Kumar et al. Agric & Food Secur (2018) 7:31 https://doi.org/10.1186/s40066-018-0183-3 Agriculture & Food Security REVIEW Open Access Millets: a solution to agrarian and nutritional challenges Ashwani Kumar1,2* , Vidisha Tomer2, Amarjeet Kaur1, Vikas Kumar2 and Kritika Gupta2 Abstract World is facing agrarian as well as nutritional challenges. Agricultural lands with irrigation facilities have been exploited to maximum, and hence we need to focus on dry lands to further increase grain production. Owing to low fertility, utilization of dry lands to produce sufcient quality grains is a big challenge. Millets as climate change compli- ant crops score highly over other grains like wheat and rice in terms of marginal growing conditions and high nutri- tional value. These nutri-cereals abode vitamins, minerals, essential fatty acids, phyto-chemicals and antioxidants that can help to eradicate the plethora of nutritional defciency diseases. Millets cultivation can keep dry lands productive and ensure future food and nutritional security. Keywords: Millets, Dry lands, Nutrition, Nutri-cereals, Micronutrient defciency Background up to 50–56% in 2100 AD, and 78% of dry land expan- Progress in scientifc knowledge and technological inno- sion is expected to occur in developing countries [2–4]. vations have led mankind into yet another stage of mod- According to the report of World Bank, hunger is a chal- ern civilization. Application of novel research strategies lenge for 815 million people worldwide [5]. Te spate of into fundamental and translational research has brought farmer’s suicides in an agriculture-based country like an all-round development. In agriculture, strategized India has reached to an average of 52 deaths/day, and technological innovations, viz. development and selec- reports of farmers selling their blood to earn a livelihood tion of high yielding variety, use of synthetic fertilizers in drought-hit region of the country depict the severity of and pesticides, mechanization and irrigation facilities, the agrarian crisis [6]. have resulted in sufcient availability of food. Estimated Sustainable crop substitutes are needed to meet the global cereal production was 2605 million tons in 2016 world hunger (cereal demand) and to improve income of and was forecasted to be 2597 million tons in 2017 [1]. farmers. Role of millets cannot be ignored for achieving Several short-sighted measures have enhanced pro- sustainable means for nutritional security (Fig. 1). Inter- ductivity but have undermined sustainability and are national crops research institute for the semi-arid tropics eroding the very capacity of resource base leading to (ICRISAT) is focusing on increasing the productivity of nutrient defcient saline soil and lowering water beds. millets and has included fnger millet (Eleucine corcana) In addition, changing climatic conditions have further as sixth mandatory crop [3, 4]. Millets abode vital nutri- hastened the vulnerability of farmers towards declining ents and the protein content of millets grains are con- crop production. Dry lands constitute 40% of the global sidered to be equal or superior in comparison to wheat land surface and are home for about 1/3rd of the global (Triticum aestivum), rice (Oryza sativa), maize (Zea population. Tese low fertile soils are predicted to elevate mays) and sorghum (Sorghum bicolor) grains [7]. Te role of millets in designing the modern foods like multigrain and gluten-free cereal products is well known [8]. Due to *Correspondence: [email protected] the richness of millets in polyphenols and other biologi- 1 Food Science and Technology, Punjab Agricultural University, Ludhiana, cal active compounds, they are also considered to impart Punjab 141004, India Full list of author information is available at the end of the article role in lowering rate of fat absorption, slow release of © The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Kumar et al. Agric & Food Secur (2018) 7:31 Page 2 of 15 Fig. 1 Benefts of millets in a nutshell sugars (low glycaemic index) and thus reducing risk of 8.0 [12]. Millets can be a good alternative to wheat espe- heart disease, diabetes and high blood pressure. Due to cially on acidic soils. Rice is very sensitive to saline soils increased awareness regarding the health promoting and has poor growth and yield on a soil having salinity profle of millets, inclination towards their consumption higher than 3dS/m [13]. On the other hand, millets like has been observed. Present review envisages