UNIT III: Root Crops
Carrot (Daucus carota L.), Radish (Raphanus sativus L.), Turnip (Brassica rapa subsp. rapa), and Beetroot (Beta vulgaris L.)
A. CARROT (Daucus carota L.)
1. Introduction
Carrot is a popular root vegetable known for its rich beta-carotene (Vitamin A precursor) content. It is consumed raw, cooked, or processed into juice and pickles.
2. Botany and Taxonomy
- Family: Apiaceae
- Chromosome number: 2n = 18
- Origin: Afghanistan
- Types: Eastern (Asiatic) – purple/red roots; Western – orange roots
- Root type: Taproot (conical/cylindrical)
- Pollination: Cross-pollinated, mainly by insects
3. Climatic and Soil Requirements
- Climate: Cool-season crop
- Temperature: 16–24°C
- Soil: Deep, loose, friable sandy loam; pH 6–7
- Avoid heavy soils to prevent forked roots
4. Varieties
- Temperate: Nantes, Chantenay, Danvers
- Tropical: Pusa Rudhira Red, Pusa Kesar, Pusa Meghali
5. Sowing Time and Method
- Time: October–November
- Method: Direct sowing
- Spacing: 30 × 5–7 cm
6. Seed Rate and Seed Treatment
- Seed rate: 6–8 kg/ha
- Treatment: Soak in water for 12 hours; Trichoderma or Captan @ 2–3 g/kg
7. Nutrient and Irrigation Requirements
- FYM: 20 t/ha
- NPK: 60:40:40 kg/ha
- Irrigation: Light and frequent; critical at root development stage
8. Intercultural Operations and Weed Control
- Weeding: At 20–30 days and 45 days
- Mulching: Organic mulch conserves moisture and suppresses weeds
9. Physiological Disorders
- Forking: Forking, also known as stubbing or splitting, is a common physiological disorder in carrots characterized by the taproot splitting into multiple, branched roots. Caused by hardpan soil or fresh FYM.
- Splitting: Splitting or cracking in carrots occurs when there's a sudden increase in moisture after a period of drought, leading to rapid growth and cell swelling that the root can't handle. Caused by excess moisture.
10. Harvesting
- 90–120 days after sowing
- Harvest when roots attain proper size and color
11. Post-Harvest Management
- Washing and grading
- Storage: 0–1°C and 90–95% RH
12. Plant Protection Measures
- Pests: Carrot fly, aphids – control with neem oil or systemic insecticides
- Diseases: Alternaria leaf blight – Mancozeb spray
13. Seed Production
- Method: Root-to-seed
- Isolation distance: 1000 m (foundation), 500 m (certified)
- Seed yield: 500–800 kg/ha
B. RADISH (Raphanus sativus L.)
1. Introduction
Radish is a fast-growing root vegetable eaten raw, cooked, or pickled. It is rich in vitamins and minerals and used in salads.
2. Botany and Taxonomy
- Family: Brassicaceae
- Chromosome number: 2n = 18
- Origin: Central and Southeast Asia
- Types: Asiatic (tropical) and European (temperate)
- Pollination: Cross-pollinated, entomophilous
3. Climatic and Soil Requirements
- Climate: Cool-season crop
- Temperature: 10–18°C
- Soil: Sandy loam, deep and well-drained; pH 5.5–6.8
4. Varieties
- Tropical: Pusa Chetki, Pusa Desi, Arka Nishant
- Temperate: White Icicle, Rapid Red White Tip
5. Sowing Time and Method
- Time: August–February (plains); March–August (hills)
- Method: Direct sowing
- Spacing: 30 × 10 cm
6. Seed Rate and Seed Treatment
- Seed rate: 8–10 kg/ha
- Treatment: Captan or Thiram @ 3 g/kg
7. Nutrient and Irrigation Requirements
- FYM: 20 t/ha
- NPK: 60:40:40 kg/ha
- Irrigation: Every 6–7 days; avoid waterlogging
8. Intercultural Operations and Weed Control
- Weeding: At 20–25 days
- Mulching: Organic mulch maintains moisture and reduces weeds
9. Physiological Disorders
- Pithiness: Due to delayed harvesting or high temperature
- Hollowness: Rapid growth or moisture stress
10. Harvesting
- Duration: 30–50 days depending on variety
- Harvest when roots attain marketable size
11. Post-Harvest Management
- Wash, grade, and bundle
- Store at 0–1°C and 90–95% RH
12. Plant Protection Measures
- Pests: Aphids, flea beetles – spray Imidacloprid or neem oil
- Diseases: White rust, downy mildew – Mancozeb or Copper oxychloride
13. Seed Production
- Method: Root-to-seed
- Isolation distance: 1000 m (foundation), 500 m (certified)
- Seed yield: 400–600 kg/ha
C. TURNIP (Brassica rapa subsp. rapa)
1. Introduction
Turnip is a nutritious root vegetable consumed as a cooked vegetable or salad. Both roots and tender leaves are edible.
