Taxonomy, Origin, and Chromosomal Configuration of Major Pulses
Pulses, or grain legumes belonging to the family Fabaceae (subfamily Papilionoideae), are vital sources of dietary plant protein, restorative green manure, and atmospheric nitrogen fixation. Understanding their taxonomic hierarchy, center of origin, and cytogenetics is essential for UP TGT/PGT Agriculture aspirants.
- Chickpea (Gram): Scientifically known as Cicer arietinum, family Fabaceae, origin in South-Western Asia (Afghanistan/Persia). Diploid chromosome number is 2n = 2x = 16. It is further divided into two main botanical types: Kabuli (white flowers, large beige seeds, 2n=16) and Desi (pink/purple flowers, small coloured seeds, 2n=16).
- Pigeonpea (Red Gram / Tur): Cajanus cajan, origin in Africa (specifically India/Africa region), 2n = 22. It is a perennial shrub often cultivated as an annual crop.
- Mungbean (Green Gram): Vigna radiata, origin in India, 2n = 22.
- Urdbean (Black Gram): Vigna mungo, origin in India, 2n = 22.
- Lentil (Masoor): Lens culinaris, origin in Near East / Mediterranean, 2n = 14.
- Field Pea: Pisum sativum var. arvense, origin in Mediterranean / Central Asia, 2n = 14.
Agro-Climatic Requirements, Soil, and Field Preparation
Grain legumes thrive under specific environmental conditions. Excess moisture or heavy waterlogging is universally fatal to pulse crops due to oxygen starvation in the root zone, which inhibits root respiration and deactivates nitrogenase enzyme activity in root nodules.
- Temperature Ranges: Cool-season pulses (Chickpea, Lentil, Field Pea) require an optimum temperature range of 15°C to 25°C for vegetative growth and 25°C to 30°C for grain filling. Warm-season pulses (Mungbean, Urdbean, Pigeonpea) require 25°C to 35°C.
- Soil Type: Well-drained sandy loam to clay loam soils with a neutral pH range of 6.5 to 7.5 are ideal. Highly acidic soils require lime application, while sodic soils require gypsum amendment.
- Tillage Operations: One deep ploughing followed by 2 to 3 harrowings and planking to achieve a fine, weed-free, and firm seedbed. Conservation agriculture practices like zero-tillage sowing are increasingly popular in rice-fallow systems.
Seed Rate, Seed Treatment, Sowing Geometry, and Inoculation
Agronomic management of seed and sowing ensures optimum plant population density and vigorous early establishment, which directly influences yield realization.
- Seed Treatment: Seeds must be treated with Carbendazim or Thiram at 2.5 g/kg of seed to suppress soil-borne pathogens like Fusarium oxysporum and Rhizoctonia species.
- Biofertilizer Inoculation: Crucial step involving Rhizobium cultures (specific to each pulse species, e.g., Rhizobium leguminosarum for lentil and pea; Bradyrhizobium sp. for pigeonpea and mungbean) along with Phosphate Solubilizing Bacteria (PSB like Bacillus megaterium) at 20-25 g/kg seed.
- Seed Rates and Spacing: Chickpea (Desi: 75-80 kg/ha, Kabuli: 100 kg/ha; Spacing: 30-40 cm × 10 cm); Pigeonpea (Straight: 15-20 kg/ha; Spacing: 50-60 cm × 20 cm); Mungbean (20-25 kg/ha; Spacing: 30 cm × 10 cm); Urdbean (20-25 kg/ha; Spacing: 30 cm × 10 cm).
Nutrient Management and Biological Nitrogen Fixation (BNF)
Although pulses fix atmospheric nitrogen via symbiotic association with Rhizobium bacteria housed in root nodules, they require a starter dose of nitrogen and adequate phosphorus for root proliferation.
- Starter Nitrogen Dose: An application of 15-20 kg N/ha is recommended to kickstart early vegetative growth before functional root nodules are established.
- Phosphorus Requirement: Phosphorus is the master nutrient for pulses, essential for root growth, nodulation, and energy transfer. Applied entirely as basal dressing through Single Super Phosphate (SSP) at 40-60 kg ext{P}_2 ext{O}_5/ha. SSP also supplies essential Calcium (19%) and Sulphur (12%).
- Sulphur and Micronutrients: Application of 20 kg S/ha enhances protein synthesis (methionine and cysteine amino acids). Foliar spray of Boron and Molybdenum aids in flower retention and nitrogenase enzyme activity.
Water Management and Critical Stages of Irrigation
Pulses are predominantly grown under rainfed conditions (approximately 85% area), but providing supplemental irrigation at critical moisture-sensitive stages drastically boosts grain yield.
- Critical Stages in Chickpea: Pre-flowering stage (30-35 DAS) and Pod formation / grain filling stage (75-80 DAS).
