Grass Peas (Lathyrus sativus)

How to Grow

While used mainly as food, forage, and livestock feed, grass pea can also be grown as an ornamental and used medicinally (Wiraguna et al., 2020). The most prominent grass pea production regions are in South Asia and East Africa, specifically Bangladesh, India, Pakistan, and Ethiopia (Lambein et al., 2019). Total production of grass pea is estimated at 1.2 million tons on 1.5 million hectares. Ethiopian production recently increased in total land area as well as amount harvested (Lambein et al., 2019). Bangladesh also followed this trend through the expansion of its total planted area in dry and flooded fields (Lambein et al., 2019). While still a production center, Europe has mostly de-emphasized grass peas in favor of better-known crops like chickpeas (Grela et al., 2010).

Grass peas are versatile in many ways through their ability to thrive in an extensive range of soil conditions, elevations, water levels, and other abiotic stresses (Lambein et al., 2019; Wiraguna et al., 2020). They are often grown as a summer crop in high altitudes as well as a winter crop at lower elevations (Lambein et al., 2019).

Grass peas are most prominent in arid and semiarid regions where more common legumes are not as well suited. Their ability to do well in low water conditions and their adaptability to poor-quality soils makes them extremely attractive to impoverished farmers. Their morphological adaptative mechanisms to drought conditions include narrow leaves, winged stems, and a deep root system (Lambein et al., 2019). Physiological adaptations include an elevated ability to adjust the plant's osmotic potential and the upregulation of antioxidant enzyme genes (Lambein et al., 2019).

Waterlogging can be a problem in locations with monsoon climates. The influx of water into the soil blocks a root's access to oxygen and can lead to a crop doing poorly if left in stagnant water for too long before the field can drain (Smartt et al., 1994). Farmers in Ethiopia use grass peas' tolerance of this stress to their advantage, commonly growing it during their monsoon season in high clay-content soil prone to waterlogging (Wiraguna et al., 2020). This practice extends their growing season by several months on land that would probably not be used otherwise until after the monsoon season ends.

In terms of soil, grass peas are relatively undemanding and are good nitrogen fixers (Smartt et al., 1994). Grass peas have a high yield potential at low fertilization levels and hardy root systems that help them thrive in a broad range of soil types, from volcanic soils in Ethiopia to heavy clay soils in Bangladesh (Lambein et al., 2019; Grela et al., 2010). They are commonly used as an intercrop with wheat and rice, staple crops in the same regions (Lambein et al., 2019). They do very well in crop rotations due to their ability to improve soil conditions, reduce disease incidence, and lessen weed growth (Grela et al., 2010). All these qualities reduce its cost of production.

Uses

Grass peas are a popular food across several continents in a wide range of dishes. Many countries in Europe, Africa, and South Asia have numerous ways to prepare and eat them. Cooking, boiling, roasting, making them into drinks or sauces, and even eating uncooked seeds are all common ways for them to be consumed (Lambein et al., 2019). Grass pea seeds are remarkably high in protein, at a content level of about 27%, compared to chickpeas (Cicer arietinum), which commonly have only about 18% protein content (Wiraguna et al., 2020). They are also strong sources of starch, fiber, and secondary metabolites. (Soren et al., 2015). Because of this, a substantial portion of grass peas' major production regions uses them as a primary protein supplement in their diets (Kumar et al., 2013). However, as in many grain legumes, grass pea is deficient in the sulfur-containing amino acids cystine and methionine (Lambein et al., 2019).

Grass peas are one of the hardiest but also most underutilized crops (Kumar et al., 2013). There are several reasons that help contribute to this underutilization, one of the main ones being an issue that can arise if grass peas are a population's major source of protein for an extended period of time (Wiraguna et al., 2020). If grass peas are more than 20% of a diet's protein content over a period of three consecutive months, it can lead to the development of a neurological disorder called neurolathyrism, due to the presence of the neuroexcitatory amino acid β-ODAP acid (Wiraguna et al., 2020). A stigma against grass peas has developed because of this, despite their significant dietary advantages and tolerance to abiotic stress.