New strategies to address world food security and elimination of malnutrition: future role of coarse cereals in human health

As we face increasing challenges of world food security and malnutrition, coarse cereals are coming into favor as an important supplement to human staple foods due to their high nutritional value. In addition, their functional components, such as flavonoids and polyphenols, make them an important food source for healthy diets. However, we lack a systematic understanding of the importance of coarse cereals for world food security and nutritional goals. This review summarizes the worldwide cultivation and distribution of coarse cereals, indicating that the global area for coarse cereal cultivation is steadily increasing. This paper also focuses on the special adaptive mechanisms of coarse cereals to drought and discusses the strategies to improve coarse cereal crop yields from the perspective of agricultural production systems. The future possibilities, challenges, and opportunities for coarse cereal production are summarized in the face of food security challenges, and new ideas for world coarse cereal production are suggested.


Introduction
Coarse cereals are mainly grain and legume crops other than Rice (Oryza sativa L.), Maize (Zea mays L.), Potato(Solanum tuberosum L.), Wheat(Triticum aestivum L.), and Soybean (Glycine max (L.) Merr.), such as Buckwheat(Fagopyrum esculentum), quinoa(Chenopodium quinoa Willd.),Oats(Avena sativa L.), Peas(Pisum sativum L.), Mung beans(Vigna radiata (L.) R. Wilczek), Sorghum(Sorghum bicolor (L.) Moench), Barley(Hordeum vulgare L.) and Lentils(Lens culinaris Medik.), among others.These crops are mainly grown in semi-arid areas, and most of the time they can only rely on rain-fed agricultural systems, with almost no external input (Rai et al., 2008).Most of these grains contain unique nutritional and functionally active ingredients that make a significant therapeutic contribution to human immunity and the treatment of various chronic diseases, such as weight management, diabetes prevention, Cancer prevention, Cardiovascular diseases (CVD), etc (Kaur et al., 2014).Their secondary metabolites or phytochemicals have antioxidant properties and are rich in highquality protein, dietary fiber, vitamins and various minerals (especially micronutrients) (Bouis, 2000).More importantly, some compounds are helpful to fight ischemic stroke, cardiovascular disease, cancer, obesity and type II diabetes (Jones et al., 2000;Jones, 2006).With the increasing awareness of health care, more attention is being paid to coarse cereals, with promising development of the coarse cereal industry (Fu et al., 2020).
Globally, the support of environment, society and economy cannot be separated from the food system (Metabolic, 2017).In particular, the current global epidemic situation is still severe, and coupled with unstable global geopolitical risks, global food security faces serious challenges.Coarse cereals generally have short growth cycles and are important and, in fact, irreplaceable in restructuring the cropping industry (Rai et al., 2008).Coarse cereals are also important for improving dietary structure and promoting nutritional health.As such, We can consider it they play an important role in eradicating hunger, ensuring food security, and improving the accessibility and affordability of healthy diets.Therefore, strengthening the production of coarse cereals is one of the most important strategies for ensuring world food security.
In the field of commercial food, the public acceptance of coarse cereals and related research and development and investment have been ignored.People are paying more and more attention to food security and nutrition.In addition, the current population growth needs more grain output as a stable backing.The development prospects of these miscellaneous grains will be better and better in rural or urban markets, poor or rich markets.Coarse cereal plants are very resistant and adaptable, especially in the face of drought, making their production and output more stable under today's complex and changing natural conditions.In recent years, many countries have gradually adjusted their planting strategies with a consideration of these plants' strong resistance to drought conditions, leading to a significant increase in harvesting area of coarse cereals.However, extreme climatic conditions are posing new challenges to the production of coarse cereals worldwide.To date, research on coarse cereals has rarely been reported and we lack an in-depth understanding and strategies related to the improvement of cultivation conditions and management.This paper therefore describes the importance of coarse cereals for world food security, summarizes systematic strategies to increase their production by analyzing the current status of their production management, and further lays out future challenges, possibilities and opportunities for coarse cereal production, while providing new ideas for coarse cereal production worldwide.
2 The importance of coarse cereals in world food security and human health

