Lettuce Seed Germination Lab
The Role of Phytochrome in Lettuce Seed Germination
Abstract
This experiment was performed to determine the role of phytochrome in lettuce seed germination. In order to conduct this experiment three different types of Grand Rapids lettuce seeds were chosen: Waldmann, Concept, and Two Star. Each of these seeds were exposed to the following regulated courses of light exposure for ten minutes after they had imbibed for five minutes: Red, White, Far Red, and Darkness. It was hypothesized that the seeds would germinate in both red and white light, but germination would not take place under far red light or darkness. The results were that exposure to the white light produced the highest percentage of germination rates in the Waldermann variety of lettuce seed followed by exposure to the red light. Neither the concept nor the two star lettuce seed germinated. As suspected, the seeds that were exposed to darkness produced the percentage of germination. The far red light also failed to produce any germination in the Waldermann …show more content…
variety of lettuce seed. With the seeds germinated, the hypothesis was met in that the white light generated the highest percentage of germination and darkness caused no germination.
Introduction
The purpose of this experiment was to determine what role phytochrome in lettuce seeds would play when exposed to different types of light. Exposure to light is necessary to the growth of plants. In addition to detecting light, plants are also aware of the lights intensity, wavelength, and direction. All of these factors add to the form and structure of the plant. Phytochrome, which is a type of chromophore, is important in determining the plants ability to control light responses. A phytochrome is a type chromophore that responds to red and far-red light by interconverting between its two forms, Pr and Pfr. The Pr form is sensitive to red light, while the Pfr form is sensitive to far-red light (McRae 2013).
Materials and Methods
Three varieties of Grand Rapids lettuce seeds were used to test the role of phytochrome in seed germination: Waldmann, Concept, and Two Star.
A total of four petri dishes were removed in the dark, using only a green safelight. They were then labeled with the variety of seed, group name or initials, the date, and the light treatment. Filter paper was added to each pert dish and then 2-3 dropperfuls of water were added to each plate so that the filter paper was very moist for germination. Then 25 lettuce seeds were placed into each dish. The light regimens were White, Red, Far-Red, and Darkness. Each dish was exposed to their labeled light regimen for 10 minutes. They were kept level and wrapped in foil immediately after exposure. After 48 hours, the seeds were revisited and the total number of seeds germinated in each dish was determined, then figured into a percentage. All the information was gathered together and put into
graph.
Results
After forty 48 hours of exposure had passed, the results were viewed. Two Star and Concept varieties had no germination under any type of light. Waldmann was the only variety of seed to germinate. The total number of germinated seed in each category was divided by the total number of seeds in each variety under each light at the time of the experiment. Then, this number was multiplied by one hundred. This was done to determine the percentage of germination. This was the formula used to calculate the percentage of germination: [(Number of seeds germinated/ total number of seeds) x 100]. The percentages of germination were both in the Waldmann category. Red light germination was 3.6% and white light germination was 7.1%.
Discussion
Three varieties of Grand Rapids lettuce seeds were used to determine phytochrome’s response to different light exposures: Waldmann, Concept, and Two Star. The hypothesis was supported by the conclusion the experiment when the evidence of the Waldmann variety produced germination in both white and red light. Neither the Concept or the Two Star variety produced and germination in any type of light. There were many different factors that could have played a role in the lack of production including how the seeds were produced, how the seeds were stored, who handled the seeds, what light the seeds had been exposed to previously, the amount of water in each dish, etc. Researchers have found that flowering and other responses to photoperiod are controlled by night length, not day length. These researchers found that if the light portion of the photoperiod is broken by a brief exposure to darkness, flowering proceeds. However, if the dark part of the photoperiod is interrupted by even a few minutes of dim light, short-day plants will not flower (Reece et al 2014). This might explain what happened in the experiment with bot the Concept and Two Star producing no germination.
Works Cited
McRae J., Sparace K. Biology 102 Lab Manual. Pendleton (SC): Tri-County Technical College
Press.
Reece, J.B., Urry, L.A., Cain, M.L., Wasserman, S.A., Minorsky, P.V., Jackson, R.B. 2014. Cambell Biology, 10th Edition, Pearson Education Inc, San Fransisco, CA. pp 851-854.
