Seeds are a plant’s way of reproduction. They contain an embryo and food reserves enclosed in a protective seed coat or coats.
Most seeds require the right conditions to germinate. These include proper soil moisture and temperature.
Germination
The germination of seeds is the process by which they transform into a plant. It begins with a stage called imbibition, during which the seed absorbs water and softens and swells.
It also involves the growth of radicles, which will become the primary roots for the seedling. Roots help to supply the plant with water and nutrients while it is growing.
Some plants, however, have no roots and only shoots. These parts of the plant grow upward in search of light and sunlight.
Temperature is another important factor in the germination of seeds. It affects the rate of cellular metabolic and growth rates of the embryo within the seed.
The optimum temperature for most crops is 25-30degC, though some require lower or higher temperatures. Some seeds need to be exposed to cold temperature to break dormancy (vernalization).
Dormancy
Many animals and plants use dormancy as an adaptive strategy to reduce stressors like weather change, food shortages or habitat insufficientness. They are able to do so by lowering their demands for food and water or by making themselves less active.
Dormancy can be defined as a period when a seed is stopped from germinating under certain environmental conditions, which include temperature, light, gas, water, and chemical inhibitors that prevent germination. These conditions may be temporary, lasting from days to months or even years.
Different kinds of dormancy exist, and some are highly advantageous to a plant. For example, dormancy induced by inhibitors in the seed coat is highly beneficial for desert species like legumes.
Perennation
Perennation is the ability of an organism, mainly plants, to stay alive from one germinating season to the next. It usually involves development of a perennating organ (such as a rhizome or tuber) that stores sufficient nutrients to sustain the organism during an unfavourable season and develops into one or more new plants in the following year.
This is important to a plant because it means that it will be able to survive even when the environment becomes unfavourable for it. It also means that it will be able to propagate its young through the formation of a bud or a new shoot.
A number of herbaceous plants have developed belowground perennation structures to cope with frost stress. These structures can protect the plant from freezing temperatures and also provide insulation from snow and litter.
Dispersal
Dispersal is a fundamental life-history stage that allows organisms to reduce competition between kin and to colonize new, suitable habitats. In scenarios of global change, dispersal is especially important because it determines whether organisms can adapt to future changes in their abiotic and biotic environment.
Seed dispersal by animals is a complex process that involves many stages, including the selection of specific fruit species and dispersal vectors, the physical pre-processing of fruits prior to eating, and the deposit of intact seeds or fruit in a viable condition (SS2a-3). The effectiveness of dispersal depends on plant traits that are under environmental control.
For example, plants protect their nutritious fruits against fungus infections or other damage by invertebrates by using secondary compounds that make these fruits less attractive to fruit predators. This protects the seed from being eaten but makes it less attractive to seed dispersers, resulting in reduced seed dispersal success.
