Quinoa is a highly nutritious and abiotic stress-tolerant crop that can be used to ensure food security for the rapidly growing world population under changing climate conditions. Various experiments, based on morphology, phenology, physiology, and yield-related attributes, are being conducted across the globe to check its adoptability under stressful environmental conditions. High weed infestation, early stand establishment, photoperiod sensitivity, loss of seed viability after harvest, and heat stress during its reproductive stage are major constraints to its cultivation.
1. Introduction
There is a high amount of pressure on food system to feed the rapidly growing world population and promote the sustainability of different resources related to agriculture and environmental protection. Intensive agriculture, especially the use of higher inputs over the last few decades, imposes a severe threat to the sustainability of agro-ecosystem
[1].
Modern breeding and biotechnology have vastly improved the production of major crops over the past few years; however, an overdependence on conventional crops has resulted in reduced crop diversity in the fields
[2]. Moreover, global warming is also threatening food security by decreasing the yield of important grain crops due to the rise in temperature
[3]. Hence, the search for alternative crops has become critical not only to improve the nutritional status of foods, but also to guard against climate change. This includes a need to introduce crops that are resilient to climate change in order to feed the world’s growing population. Over the past few years, food crops with high genetic diversity, the ability to tolerate abiotic stresses (drought, salinity, high temperature, and frost), higher profit margins, and higher nutritional profiles and values have gained attention
[4][5]. One example of a genetically diverse and highly nutritious crop is quinoa, which has gained a huge amount of attention from the world
[6]. Beyond its area of origin, it is now being cultivated in 120 countries around the world
[7]. It is a dicotyledonous, annual, and self-pollinated plant, which has been grown in the arid and Altiplano areas of South America for centuries. It has an excellent potential to be adopted in a wide range of altitudes, ranging from 0 to 4000 m, with an ability to grow and produce seeds in warm environments and in extremely cold temperatures
[8]. Quinoa is a pseudo-cereal with a high nutritional profile and a great ability to survive in saline soils
[9]. It has low water requirements as compared to traditional cereal crops (
Table 1).
There has been a remarkable increase in the cultivated area of quinoa in the last few years (2000–2019), especially in the Bolivian region, with increases from 35,690 to 64,789 ha
−1, and in Peru, with increases from 27,578 to 37,625 ha
−1. The major importers of their harvests are the United States of America (53%), Canada (15%), France (8%), Germany (4%), the Netherlands (4%), Australia (3%), and the UK (2%)
[10]. A crop like quinoa, which has a great potential to survive against stresses, is an ideal option to ensure food security, decrease pressure on conventional crops, and increase farm productivity
[11]. The quinoa plant has a great potential to minimize hunger by directly enhancing productivity under marginal environmental conditions where main conventional crops have failed to perform
[12]. It is the need of the hour to integrate quinoa into the agri-food systems for food and nutrient security because of its resilience to climate change.
2. Extraordinary Nutritional Properties
Quinoa is a rich source of nutrients, has a positive impact on health, and plays a significant role in reducing various diseases. Due to its high nutritional value, quinoa can be used as an alternative to conventional food crops (wheat, maize, and rice), and its flour can be mixed with cereal grain flours to improve the nutritional status of conventional food crops. Due to its great genetic variability, the starch content in quinoa seeds varies approximately from 52% to 74% (dm). The starch properties determine the quality of the quinoa seed. The presence of all the essential amino acids determines the quality of a protein, which directly impacts the nutritional profile of a food. Protein contents in quinoa seeds vary from 9.1 to 15.6%
[13], and it lacks gluten, which makes it ideal for gluten-allergic people. Quinoa has an excellent essential amino acid proportion, with a high percentage of lysine (5.1 to 6.4%) and methionine (0.4 to 1%)
[14]. Due to it being well-balanced and having of all the essential amino acids, quinoa grain protein is considered superior to other cereals. Its leaves can be used for human consumption but also as protein-rich animal fodder
[15].