Abstract
This experiment was performed to determine the role of phytochrome in lettuce seed germination. In order to conduct this experiment three different types of Grand Rapids lettuce seeds were chosen: Waldmann, Concept, and Two Star. Each of these seeds were exposed to the following regulated courses of light exposure for ten minutes after they had imbibed for five minutes: Red, White, Far Red, and Darkness. It was hypothesized that the seeds would germinate in both red and white light, but germination would not take place under far red light or darkness. The results were that exposure to the white light produced the highest percentage of germination rates in the Waldermann variety of lettuce seed followed by exposure to the red light. Neither the concept nor the two star lettuce seed germinated. As suspected, the seeds that were exposed to darkness produced the percentage of germination. The far red light also failed to produce any germination in the Waldermann …show more content…
variety of lettuce seed. With the seeds germinated, the hypothesis was met in that the white light generated the highest percentage of germination and darkness caused no germination.
Introduction
The purpose of this experiment was to determine what role phytochrome in lettuce seeds would play when exposed to different types of light. Exposure to light is necessary to the growth of plants. In addition to detecting light, plants are also aware of the lights intensity, wavelength, and direction. All of these factors add to the form and structure of the plant. Phytochrome, which is a type of chromophore, is important in determining the plants ability to control light responses. A phytochrome is a type chromophore that responds to red and far-red light by interconverting between its two forms, Pr and Pfr. The Pr form is sensitive to red light, while the Pfr form is sensitive to far-red light (McRae 2013).
Materials and Methods
Three varieties of Grand Rapids lettuce seeds were used to test the role of phytochrome in seed germination: Waldmann, Concept, and Two Star.
A total of four petri dishes were removed in the dark, using only a green safelight. They were then labeled with the variety of seed, group name or initials, the date, and the light treatment. Filter paper was added to each pert dish and then 2-3 dropperfuls of water were added to each plate so that the filter paper was very moist for germination. Then 25 lettuce seeds were placed into each dish. The light regimens were White, Red, Far-Red, and Darkness. Each dish was exposed to their labeled light regimen for 10 minutes. They were kept level and wrapped in foil immediately after exposure. After 48 hours, the seeds were revisited and the total number of seeds germinated in each dish was determined, then figured into a percentage. All the information was gathered together and put into
graph.
Results
After forty 48 hours of exposure had passed, the results were viewed. Two Star and Concept varieties had no germination under any type of light. Waldmann was the only variety of seed to germinate. The total number of germinated seed in each category was divided by the total number of seeds in each variety under each light at the time of the experiment. Then, this number was multiplied by one hundred. This was done to determine the percentage of germination. This was the formula used to calculate the percentage of germination: [(Number of seeds germinated/ total number of seeds) x 100]. The percentages of germination were both in the Waldmann category. Red light germination was 3.6% and white light germination was 7.1%.
Discussion
Three varieties of Grand Rapids lettuce seeds were used to determine phytochrome’s response to different light exposures: Waldmann, Concept, and Two Star. The hypothesis was supported by the conclusion the experiment when the evidence of the Waldmann variety produced germination in both white and red light. Neither the Concept or the Two Star variety produced and germination in any type of light. There were many different factors that could have played a role in the lack of production including how the seeds were produced, how the seeds were stored, who handled the seeds, what light the seeds had been exposed to previously, the amount of water in each dish, etc. Researchers have found that flowering and other responses to photoperiod are controlled by night length, not day length. These researchers found that if the light portion of the photoperiod is broken by a brief exposure to darkness, flowering proceeds. However, if the dark part of the photoperiod is interrupted by even a few minutes of dim light, short-day plants will not flower (Reece et al 2014). This might explain what happened in the experiment with bot the Concept and Two Star producing no germination.
Works Cited
McRae J., Sparace K. Biology 102 Lab Manual. Pendleton (SC): Tri-County Technical College
Press.
Reece, J.B., Urry, L.A., Cain, M.L., Wasserman, S.A., Minorsky, P.V., Jackson, R.B. 2014. Cambell Biology, 10th Edition, Pearson Education Inc, San Fransisco, CA. pp 851-854.