Pigeon Pea
Cajanus cajan
The Pigeon Pea (Cajanus cajan) is a perennial legume shrub belonging to the family Fabaceae, widely cultivated across tropical and subtropical regions as a vital food crop. It is one of the most important grain legumes in semi-arid tropical farming systems, valued for its drought tolerance, nitrogen-fixing ability, and nutritional versatility.
• Common names include pigeon pea, red gram, arhar, tuvar, and gandul
• A key staple in South Asian, East African, and Caribbean cuisines
• Serves as a critical source of plant-based protein for over 1.5 billion people worldwide
• Plays a central role in sustainable agriculture through biological nitrogen fixation
Taxonomie
• Center of origin: Peninsular India, particularly the Eastern Ghats and Deccan Plateau regions
• Wild progenitor: Cajanus cajanifolia, native to tropical deciduous woodlands of India
• Archaeological evidence from peninsular India dates pigeon pea cultivation to at least 3,500 years ago (~1500 BCE)
• Dispersed to East Africa approximately 2,000–3,000 years ago, likely via ancient Indian Ocean trade routes
• Subsequently introduced to the Caribbean, Central America, and Southeast Asia during the colonial era
• Today cultivated across more than 50 countries, with India accounting for roughly 65% of global production
Root System:
• Deep taproot system extending 1.5–3 meters into the soil, contributing to exceptional drought tolerance
• Extensive lateral root network
• Root nodules harbor nitrogen-fixing Rhizobium bacteria, capable of fixing 40–200 kg of nitrogen per hectare per year
Stem:
• Woody at base, herbaceous toward the apex
• Green to slightly pubescent when young, becoming brown and woody with age
• Branches are typically angular or ribbed
Leaves:
• Trifoliate (three leaflets per leaf), alternate arrangement
• Leaflets are lanceolate to elliptic, 5–10 cm long, with entire margins
• Upper surface is dark green and glabrous; lower surface is densely covered with fine silky hairs (tomentose), giving a silvery-green appearance
• Stipules are small and linear
Flowers:
• Papilionaceous (butterfly-shaped), typical of the Fabaceae family
• Color ranges from yellow to orange-yellow, sometimes with red or purple markings on the standard petal
• Arranged in terminal or axillary racemes, 5–15 cm long
• Predominantly self-pollinated but outcrossing rates of 5–40% have been recorded depending on pollinator activity
Fruit & Seeds:
• Pods are straight or slightly curved, 5–9 cm long, containing 3–7 seeds
• Pods are pubescent, sometimes with glandular hairs, and may be green, purple, or mottled
• Seeds are round to ellipsoid, 4–8 mm in diameter
• Seed color varies widely: cream, brown, grey, purple, or mottled, depending on variety
• 100-seed weight ranges from 5 to 16 grams depending on cultivar
Climate:
• Optimal temperature range: 18–35°C; can tolerate temperatures up to 40°C for short periods
• Grows from sea level up to 3,000 meters elevation
• Requires 600–1,000 mm annual rainfall but is one of the most drought-tolerant grain legumes
• Can survive prolonged dry spells due to its deep taproot system
• Sensitive to waterlogging and frost
Soil:
• Adaptable to a wide range of soil types, from sandy loams to heavy clays
• Prefers well-drained soils with pH 5.0–7.0
• Tolerates poor, degraded, and low-fertility soils better than most grain legumes
• Does not tolerate saline or waterlogged conditions
Ecological Role:
• Biological nitrogen fixation enriches soil fertility, making it an ideal intercrop and rotation crop
• Commonly intercropped with sorghum, millet, maize, and groundnut in traditional farming systems
• Provides habitat and nectar for pollinators including bees and butterflies
• Used as a cover crop and in agroforestry systems for soil conservation
Per 100 g of mature dry seeds (approximate values):
• Energy: ~340–350 kcal
• Protein: 18–24 g (one of the highest among commonly consumed legumes)
• Carbohydrates: 57–63 g
• Dietary fiber: 10–15 g
• Fat: 1.5–2.5 g
• Folate (B9): 150–250 μg (excellent source)
• Iron: 4–6 mg
• Magnesium: 120–180 mg
• Potassium: 1,100–1,400 mg
• Zinc: 2–3 mg
• Rich in essential amino acids, particularly lysine and tryptophan, though relatively low in methionine and cysteine
• Green (immature) pods and seeds are rich in vitamin C, vitamin A, and chlorophyll
• Contains anti-nutritional factors such as trypsin inhibitors, tannins, and phytic acid, which are significantly reduced by cooking
• Low glycemic index, making it suitable for diabetic diets
• Raw or undercooked seeds contain anti-nutritional factors including trypsin inhibitors, lectins (hemagglutinins), tannins, and phytic acid, which can impair protein digestion and mineral absorption
• These compounds are effectively deactivated by soaking and thorough cooking (boiling for at least 30 minutes)
• Some individuals, particularly of African descent, may carry a genetic deficiency of glucose-6-phosphate dehydrogenase (G6PD); ingestion of raw or undercooked pigeon peas has been associated with hemolytic favism in rare cases, similar to the reaction caused by fava beans (Vicia faba)
