Chapters 5.41

5.41 -chaya as a viable food source for smallholder farmers in the developing world

Eva M. Varga , University of Guelph, Canada

Suggested citation for this chapter.

Varga,E. (2022) chaya as a viable food source for smallholder farmers in the developing world, In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org

Origin and domestication of chaya

The people of the Maya civilization cultivated a bushy perennial plant called chaya consumed for its high-protein, nutritious leaves (Ross-Ibarra & Molina-Cruz, 2002) which has potential to help smallholder farmers adapt to climate change. The leaves of chaya (Cnidoscolus chayamansa), the common name today, was a significant nutritional source to ancient peoples living in parts of the Yucatán peninsula in modern day Mexico (Ross-Ibarra & Molina-Cruz, 2002). Native to Mesoamerica, historical evidence as chronicled by the Spanish since the 16th century suggests this plant was a familiar crop and extensively consumed (Amaya et al., 2020; Ross-Ibarra & Molina-Cruz, 2002). The genus includes 40-50 different species endemic to Mesoamerica exhibiting similar traits like stinging hairs on branches and leaves, distinct petiolar glands, and a few branches of clustered white flowers atop the canopy (McVaugh, 1944). Regular consumption of choice species resulted in the selection and subsequent domestication of the varieties best suited for human consumption like Cnidoscolus chayamansa and Cnidoscolus aconitifolius (Kuri-García et al, 2017). Cnidoscolus chayamansa does not present stinging hairs on its broad leaves or branches and was identified as the edible 'chaya mansa' meaning docile or gentle chaya (McVaugh, 1944).

Nutritional value and safety

In some communities today, chaya is eaten like ordinary spinach. Predominantly consumed today in Central America, in recent years, the plant has been introduced abroad to Texas and Florida in the United States, a few countries in Africa including Burkina Faso, as well as east Asia (Kuti & Kuti, 1999). Chaya leaves and young shoots are highly nutritious, on par with ordinary spinach in both vitamin B1 (thiamin) and B2 (riboflavin) but have significantly higher amounts of vitamin C and beta-carotene (Kuti & Kuti, 1999). Comparatively, 100 g of fresh chaya leaves constitute approximately four times the adult requirement for vitamin C, which is eight times the amount found in spinach (Amaya et al., 2020). Chaya is also rich in minerals, including calcium, phosphorus, iron, and potassium. Both varieties showed increased amounts of mineral content after cooking, except potassium (Kuti & Kuti, 1999). The amino acid profile is remarkable in chaya leaves. A comparative study between Cnidoscolus chayamansa and Cnidoscolus aconitifolius and spinach revealed that both chaya varieties have higher protein content than spinach even after cooking (Kuti & Kuti, 1999). Cnidoscolus chayamansa has the highest protein content, including per 100 g of raw edible leaves, 2.3 g histidine, 1.4 g isoleucine, 3.2 g leucine, 2.0 g lysine, 1.6 g methionine, 1.9 g phenylalanine, 3.2 g threonine and 4.6 g valine; these,compose 8 of the 9 essential amino acids. It is deficient only in tryptophan. In Cnidoscolus aconitifolius leaves, the essential amino acids methionine, phenylalanine and tryptophan are lacking (Kuti & Kuti, 1999). Eaten primarily for its pleasant flavour in Guatemala, the nutritional value is highly regarded in Yucatán, recognized for high protein content; the leaves are consumed as a replacement for meat on occasion (Ross-Ibarra & Molina-Cruz, 2002).

Chaya leaves contain poisonous cyanogenic glycosides, requiring 5-10 minutes of boiling to adequately leach out the cyanide for safe human consumption (González-Laredo et al., 2003). After chaya leaves are cooked, there is a nominal decrease in nutrients (Kuti & Kuti, 1999). The water used for boiling retains vitamin C from the plant but not the cyanide; therefore, cooking water can be consumed (Kuti & Konuru, 2004).

