Lathyrus sativus originated from the Balkan Peninsula in the early Neolithic age. It may have been the first domesticated crop in Europe around 6000 BCE. Grass pea is now widely cultivated and naturalized in many areas of southern, central and eastern Europe, around the Mediterranean Basin and in Iraq and Afghanistan. Grass pea is an economically important crop in Bangladesh, India, Pakistan, Nepal, and Ethiopia.
Grass pea (Lathyrus sativus) is a dual purpose annual legume grown for its seeds for human consumption, and fodder for livestock feeding. Grass pea is one of the preferred legume seeds in low fertility soils and arid areas because of its outstanding tolerance of dry or flooding conditions, but its contains a toxic component that may cause paralysis in humans and livestock if consumed in excessive amounts. Grass pea has a great scope as food, feed, and fodder crop under climate change. Consumption of grass pea as a normal diet is safe and holds promise in diversified agrictltiral food systems in rainfed dryland regions.
Grass pea has a variable habit and can be trailing or climbing. It is many-branched with slender stems up to 60 cm in height. It has a deep and strong taproot. The leaves are pinnate, opposite, encompassing 2 pairs of leaflets and a terminal tendril. The leaflets are sessile, linear-lanceolate, 5- 7.5 cm long x 1 cm broad. The flowers are solitary, borne on axillary shoots. They can be bright blue, reddish purple, red, pink, or white in colour. Grass pea fruits are pods with 3-5 seeds. The pods are oblong, flat, about 2.5-4.5 cm in length, 0.6-1.0 cm in width and slightly curved. The seeds are 4-7 mm in diameter, angled and wedge-shaped. They are usually white, brownish-grey or yellow but spotted or mottled forms exist.
Grass pea is a spring crop in temperate areas and a winter crop in subtropical regions. It can be cultivated from sea level up to an altitude of 1200 m in India, and from 1700 m to 2700 m in Ethiopia, and more generally in areas where average temperatures are within 10-25°C. It is a staple food for the low income groups in some areas of Central India. Consumption of lathyrus sativus seeds in quantities exceeding 30% of the total diet for more than six months have been known to cause paralysis. The overall incidence of the disease in the endemic area is about 4%. Men are more susceptible than women. The active neurotoxic principle is B(N) oxalyl amino alanine (BOAA), which is present as a free aminoacid in the seed cotyledons to the extent of about one percent.
Onset is of three types: (1) acute, (2) subacute, and (3) insidious. The continued use of L.sativus produces neurolathyrism, which is characterised by progressive spastic paraplegia with preservation of sphincters, sensation and mental activity. It progresses irreversibly into four stages of physical disability. There may be pain in the back or weakness of legs, and difficulty in sitting down and getting up. Later the patient is unable to walk without the aid of a stick, the legs tremble and dragged along with difficulty and spastic gait characterised by a walk on tiptoes with the legs crossing scissor-wise. Later complete paraplegia occurs. There is no atrophy or loss of the tone of muscles, and no reaction of degeneration. The knee jerks are increased, ankle clonus is marked and Babinski's sign is present.
Steeping the pulse in hot water and parboiling remove 90% of toxic aminoacid. Rich diet with exclusion of the pulse, massage and application of electricity are useful. Death is very rare. At autopsy lateral columns of the spinal cord show sclerosis.
The worldwide demand for feed is increasing as a result of the growing demand for high-value animal protein, and grass pea could be a potential source of protein for animal feeds. Therefore a growing interest has been generated in reinforcing the cultivation of grass pea, thereby increasing and diversifying the protein supply for food and feed purposes and taking advantage of the positive footprint of grass pea on water, nitrogen, and carbon. Grass pea (Lathyrus sativus) is one of the hardiest but most underutilized crops for adaptation to fragile agro-ecosystems, because of its ability to survive under extreme climatic conditions such as drought, water stagnation and heat stress.