Maize (Zea mays) – The Queen of Cereals

Botanical and General Information

• Botanical Name: Zea mays
• Origin: Central America
• Chromosome Number: 2n = 20
• Pollination: Cross-pollinated crop
• Tillering: Non-tiller plant
• Protein Content: Approximately 10%
• Referred to as: Drosophila of crop plants due to its use in genetic studies

Research and Development

• First All India Co-ordinated Research Project on Maize: Initiated in 1957
• Project Directorate of Maize Research: Located at Pusa, New Delhi
• Yield Potential: Maize has the highest yield potential among cereals
• Plant Type: Monoecious, C4 plant with separate male and female inflorescences

Hybrid Development:

• Concept of hybrid maize: M. East and G.H. Shull
• F. Jones (1920): Proposed double cross technique for hybrid seed production
• Commercial production involves cytoplasmic-genetic male sterility with restorer lines
• Double cross techniques are still commonly used in India
• Inbred Line: A genetically pure line developed through repeated self-pollination and selection.
• Nutritional Deficiency: Exclusive maize diets can lead to pellagra due to low levels of niacin and tryptophan
• Major Rabi Maize Growing State: Bihar

Isolation Distance for Seed Production:

• Composite: 400 m
• Hybrid: 600 m

Climatic Requirements

• Optimum Temperature for Germination: 21°C
• Ideal Growth Temperature: 32°C
• Water Requirement: 500–800 mm
• Environmental Sensitivity: Susceptible to excess water and moisture stress
• Growth Habit: Warm-season crop, needs warm night temperatures for high yield
• Root Type: Seminal roots support seedlings early on
• Sowing Direction: East–West sowing improves light interception and yield
• Gametocide Used: Mendok – for inducing male sterility

Major Maize Producing States in India

• Karnataka
• Andhra Pradesh
• Madhya Pradesh
• Maharashtra
• Bihar
• Rajasthan
• Uttar Pradesh

Globally, the USA is the largest producer, followed by China and Brazil.

Botanical Description of Inflorescence

• Male Inflorescence (Tassel): Terminal, branched panicle with staminate flowers
• Female Inflorescence (Ear or Cob): Axillary, pistillate cluster
• Silk: Long style and stigma of the female flower
• First Appearance: Tassel (male flower appears first)

Classification of Maize

According to Shurtevant (1899) – based on endosperm characteristics:

Varieties of Maize

• Double Cross Hybrids (Released in 1961); Ganga-1, Ganga-101, Deccan, Ranjeet
• Top Cross Hybrids; Ganga-2, Hi-Starch Top cross hybrid = inbred line × open-pollinated variety
• Composite Varieties (Released in 1967); Vikram, Vijay, Amber, Kisan, Jawahar, Sona
• Early Duration Composites; Pratap, Agety-76, Kanchan, Laxmi, Tarun
• High-Lysine Composites (1971); Protina (4% lysine), Shakti, Rattan, Rich in lysine and tryptophan
• Synthetic Variety; Amber – advanced generations of multiple hybrids maintained through open-pollination
• Quality Protein Maize (QPM) Varieties; Developed using the Opaque-2 gene; Shaktiman-1, Shaktiman-2, HQPM-1

Seed and Field Information

Seed Rate:

• Composites: 15–20 kg/ha (Kharif)
• Hybrids: 25 kg/ha
• Fodder Purpose: 40–50 kg/ha
• Spacing (Row × Plant): 60 × 20 cm
• Critical Stage for Water Requirement: Between tasseling and silking
• Average Yield: ~4 tonnes/ha

Importance and Uses of Maize

• Food: Consumed directly as boiled/roasted corn, popcorn, cornflakes, corn flour, etc.
• Fodder: Green maize is a major fodder for cattle; silage preparation is common.

Industrial Uses:

• Starch Industry: For adhesives, textile sizing, and paper industry
• Alcohol Industry: Used in ethanol production
• Corn Oil: Extracted from the germ
• Glucose & Dextrose: Produced from maize starch
• Pharmaceuticals: Used in the production of antibiotics like penicillin
• Maize By-products: Used in cosmetic, plastic, and bioplastic industries
• Biofuel: Maize is a source for ethanol (eco-friendly alternative fuel)

Genetics and Breeding

• Genetic Engineering: Maize is one of the first crops to be genetically modified for traits like pest resistance (Bt maize) and herbicide tolerance.
• Bt Maize: Contains genes from Bacillus thuringiensis to resist stem borers
• QPM (Quality Protein Maize):
  • Enriched with lysine and tryptophan
  • Solves protein deficiency in human diet
  • Popular QPM varieties: Shaktiman-1, 2, 3, 4, HQPM-1, 4, 5, 7

Pests and Diseases

Major Insect Pests:

• Stem Borer (Chilo partellus)
• Fall Armyworm (Spodoptera frugiperda) – Recently a major invasive pest
• Shoot fly (Atherigona soccata)
• Cutworm, Aphids, Thrips

Important Diseases:

Integrated Pest Management (IPM) and resistant varieties are key to managing pest and disease pressure.

Nutrient Management

• Nitrogen: 120–150 kg/ha
• Phosphorus: 60–75 kg/ha
• Potash: 40–60 kg/ha
• Zinc Deficiency: Common in maize, correctable with ZnSO₄ @ 25 kg/ha
• Boron Deficiency: Can cause “white bud” and sterility in tassel

Soil Requirement

• Well-drained, fertile loamy soils with good water holding capacity
• Soil pH: Optimal range is 5 to 7.0
• Tolerates slightly acidic to neutral soils
• Waterlogging sensitive

Growth Stages of Maize

• Germination (0–7 days)
• Seedling Stage (7–20 days)
• Vegetative Phase (V1 to Vn)
• Tasseling Stage
• Silking Stage
• Grain Filling Stage
• Physiological Maturity
• Harvesting Stage

Tasseling to silking is the most sensitive period for water and nutrient stress.

Harvesting and Post-Harvest

• Harvesting Time: When the husk turns brown and kernels are hard and shiny
• Moisture Content at Harvest: Around 20%, reduced to 12-13% for storage
• Storage: Airtight containers or gunny bags in moisture-proof stores to prevent pest attack (e.g., Sitophilus or maize weevil)