The resilience of chaya in various climates

Chaya grows in diverse climates, from tropical environments with a long rainy season to semi-arid zones (Amaya et al., 2020). Chaya is found growing across the landscape from south Texas, throughout Mexico into the Yucatán peninsula as far south as Colombia, suggesting different varieties prefer certain growing conditions (Ross-Ibarra & Molina-Cruz, 2002). Chayamansa, the 'sweet chaya' and most edible variety, grows throughout the Yucatán peninsula. The tropical climate, relatively arid, is marked by distinct dry and wet seasons where annual rainfall is 900-1000 mm on the west coast and 1200-1400 mm on the east coast; although the plant prefers greater than 720 mm annual rainfall, it can tolerate less than 500 mm per year (Ross-Ibarra & Molina-Cruz, 2002) which would make it suitable for rainfall vulnerable regions of the world.

Chaya can be grown in degraded soils under non-irrigated desert conditions with full sun, and I humid areas with low light and water saturated acidic soils (pH below 6) (Ross-Ibarra & Molina-Cruz, 2002). The arid and semi-arid tropics typically contain soils with low fertility and a limited capacity to retain nutrients (Beach, 1998). Chaya has grown well in the alkaline limestone soils of the Yucatán peninsula, suggesting it can be cultivated in other regions with poor soils (Ross-Ibarra & Molina-Cruz, 2002). Although it is drought tolerant, productivity is limited without irrigation (Amaya et al., 2020). A controlled study conducted in the central Yucatán peninsula revealed the plant has a high demand for nitrogen (Ebel et al., 2019). Another controlled study of Cnidoscolus chayamansa at various planting densities revealed that when the soil was covered by excess vegetation, this prevented loss of soil moisture and retained the nitrogen content resulting in higher yield (Colegio et al., 2012).

Propagating chaya and agricultural productivity

Wild varieties produce seeds but the cultivated domesticated varieties rarely do, thus new plants are sown by stem cuttings placed directly into the soil; once the plant is well-rooted, chaya is fast-growing, and leaves can be harvested as early as 2-3 months later (Munguía-Rosas et al., 2019; Ross-Ibarra & Molina-Cruz, 2002). Large chaya trees with the broadest leaves are selected for succulent stems, 10 to 20 inches long, preferably with young leaf shoots as they are the most effective to ensure good rooting (Munguía-Rosas et al., 2019). Cultivation is not labour intensive; maintenance requires simple pruning (needing only a knife) to maintain the desired height whereby the average adult human can easily reach the leaves to harvest them by hand (Amaya et al., 2020).

Chaya farmers consider the shrub to be an easy-growing plant with significant pest and disease resistance, which may be attributed to its cultivation by smallholders (Amaya et al., 2020; Ebel et al., 2019). One study revealed that by year two, the tree could be harvested for its leaves up to three times per year; the plants were more productive during the dry season, but the soil around the plants was intercropped to retain soil humidity and prevented evaporation (Ebel et al., 2019). As noted above, chaya is deficient in one essential amino acid, tryptophan, so intercropping a legume or squash rich in tryptophan would contribute to the farmers' nutritional requirements while retaining soil moisture, providing nitrogen for the plant, and suppressing weeds (Kuti & Kuti, 1999).

Medicinal properties of chaya

Most subsistence farmers rely on traditional medicine for their primary health care needs almost exclusively derived from plants (Soetan & Aiyelaagbe, 2009). Prompted by historical references to this plant's healing properties, recent studies indicate that chaya offers protection for preventative and therapeutic purposes well beyond its nutritional benefits (Kuri-García et al, 2017). In Mexico and Guatemala, chaya is used in traditional medicine to cure diabetes, kidney problems, and high cholesterol (Ebel et al., 2019). People claim it cleans the circulatory system, eases menstrual pain, and improves eyesight and digestion (Ebel et al., 2019). The high levels of carotenoids in chaya may be why the plant is recognized for its immune system and anti-inflammatory properties (Kuri-García et al, 2017).