Coarse cereals as an important addition to world food security
The 2022 Global Food Crisis Report, released by the Food and Agriculture Organization of the United Nations (FAO), indicated that the global food shortage in 2021 will have affected about 193 million people, involving a total of 53 countries or regions.In recent years, the global incidence of moderate to severe food insecurity has been on the rise (Figure 1) (FAO et al., 2022).From 2014 to 2020, the incidence of moderate food insecurity increased by 4.2%, and that of severe food insecurity by 3.6%.Since coarse cereals do not compete with major food crops for land, increasing their cultivation area has become a preferred option for many countries to increase production to meet market demand.The harvested area and production of coarse cereals (Figures 2, 3D) worldwide are showing continuous increases, suggesting the potential for coarse cereals to eliminate hunger and ensure food security (Food and Agriculture Organization of the United Nations (FAO), 2022).

Steady increase in the harvested area of coarse cereals
According to FAO, the global harvested area of coarse cereals was mainly distributed in semiarid and arid regions, showing a clear upward trend over 10 years (Figure 2).For example, from 2011 to 2020, a tremendous increase in the total harvested area of coarse cereals was noted in Oceania (+22.25%),followed by the Americas (+8.43%) and Africa (+6.95%).At the same time, in Europe, the total harvested area decreased by 4.16%.
The cultivation of different coarse cereals in different regions depends on the cultivation habits and climatic conditions.Therefore, the total harvest area of different coarse cereals in each country also varies greatly (Figure 4) (Food and Agriculture Organization of the United Nations (FAO), 2022).In 2020, many coarse cereals were grown in Russia, with the largest harvested area, including barley, buckwheat, and oats.These coarse cereals were also widely distributed in other countries.For instance, barley was distributed in Australia, Incidence of food insecurity (%).

Steady increase in total production and trade of coarse cereals
The total world import and export value of coarse cereals increased from 11,244 to 34,487 billion US dollars from 2000 to 2020 (Figure 3A).The total world import and export volume of coarse cereals increased from 79.66 to 121.73 million tons (Figure 3B), an increase of 52.81%.Among the coarse cereals, barley, with a proportion of 58.19%, occupies an absolute dominant position in the import and export trade volume, while the trade volumes of quinoa and buckwheat are lowest, with a proportion of no more than 0.5%.
According to FAO (Food and Agriculture Organization of the United Nations (FAO), 2022), the share of total world coarse grain production in 2020 varied considerably between continents (Figure 3C); Europe and Asia were the main sources of coarse cereals, accounting for  32.05% and 29.32% of the world's total production, respectively.Next, Africa and the Americas accounted for 18.08% and 16.99%, respectively, and Oceania accounted for the lowest proportion at 8.95%.From 2011 to 2020, the trend for the total global production of coarse cereals by continent followed a pronounced increase in Africa, the Americas, Asia, and Europe, while that in Oceania tended to remain the same (Figure 3D).The increased production in Africa, the Americas, and Asia was due to an increase in planted and harvested areas.In contrast, there was an increase in total production in Europe despite a decrease in harvested area, suggesting that the coarse cereal yield in the region increased, perhaps due to optimization of planting structures.Surprisingly, there was an increase in harvested area in Oceania; the fact that its total production remained the same might be due to the frequent occurrence of catastrophic climate events and changes in agricultural policies in Oceania in recent years.
Overall, the total global production and consumption of coarse cereals have gradually increased in recent years.The enhanced global yields of coarse cereals indicate increased investment in agricultural science and technology for these cereals.The closer attention paid to coarse cereals worldwide has promoted world trade and indicates that the international status of these crops has gradually risen with economic development.
2.2 Coarse cereals are important choices for human food security and a healthy diet

Rich nutritional and functional components of coarse cereals
Unlike major food crops, coarse cereals are rich in nutritional components such as dietary fiber, amino acids, flavonoids, and phytosterols, functional components including polyphenols, glycols, anthraquinones, and alkaloids, and high-quality proteins, fats, and carbohydrates (Fu et al., 2020).The nutritional and functional components of different coarse cereals vary significantly, and are summarized in Table 1 for barley, buckwheat, quinoa, oats, lentils, mung beans, sorghum, and peas, with more than 80 nutrients.Some of the functional components are very scarce, for example, chiral inositol, a sugar alcohol that is found only in buckwheat and mung beans (Hao et al., 2021).These nutritional functional components basically exist in all parts of the plants.In summary, the nutritional and functional components of coarse cereals are rich and diverse, providing more options for product processing and healthy dietary therapy.

