Plant Reproduction and Germination

Germination is the process by which a seed develops into a new plant. The embryo within the seed resumes growth under favorable conditions, using the stored food in the seed. Pollination is the transfer of pollen, cleavage refers to cell division in early embryos, and fertilization is the fusion of gametes.

Dicotyledons (dicots) are plants with two seed leaves (cotyledons) in their embryos. This distinguishes them from monocotyledons (monocots) which have only one seed leaf. Common examples include beans, peas, and most trees.

 Angiosperms are further divided based on the number of cotyledons that form the seed.

 Reason: The practice of growing four to five fish species in a single fish pond is known as composite fish culture. In such systems, these species are selected so that there does not exist any competition for food among them having different types of food habits. E.g. catlas are surface feeders, rohus feed in the middle zone of the pond, mrigals and common carps are bottom feeders and grass carps feed on the weeds. These species when together can use all the food in the pond without competing with one another. This increases the fish yield from the pond. One problem with such composite fish culture is that many of these fish breed only during monsoon. Even if fish seed is collected from the wild, it can be mixed with that of other species as well. So, a major problem in fish farming is the lack of availability of good quality seed. To overcome this problem, ways have been worked out to breed these fish in ponds using hormonal stimulation. This has ensured the supply of pure fish seed in desired quantities. Change in food habits will not work as already the fishes selected for composite farming have different food habits. Therefore, improving their feed will also not help in getting pure fish seed. Satellites and echo-sounders are used to locate large school of fish in the open sea.

Seeds should be properly moistened before sowing.

Seed cover protects the embryo and cotyledons. It provides the necessary food energy until roots and true leaves are formed.

Wheat is a monocotyledonous plant as its seeds contain only one cotyledon.

Mustard seeds are exalbuminous dicot seeds.

In albuminous or endospermic seeds, endosperm is present and the cotyledons are thin and membranous.

Coleoptile is a sheath present in the seeds of monocots and it protects the plumule as it grows out of the soil.

Endosperm of the seed is a special food storing tissue.

A single cotyledon is present in a maize grain and is called scutellum.

The outer covering of bean seed is called testa. It protects the embryo from any injury.

In dicot seeds, plumule is large and its leaves are folded.

If the hypocotyl elongates rapidly, comes above the soil and cotyledons are pushed above the soil, it is called epigeal germination.