4. Retention of inhibitors. Seed coat prevent the escape of inhibitors from the seed.
5. Inhibitor production. Seed coat and pericaps may contain relatively high concentration of growth inhibitors
Embryo dormancy refers to a dormancy that is inherent in the embryo and is not due to any influence of the seed coat or other surrounding tissues. It thought to be due to the presence of inhibitors as well as absence of growth promoters. The loss of embryo dormancy is often associated with a sharp drop in the ratio of ABA (inhibitor) and GA (promoter) (Taiz, n.d.). Breaking coat-imposed dormancy seed depens on seed type. Some seeds require a period of cold (chilling), some must pass through animal’s digestive tract to become scarified some must go through process of after-ripening, defined as metabolic changes that must take place in a seed in order for it to overcome dormancy (Environment, n.d.). The most critical factor for seed germination is water. It is essential for enzyme activation, and the use of reserve storage material. In terms of temperature, there is minimum, optimum, and maximum temperature at which germination will occur. Oxygen is required for seed germination, concentration of carbon dioxide higher than 0.03% retard germination, nitrogen gas has no influence (McDonald, n.d.) Seed germination can be divided into three main phases:
1. Activation. This phase starts with imbibition, the uptake of water by the seed and increase in seeds volume. Respiration increases, and various enzymes involved in digestion are manufactured. The cells of the embryo begin to elongate, and the radicle begins to grow.
... middle of paper ...
...rane pulls away from the cell wall. This process called plasmolysis, causes the plant to wilt and can be lethal to the cell and the plant. (pearson) High sodium levels also disrupt the chemi¬cal and physical composition of soil clays. As a result, the soil surface has low permeability to air, rain and irrigation water. The soil is sticky when wet but forms hard clods and crusts upon drying. This type of soil is called sodic soil. (soiltesting) Higher concentration of salt in soil has negative effect on seeds germination, plants growth and plants life span. Unnecessery fertilization, irrigation water with high concentration of salt, over use of salts on our roadways negatively affects agricultural plans on field and also to plants alongside the roads. It’s our responsibility to minimize the effect we have on our environment, keep the diversity of plants we have.
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