The important role of functional components in coarse cereals
Studies show that all coarse cereals contain functionally active ingredients that improve immunity and can be used to treat chronic diseases.Hostetler et al. (2017) summarized the polyphenolic components (flavonoids and phenolic acids) that are enriched in coarse cereals, which exhibit antioxidant properties by scavenging or reducing free radicals in the body.Polyphenolic components also have hypoglycemic, lipid-lowering and anticancer effects (Anantharaju et al., 2016).Anthraquinones, present in coarse cereals, are commonly used in laxatives because of their strong activity (Malik and Muller, 2016).Zou et al. (2021) concluded that buckwheat is a medicinal food crop, and its functional components are effective at reducing the incidence of tumors, atherosclerotic cardiovascular diseases, hypertension, and diabetes.b-Glucan, which is highly enriched in oats, can improve immune function by enhancing metabolism and modulating immune cell responses (Ji et al., 2003).Vitamin E, which is rich in barley, prevents aging, protects the skin, and is also effective at promoting blood circulation (Do et al., 2015).Table 2 shows all the compounds found only in coarse cereals and their importance to health.

The relationship between coarse cereals and a healthy diet
According to United Nations International Children's Emergency Fund (FAO et al., 2022), the challenges to achieving the 2030 global nutrition goals remain enormous; in 2020, an estimated 149 million (22%) children (under 5 years of age) worldwide exhibited stunted growth and 45.4 million (6.7%) children under 5 showed signs of wasting.At the same time, the global cost of healthy diets has increased significantly, and therefore their affordability has decreased.In 2020, the population who were not able to afford healthy diets was approximately 3.1 billion, 112 million more than in 2019.In addition, surveys by FAO (FAO et al., 2022) suggest that the economic impact of COVID-19 and the measures taken to contain it have led to higher consumer costs for food.However, the reality may be even bleaker, because the impact of the COVID-19 outbreak on human nutritional indicators is still under observation.
In conclusion, coarse cereals have become one of the major food sources for human health due to their dual roles as functional foods and healthy dietary supplements.The United States Food and Drug Administration (FDA) recommends a daily intake of more than 3 g of b-glucan soluble fiber, which can reduce cholesterol by 23%, and cereals containing b-glucan are classified as functional foods (Bernstein et al., 2013;Maheshwari et al., 2019).With the increasing awareness of coarse cereals and their nutritional and functional benefits, more research on coarse grains and their application to dietary guidelines are expected.

Response mechanisms in coarse cereals for drought adaptation
Arid and semiarid areas account for about 35% of the world's land mass, with a yearly increasing tendency.The reduction in crop   (Menga et al., 2014;Saberi et al., 2018;Salacheep et al., 2020;Castaldo et al., 2022) yield caused by drought exceeds the total yield reduction caused by other environmental factors (Xiang et al., 2020).Approximately 25% of global agricultural land is affected by drought (Hidri et al., 2016), making it one of the major abiotic factors limiting crop production.
Coarse cereals have a range of morphological and physiological responses to different environments.The long-term cultivation of coarse cereals could promote their adaption to drought conditions by regulating their morphological and physiological responses to drought (Sayed et al., 2012;Nxele et al., 2017;Lin and Chao, 2021).

Distribution of coarse cereals in relation to climate
By simultaneously observing the global distribution and production of coarse cereals (Figures 4, 3) and global changes in precipitation and temperature by country or region (Figures 5, 6), we found that the harvested area, temperature changes, and total coarse cereal production show a simultaneous increase, while the change in monthly average surface precipitation presents an opposite trend.These trends illustrate that countries or regions with water scarcity and aridity have larger harvested areas of coarse cereals.In contrast, countries or regions with high rainfall have relatively lower harvested areas and total production of coarse cereals.This may be because the low precipitation conditions are unsuitable for other major food crops, whereas coarse cereals adapt well to water deficiency, can be grown in more areas and produce better yields, making them a better choice for arid or semiarid regions (Killi and Haworth, 2017).The global average monthly surface precipitation (From January 2011 to December 2020).Unit: mm.

