Germination Essay

803 Words4 Pages
1. Introduction Germination is the process in which we awaken the embryo, increases seed metabolism and toggles the massive reproduction that causes a new plant to grow. The main mechanism that triggers this process is simply liquid water. When water gets into the embryo and hydrates its cells, it speeds up metabolism and allows the process of cell division and growth to rapidly increase. However it is not always simple to start this process since several impairments both chemical and physical – can exist for successful germination (Fernandez, 2010). Seeds are said to be dormant if the seeds fail to germinate after processing and placement in favourable growing conditions. In some dormant seeds morphological changes must take place before germination can start. For others, parts of the seed must undergo physiological changes before germination can occur (Krugman et. al. 1974). Generally, there are two types of dormancy- seed coat dormancy and internal dormancy. Seeds with seed coat dormancy usually have a seed coat that is impermeable to oxygen and/or water. Occasionally the dormancy is caused by an inhibiting chemical in the epidermis or adjacent interior membranes. These seeds remain on or in the ground without germinating under natural conditions. Germinate only when the seeds have weathered sufficiently, to allow penetration of water, exchange of gases, or neutralization of inhibiting chemicals, Seeds of some species germinate only after being subjected to fire. Depends upon the species and the environmental conditions, the length of time involved can be several years or more, (Emery 1987). Internal dormancy is a general term encompassing a number of physiological conditions that delay germination. Not all of these conditions... ... middle of paper ... ...s. Impermeability to water, gas and mechanical constraint of the seed coat are the causes for dormancy of hard seeds. Hard seed percentage can be affected by all of the genetic factors, maternal environment, storage conditions, collecting methods and the degree of maturity, moisture content, size, shape and colour of seeds. The methods for breaking dormancy in hard seeds are generally classified into physical, chemical and biological treatments, which hasten germination by improving seed coat permeability, gas exchange, and water entrance and relieve mechanical constraints. The physical methods include mechanical scarification, low and high temperature, hydration-dehydration, irradiation, high pressure and other physical treatments, and the chemical methods include acid scarification, alkali solution soaking and other organic chemical treatments. (Yang et al, 2006)
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