Seed a miniature plant in agriculture

Seed is fertilized mature ovule, consisting of embryonic plant, store of food and protective seed coat.  In broad sense seed is a propagated material used in agriculture for planting and regeneration purpose.

Seed is the foundation of agriculture. Technology has modernized much of farming’s day-to-day operations, but without a steady supply of high-quality seed, yields and crop quality would be greatly decreased.

Seed quality plays important role in production of agronomic and horticultural crops. Characteristics such as trueness to variety, germination percentage, purity, vigor, and appearance are important to farmers planting crops.

Achieving and maintaining high seed quality is an ultimate goal of professional seed producer. Thus, Seed is the most vital and crucial input for crop production to increase the productivity without adding appreciably to the extent of land now under cultivation by planting quality seed.

Seed Structures:

Knowledge of seed structure can help in understanding how seeds respond during harvesting, conditioning, germination, and seedling emergence.

Seed can be divided into two major classifications; (This classification is based on number of cotyledons (seed leaves) in a seed)

1. Monocots (monocotyledons)
2. Dicots (dicotyledons)

Monocots contain one cotyledon, whereas dicots have two.

Examples of plant species having monocot seeds are grasses, such as small grains, corn, or turfgrasses and other crops such as onions. Plants with dicot seeds include legumes, such as peas, peanuts, soybeans, and clover. Other crops such as cotton and tobacco.

Basic structures of seed:

Seeds are composed of three basic structures;

1. Seed covering (seed coat or testa)
2. Embryonic axis (embryonic root or radicle and shoot or plumule)
3. Supporting tissues (the cotyledons and endosperm)

Seed coat regulates water uptake by mature seeds. Variations in seed covering characteristics, especially in dicots, often affect the quality of seed when exposed to adverse weather. The embryonic axis normally includes the miniature plant, consisting of the root and shoot.

Cotyledons and endosperm are usually considered supporting tissues. They are useful to the developing plant as a reserve food source through the course of germination and emergence until the plant can make its own food through photosynthesis.

Attributes of Quality seed: 

According to International Seed Testing Association (ISTA).

1. Genetic purity of seed:

2. Physical purity of seed:

Seed should have required level of physical purity in all type of crops.

3. Free form other crop seeds:

Designated inseparable crop seeds are the plants seeds cultivated crops found in the seed fields and whose seeds are similar to crop seed that is difficult to separate them economically by mechanical means, cause physical admixtures with the crop seeds only when these crops mature approximately at the same time when seed crop matures.

Examples: In barley: oats and wheat seeds.

4. Free from objectionable weed seeds:

 These are seeds of weed species which are harmful.

1. 1. The size and shape of weed seeds are similar to the crop seed and difficult to separate them by mechanical means.
   2. Weeds growth habit is determinate type and compete with the crop for all resources.
   3. Weed plant parts are poisonous or injurious to human and animals.
   4. Weed plants also serves as alternative hosts for pests and diseases.

Examples:

Bersem: chicory
Paddy: wild paddy (Oryza sativa var. fatua)
Wheat: Convolvulus arvensis (Hirankuri)

• Free from designated diseases:

 It refers to the diseases specified for the seed certification which may cause contamination of seed lot.

Examples:

Loose smut of wheat (Ustilago tritici),

Kernal smut of sorghum (Sphacelotheca sorghi)

Grain smut of pearl millet (Tolyposporium penicillariae)

• Optimum moisture content:

Benefits of Quality Seeds:

1. The good quality seed has high return per unit area as the genetic potentiality of the crop can be fully exploited.
2. Less infestation of land with weed seed/other crop seeds.
3. Less disease and insect problem.
4. Minimization of seed/seedling rate i.e., fast and uniform emergence of seedling.
5. They are vigorous, free from pests and disease.
6. They can be adopted themselves for extreme climatic condition and cropping system of the location.
7. The quality seed respond well to the applied fertilizers and nutrients.
8. Uniform in plant population and maturity.
9. Handling in post-harvest operation will be easy.

Conclusion:

Quality seed improve agriculture and agrarian societies. Seed quality can be used as scared. Crop status depends on seed material and good seed in good soil have optimum germination and yields abundantly.

Response of other treatments depend on seed material. Seed quality has been treated as sacred, being an important factor in the improvement of agriculture and agrarian societies.

Authors: Ehsan Khalid* and Faryal Fatima

Seed Physiology Lab, Department of Agronomy, University of Agriculture, Faisalabad-38040, Pakistan