2. Botany and Taxonomy
- Family: Brassicaceae
- Chromosome number: 2n = 20
- Origin: Europe and Central Asia
- Root type: Swollen taproot (globular or conical)
- Pollination: Cross-pollinated, insect-mediated
3. Climatic and Soil Requirements
- Climate: Cool-season crop
- Temperature: 10–15°C
- Soil: Sandy loam, rich in organic matter; pH 5.5–7.0
- Avoid heavy clay soils to prevent malformed roots.
4. Varieties
- Tropical: Pusa Sweti, Pusa Chandrima
- Temperate: Purple Top White Globe, Golden Ball
5. Sowing Time and Method
- Time: September–November (plains); March–July (hills)
- Method: Direct sowing
- Spacing: 30 × 10 cm
6. Seed Rate and Seed Treatment
- Seed rate: 4–6 kg/ha
- Treatment: Thiram or Captan @ 2–3 g/kg
7. Nutrient and Irrigation Requirements
- FYM: 20 t/ha
- NPK: 60:40:40 kg/ha
- Irrigation: Light and frequent, especially during root formation
8. Intercultural Operations and Weed Control
- Weeding: At 25–30 days
- Mulching: Organic mulch for moisture conservation and weed control
9. Physiological Disorders
- Cracking: Caused by irregular watering
- Pithiness: Due to over-maturity
10. Harvesting
- Duration: 45–60 days depending on variety
- Harvest when roots are tender and attain marketable size
11. Post-Harvest Management
- Wash, trim tops, and grade
- Storage: 0–1°C and 90–95% RH
12. Plant Protection Measures
- Pests: Aphids, flea beetles – neem oil or Imidacloprid spray
- Diseases: Downy mildew, leaf spot – Mancozeb or Copper oxychloride spray
13. Seed Production
- Method: Root-to-seed
- Isolation distance: 1000 m (foundation), 500 m (certified)
- Seed yield: 500–800 kg/ha
D. BEETROOT (Beta vulgaris L.)
1. Introduction
Beetroot is a nutritious root crop valued for its deep red/purple color due to betalain pigments. It is used in salads, juices, pickles, and as a natural coloring agent.
2. Botany and Taxonomy
- Family: Amaranthaceae (formerly Chenopodiaceae)
- Chromosome number: 2n = 18
- Origin: Mediterranean region
- Root type: Swollen taproot (globular or cylindrical)
- Pollination: Cross-pollinated, wind-pollinated
3. Climatic and Soil Requirements
- Climate: Cool-season crop
- Temperature: 15–20°C
- Soil: Sandy loam to loamy soil; pH 6.0–7.5
- Avoid acidic and saline soils.
4. Varieties
Detroit Dark Red, Crimson Globe, Crosby’s Egyptian
5. Sowing Time and Method
- Time: October–December (plains); March–June (hills)
- Method: Direct sowing
- Spacing: 30 × 7–10 cm
6. Seed Rate and Seed Treatment
- Seed rate: 6–8 kg/ha
- Treatment: Soak seeds for 12–24 hours before sowing
7. Nutrient and Irrigation Requirements
- FYM: 20 t/ha
- NPK: 60:40:40 kg/ha
- Irrigation: Regular light irrigation; avoid waterlogging
8. Intercultural Operations and Weed Control
- Weeding: At 20–25 days
- Mulching: Helps in moisture conservation
9. Physiological Disorders
- Zoning (ring formation): Genetic or temperature fluctuation
- Root cracking: Due to irregular watering
10. Harvesting
- Duration: 60–80 days depending on variety
- Harvest when roots attain appropriate size and color
11. Post-Harvest Management
- Remove tops, wash, and grade
- Storage: 0–2°C and 95% RH
12. Plant Protection Measures
- Pests: Leaf miners, aphids – neem oil or systemic insecticides
- Diseases: Cercospora leaf spot – Mancozeb or Carbendazim spray
13. Seed Production
- Method: Root-to-seed
- Isolation distance: 1000 m (foundation), 500 m (certified)
- Seed yield: 800–1000 kg/ha
