eChapters

The important events involved in seed development and maturation include

• Pollination
• Fertilization
• Development of the fertilized ovule by cell division
• Accumulation of reserve food material
• Loss of moisture content

• The seed production of varieties and hybrids should be carried out carefully by following various techniques in the region where they are well adopted.
• The various factors affecting quality seed production includes,
  1. Agro climatic factors / Ecological factors - edaphic and climatic factors
  2. Production factors
  3. Post harvesting handling of seed
  4. Seed quality control factors

Seed Processing

Seed processing may be understood to comprise all the operations after harvest that aim at maximizing seed viability, vigour and health. It includes cleaning, drying, seed treatment, packaging and storage.

Seed Packing

Seed packaging is the process of filling, weighing and sewing of bags with seed. The choice of packaging materials and amount of seeds to be packed depends on kind of seeds to be packed, duration of storage, storage environment, the seed moisture content, the cost of seed, the cost of packaging material, the geographical area where the seeds will be stored.

Seed certification

It is a legally sanctioned system for quality control and seed multiplication and production. It involves field inspection, pre and post control tests and seed quality tests. As per Indian Seed Act seed certification is voluntary and it is not compulsory. The seed that is sold in the market is of two types certified seed or truthfully labelled seed. Whereas truthfully labelled seed is one which is being produced and marketed by the producing company by maintaining the labelling standards.

Harvesting is one of the agronomic management practices that require technical knowledge on maturation of the crops. This knowledge is much important in seed production than in commercial production.

Physiological maturation

• It is the stage of accumulation of maximum dry matter within the seeds. The moisture content of the seed at this stage will be in decreasing order (25-30%) and is expressed with maximum dry weigh of seed, germination and vigour potential. The physiological maturation is represented for individual seed and this maturation will not be the same for the population, due to differential flowering habit.
• The attainment of physiological maturation is represented by sigmoid curve of growth pattern. The physiological maturation can be represented both as duration and visible symptoms.

Removal of seeds from dry fruits is known as threshing while that of wet fruits is known as extraction. Threshing involves beating or rubbing the plant material to detach the seed from its pod or fruit. The detached seed is then winnowed to remove chaff, straw and other light material from the seed.

Threshing / extraction methods

1. Mechanical threshing

• Various types of threshing machines with adjustable cylinder speeds are available for extraction of vegetable seeds.
• Care must be taken to avoid damage to the seed during mechanical threshing, by properly adjusting the speed of the beaters, the width of the gap between the beaters and the concave, the airflow and the sieve sizes.

Seed sampling

Seed sampling is to draw a portion of seed from seed lot that represents the entire seed lot. Seed lot is a uniformly blended quantity of seed either in bag or in bulk.

Purity analysis

Purity of a seed lot indicates in percentage how large a fraction is made up of pure seeds of the species in question, and how much is made up of inert matter and other seeds. Impurities may be any non seed material (leaf, flower, fruit fractions, soil etc.), small fractions of seeds of the actual species, as well as seeds of other species. Pure seed may include both dead and empty seed, plus damaged seed, purity does not tell anything about viability. The purity analysis of a seed sample in the seed testing laboratory refers to the determination of the different components of the purity viz., pure seeds, other crop seeds, weed seeds and inert matter. Each component is reported as a percentage of total weight. The objective of the purity analysis is to determine whether the submitted sample conforms to the prescribed physical quality standards with regard to physical components. Large seeds are generally easy to clean and purity analyses are therefore often omitted. However, for smaller seeds contamination with other seeds may occur e.g., during processing.

Seed germination

It is defined as the emergence and development from the seed embryo, of those essential structures, for the kind of seed in question, indicates its ability to produce a normal plant under favourable conditions. The seedlings devoid of an essential structure; showing weak or unbalanced development; decay or damage affecting the normal development of seedling are not considered in calculating the germination percentage.

Seed viability tests

Only two methods, the Topographical tetrazolium (TZ) test and the embryo excision test were previously accepted by the International Seed Testing Association as official methods for some species of seeds. ISTA has recently accepted the X-ray method as a valid alternative to the cutting test for the detection of empty and insect-damaged seeds. The following tests can be applied depending on the circumstances.

Part I - Preliminary

1. Short title: These rules may be called the Seeds Rules, 1968
2. Definitions: In these rules, unless the contest otherwise requires.

