The purpose of this experiment is to determine how varying levels of light and kinetin affect the growth of Bibb lettuce in a microgravity environment. The project is significant because in order to live long-term in space, it is necessary to understand what effects microgravity has on plants, how to counter negative effects, and to be able to produce healthy and productive plants.
For this project, there are five different kinetin levels being used. The results show the different kinetin levels under a light intensity of 80 milliwatts. Each kinetin group contains 18 plants, for a total of 90 plants. Plants were germinated in mixtures containing 0%, 25%, 50%, 75%, and 100% kinetin.
The clinostat is a rotating wheel. It rotates slowly and, in doing so, disorients the plants, making it difficult for them to detect the direction of gravity. Stem length, leaf broadness, and leaf color were measured weekly.
It was hypothesized that plants exposed to an elevated level of kinetin will account for a higher leaf color, broader leaves, and less vertical growth. An electronic digital caliper was used to measure stem lengths and leaf broadness. A color chart was created to identify the color of the leaves. A z-test was conducted after collecting final data. In conclusion, the first hypothesis was rejected, the second cannot be determined at the present and the third hypothesis was accepted.
The purpose of this experiment is to optimize the growth of Bibb lettuce in a microgravity environment.
The project is significant because in order to be able to live long-term in space, it is necessary to understand what affects microgravity has on plants, how to counter negative effects, and to be able to produce healthy and productive plants.
H0: Exposure to various levels of kinetin will have no significant difference in growth compared to the control.
H1: Exposure to an elevated level of kinetin will account for a higher leaf color.
H2: Exposure to an elevated level of kinetin will account for broader leaves.
H3: Exposure to an elevated level of kinetin will account for less vertical growth.
H0: Exposure to various levels of light will have no significant difference in growth compared to the control.
H1: Exposure to an elevated level of light will account for a higher leaf color.
H2: Exposure to an elevated level of light will account for broader leaves.
H3: Exposure to an elevated level of light will account for less vertical growth.
Photosynthesis
Photosynthesis is the process of using light energy to convert carbon dioxide and water into glucose and oxygen. The formula for photosynthesis is 6CO2 + 12H2O + Light Energy C6H12O6 + 6O2 + 6H2O, which means that six carbon dioxide molecules plus twelve water molecules combined with light energy produce a molecule of sugar, six molecules of oxygen, and six molecules of water. Photosynthesis occurs in the chloroplasts of the plant cell. During the process of photosynthesis, the plant releases oxygen, a vital element in life processes. As long as a plant receives its required amount of light, it should produce plenty of oxygen.
Microgravity
Microgravity is not the absence of gravity; it is simply any environment with gravity less than that of Earth’s. However, microgravity doesn’t just exist outside of Earth. On Earth, it is possible to create brief instances of microgravity. When roller coasters move in a steady up and down movement (parabolas), they give you a few seconds of microgravity. This is the same concept used to create the “Vomit Comet.”
Plants in Microgravity
One of the main affects of microgravity is the orientation of the roots and shoots of the plants. Microgravity confused the plant by not allowing it to detect where gravity is coming from. Very little is actually known about the extent of microgravity’s effects due to our current inability to create long-term microgravity conditions on Earth.
Microgravity Simulation and the Clinostat
A common instrument used to simulate microgravity is the clinostat. The clinostat is essentially a rotating wheel that contains compartments for plants. By rotating, it disrupts the plant’s sense of gravity (gravitropism), a effect similar to that of an actual microgravity environment.
Terraformation
Terraformation on Mars is something that may have a chance of becoming a reality. The current annual temperatures of Mars is -55oC, much too cold for human habitation. At one NASA conference, several ideas were thrown around. One possible solution came from Margarita Marinova, an MIT undergraduate at the time. Marinova suggested using perfluorocarbons (PFCs) to help initiate the planet’s warming process. Marinova has studied the effects of PFCs in partnership with Chris McKay of NASA’s Astrobiology Institute. There are several advantages to using PFCs. They are considered super greenhouse gases, so a small amount would warm the planet significantly. PFCs also have a long lifespan and they don’t have any negative effects on living organisms. In addition, PFCs don’t destroy ozone.
Plant Hormones
Two common plant hormones are auxins and cytokinins. Both are vital to a plant’s growth and development. Auxin’s primary functions are to stimulate cell elongation, cell division, differentiation, and root initiation; mediate phototropism and gravitropism; and delay leaf senescence. A common natural auxin is indole-3-acetic acid (IAA). Cytokinins, such as kinetin, affect root growth and differentiation; stimulate cell division and growth, germination, leaf expansion, shoot initiation, and bud formation; delay senescence; and release of apical dominance.