• The leaves and stems contain alkaloids (e.g., cajanine) and flavonoids that may have mild toxic effects if consumed in very large quantities, though they are used safely as animal fodder and in traditional medicine
• No significant toxicity has been reported from consumption of properly prepared pigeon pea seeds
Climate & Season:
• Planting is timed with the onset of the rainy season in tropical regions
• In India, the main (kharif) crop is sown in June–July and harvested in December–March
• A second (rabi) crop may be planted in October–November in some regions
• Requires a growing season of 120–200 days depending on variety (short-, medium-, and long-duration types)
Light:
• Requires full sun for optimal growth and yield
• Does not tolerate shade well
Soil:
• Well-drained loamy to sandy-loam soils are ideal
• Avoid waterlogged or heavy clay soils
• Soil pH of 5.0–7.0 is optimal
Watering:
• Primarily rainfed; supplemental irrigation can significantly improve yields
• Drought-tolerant once established, but moisture stress during flowering and pod-filling reduces yield
• Waterlogging is highly detrimental
Spacing & Sowing:
• Seeds sown directly at 2–5 cm depth
• Row spacing: 45–75 cm; plant-to-plant spacing: 15–30 cm
• Seed rate: 15–25 kg per hectare depending on variety and spacing
Propagation:
• Exclusively by seed; no vegetative propagation methods are commonly used in commercial cultivation
• Seeds benefit from inoculation with appropriate Rhizobium strains in soils where pigeon pea has not been previously grown
Common Problems:
• Pod borer (Helicoverpa armigera) — the most devastating pest, causing yield losses of 20–60%
• Fusarium wilt (Fusarium udum) — a major soil-borne fungal disease
• Sterility Mosaic Disease (Pigeon pea Sterility Mosaic Virus) — transmitted by the eriophyid mite Aceria cajani
• Phytophthora blight, Alternaria leaf spot, and powdery mildew
• Parasitic weed Striga spp. can cause severe yield losses in African cultivation
Food Uses:
• Dry seeds (dhal) are a dietary staple across South Asia, consumed as split lentils in soups, stews, and curries
• Green pods and immature seeds are eaten as a vegetable (e.g., in Caribbean and East African cuisines)
• Flour from dried seeds is used in bread, porridge, and traditional snacks
• Sprouted seeds are consumed for enhanced nutritional value
• Canned pigeon peas are widely available as a convenience food
Agricultural & Agroecological Uses:
• Intercropped with cereals (sorghum, millet, maize) to improve soil nitrogen content
• Used as a cover crop and green manure to prevent soil erosion and improve soil organic matter
• Alley cropping systems in Africa and Southeast Asia
• Provides high-quality livestock fodder from leaves, pods, and seed meal
Traditional Medicine:
• In Ayurvedic medicine, pigeon pea leaves are used to treat diabetes, wounds, and inflammation
• Leaf extracts have demonstrated anti-inflammatory, antioxidant, and hepatoprotective properties in laboratory studies
• Used in traditional African medicine for treating measles, hepatitis, and anemia
Industrial & Other Uses:
• Fuelwood from woody stems in rural communities
• Stems used for basket weaving and thatching in some regions
• Seed meal used as a protein-rich animal feed supplement
• Being explored as a source of plant-based protein for commercial food products
Anecdote
The pigeon pea holds a remarkable place in both agricultural history and modern science: • In 2011, the pigeon pea became the first seed legume — and among the first crop plants in the developing world — to have its complete genome sequenced. The effort was led by the International Initiative for Pigeonpea Genomics (IIPG), involving research institutions from India, China, the United States, and other countries. The genome spans approximately 833 million base pairs across 11 chromosomes. • The deep taproot of the pigeon pea can penetrate more than 2 meters into the soil, accessing water and nutrients unavailable to most other crops. This makes it a lifeline crop for smallholder farmers in drought-prone regions of sub-Saharan Africa and South Asia. • Pigeon pea is sometimes called the "poor person's meat" because of its high protein content and affordability, providing critical nutrition to hundreds of millions of people in developing countries. • In Hawaii, pigeon pea (known as "pi pokoliko" or "pi nunu") was introduced in the early 19th century and became so naturalized that many Hawaiians consider it a traditional crop, though it is not native to the islands. • The plant's ability to fix atmospheric nitrogen — up to 200 kg per hectare per year — means it can essentially fertilize itself and the crops grown alongside it, reducing or eliminating the need for synthetic nitrogen fertilizers. • Pigeon pea flowers produce no scent but are rich in nectar, attracting a wide variety of pollinators. Despite being primarily self-pollinating, the plant maintains surprisingly high genetic diversity, a puzzle that has fascinated plant geneticists for decades.
En savoir plus
