Biology IA 2.docx - Colina 1 Colina 2 Personal Engagement...

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Colina 1
Colina 2Personal EngagementLiving in a city where there are four seasons annually, I wondered if certain temperatures influenced plant growth. How would certain plants be affected by the hot summers and cold winters, and would it be possible to grow plants in both the cold and warm environments? Upon further research, I learned that a seed must first germinate to fully mature into a plant and therefore this investigation will befocused on seed germination. For this investigation, I chose the seeds “Beta Vulgaris” and “Nasturtium Officinale”, more specifically the Detroit Dark Red Beet and the Watercress. These seeds were elected fortheir proposed fast germination time, and their ability to germinate without sunlight.Background InformationThe Detroit Dark Red Beet and the Watercress are angiosperms, as well as dicots. In a dicot seed, there are two cotyledons as well as embryonic leaves, an embryonic shoot, an embryonic root and a seed coat. Before the seed germinates, it undergoes a period of dormancy, “a block to the completion of germination of an intact viable seed under favourable conditions”.1This dormancy can be caused by many factors and a system of the classification of dormancy factors has been created.2Physiological Dormancy (PD) is a common form or dormancy found in angiosperms. There are three levels of PD, PD deep, PD intermediate and PD non-deep. PD deep seeds donot grow, or if they do produce abnormal seedlings. A stratification method, a flocculation of cold and warm temperatures, may be able to break the dormancy. PD intermediate seeds can produce normal seedlings; a stratification method (depending on the species) must be undertaken for dormancy to be broken. PD non-deep seeds produce normal seedlings, and depending on the species, stratification methods greatly increase germination. Morphological Dormancy (MD) is evident in seeds whose embryosare underdeveloped. Rather than being Physiologically dormant, these seeds require time to germinate. Morphophysiological Dormancy (MPD) is where a seed has both a PD and MD dormancy. Along with a stratification method, these seeds require more time to germinate than MD seeds. Physical Dormancy (PY) is caused when water is unable to penetrate the coating of the seed. These seeds will remain dormantunless a factor enables water to penetrate seed coat. A seed will undergo the methods necessary to overcome each dominancy listed in their natural environment, and therefore it is important to then keep seeds in “favourable conditions”. These conditionscan be dependent but are not limited to Temperature, Light, Oxygen and Water3. Oxygen is required for the germinating seeds metabolism. If the seed receives an insignificant amount of oxygen, the seed will not germinate. Temperature is also important for germination. Each seed has an optimal temperature for germination. Plants need light to perform photosynthesis, however depending on the species, light will not affect the germination of a seed.

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