Certified Seeds

Certified Seed: Certified seed is produced from foundation, registered or certified seeds. This is so known because it is certified by a seed certification agency, in this case State Seed Certification Agency, to be suitable for raising a good crop. The certified seed is annually produced by progressive farmers according to standard seed production practices. To be certified, the seed must meet the prescribed requirements regarding purity and quality. These standards vary from one crop to another.

Requirements of certified seed: Seed has to meet certain rigid requirements before it can be certified for distribution. The first and foremost requirement is that the seed must be of an improved variety released by either the Central or a State Variety Release Committee for general cultivation and notified by the Ministry of Agriculture, Government of India; this is essential for the seed to be certified. The other requirements are related to genetic purity, freedom from weeds, diseases and pests, germination, etc. The various requirements for certified seeds are summarized in the table for some of the field and vegetable crops. It may be noted that there is considerable variation in the requirements for certification in various crops. In certain cases, e.g., maize (Z.mays), the requirements are more rigid than in the others. These requirements are briefly described below.

Genetic Purity: Genetic purity means the absence of seeds of other varieties of the same crop species as well as of other crop species. Genetic purity ensures that the seed is of the variety under certification, and that there is no mixture from other varieties or other crops. The standard of genetic purity is very high; the amount of contamination permitted ranges from 0-0.1 per cent. In most of the cases, contamination by seeds of other crop species is permitted to a small degree (up to 0.1 per cent), but contamination by seeds of other varieties of the same crop is generally not permitted

Physical Purity: Physical purity implies freedom of seed from inert matter and defective seed. Inert matter consists of nonliving material such as sand, pebbles, soil particles, straw, etc. Defective seeds are those seeds that are broken, diseased, insect infested, shrivelled and unfit for germination. A broken seed larger than half of the normal seed is not considered defective provided the embryo is not damaged. The total amount of permissible contamination by inert matter and defective seed ranges from 1.0 per cent in the case of maize ( Z. mays) to 5 per cent in the case of carrot.

Germination: A high percentage of germination is necessary to obtain a good crop stand with the minimum amount of seed. The percentage of germination required for certification is high in a crop like maize (90%), moderate in several others e.g., jowar (80%), wheat (85%), rice (80%), etc. and relatively low in many others, e.g. cauliflower (65%), bhindi (65%), carrot (60%) and chillies (60%). Thus the minimum standard of germination of seed certification varies considerably from one crop to the other.

Freedom from Weed Seeds: Freedom from weed seeds is necessary to prevent weeds from spreading through seed and to reduce losses caused by weeds. The maximum amount of weed seeds permitted is very low; it varies from zero per cent in crops like maize (Z.mays) and tomato (L.esculentum) to 0.2 per cent in cauliflower (B.oleracea), onion (A.cepa), carrot (D.carota) etc. For some crop species, some weeds are classified as objectionable or noxious weeds. In such crops, the certified seed is required to be free from seeds of the noxious weed species.

Freedom from Diseases : The certified seed must be free from seed-borne diseases. If the seed is contaminated with pathogens, it is likely to lead to an epidemic and a total loss of the crop. The presence of seed-borne pathogens is prevented in two ways; first, by effective control of diseases in the standing crops, and second, by treating seeds with disinfectants and protectants. The maximum permissible frequently of diseased seeds is given in the table.

Optimum Moisture Content: The seeds must be dried to an optimum moisture level for efficient processing and safe storage. The level of optimum moisture varies from one crop species to another. It varies from 13 per cent in case of rice to 7 per cent in the case of cauliflower and watermelon (C.vulgaris). A moisture content higher than the recommended level

1. leads to a loss in seed viability

2. promotes growth of microorganisms, particularly moulds,

3. favours attacks by storage insect pests,

4. increases the chances of damage to seeds by fumigants, and

5. interferes with processing because damp seeds tend to stick together.

Table: Germination and purity standard for certified seeds of different crops.