Lighting and Plants
Plants require light in order to grow. They use light energy to convert carbon dioxide and water into glucose and oxygen (6CO2 + 12H2O + Light Energy C6H12O6 + 6O2 + 6H2O). White light contains all wavelengths of light. Plants use very little of the yellow and green wavelengths of light, reflecting them instead, which is why they appear green. They mostly use red and blue wavelengths, requiring more red than blue. Incandescent bulbs are discouraged because while they release a lot of red light, they are a poor source of blue light (Trinklein). “Cool-white fluorescent tubes produce a small amount of red rays in addition to orange, yellow-green, and blue rays. However, the red light produced usually is not enough for plants unless windows or other artificial lights produced additional red rays…. Special fluorescent tubes have also been developed for growing plants. These have a higher output in the red range to balance out the blue output (Trinklein).” The plants should receive 16-18 hours of light if that is the only light they are receiving. If they are receiving light from another source, 12-14 hours is sufficient. If plants do not receive adequate lighting, they may have longer stems and lengths between leaves. The leaves may be smaller than those that receive adequate lighting. The coloring may be a pale green and some leaves, typically lower ones, may yellow and drop (Trinklein).
Bibb Lettuce
Bibb Lettuce is a loose headed type lettuce. It is leafy with a “buttery appearance.” When healthy, it has bright green leaves. Bibb Lettuce will become bitter if temperatures rise above 95oF.
Hydroponics
Hydroponics is the study of growing plants in materials other than soil. There are a plethora of different medias available besides soil, including, but not limited to, expanded clay, rockwool, perlite, vermiculite, sand, and gravel. There are several techniques useful for a hydroponics environment such as continuous flow, flood and drain (ebb and flow), and top irrigation.
Medias
Choosing the hydroponics medium is important as all plants need some kind of support. Here are some descriptions of the aforementioned medias:
Expanded Clay
Expanded clay is clay baked into different shapes, usually balls or pebbles. They can be reused for multiple plants.
Rockwool
Rockwool is basalt rock, heated at high temperatures and spun into different shapes, usually cubes. It is important to avoid inhalation as it may cause irritation.
Perlite
Perlite is volcanic rock heated into lightweight glass pebbles.
Vermiculite
Similar to perlite, it has been heated until expanded into pebbles. It also holds more water than perlite.
Sand
Sand is often highly discouraged as a medium as it doesn’t drain well, can clog up roots, and has to be sterilized between uses.
Gravel
If using gravel, wash it thoroughly before use. It has many advantages as it’s cheap, easy to clean, and won’t waterlog.
Techniques
The technique used for hydroponics can have a profound effect on the plant. The following are some of the most common and most effective techniques used in hydroponics:
Continuous Flow
In the continuous flow technique, nutrient solution constantly flows past the roots of the plants.
Ebb and Flow
The ebb and flow technique generally consists of using a reservoir filled with nutrient solution which will pump solution up for a set time then let it drain and repeat.
Top Irrigation
Top irrigation consists of periodically applying a nutrient solution to the surface of the medium.
Chemical Safety
For all chemicals
1. During the part of the experiment that will be performed at school, all chemicals will be used in accordance with the MSDS.
2. The use of all chemicals will be done while wearing gloves, aprons, and goggles.
3. All chemicals that release fumes will be placed under the fume hood to prevent the release of fumes into the classroom.
4. A fire blanket, fume hood, fire extinguisher, eyewash station, and shower are available for use.
5. Upon leaving the lab, hands will be washed and all chemicals will be stored in a locked ventilated chemical storeroom.
Chemical Disposal
FloraGro
Completely dissolve each substance in water in a separate container. Rinse this solution down the drain with a tenfold excess of water. Then rinse the solution of a second substance down the drain with a tenfold excess of water. Repeat as necessary.
Kinetin
Completely dissolve each substance in water in a separate container. Rinse this solution down the drain with a tenfold excess of water. Then rinse the solution of a second substance down the drain with a tenfold excess of water. Repeat as necessary.
*All chemicals are to be used in experimentation and are therefore not subject to any of the disposal methods described above.*
Electrical Power Safety
1. Limit the use of high power devices around water.
2. Never use frayed or cut wires when plugging in a device.
3. Never overload the outlet and use a surge protector.
4. All electrical devices should have an emergency cut off switch or “kill” switch.
5. Shut off and unplug all devices when not in use or when you leave the room unattended.
Sharp Object Safety
1. Use caution when using a sharp object.
2. Restrict the use of sharps to a minimum.
3. Do not use bent or broken needles, knifes, or razor blades
4. Cover or cap needle after every use.
5. Discard used syringes, needles, and scalpels into an approved sharps container.
6. Bring all needles in a sharps container to a local fire station for disposal.
Preparing the Clinostat
1. Clean the clinostat.
2. Set up the plant compartments.
3. Check to make sure system is working.
4. Check to make sure lights are working.
5. Condition the rockwool.
6. Fill the tray with hydroponics nutrient solution.
7. Once plants are ready, move them into environment.
Cultivating the Bibb Lettuce
1. Plants will be split into several different groups: 20 mL water, 5 mL kinetin/15 mL water, 10 mL kinetin/10 mL water, 15 mL kinetin/5 mL water, and 20 mL kinetin. There will be 100 plants total, 20 per group.
2. Plants will be germinated in petri dishes containing the above mixtures of hormones.
3. Plants will mature in the clinostat.
Collecting the Data
1. Measurements will take place once a week until the end of experimentation.
2. Measurements will include leaf count, leaf coloration, width of the leaf, and height of the plant measuring from the end of the root to where the stem splits for leaves.