the agrarian pearl millet (Pennisetum glaucum) and fnger millet can requirements, nutritional information and health ben- grow up to a soil salinity of 11–12 dS/m. Millets have a efts imparted by these grains. Review also explores the low water requirement both in terms of the growing millet-based products made traditionally along with the period and overall water requirement during growth. latest researches conducted worldwide. Te rainfall requirement of certain millets like pearl mil- let and proso millet (Panicum miliaceum) is as low as Agrarian importance of millets 20 cm, which is several folds lower than the rice, which Te demand of food will increase proportionately with requires an average rainfall of 120–140 cm [13]. Most growth in world population. At present about 50% of of the millets mature in 60–90 days after sowing which world’s total calorie intake is derived directly from cere- makes them a water saving crop. Barnyard millet (Echi- als [9]. Rice, wheat and maize have emerged as the major nochloa frumentacea) has the least maturation time of staple cereals with a lesser extent of sorghum and mil- 45–70 days among millets, which is half to the rice mat- lets. Sharma [10] reported that an increase in the areas uration (120–140 days) time [14]. Millets fall under the of crops with intense water requirements like rice, sug- group of C4 cereals. C4 cereals take more carbon diox- arcane (Saccharum ofcinarum) and cotton (Gossypium) ide from the atmosphere and convert it to oxygen, have has resulted in the increase in 0.009% in the distance high efciency of water use, require low input and hence between the ground level and ground water table and are more environment friendly. Tus, millets can help to this loss is approximately equivalent to a loss of 7191 L phase out climatic uncertainties, reducing atmospheric of ground water per hectare. Tere is a lesser possibil- carbon dioxide, and can contribute in mitigating the cli- ity of increasing the production of major staple cereals mate change. Te major millets and their growing con- as the world is already facing the challenges of increase ditions in comparison to the staple cereals, i.e. rice and in dry lands and deepening of ground water level [3, 10]. wheat, are tabulated in Table 1. According to the report of the National Rainfed Area Scientifc interventions in terms of the use of molecular Authority (NRAA) even after realizing the full irrigation biomarkers, sequence information, creation of mapping potential, about half of the net sown area will continue to populations and mutant have led to the development and remain rainfed [11]. Tis alarms the need of shifting to release of high yielding varieties of millets throughout the alternative of current cereal staples. the world [22, 29]. Newly developed hybrids are resistant Millets cultivation can be a solution to this problem to diseases and has increased per hectare production as as these can grow on shallow, low fertile soils with a pH compared to their parent varieties [29, 30]. Millets have of soil ranging from acidic 4.5 to basic soils with pH of abundant natural diversity, and the release of new hybrids Kumar Kumar et al. Agric & Food Secur (2018)7:31 &Food Agric et al. Table 1 Optimum agrarian conditions for major cereals and millets Crop Scientifc name Optimum soil Height range Temperature pH Soil salinity Rainfall required Maturity time References type (dS/m) (days) Rice Oryza sativa Heavy to sandy Sea level up to 21–37 °C 6.5 to 8.5 Less than 3.0 dS/m Range 100–300 cm 100–160 [13] loam 2500 m Average 120–140 cm Wheat Triticum aestivum L. Light clay or heavy Sea level to 2500 m Range 1.3–35 °C 6.0 to 7.0 6.0 dS/m Range 30–100 cm 90–125 [15, 16] loam Average 15.5 °C Sorghum Sorghum bicolor Clay loamy soils to Sea level to 3000 m Range 7–30 °C 5.0–8.0 4–6 dS/m 40–100 cm 90–120 [17, 18] shallow soils Average 26–30 °C Pearl Millet Pennisetum glacum Loamy soils, shal- Sea level to 2700 m 30–34 °C 6.0–7.0 11–12 dS/m 20–60 cm 60–70 [19] low soils, soils *can grow up to *can grow up to *yields are eco- with clay, clay 46 °C 8.0 pH nomically well loam and sandy up to ECe 8dS/m loam texture Finger millet Eleusine coracana Rich loam to poor Sea level to 2300 m 26–29 °C 4.5 to 7.5 11–12 dS/m 50–60 cm 90–120 [20] upland shallow *lower productivity soils below 20 °C Proso millet Panicum miliaceum Sandy loam, 1200–3500 m 20–30 °C 5.5 to 6.5 – 20–50 cm 60–90 [21] slightly acidic, above sea level saline, low fertil- ity soils Foxtail Millet Setaria italica L.