Background informationLight is one of the most important factors in seed germination. Apart from humidity and oxygen, light is known to ease seed dormancy and consequently facilitates the process of seed germination. However, this positive role is not always the case particularly in light independent seeds such as Delphinium. Although light also, plays a significant role in other plant processes like photosynthesis, studies have indicated that it inhibit germination in light-dependent plants. Even so, it’s not clear about the role different wavelength of light plays in the germination of Delphinium seeds. Scientific studies and literature demonstrate that light could affect the process of germination by either activating the processor and acting as an inhibitor. In fact, according to a study by Abdullatee et al. (2011), different aspects of light could differently affect the rate and the process of germination.
Different wavelength determines the type of Light color. While white color represents the shortest wavelength of about 400-700 nm, blue on the other end have a wavelength of about 660nm. Other common colors such as yellow, green and red all have a varying wavelength of 475nm, 510nm and 570 respectively. Since several studies have suggested that light with the longest wavelength (white) significantly influence and increase the rate of photosynthesis, it would be expected that the same would happen it comes to seed germination. However, the matter becomes more complicated when dealing with a plant that germinates under dark light such as Delphinium seeds. It is not clear whether light with short wavelength facilitates seed germination faster compared to those under longer wavelength.
Apart from this concept of different effects of light on photosynthesis, studies evidently show that red light activates seeds from a myriad of plants, lichens, spores and mosses. From the literature, Delphinium seed, germinate under the dark light (Byun et al. 2014). Consequently, many would argue that white light plays an inhibitory role in germination and development of Delphinium seed. Therefore, an experiment of testing the effect of light wavelength on the germination of Delphinium seed would provide useful and essential information on the role of colored light in the process of germination. Most importantly, the results would pave the way for a more productive way of germinating and producing Delphinium plants due to its viable role in the horticultural industry.
Principally, The question that most researchers find hard to answer, however, is whether the difference in colored light in the germination of such seeds results from the effect of wavelength or different activation energy. From the literature, it’s widely accepted that most seeds have different and varying pigments that play a significant role in the germination and both growth and development of plants. Since all colored light including white, green, orange, blue, yellow and purple have different activations levels for the plants, it would be important to assess this level of activation. In this experiment, therefore, dark color would act as the control.
Similarly, it would be important to assess whether wavelength as in the case of red has any possible effects in the germination of Delphinium seed. The objectives of this experiment were, therefore, set with the assumptions that, (1) red light (shortest wavelength) would be expected to activate germination faster compared to other types of lights and (2), different colored light exhibit varying level activation role in the germination of the Delphinium seed.
Research question: What is the effect of different light wavelength (different colors) on the germination of Delphinium seed?
Hypothesis: If various colors have different wavelength with different activation capabilities on Delphinium seed, then the rate and the process of germination for this process would be different under different light colors. Furthermore, just like photosynthesis, colors with varying wavelength differ in the way the influence photosynthesis. It would be expected that various color colored would exhibit different influential abilities to the germination process. Under the same hypothesis, the white color would not be expected to activate any Delphinium seed, and therefore no germination would be expected under this type of light.
Independent variable: Various colored lights used in the experiment
White light, Red light, and blue light and purple light
Dependent variables: The rate of germination; measured as; time is taken for the seed to germinate and the number of seedlings that actually germinate under different light types.
The time it took for every seed to germinate under different colored light
Temperature- experiment performed at standard temperature
Bulb- produced the type of light with similar amount of heat
Plastic spatula utilized in placing the Delphinium seed for germination
Sodium bicarbonate used to produce the amount of carbon dioxide need for photosynthesis
Timer; used to record the number of days, or the time it took for every seed to germinate subjected under different light conditions.
Standard polycarbonate Petri dishes, tap water, towel, trapezoid wires, colored plastic filters, polypropylene film of color; white, blue and Red, yellow and purple,
Delphinium seed plants were counted and placed in standard plastic polycarbonate Petri dishes in preparation for germination. These Petri dishes were placed in most towels to provide moisture need for the process of germination. The entire petri dish together with the moist towel was then placed in a wired trapezoid wires without any lid. The Petri dishes were then covered with Polypropylene film of red, orange, yellow, spring green, sky blue and, pink, purple and clear color. A standard temperature was maintained by a heating system while the light was provided by two fluorescent tubes provided 38 cm above the Petri dishes. The light was then provided or introduced 12 hours followed by another 12 hours of darkness. To check for germinating seeds, the sprouting radicle was used as a point of reference. A regular inspection was done to count the number and the time of germination. The presence of cotyledon was not considered germination.
Some probably sources of errors for this lab experiment was in the concept of distinguishing light elements. Although standard polypropylene film for various colors was used in this experiment, there was no possibility of standardizing the intensity of the color of the material used. Similarly, the use of the white fluorescent tube in itself is questionable because light bulbs have significant difference with the standard sunlight in both light intensity and radiation. Although constant heat or temperature was regulated using a conventional heating system, and a source of water provided by the moist towel, intrinsic factors for germination including seed dormancy, maturity, and seed potential was not considered. Because this project was a home-based project, other variables such as lack of standard heating system and the environment of experiment could have altered the expected results. However, this analysis provided valuable information and skills regarding accuracy and precision, drawing on inferences and subsequently sharpened skills in future experiment or research.
Regardless of the requirement of light or dark color, different colored light affects the rate of germination differently. Some colored light may also greatly influence or hasten germination process even when seed conditions such as dominance are still in play. Therefore, one can accelerate the process of seed germination through various colored light exposure or prolonged, contact of particular colored light. It is not hard to elucidate that improved colored exposure for various seed type could eventually reveal one probably optimum color for efficient germination and production of Delphinium seed.
- Abdullateef, R.A., and Mohamad B.O. “Effects of visible light wavelengths on seed germinability in Stevia rebaudiana Bertoni.” International Journal of Biology 3.4 (2011): 83.
- Byun, A, Mao M., and Randeep S. “The effect of different wavelengths on the germination time of Arabidopsis thaliana wild type and mutant type seeds.” The Expedition 3 (2014).
- Clipsham, M., et al. “Effect of different light wavelengths on the overall growth of Arabidopsis thaliana seedlings.” The Expedition 4 (2015).
- Jala, A. “Effects of different light treatments on the germination of Nepenthes mirabilis.” International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies 2.1 (2011): 083-091.