Seed Germination

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Introduction: Seed germination is a process where the quiescence seed imbibed with water, the seed radical elongates and breaks through the seed coat surrounding the embryo. However, most of the plant seeds do not germinate immediately and they under goes period of dormancy. These dormant seeds are normally dehydrated, containing inactive enzymes and resistant to unfavorable condition. These characteristic allowed the seed to be dispersed before germination occur and survive adverse environmental condition such as drought. In order for a seed to break its dormancy, optimum conditions were required for seed to germinate. There are three important conditions for seeds to germinate: suitable temperature, sufficient water supply, and also satisfactory level of oxygen. Water supply is important as it is used to rehydrate the seed tissues and induce breakage of the seed coat which posted as a physical barrier for radical to elongate (Debeaujon et al., 2000). Besides that, oxygen is also an essential element for seed germination because aerobic respiration of the seed tissues produces energy, ATP, which is required for further development of embryo. The optimum temperature for potential seed germination varies on plant species but it is one of the important factors that affect seed germination. Factors such as light and hormones also contribute in seed germination process. The exposure of light is critical for certain plant seeds to germinate, furthermore, light have an indirect effect to the surrounding temperature. Hormones are important as they signal the production of enzyme in seed to perform process such as mitotic division, degradation of cell wall, and cell differentiation. Thus, the aim of this experiment is to investigate the effect of light, planting depth and hormones on seed germination. Materials and Methods: In section A, effect of light on seed germination was studied. The materials used in section A was 100 lettuce seeds, 100 green beans, 4 Petri dishes, cotton wool, and 4 filter papers. 2 Petri dishes were labeled as water + light (LS) and water + dark (LS). The other 2 Petri dishes were labeled as water + light (GB) and water + dark (GB). All the Petri dishes were placed with filter paper that was moistened by 2mL of water. Then, 5mL of water is used to moisten the cotton wool which was placed on top of all the Petri dishes. 50 lettuces seeds were placed to each Petri dish that was labeled LS and 50 green beans were placed to each Petri dish that was labeled GB.
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