Economics and gender

A study conducted in Guatemala, where chaya is frequently eaten, identified problems like low yield efficiency, broken infrastructure, poor value chain coordination, access, and low demand tied to low awareness as factors that limit the production and consumption of this crop (Amaya et al., 2020). There have not been intensification efforts due to both supply and demand-side constraints. People are unaware of its high nutritional properties, while some consumers willing to buy chaya cannot find it (Amaya et al., 2020). A Spanish text cited that wild chaya was used as a famine food; consequently, chaya is associated with the ‘food of the poor’, defamed by younger generations (Ross-Ibarra & Molina-Cruz, 2002). It is grown in home gardens and can supply feed for livestock as raw shred chaya is excellent fodder for chickens (Ross-Ibarra & Molina-Cruz, 2002). Post farmgate steps are not well defined, resulting in reduced or no value addition attributed to this product; thus, farmers' adoption to cultivate chaya is less likely as there is a narrow market opportunity (Amaya et al., 2020). The gender gap issue persists in developing countries, and though concern for nutritious food is prioritized by women, their opinions are often suppressed (Maselli et al., 2015). Women are the primary cultivators, managers and sellers of chaya by a wide margin and were identified as those with a better understanding of its market potential and its facets (Amaya et al., 2020). Large price discrepancies were found within the same region for chaya (Amaya et al., 2020).

The most impoverished populations are highly price-sensitive and, thus, very conservative with their eating patterns; therefore this low-cost leafy green may be a viable food source for many (Saltzman et al., 2013). Perishability is not a significant constraint as the leaves can be kept fresh without cooling for 20 days; this may present an opportunity to transport the leafy green to inner-city markets where it can be sold at a premium to people with higher purchasing power (Ebel et al., 2019; Amaya et al., 2020). Ease of propagation makes this crop easy to ensure continuity and secure a steady supply to markets which would benefit women the most.

Conclusion

This plant is ideal for subsistence farmers who are overwhelmingly protein and micronutrient deficient (Saltzman et al., 2013). As a leafy green vegetable, there should be no cultural resistance to this food since leafy greens are widely consumed in Africa and Asia, but facts about this plant should be shared with trusted local leaders in communities to ensure acceptance. Stem cutting propagation makes this plant accessible and affordable for smallholder farmers and can spur cooperation within communities – however it may limit its initial distribution globally compared to seed-propagated crops. Multiple harvests from healthy mature plants can provide some nutrient assurance throughout the food calendar year.

More research is needed for the edible varieties in a subsistence environment under rainfed conditions and to explore what strategies can be undertaken to retain water in the soil during dry periods and prolonged drought. Better methods can be developed to ensure a high survival rate of new cuttings, to maximize yield, and inform choices of beneficial soil amendments. Alternative methods to boiling and drying leaves should be developed that could extend the shelf life of chaya to help smallholders during the dry season. Processes like pickling after boiling using vinegar, salt, or oil, pulverizing chaya into a powder, or flavoured chaya chips are processing methods that can be done in small communities and sold in areas where there is a higher purchasing power. It is vital to inform communities of this crop; it is worthy of revival as it is useful, nutritious, demands little attention or inputs to grow, and presents tremendous economic opportunities (Saltzman et al., 2013).

Helpful brochures and videos

Woman harvests and washes chaya, shows how she had planted the trees on her property, how quickly they grew into tall trees and the benefit of shade from the tree: https://www.youtube.com/watch?v=wykCWcEnylk Man growing chaya in Florida shows two varieties with different leaves, he offers to send cuttings to viewers, he talks of the nutritional value and ease of

propagation: https://www.youtube.com/watch?v=OkcK374KU2Y&t=17s

Instructional video link about how to propagate from stem cuttings: https://youtu.be/0f8-m0kPGxk

CGIAR 4 pgs. coloured comprehensive fact sheet: https://cgspace.cgiar.org/bitstream/handle/10568/98431/Value_Amaya_2018.pdf?sequence=1&isAllowed=y

CGIAR 2 pgs. Coloured sheet including basic nutrition and processing information: https://cgspace.cgiar.org/bitstream/handle/10568/103501/Chaya_Bioversity_UVG_2017_eng.pdf?sequence=1&isAllowed=y

References

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