- Critical Stages in Pigeonpea: Branching and flowering stage, and pod development stage. Water stagnation must be strictly prevented by providing lateral surface drainage channels.
- Critical Stages in Summer Mungbean/Urdbean: Irrigation at 10-12 days intervals, specifically at pre-flowering and pod filling stages. Avoid irrigation during peak flowering to prevent flower drop.
Crop Protection: Major Pests, Diseases, and Integrated Management (IPM)
Plant protection in pulses is challenging due to overlapping vegetative and reproductive phases that attract lepidopteran borers and fungal wilts.
- Insect Pests: Gram Pod Borer (Helicoverpa armigera) is the most destructive pest attacking chickpea and pigeonpea. Larvae bore into pods and feed on developing grains. Management: Pheromone traps at 5 traps/ha, installation of bird perches (50/ha), and spraying of Indoxacarb 14.5% SC or Nucleopolyhedrovirus (NPV). Leafhopper (Amarasca biguttula biguttula) and Whitefly (Bemisia tabaci) act as vectors for Yellow Mosaic Virus (YMV) in mungbean and urdbean.
- Fungal Diseases: Wilt caused by Fusarium oxysporum f. sp. ciceri in chickpea is a soil-borne vascular disease causing sudden drying of plants. Management: Deep summer ploughing, crop rotation, and use of resistant varieties (e.g., Avrodhi). Ascochyta Blight (Ascochyta rabiei) and Sterility Mosaic Virus (vector: Aceria cajani) in pigeonpea.
Agronomic Profile Comparison of Major Kharif and RABI Pulses
| Crop Name | Botanical Name | Season | Optimum Seed Rate (kg/ha) | Critical Irrigation Stages |
|---|---|---|---|---|
| Chickpea (Gram) | Cicer arietinum | Rabi | 75 - 100 | Pre-flowering & Pod formation |
| Pigeonpea (Tur) | Cajanus cajan | Kharif | 15 - 20 | Pre-flowering & Pod development |
| Mungbean (Green Gram) | Vigna radiata | Kharif / Summer | 20 - 25 | Pre-flowering & Pod filling |
| Lentil (Masoor) | Lens culinaris | Rabi | 30 - 40 | Crown root / Pre-flowering & Pod filling |
Memory Trick / Mnemonic
Mnemonic for Critical Irrigation Stages in Chickpea
FP - First Pre-flowering, Second Pod-filling (Think: 'FP' like Fast Pass)
F stands for Flowering / Pre-flowering stage (30-35 DAS) and P stands for Pod development / grain filling stage (75-80 DAS), which are the two most critical irrigation thresholds for chickpea.
Memory Trick / Mnemonic
Mnemonic for Major Kharif Pulses Botanical Names
RAMU (Radiata, Mungo)
R stands for Radiata (Mungbean = Vigna radiata) and MU stands for Mungo (Urdbean = Vigna mungo).
⚡ High-Yield Exam Points (UP TGT / PGT Focus)
- Chickpea is also known as Bengal gram, Gram, or Chana, and belongs to the family Fabaceae with chromosome number 2n = 16.
- Pigeonpea is a cross-pollinated crop facilitated by insects (often cross-pollinated up to 20-70%).
- Single Super SSP is preferred in pulse fertilization because it supplies 16% ext{P}_2 ext{O}_5, 19% Calcium, and 12% Sulphur.
- Yellow Mosaic Virus (YMV) in mungbean and urdbean is transmitted by the whitefly vector Bemisia tabaci.
- Nipping (removal of apical buds) is a unique cultural practice in chickpea performed at 30-45 DAS to encourage lateral branching and increase pod yield.
- The most destructive insect pest of chickpea and pigeonpea is the gram pod borer, Helicoverpa armigera.
- Rhizobium inoculation should always be done in the shade to prevent ultraviolet ray damage to living bacteria.
- Protein content in pulses generally ranges from 20% to 25%, with soybean exceptionally having 40% protein (though botanically an oilseed-pulse).
- Avrodhi is a wilt-resistant variety of chickpea recommended for cultivation in Uttar Pradesh.
- Optimum storage moisture content for safe storage of pulse grains is 9% to 10%.
⚠️ Common Mistakes & Exam Pitfalls
- Error: Confusing Kabuli chickpea seed rate with Desi chickpea seed rate. Scientific Fact: Kabuli chickpea has larger seeds and requires 100 kg/ha seed rate, whereas Desi chickpea requires 75-80 kg/ha.
- Error: Applying heavy nitrogenous fertilization to boost pulse growth. Scientific Fact: Excessive nitrogen inhibits root nodulation and nitrogenase activity; only a starter dose of 15-20 kg N/ha is recommended.
- Error: Assuming pulses can withstand waterlogging. Scientific Fact: Pulses are extremely susceptible to waterlogging; poor aeration leads to root rot and mortality.