A seed is the initial capital of a plant and has the functions of perpetuation, multiplication and dissemination, which are vital to the plant species lacking vegetative propagation. All flowering plants may not bear seeds, all seed-bearing plants may not produce new plants from their seeds and all seeds, which bear on mother plant, may not produce new plants. The weight of each seed varies from less than a milligram as in tobacco to a few grams as in beans of castor. Sizes depend mostly on the form of the ovary, the location of the seed and fruit on the mother plant, the conditions under which the mother plant is growing, specially during the developmental stage of the seed and the genetic character of the plant. Seeds may remain viable both in soil and in the storehouse for years. A seed consists of three main parts:
- Embryo which in due course gives rise to the new plant;
- Endosperm or the storage tissues which contain the substances the nourish the embryo during its development prior to and for sometime after germination; and
- Seed coat or a protective covering which shields the embryo and endosperm.
Quality seed ensures a uniform crop establishment with uniform vigour and population of seedlings per unit area of the field. The selection of good seeds is of prime importance for raising crops and reaping a rich harvest. A quality seed should possess the following characteristics.
The seeds should be of adaptable crop variety or hybrid and their duration should be according to the agro-climate and cropping systems of the locality;
The seeds should be pure (true or false), with high sowing quality (viable seeds that germinate rapidly to give rise to strong and vigorous seedlings under normal conditions), good yield potential, evenness in growth pattern and maturity and should meet the purpose of cultivation;
The seeds should be free from seed-borne diseases and physiological disorders due to deficiency of plant nutrients or blonding or bleaching due to adverse weather conditions during seed development or in the post maturity period respectively.
The seed should be large (depending upon variety), plump, bold, uniform in size, shape, colour, texture, development and of proper test weight; the seed should be clean and free from inert matter such as crushed rock, dirt, grit, chaff and trash, as well as from adhered soil, sticky substances such as pulp or the juice of the fruit;
The seed should be free from noxious or objectionable weed seeds;
The seed should be free from insects, insect eggs, disease spores etc., in or on the seeds;
The seed should be whole, not broken, crushed, peeled off, half filled, half rotten or affected with damp;
The seed should be as fresh as possible or of the proper age;
The seed should contain a required amount of moisture.
The location of the seeds in the cobs, earheads, panicles and capsules as well as the location of fruiting bodies such as factors in the formation of different quality seeds. The germination of seeds depends upon their natural pecuffarities and biological conditions. For many types of seeds additional time is required to complete the post-harvest maturation process. With a more prolonged dry storage, seed germination falls sharply and in some cases no germination occurs.
Ag.
Technologies
(Seeds)
