by Roshan Kumar Singh, Nese Sreenivasulu and Manoj Prasad
Most underutilized crops are meagrely cultivated in hunger-prone regions and have the potential to alleviate food and nutrient deficiency of a larger population if produced in combination with staple crops, for example, the rice-fallow system in Eastern India. The rice-fallow intensification system is introduced by leaving residue much after rice harvest helps to maintain the soil moisture to introduce diversified pulses and alternatively by introducing the appropriate irrigation system vegetables be grown after rice cropping.
Several crops with enormous nutritional values were once largely consumed by mankind. However, due to selective domestication, most of them had become marginally cultivated in a confined region. It is an estimate from various studies on the evaluation of mankind that about 80,000 plant species have been directly used by humans for food, fodder, fiber, medicine, and industrial purposes.
Among these, more than 25,000 are edible and about 7,000 have either been domesticated or collected from the wild for food at one time or another. At present, merely 30 species are being cultivated for food, among which six crops including rice, wheat, maize, potato, soybean, and sugarcane share more than 75% of total plant-derived energy intake.
The Green Revolution in Asia occurred due to the introduction of high-yielding rice and wheat varieties with excess soil nitrogen application has uplifted the undernourished incidences from one in three people being hungry during 1960 to roughly one out of ten in the present date. However, the advent of the Green Revolution has negatively impacted crop diversity in developing countries.
Narrowing down of crop diversification together with the consumption of highly processed food and sedentary life resulted in double-burden nutritional challenges with nearly 2 billion people still suffering from malnutrition and additional 1.9 billion people suffering from obesity and non-communicable diseases due to higher caloric intake. Switching to crops with higher caloric yields has ended the cultivation of super-nutrient crops and general awareness of broader climatic adaptation of several native species to be grown in marginal environments.
Underutilized food crops can be broadly divided into 5 categories including pseudocereals and millets; grain legumes; root and tubers; leafy vegetables; and fruits. Most species belonging to pseudocereals and millets are of Chinese or African origin with a long history of cultivation.
Broomcorn (Panicum miliaceum) and foxtail millet (Setaria italica) were the first domesticated species before rice or any other crops. An indigenous African legume bambara groundnut (Vigna subterranea) is known for its adaptability in poor soils of hot and arid environments where other crops fail to grow. It also fixes an enormous amount of nitrogen to the soil (~ 90 kg/h) which boosts the production of intersessional crops.
The underutilized crops possess dense nutrients with higher micronutrients, rich in dietary fiber, resistant starch, protein, and bioactives with low glycemic index properties while being highly adapted to agro-climate niches. Due to their poor yields and lack of national policy to link with the value chain for promoting agro-business, these underutilized crops were not mainstreamed. Their ignorance has led to the erosion of genetic diversity and unique gene pools from cultivation areas.
Most underutilized crops are meagrely cultivated in hunger-prone regions and have the potential to alleviate food and nutrient deficiency of a larger population if produced in combination with staple crops, for example, the rice-fallow system in Eastern India. The rice-fallow intensification system is introduced by leaving residue much after rice harvest helps to maintain the soil moisture to introduce diversified pulses and alternatively by introducing the appropriate irrigation system vegetables be grown after rice cropping.
These underutilized crops have not gained much attention due to limited commercial gain and a lack of awareness among consumers. Re-diversification of crops has now been essential to eradicate triple burden nutritional challenges such as malnutrition, non-communicable diseases, and zero hunger under sustainable agricultural production.
This requires holistic strategies of global policy, research priorities to increase the productivity of underutilized crops, deploying various modern technologies for trait improvement (precision breeding through genomic selection and marker-assisted selection methods and modernizing the breeding programs), implementing crop rotation systems, improving the value chain and marketability, and most importantly building confidence among local farmers.
In a case study during the middle of the last decade, diversification of the cropping system has enhanced productivity and climate resilience in Zambia. Rotation of underutilized crops with existing crop systems may disrupt the disease and pest cycle, replenish soil nutrients, and diversify the presence of pollinators. Rotations with Indian mustard (Brassica juncea) and wild rocket (Diplotaxis tenuifolia) significantly reduced the cucumber wilt disease caused by Fusarium oxysporum. The rotation system resulted in enhanced soil bacterial diversity and abundances of potential plant-beneficial microorganisms including Pseudomonas spp. and 2,4-diacetylphloroglucinol (an antifungal) producers.
The major advantage behind promoting the use of underutilized crops is their immense nutritional value for eradicating hidden hunger. Most of the underutilized crops are superior to staple crops in terms of their nutritional properties. For example, millets and super-nutrient crops such as quinoa, chia, and teff are recognized with several folds higher carbohydrate quality with rich dietary fiber sources and high-quality protein sources with enriched essential amino acids than modern varieties of rice and wheat.
Millet grains are also rich in minerals and dietary fibers. Similarly, in legumes, protein content and essential amino acids in seeds and vegetative parts of grass pea (Lathyrus sativus) are manifolds higher than other legumes including alfalfa (Medicago sativa), garden pea (Pisum sativum), and broad bean (Vicia faba). Further, through symbiotic nitrogen fixation with Rhizobium leguminosarum, they also add up to 125 kg/ha nitrogen to the soil.
This improves the productivity of non-legume crops growing in the inter-season. Several lesser-known leafy vegetables including Asparagus officinalis, Citrullus lanatus, Basella alba, Ipomoea aquatica, Moringa oleifera, and others are rich sources of fibers, vitamins, and minerals. Altogether, it is realized that underutilized crops are nutritionally superior as compared to regular crops which demonstrates their potential in attaining United Nations’ Sustainable Development Goal (SDG) 2, which is zero hunger.
Uniformity in crop selection over the larger areas has strained modern agriculture in the era of changing climates with emerging diseases, and pests. Therefore, (a) bringing in modern breeding technologies to improve the genetic gain for increased productivity with novel nutritional value in minor crops, (b) reintroduction of missing alleles for enriched nutritional content in the staple crops, and (c) undertaking re-diversification of food crop cultivation under crop rotation systems have now been essential to ensure nutritional security and establishment of a sustainable agriculture system.
De novo domestication of wild crops is also needed to be initiated through genome editing technologies and speed breeding techniques for their impact on enhancing nutritional quality for some of the underutilized crops and major cereals to improve the livelihood of small-income farmers. In addition, coupling best agronomic practices together with mechanization are desired.
Integration of new crops into the existing cropping system might also require the application of different types of machinery for sowing and harvest and also depending on the crop, after-harvest processing procedures, which should be provided for the farmers. Extensive research investments and appropriate policies are required to mainstream their cultivation.
At the same time, it is also necessary to create awareness among people regarding the benefits of the consumption of nutritious crops. For an initiative, recognizing the nutritional and socio-economic values of millet crops, the Food and Agriculture Organization (FAO) of the United Nations has announced the year 2023 as the “International Year of Millets”.
However, several questions still remained unanswered: (i) how longer duration it will take to market value addition and link farmers cultivating underutilized crops? (ii) Could intercrop breeding systems ever be implemented to share genetic benefits among closely related crops? (iii) What should be national and international policies required to ensure the sustainable use of these wild resources?
Read the study:
Singh RK, Sreenivasulu N, & Prasad M. (2022) Potential of underutilized crops to introduce the nutritional diversity and achieve zero hunger. Funct Integr Genomics