Preliminary

1. Short title and extent

1. This Order may be called the Seeds (Control) Order, 1983
2. It extends to the whole of India
3. It shall come into force on the 30th December, 1983

A bill to provide for regulating the quality of seeds for sale, import and export and to facilitate production and supply of seeds of quality and for matters connected therewith or incidental thereto. Be it enacted by Parliament in the Fifty-Fifth Year of the Republic of India as follows

Introduction

The seed industry has witnessed a substantial change in the 20th century, with farmers relying on purchasing seeds from market with better traits rather than relying on seeds from previous season’s harvest. Developments in seed technology have increased the momentum of the industry’s growth, and the introduction of genetically modified crops has further boosted the seed market. The value of global seed market has tripled since 2000 and reached US$ 54 billion in 2014 (Indian Seed Market (pdf), www.icfa.org.in).

Seed Health Testing

Science of determining the presence or absence of disease causing agents such as fungi, bacteria and viruses and insects in the seed samples.

Seed Borne disease

The seed primordial or the maturing seed may be infected either (i) directly from the infected plant through the flower or fruit stalk and the seed stalk or directly from the seed surface, or (ii)infection from outside may be introduced through stigma or ovary wall or pericarp, and the flower or fruit stalk, and later through the seed coat. A pathogen may penetrate several of these parts of the seed and in turn infect them. The infestation /contamination of the seed may occur during harvesting, threshing and processing. Visualizing the importance of seed borne diseases the Central Seed Certification board has prescribed certification standards for foundation and certified seed for several diseases.

The pathogen may carry with the seeds in three ways.

• Admixture: Pathogens are independent of seeds but accompany them. They are mixed with health seeds during threshing.
• External:The pathogen may be present on seed surface as spores, oospores and chlamydospores.
• Internal: Pathogens establish within the seed with definite relationship with seed parts.

An Act to provide for regulating the quality of certain seeds for sale, and for matters connected therewith. It enacted by Parliament in the Seventeenth Year of the Republic of India.

1. Short Title, Extent and Commencement

• This Act may be called the Seeds Act, 1966.
• It extends to the whole of India.
• It shall come into force on such date as the Central Government may, by notification in the Official Gazette, appoint, and different dates may be appointed for different provisions of this Act, and for different States or for different areas thereof.

Aims and Objectives

It has become evident that in order to achieve the food production targets of the future, a major effort will be required to enhance the seed replacement rates of various crops. This would require a major increase in the production of quality seeds, in which the private sector is expected to play a major role. At the same time, private and Public Sector Seed Organisations at both Central and State levels, will be expected to adopt economic pricing policies which would seek to realise the true cost of production. The creation of a facilitative climate for growth of a competitive and localised seed industry, encouragement of import of useful germplasm, and boosting of exports are core elements of the agricultural strategy of the new millennium.

Biotechnology will be a key factor in agricultural development in the coming decades. Genetic engineering/modification techniques hold enormous promise in developing crop varieties with a higher level of tolerance to biotic and abiotic stresses. A conducive atmosphere for application of frontier sciences in varietal development and for enhanced investments in research and development is a pressing requirement. At the same time, concerns relating to possible harm to human and animal health and bio-safety, as well as interests of farmers, must be addressed.

Globalization and economic liberalization have opened up new opportunities as well as challenges. The main objectives of the National Seeds Policy, therefore, are the provision of an appropriate climate for the seed industry to utilize available and prospective opportunities, safeguarding of the interests of Indian farmers and the conservation of agro-biodiversity. While unnecessary regulation needs to be dismantled, it must be ensured that gullible farmers are not exploited by unscrupulous elements. A regulatory system of a new genre is, therefore, needed, which will encompass quality assurance mechanisms coupled with facilitation of a vibrant and responsible seed industry.

Seed marketing is one of the most vital components of seed technology. Broadly, it includes such activities as production, processing, storage, quality control and marketing of seeds. In the narrow sense, however seed marketing refers to the actual acquisition and selling of packed seeds, intermediate storage, delivery and sales promotional activities. Seed marketing comprises the following:

1. Demand forecasts (assessment of effective demand)
2. Marketing structure
3. Arrangements for storage of seeds
4. Sales promotional activities
5. Post-sales service
6. Economics of seed production and seed pricing

Heterosis

The superiority of F₁ hybrid over both its parents in terms of yield or some other characters or heterosis is increased vigours, growth, yield or function of a hybrid over the parents, resulting from crossing of genetically diverse organisms. The term heterosis was first coined by Shull in 1914. Generally heterosis manifested as an increase in vigour, size, growth, yield or some other characteristics. But in some cases, hybrid may be inferior to the weaker parent this is also regarded as heterosis.