The average oil contents of quinoa grains range from 2 to 9.5%, and mainly comprises linolenic acid (omega 3), which is helpful against cardiovascular diseases. It also enhances insulin sensitivity. The concentration of oleic acid (omega 9) and linolenic acid in quinoa are 27.7% and 38.9%, respectively. There is a region-to-region variability in the lipid content of quinoa. The Andean-region genotypes contain more lipid contents, primarily linolenic acid (4.8%) (omega 3) and linoleic acid 50.2% (omega 6)
[16]. A considerable amount of micronutrients, especially iron, copper, calcium, magnesium and zinc, are present in quinoa seed
[17]. Quinoa seed also contains a relatively higher amount of vitamin E, B2, and carotene than conventional cereals
[18].
Table 1. Nutritional profile, global production, genome description, and abiotic stress tolerance of quinoa in comparison to the main cereals.
|
Quinoa |
Wheat |
Maize |
Rice |
Publication |
Nutritional profile |
Crude protein (% dry weight) |
12–20 |
12 |
8.7 |
7.3 |
[19][20][21][22] |
Total fat (% dry weight) |
5 |
1.6 |
3.9 |
0.4 |
Fiber (% dry weight) |
5–10 |
2.7 |
1.7 |
0.4 |
Total Carbohydrates (% dry weight) |
59.7 |
70 |
70.9 |
80.4 |
Gluten presence |
Gluten free |
12–14% |
Gluten free |
Gluten free |
Glycemic index |
53 |
43 |
66 |
56 |
Minerals (mg/100 g dry weight) |
Magnesium |
249.6 |
169.4 |
137.1 |
73.5 |
[23][24] |
Calcium |
148.7 |
50.3 |
17.1 |
6.9 |
Iron |
13.2 |
3.8 |
2.1 |
0.7 |
Potassium |
926.7 |
578.3 |
377.1 |
118.3 |
Phosphorus |
383.7 |
467.7 |
292.6 |
137.8 |
Vitamins |
Niacin |
0.5–0.7 |
5.5 |
1.8 |
1.9 |
[25] |
Thiamine |
0.2–0.4 |
0.45–0.49 |
0.42 |
0.06 |
Folic Acid |
0.08 |
0.08 |
0.03 |
0.02 |
Riboflavin |
0.2–0.3 |
0.17 |
0.1 |
0.06 |
Global production perspective |
Global market price (USD Tons−1) |
3580 |
205.76 |
143.91 |
376.00 |
[26][27][28] |
Grain yield (tons ha−1) |
0.76 |
3.49 |
5.87 |
4.76 |
Global production (million tons) |
147 |
770 |
1210 |
787 |
Global cultivated area (million ha) |
0.191 |
220.75 |
205.87 |
165.25 |
Genome organization |
Ploidy level |
Allotetraploid |
Tetraploid |
Diploid |
Diploid |
[29][30] |
Genome size |
1.5 Gb |
~17 Gb |
2.4 Gb |
2.4 Gb |
Chromosome no. |
36 |
42 |
20 |
24 |
Genes annotated |
62,512 |
3685 |
330 |
56,284 |
Abiotic stress tolerance |
Salinity stress |
150–750 mM NaCl |
125 mM NaCl |
ModeratelySensitive to salt stress |
4–8 dSm−1 |
[31][32][33][34][35][36][37][38][39] |
Heat stress |
35 °C |
32 °C |
36 °C |
40–45 °C |
Drought stress (water requirement) |
300–400 mm |
325–450 mm |
500–800 mm |
450–700 mm |
3. Resistance to Adverse Environmental Conditions
Almost 50% of agricultural productivity is lost due to a wide range of abiotic stresses, i.e., salinity, drought, heavy metals, waterlogging, frost, excess heat, and UV-B. Most of these stressors usually occur in combination
[40]. Quinoa, as it is drought-tolerant, has excellent potential for adaptation to the extreme arid conditions of Northern Chile and Argentina, Peru, and Bolivia
[41]. Its cultivation has been expanded to the arid and semi-arid regions of Asia, the Mediterranean, North Africa, and the Near East
[42]. The mechanisms that quinoa usually adopts against drought stress are classified into three categories. The physiological strategies include plasma membrane stabilization, stomatal conductance, antioxidant defense, plant growth regulation, and osmotic adjustment. The avoidance mechanisms include deep root systems and molecular approaches. Anthesis and milking are the two most drought-sensitive stages for quinoa
[43]. Osmolyte accumulation, the synthesis of ROS, the accumulation of soluble sugars and proline are other mechanisms in quinoa that are involved in the adjustment of cell osmotic potential. These mechanisms enable the quinoa plant to survive and produce seeds under drought conditions
[44].