Morphological and physiological response mechanisms for drought adaptation in coarse cereals
The required mechanisms to cope with drought in mixed crops are complex and synergistic.The crop responds to water deficit by reducing respiration, increasing the activity of its own antioxidant enzymes and non-enzymatic antioxidant content, and increasing the content of osmoregulatory substances to improve cell water retention.

Growth period and morphological adaptations
We found that most coarse cereals can enhance their adaptability to the environment by altering their growth period or morphology.Table 3 summarizes the fertility period of different coarse cereals.The average fertility period of coarse cereals is around 58-62 days shorter than that of the major food crops.At the same time, coarse cereals adapt to the environment through certain morphological changes under drought conditions.Sallam et al. ( 2019) found that barley reduces plant height and leaf number under the condition of water shortage, as compared to controls, and the thickness of the leaf tissue and diameter of the vascular bundle in flag leaves are correspondingly reduced to adapt to the drought conditions.Lentils adapt to drought conditions by leaf drying, leaf curling and slowed growth rate, thereby reducing water and nutrient consumption (Akter et al., 2021).Buckwheat flowers and sets early under drought conditions, with rapid leaf decline and a shortened reproductive period (Hou et al., 2019).

Physiological response
As shown in Figure 7, water deficiency causes leaf curling and wilting, and photosynthesis inhibition, resulting in reduced crop growth.In addition, coarse cereals develop rapid physiological responses or specific adaptive mechanisms under drought conditions, making them more drought-tolerant or drought-resistant.For instance, drought limits the operation and metabolism of photosynthesis in quinoa, but the plant still retains some of its photosynthetic capacity to maintain its growth and development; thus, it is strongly drought-tolerant (Killi and Haworth, 2017).Moreover, its photosystem II is better adapted to drought and has a relatively more efficient photosynthetic capacity during the nutritional phase compared to other growth stages (Fghire et al., 2015).Under drought conditions, coarse cereals Global temperature change in 2020.Unit: °. such as buckwheat can accumulate more proline to cope with the adverse effects of water shortage (Yao et al., 2017).Certainly, the rapid response and changes in hormone levels are also important regulatory means, and the rapid increase in abscisic acid content in barley leaves under water deficit inhibits leaf transpiration and water transport in the root system; thus, early maturation of barley is induced without altering grain composition-proper grain development is ensured and maintained (Staroske et al., 2016).In vivo, 1-aminocyclopropane-1-carboxylate deaminase (ACC deaminase) mitigates the negative effects of water deficiency by reducing ethylene levels and increasing relative water content of lentils (Zafar-ul- Hye et al., 2021).Similarly, mung beans respond rapidly to drought at the hormonal level, exhibiting promoted growth via inhibition of ethylene synthesis (Sarapat et al., 2020).
Osmolytes are low-molecular-weight organic compounds or compatible highly soluble solutes, including amino acids, sugars, sugar alcohols, and quaternary ammonium compounds (Bilal et al., 2019).In addition to hormonal alterations, when confronted with a water-deficient environment, coarse cereals can quickly adapt to the conditions and satisfy their growth needs by completing osmoregulation of osmolytes at the cellular level.Under drought conditions, coarse cereals tend to increase the concentration of osmolytes, such as proline, inositol, alginates, and betaine, in order to reduce cellular osmotic pressure and maintain cellular water retention (Khan et al., 2015).
At present, some drought-induced TFs have been identified (FtMYB9,FtMYB10,FtMYB13,from FtNAC2 to FtNAC9,FtbZIP5 and FtbZIP83,FtbHLH3), But it mainly focuses on the changes of gene regulation of tartary buckwheat under drought (Gao et al., 2016;Gao et al., 2017;Huang et al., 2017;Yao et al., 2017;Deng et al., 2019;Li et al., 2019;Sun et al., 2019).Many studies have shown that the gene encoding LEA protein is induced to maintain the stability of membrane and protein, and can alleviate cell damage under water shortage conditions (Shinozaki and Yamaguchi-Shinozaki, 2007;Roychoudhury et al., 2013;Shi et al., 2020).The continuing conundrum of the LEA proteins.Naturwissenschaften 94:791-812.Huang et al. conducted the transcriptome analysis of tartary buckwheat under drought stress for the first time, and confirmed that LEA protein participated in the response of tartary buckwheat to drought stress (Huang et al., 2021).Development and flowering time of barley were correlated with a differential down-regulation of the flowering promoters s flowering locus T1 and the Barley mads-box genes BM3 and BM8.The researchers also found that that PPD-H1 Affects developmental plasticity in response to distress in Barley (Gol et al., 2021).Researchers discovered gene-LOC110713661 and gene-LOC110738152 May be the key genes for troubleshooting tolerance in quinoa through transcript ome and metablome association analysis (Huan et al., 2022).The expression levels of CqCIPK11, CqCIPK15, CqCIPK37 and CqCBL13 increased significantly under drought stress (Zhu et al., 2022).On the other hand, the up regulated of PP2C, ABF, SNR K2, GID1, Jaz, and MyC2 genes may enhance the fault tolerance of oat (Gong et al., 2022).It is confirmed by experiments that drought will cause high expression of VrNAC13, so researchers speculate that this gene can regulate the stress resistance of mung beans (Zhang et al., 2023).SbNAC9 improves drought tolerance by enhancing scavenging ability of reactive oxygen species and activating stress-responsive genes of sorghum (Zheng et al., 2023).

