shift in focus towards increasing production by using agriculturally marginal lands for crops that are less exploited but that have immense potential for diverse uses (Partap et al., 1998).

      The emphasis on a handful of major crops has narrowed the number of species on which global food security depends. The consequences of crop failures from unforeseen stresses, pests and diseases can be catastrophic (Prescott-Allen and Prescott-Allen, 1990). The past three decades have seen a wide range of research interests on underutilized crops and a number of significant programmes have been undertaken in both developing and developed countries to promote underutilized species for agricultural systems, as alternative crops or as sources of new products.

       1.1 Underutilized Crops

      Underutilized or neglected crop species are often indigenous ancient crop species that are still used at some level within the local, national or even international communities, but have the potential to contribute further to the mix of food sources (Mayes et al., 2011). These species appear to have considerable potential for use yet their potential is barely exploited, if not totally neglected, in agricultural production. Many underutilized crops were once more widely grown but are today falling into disuse for a variety of agronomic, genetic, economic and cultural reasons (Hammer et al., 2001). Farmers and consumers are using these crops less because they are not competitive with other crop species in the same agricultural environment. Orphan, abandoned, new, underutilized, neglected, lost, under-used, local, minor, traditional, forgotten, alternative, niche, promising, underdeveloped: these and other terms are often used as synonyms for underutilized species (Padulosi and Hoeschle-Zeledon, 2004). Underutilized crops are often known as ‘new crops’, not because they are ‘new’ but because they have been taken up by agricultural researchers and commercial companies for a new market. The main features of the underutilized crops are that they are:

      • important in local consumption and production systems;

      • highly adapted to agroecological niches and marginal areas;

      • represented by ecotypes or landraces;

      • cultivated and utilized drawing on indigenous knowledge;

      • characterized by fragile or non-existent seed supply systems;

      • hardly represented in ex situ gene banks and

      • ignored by policy makers and excluded from research and development agendas (Padulosi and Hoeschle-Zeledon, 2004).

      Moreover, the limited information available on many important and frequently basic aspects of neglected and underutilized crops hinders their development and sustainable conservation (Hammer et al., 2001).

      Many wild and underutilized plants have potential for more widespread use and could contribute to food security, agricultural diversification and income generation (Vietmeyer, 1986; Anthony et al., 1995). Neglected and underutilized crops represent an important source of revenue for local economies and are part of the rich cultural and traditional heritage of communities around the world (IAEA, 2004). In addition to this, these crops are important sources of resistance genes for biotic and abiotic stress breeding that can also be used for the genetic improvement of crops. Compared with the major crops, they require relatively low inputs and, therefore, contribute to sustainable agricultural production. Underutilized crops have great potential to alleviate hunger directly, through increasing food production in challenging environments where major crops are severely limited, through nutritional enhancement to diets focused on staples and through providing the poor with purchasing power, helping them buy the food that is available (Mayes et al., 2011).

       1.2 Chenopodium as an Underutilized Plant

      Among a number of underutilized species, members of the genus Chenopodium (family Amaranthaceae) are most promising since they have the ability to thrive and flourish under stressful conditions (Bhargava et al., 2003, 2006a; Jacobsen et al., 2003a) as well as on soils with minimum agricultural inputs. Many complex adaptive modifications related to breeding system, seed dispersal and their germination account for the success of the members of this genus in colonizing disturbed habitats (Williams and Harper, 1965; Dostalek, 1987). With a shift in focus towards production on agriculturally marginal lands, Chenopodium has a significant role to play both as a nutritious food crop and as a cash crop. The genus Chenopodium, commonly known as ‘goosefoot’, comprises about 250 species (Giusti, 1970) that include herbaceous, suffrutescent and arborescent perennials, although most species are colonizing annuals (Wilson, 1990). Some well-known species include C. quinoa, C. pallidicaule, C. berlandieri ssp. nuttalliae, C. ambrosioides, C. murale and C. amaranticolor. Chenopodium spp. have been cultivated for centuries as a leafy vegetable and subsidiary grain crop in different parts of the world (Risi and Galwey, 1984). Although only three species (C. quinoa, C. pallidicaule and C. berlandieri subsp. nuttalliae) are reported to be cultivated (Heiser and Nelson, 1974; Wilson, 1980; Bhargava et al., 2006a, 2007), the leaves and tender stems of numerous other species are consumed as food and fodder (Tanaka, 1976; Kunkel, 1984; Partap, 1990; Moerman, 1998; Partap et al., 1998). The foliage of Chenopodium is an inexpensive and rich source of protein, carotenoids and vitamin C (Koziol, 1992; Prakash et al., 1993; Bhargava et al., 2006a). The protein has a balanced amino acid spectrum with high lysine (5.1–6.4%) and methionine (0.4–1.0%) contents (Prakash and Pal, 1998; Bhargava et al., 2006a).

       1.3 Quinoa

      Of all the new-world crops, Chenopodium quinoa Willd., commonly known as ‘quinoa’, is one of the most underutilized, given its superb seed protein composition and yield potential. It is principally a grain crop, harvested and consumed in a manner similar to that for cereal grains, although its leaves are also used as a potherb (Maughan et al., 2007). Quinoa is not a true cereal grain, but rather is a pseudocereal, which is dicotyledonous. In contrast, cereals are monocotyledonous (Valencia-Chamorro, 2003). Quinoa has risen from a neglected subsistence crop of indigenous farmers to become a major