Salt stress is another obstacle to sustainable crop production. Plants grown in saline soils show impaired growth due to a salt-induced osmotic effect, nutrient imbalance, specific ionic effect, oxidative damage due to higher levels of reactive oxidative species (ROS), and an alteration in the endogenous level of hormones
[45]. Quinoa has a great potential to grow under adverse climatic and edaphic conditions
[46]. Some specific quinoa accessions perform well even under sea water
[47][48]. It is also a well-known facultative halophyte, due to its ability to maintain osmotic potential in its lower leaves. Because salt water is not a physical requirement for growth, it can perform well under canal water
[49]. Quinoa crops have the potential to play a remarkable role in maximizing productivity and farmers’ incomes in the arid regions of the world due to its potential defenses against adverse environmental conditions
[50]. Under saline conditions, the quinoa plant produces companion solutes, e.g., soluble sugar, prolines, and glycinebetaine
[51], and increased antioxidants and K/Na
[52]. Glycinebetaine is a betaine derivative, a major osmolyte in quinoa which makes it capable of tolerating adverse ecological stress situations
[53].
Frost is considered one of the main obstacles limiting agricultural productivity, especially in the high Andean regions. Quinoa is less affected by frost than all the other crops grown in this region due to its ability to tolerate frost using its specific mechanisms. Various studies conducted in greenhouses and phytotrons have shown that cultivars from the highlands of Peru (Altiplano), usually cultivated up to 3800 m above sea level, have the potential to tolerate low temperatures down to −8 °C for 4 h, while the other cultivars from the Andean region tolerate the same temperatures for 2 h
[54]. The quinoa plant can survive in the extremely low temperatures of down to −4 °C in the southern region of Bolivia in South America, and successfully grow at an altitude of 3.5 to 4.1 km above sea level. It has the capability to survive at freezing temperatures
[55]. Some experimental trials conducted at low temperatures have shown that its vegetative growth is promoted even at −16 °C. Blanket-type isolations are formed in quinoa leaves and buds that enhance its resistance against frost
[56].
4. Adaptability to Agro-Ecological Extremes
The quinoa plant has a great potential to survive under a wide range of stressful environmental conditions. It can tolerate huge ranges of fluctuations in temperature
[18]. Hence, it can be successfully grown in the Himalayas and in Africa. In 1999, quinoa was introduced into the diverse agro-climatic conditions of Morocco
[7]. Quinoa was introduced in Africa, North America, Asia, and Europe during the 20th century
[26][57]. In the 1980s, England, Denmark, and the Netherlands were the first European countries which started research on it. In Asia, China is one of the leading countries in quinoa production and industrialization. In 2019, quinoa’s area was increased to 16,670 hectares in 25 provinces of China from 12,000 ha in 2018
[58], and currently 18 varieties are registered in China. The first quinoa variety in Pakistan was registered in 2019, while quinoa was introduced there in 2009
[59]. But, even having more than 6000 landraces in the Andes, less than 60 varieties are registered in national lists and catalogues today, which would permit the crop’s cultivation in new countries
[8].
The ability of quinoa plants to synthesize protein-rich grains under diversified environmental conditions makes it an important and economically viable crop to grow in a wide range of regions
[18]. In Kenya, quinoa research results showed a high grain quality and a greater yield as compared to the Andean region of South America. These results show that quinoa has a great potential for adaptation under diverse and different environmental conditions
[60].
In food-deficient countries, especially in Africa, quinoa, as a climate-resilient and high-nutritional crop, could contribute to the reduction of poverty and enhance the food supply of this region. In Colombia and in Kenya, some quinoa genotypes can yield 4 t ha
−1. The high-yielding potential of quinoa makes it an important crop for this region to ensure food security in the future
[61]. Recently, the yield potential of seven quinoa genotypes was explored in the hot–arid regions of North Africa, and it was found that some genotypes are high-yielding and have better grain quality with short harvesting maturity
[62]. Despite the wider adaptability of quinoa, its yield is quite varied, from 108 kg ha
−1 to 9667 kg ha
−1 around the world
[35].
This entry is adapted from the peer-reviewed paper 10.3390/plants12193361