Synergistic effects of drought and specific functional components of coarse cereals
The regulation of secondary metabolites has also been found to be associated with drought (Hassan and Basahi, 2014).Drought can promote the formation of secondary metabolites in coarse cereals, which in turn might be involved in regulating the coarse cereals' own defense against unfavorable external environmental Main ways of drought stress inhibiting crop growth.
conditions, allowing for the maintenance of normal growth and development.In the process of long-term adaptation to adversity, coarse cereals have formed a synergistic relationship between adverse conditions and qualitative changes: usually, plants increase the biosynthesis of functionally active components, such as phenolic compounds, flavonoids, and anthocyanins, when exposed to drought conditions (Zahedi et al., 2021).It was found that secondary metabolites in barley may act as antioxidants, regulators of gene expression, and regulators of protein function during conditions of water deficit (Piasecka et al., 2017).Researchers have also found that drought significantly increases the total flavonoid content in sorghum (Kamali and Mehraban, 2020).Total flavonoid and rutin contents in buckwheat are also significantly increased under drought conditions (Meng et al., 2022).Flavonoids are secondary metabolites with high antioxidant activity; they scavenge reactive oxygen radicals, which in turn attenuates the damage caused by reactive oxygen radicals in buckwheat (Olmo et al., 2014).Unfortunately, the relationship between the production of many secondary metabolites and drought or other adverse conditions is still unknown.More research is needed to determine the roles and feedback mechanisms of secondary metabolites in the drought response.

Management strategies for enhancing coarse cereal yields
In view of the described characteristics of coarse cereals, this paper summarizes management strategies aimed at increasing the yield of coarse cereals in dry areas (Figure 8).Based on the high yield and high efficiency of these cereals, we suggest that the following five aspects be taken into consideration.

Optimal seed breeding and application
Seeds are the core of agriculture and play an important role in the harvest of high-quality, high-yielding coarse cereals (Xiang et al., 2016;Xiang et al., 2019a).In arid and semiarid regions, there is an urgent need to select and breed drought-tolerant crop varieties and lines that can produce high yields (Seleiman et al., 2021).Therefore, germplasm resources with different characteristics must be collected and mined for superior genes.The following traits have been suggested as key indicators of drought-tolerant crops: short growth cycle (Mwamahonje et al., 2021), high root density (Kothari et al., 2020), high osmoregulatory activity in roots (Haling et al., 2013), high stomatal conductance (Leybourne et al., 2022), high leaf relative water content (RWC) (Yamamoto et al., 2000), optimal water utilization (Guenther et al., 2003), and high plasticity (Gano et al., 2021).

