AGRONOMY LECTURE SERIES
Topic: Maize (Zea mays) - Queen of Cereals
1. Introduction, Origin & Distribution
- Origin: Central America and Mexico. Fossil pollen evidence in Mexico confirms it as the native place.
- Geographic Distribution: Widely cultivated from 58°N to 40°S latitude. It occupies the 3rd position globally in area and production (after Wheat and Rice).
- Major Producers: USA, China, Brazil, Mexico, and India. In India, major states include Rajasthan, UP, MP, Bihar, Karnataka, and Andhra Pradesh.
2. Economic Importance & Classification
Maize is a versatile crop used as food, feed, and industrial raw material.
- Usage Split: 35% Human food, 25% Poultry/Cattle feed, 15% Food processing.
- Industrial Use: Starch (65%), sweeteners, paper lamination, textile sizing, and fermentation (alcohol).
Maize Grain Types
| Type | Botanical Name | Characteristics |
|---|---|---|
| Flint Corn | Zea mays indurata | Hard starch outer layer; various colors (white, yellow, red-blue). |
| Dent Corn | Zea mays indentata | 95% of USA production; characteristic "dent" on kernel top. |
| Sweet Corn | Zea mays saccharata | Harvested at 70% moisture; 20% sugar content (vs 3% in dent). |
| Pop Corn | Zea mays everta | Small kernels; bursts at 170°C due to steam pressure. |
| Waxy Corn | Zea mays ceretina | Starch is 100% amylopectin; used for textile/paper sizing. |
3. Soil & Climatic Requirements
Climatic Requirements
- Temperature: Warm weather crop. Minimum 9°C for germination; Optimum 30°C for growth.
- Solar Radiation: Higher solar radiation leads to higher photosynthesis (C4 plant efficiency).
Soil Requirements
- Texture: Deep, fertile, well-drained loamy or silty loam soils are ideal.
- pH: Neutral to slightly acidic (6.5 - 7.5).
- Sensitivity: Highly sensitive to water stagnation (cannot withstand >4-5 hours of waterlogging).
4. Cultural Practices (Irrigated)
Season & Varieties (Tamil Nadu)
- Seasons: Adipattam (Jul-Aug), Purattasipattam (Sep-Oct), Thaipattam (Jan-Feb).
- Varieties: CO 1, COH(M) 4, COH(M) 5, COBC 1 (Baby corn).
Input Management
- Seed Rate: 20 kg/ha (Grain Maize); 25 kg/ha (Baby Corn).
- Spacing: 60 cm x 25 cm.
- Fertilizer (Blanket): 135 : 62.5 : 50 kg NPK/ha. (Apply N in splits: 25% basal, 50% at 25 DAS, 25% at 45 DAS).
- Micronutrient: Apply 12.5 kg/ha of micronutrient mixture.
Weed & Water Management
- Weed Control: Pre-emergence Atrazine 50 WP @ 500 g/ha on 3rd day. (Note: Do not use Atrazine if intercropping with pulses).
- Water Requirement: 600-700 mm.
- Critical Stages: Tasseling (most critical) and Silking. Water stress here reduces yield considerably.
5. Rainfed Cultivation & Intercropping
- Spacing: 45 cm x 20 cm.
- Fertilizer: 60:30:30 kg NPK/ha (Alfisols); 40:20:0 kg NPK/ha (Vertisols).
-
Intercropping:
Red Soils: Maize + Cowpea/Blackgram.
Black Soils: Maize + Redgram.
6. Harvesting & Yield
| Condition | Grain Yield | Fodder/Straw Yield |
|---|---|---|
| Irrigated | 5.0 tonnes/ha | 10.0 tonnes/ha |
| Rainfed | 3.0 tonnes/ha | - |
| Baby Corn | 6.0 tonnes/ha (Cobs) | 25.0 tonnes/ha (Green Fodder) |
PROFESSOR'S EXAM NOTE
Key Points for Competitive Exams:
1. Critical Stage: Tasseling and Silking are the most sensitive stages to water stress.
2. Herbicides: Atrazine is the standard pre-emergence herbicide, but strict NO for pulse intercropping.
3. Baby Corn: Harvested young (within 2-3 days of silk emergence); highly profitable with high fodder value.
