SEED QUALITY

Definition of Seed

A seed is a basic agricultural input. Biologically, it is a living organism (an embryo) embedded in supporting or food storage tissue.

Multiple Definitions:

• A ripened/fertilized mature ovule containing an embryo.
• A dry dispersal unit developed after fertilization.
• Any plant part/organ capable of regenerating into a new plant.
• A propagule maintaining intrinsic/genetic qualities of a variety/hybrid.
• A living embryo + food storage tissue + protective coat.
• Any propagative material.
• A miniature or dormant plant.
• A link between two generations.
• A carrier of service material.
• The generative part of a plant that develops into a new plant.

Widely Accepted Definition: A mature ovule consisting of an embryonic plant, a store of food, and a protective coat.

As per Seed Act (1966), seed includes:

• Seeds of food crops, edible oilseeds, fruits & vegetables
• Cotton, jute, and cattle fodder seeds
• Vegetative propagules: seedlings, tubers, bulbs, rhizomes, roots, cuttings, grafts (for food crops or cattle fodder)

Differences Between Seed and Grain

Importance of Seed

Seed is vital because it allows investment in other inputs (fertilizer, pesticide, irrigation) to be realized.

Four Key Roles:

1. Carrier of new technologies: In India, HYVs increased food production from 52 to >200 million tonnes in 50 years.
2. Basic tool for secured food supply: HYVP reduced food imports despite rapid population growth.
3. Principal means to secure yields in less favorable areas: Good quality seeds of suitable varieties immediately improve yields.
4. Medium for rapid rehabilitation after natural disasters: National Seed Reserve Stocks provide seeds for emergency resowing after floods/droughts.

Seed Quality: Definition & Major Components

Definition: Seed quality is the possession of seed with required genetic and physical purity accompanied by physiological soundness and health status.

Quality Components of Seed

1. Physical Quality

• Seeds should be clean and free from impurities.
• Free from other crop seeds, weed seeds, debris, and inert matter.
• No diseased or insect-damaged seeds.
• Uniform in size, shape, weight, and color.
• Free from stones, dust, leaves, twigs, shriveled, molded, or discolored seeds.
• Achieved by: Proper cleaning and grading after collection and before storage/sowing.

2. Genetic Purity

• Seeds must be true-to-type.
• Plants should resemble their parent variety.
• Maintain characteristics like yield, resistance, and quality traits.
• No mixing of varieties.
• Achieved by: Maintaining variety identity during seed multiplication.

3. Physiological Quality

• Refers to seed performance in the next generation.
• Includes germination ability (normal seedling production).
• Includes seed vigour (strength and rapid growth).
• Determines field emergence and crop establishment.
• Achieved by: Selecting mature seeds and proper care during extraction, drying, and storage.

4. Seed Health

• Seeds should be free from pests and diseases.
• No fungal, bacterial, or insect infestation.
• Should have good storage condition (no deterioration).
• High vigour indicates good health.
• Achieved by: Proper production, handling, and storage practices.

Key Relationships:

• All viable seeds need not be germinable, but all germinable seeds are viable.
• All vigorous seeds are germinable, but all germinable seeds need not be vigorous.

Characteristics of Good Quality Seed

A quality seed should have:

High genetic purity:

• Breeder/Nucleus: 100%
• Foundation seed: 99.5%
• Certified seed: 99.0%

High physical purity:(e.g., Maize/Bhendi: 99%; Most crops: 98%; Carrot: 95%; Groundnut: 96%)

• Good shape, size, color according to variety specifications
• High physical soundness and weight
• High germination (90% to 35% depending on crop)
• High physiological vigour and stamina
• High storage capacity (longevity/shelf life)
• Optimum moisture content: Long-term storage (6-8%); Short-term storage (10-13%)
• Free from other crop seeds (expressed as number/kg) Example inseparable seeds:Barley – Wheat, oats, gram; Wheat – Oats, gram, barley
• Free from objectionable weed seeds (harmful due to similar size, competition, toxicity, or as pest hosts) Examples:Berseem – Chicory; Wheat – Convolvulus arvensis; Paddy – Wild paddy
• Free from designated diseases (e.g., Loose smut of wheat – isolation distance Examples:Wheat – Loose smut; Sorghum – Grain smut; Mustard – Alternaria blight; Potato – Brown rot
• High market value

6. Role & Significance of Quality Seed

• Role:Certification guarantees quality, ensuring high and assured yield even under environmental stress. Efforts must focus on increasing area under quality seed production.

Significance:

• Ensures genetic and physical purity
• Gives desired plant population
• Withstands adverse conditions
• Produces vigorous, fast-growing seedlings that resist pests/diseases
• Ensures uniform growth and maturity
• Efficient root system for better nutrient absorption → higher yield
• Responds well to fertilizers and other inputs
• Guarantees at least 10-12% higher yield from improved varieties

• Seed Multiplication Concepts

Multiplication Stages for Major Crops (BS – FS – CS):