Proper management practices in field cultivation
One important approach to enhancing drought resistance in coarse cereals is to optimize the sowing time, planting density, and field management for the climatic and environmental conditions (Table 4).Proper crop rotation, intercropping, and cover cropping can effectively increase the content of soil organic matter (Turmel et al., 2011), improve soil physicochemical properties (Lehman FIGURE 8 Management strategy for increasing production of coarse cereals in arid areas.AMF, arbuscular mycorrhizal fungi.Zou et al. 10.3389/fpls.2023.1301445Frontiers in Plant Science frontiersin.orget al., 2012), and increase soil fertility (Salehi et al., 2018), by making full use of space and other resources (Araya et al., 2021).These measures can improve light-transmission conditions, increasing the efficiency of light-energy utilization in coarse cereals (Flower et al., 2012;Xiang et al., 2019b) and contributing to increased yield.Conservation tillage, which prevents soil erosion and landquality degradation (Roohi et al., 2022) is important for the construction of sustainable agricultural production systems for coarse cereals.One conservation tillage method consists of applying soil amendments, including compost (Hinojosa et al., 2018), chitosan (Hafez et al., 2020), and vermicompost (Benaffari et al., 2022), which play important roles in promoting the growth of coarse cereals and their resistance to drought.Other soil amendments, such as biochar, can improve the soil's waterholding capacity and reduce ion and infiltration toxicity (Thomas et al., 2013).Enzyme activities in the improved soil and soil wateruse efficiency will also increase (Atkinson et al., 2010;Wang et al., 2014).It has also been suggested that biochar combined with alternate root-zone drying irrigation may be a sensible way to maintain crop productivity in arid and semiarid regions of the world, thereby ensuring food security (Yang et al., 2020).
Chemical regulation is a rapid and easy growth-regulating measure in the production of coarse cereals; it is an indispensable tool for improving morpho-physiological processes in these cereals.Application of exogenous melatonin enhances antioxidant enzyme activity, reduces oxidative damage, and improves photosynthetic capacity and drought tolerance in buckwheat (Hossain et al., 2020) and oats (Gao et al., 2018).Foliar application of polyamides on mung bean improved yield by reducing the damage caused by water deficiency (Babarashi et al., 2021).In addition, exogenous application of polyamines on mung bean also increased the photosynthetic rate and induced the accumulation of osmoprotectants, improving its tolerance to water deficits (Sadeghipour, 2019).Foliar sprays of jasmonic acid on quinoa were found to increase yield by 16% compared to controls under water-deficit conditions (Keshtkar et al., 2022).Canales et al. (2019) found that salicylic acid can interact with polyamines in a complex way to build a signaling network that mitigates the adverse effects of water deficiency on oats (Gong et al., 2022).In addition to these chemicals, exogenous supplementation of glutathione during droughts can significantly enhance antioxidant components, which in turn reduce oxidative damage, indicating its significant role in improving drought resistance (Nahar et al., 2015).

Water-saving production systems
Water-saving production systems are an important strategy for coarse cereals, and for future development directions toward increasing their yields in dry areas.On the one hand, these systems can greatly improve the efficiency of limited water resource utilization, and on the other, they can facilitate the realization of increased yield of coarse cereals in dry zones.Unfortunately, irrigation water-saving systems are currently lacking in dryland cultivation of coarse cereals (Levidow et al., 2014).Therefore, the task of exploring reasonable engineering measures for drought resistance in coarse cereals is daunting.According to Du et al. (2015), a fully integrated system of sustainable water allocation is required, and deficit irrigation can be used rather than improved agricultural water allocation.Deficit irrigation plays a tremendous role in controlling the water use of crops at different stages of cultivation and in actively regulating plant growth, productivity, and development according to the crop's physiological response.

Conclusion and perspectives
Based on the complicated and changeable situation in the world today, this review draws up a systematic solution for coarse cereals (Figure 9).The total global production, harvested area, and total import and export trade of coarse cereals have been on the rise in the past 10 years, demonstrating the gradually improving status of coarse cereals in world food security.Coarse cereals contain special functional components, such as flavonoids, linoleic acid, phenolic acid, and bglucan.More importantly, due to their unique nature, different coarse cereal processing methods may affect or destroy these inherent functional components.In addition to the need to consider health aspects and delicious taste during processing, special processing processes or techniques, especially those that will retain functionally active ingredients, for example, should be the focus of future research.This will lead to a deeper consideration and utilization of coarse cereals to serve for human food security and healthy diets.
In this study, we recognize the advantages and development potential of coarse cereals in the face of today's frequent extreme Systemic solution of coarse cereals based on.First, policy support for crude processing of coarse cereals should be increased, followed by more publicity to expand market demand, as well as systematic cultivation management and selection and breeding of good varieties, without forgetting financial subsidies for farmers.Following these steps will result in a steady increase in planting area and production, and improved quality of agricultural products.The resultant wide variety of coarse cereals will increase consumers' choices for a healthy diet.In addition, the low price of coarse cereals can facilitate access to healthy diets for vulnerable groups.
climate change (drought), but development of the coarse cereals industry still faces the problem of low and unstable resources.There is still a large gap in production compared to staple grains.Therefore, research on the production of coarse cereals is also imperative.Excellent germplasm resources are key to improving the yield and quality of mixed grains, and science-and technology-led efforts should be strengthened to cultivate more excellent germplasm resources.Considering the above, and analyzing the relationship between "environment-hybridization measures," variety characteristics and regional characteristics, we can adjust and develop integratedmanagement strategies for hybrid agricultural production, and enhance the ability of these production systems to increase production, improve the sustainability of these systems, and increase the overall benefits of hybrid cultivation.For example, the more specific functional components (e.g., flavonoids), which are readily produced in coarse cereals in response to drought, can be considered rapid feedback indicators of adverse conditions; their formation has a synergistic relationship with the adverse environment as well as a defensive role under such an environment.Unfortunately, the synergistic relationship and the mechanisms of action are both unclear.Therefore, it is important to clarify these mechanisms for the construction of stressresistant cultivation or high-quality cultivation management of coarse cereals, which may be an important way to enhance stress-resistance and quality of coarse cereals in the future.
Taken together, the miscellaneous grains industry has great potential for development, but also faces many challenges, such as a lack of in-depth research and inefficient agricultural production systems (Figure 10).The former is needed for proper government guidance and the formulation of relevant policies, and the latter to help develop miscellaneous grains for the market, including production, processing, marketing, economic inputs, and industry chain extension.Development and strengthening of the miscellaneous grains industry will enable these grains to play a more important role in providing healthy human diets and world food security, among others.

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FIGURE 3World total import and export value of coarse cereals (billion US dollars) (A), World total imports and exports of coarse cereals (million tons) (B), The proportion of total coarse cereal output on all continents in 2020 (C), Total coarse cereal output on all continents from 2011 to 2020 (D).

FIGURE 2
FIGURE 2Distribution of harvested area of coarse cereals in global continents.

FIGURE 4
FIGURE 4Distribution of coarse cereals in various countries in the world in 2020.Unit: million hectares.

FIGURE 9
FIGURE 9 India, Thailand, Indonesia, and other countries, with the largest area harvested in China.Peas are mainly distributed in Canada, with the largest area harvested area, Russia, China, and India.Lentils are mainly distributed in Canada (largest area), India, and Australia.The total harvested area of coarse cereals in 2020 worldwide was 51.86 million hectares for barley, 2.
Frontiers in Plant Science frontiersin.orgTurkey,Canada, Spain, and the Republic of Kazakhstan.Buckwheat was distributed in China, and oats were grown in Canada, India, Australia, Spain, Poland, Brazil, the United States, Finland, and Argentina.Quinoa is mainly distributed in Bolivia, with the largest harvested area, as well as Peru and Ecuador; and sorghum is mainly distributed in Sudan, India, Nigeria, Niger, the United States, and Burkina Faso, with the largest area harvested in Sudan.Mung beans are mainly distributed in China,

TABLE 1
Nutrition and active compounds of coarse cereals.

TABLE 2
Unique functional components in coarse cereals and their importance to health.

TABLE 3
Nutrition and active compounds of coarse cereals.
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TABLE 4
Soil environment and planting measures suitable for coarse cereals.