Analyzing the Data
1. Data will first be organized in a date table based on groups or variables.
2. The mean or average for each group or variable will be calculated.
3. A z-test will be performed on each group using last year’s hydroponics control as the standard of comparison.
Critical Value Range: -1.96 to 1.96
Stem Lengths
0% Kinetin -24.1
25% Kinetin -45.0
50% Kinetin -43.7
75% Kinetin -29.9
100% Kinetin -51.2
Leaf Color
0% Kinetin -5.9
25% Kinetin -6.7
50% Kinetin -5.9
75% Kinetin -5.1
100% Kinetin -8.2
For plants exposed to varying levels of kinetin, the null hypothesis was rejected. There were differences in growth. The first hypothesis was rejected. Plants exposed to an elevated level of kinetin did not have a higher leaf color number than the control. The second hypothesis cannot be determined at the moment since there is currently no standard of comparison for leaf broadness. The third hypothesis was accepted. Plants exposed to an elevated level of kinetin did have less vertical growth.
Ausbrooks, C. What is Bibb Lettuce? Retrieved on September 23, 2009 from: http://www.wisegeek.com/what-is-bibb-lettuce.htm
Barry, Patrick L. Leafy Green Astronauts. Retrieved November 6, 2009 from: http://science.nasa.gov/headlines/y2001/ast09apr_1.htm
Barry, Patrick L.; Phillips, Tony. Sowing Seeds in a Magnetic Field. Retrieved on November 5, 2009 from: http://weboflife.nasa.gov/currentResearch/currentResearchFlight/sowingSeeds.htm
Barry, Patrick L. Teaming Up on Space Plants. Retrieved on November 6, 2009 from: http://science.msfc.nasa.gov/headlines/y2001/ast10may_1.htm
Biology Online. Growth and Plant Hormones. Retrieved on October 27, 2009 from: http://www.biology-online.org/11/10_growth_and_plant_hormones.htm
Cytokinins. Retrieved on October 9, 2009 from: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Cytokinins.html
Farabee, Michael J. Plant Hormones, Nutrition, and Transport. Retrieved on October 27, 2009 from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPLANTHORM.html
Farabee, Michael J. Plants and Their Structure. Retrieved on October 29, 2009 from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPLANTANAT.html
Farabee, Michael J. Plants and Their Structure II. Retrieved on October 29, 2009 from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPLANTANATII.html
Fischer, Charles Clayton; Shaufler, Ernest F. Artificial Lighting for Decorative Plants. Retrieved on September 24, 2009 from: http://www.gardening.cornell.edu/houseplants/pdfs/artificiallighting.pdf
Gardener’s Network, The. How to Grow Bibb Lettuce Plants. Retrieved on October 30, 2009 from: http://www.gardenersnet.com/vegetable/bibb.htm
Knee, Michael. Plant Hormones. Retrieved on October 27, 2009 from: http://www.hcs.ohio-state.edu/hcs300/hormone.htm
O’Donnell, Michael. Notes from class - Statistics.
Palmer, Chelsea. What Are Cytokinins? Retrieved on October 9, 2009 from: http://www.essortment.com/all/cytokinins_rfjy.htm
Perry, Leonard. Indoor Lighting for Plants. Retrieved on September 24, 2009 from: http://www.uvm.edu/pss/ppp/articles/lighting.html
Plant Biology. The Plant Hormone Cytokinin. Retrieved on October 9, 2009 from: http://www.plant-biology.com/cytokinins-hormone.php
Plant Hormones. Retrieved on October 27, 2009 from: http://www.biotopics.co.uk/plants/plhorm.html
Plant Hormones and Growth Regulators. Retrieved on October 29, 2009 from: http://extension.oregonstate.edu/mg/botany/hormones.html
Purdue University. General Format. Retrieved on September 9, 2009 from: http://owl.english.purdue.edu/owl/resource/560/01/
Purdue University. Reference List: Basic Rules. Retrieved on September 9, 2009 from: http://owl.english.purdue.edu/owl/resource/560/05/
Rowe, Arthur. Growing Plants in Space. Retrieved November 19, 2009 from: http://www.amsat.org/amsat/archive/sarex/200704/msg00093.html
Sack, Fred; Kem, Volker. Development of Gravity Sensitive Plant Cells in Microgravity. Retrieved November 5, 2009 from: http://weboflife.nasa.gov/currentResearch/currentResearchFlight/sts107SeekingTheLight.htm
Sengbusch, Peter. Cytokinins. Retrieved on October 9, 2009 from: http://www.biologie.uni-hamburg.de/b-online/e31/31c.htm
Sengbusch, Peter. Phototropism. Retrieved on October 9, 2009 from: http://www.biologie.uni-hamburg.de/b-online/e32/32b.htm
Society for Science and the Public. International Rules for Precollege Science Research: Guidelines for Science and Engineering Fairs. Retrieved August 31, 2009 from: http://sciserv.org/isef/document/Rule2010.pdf
Takahashi, Hideyuki. How Do Plants Grow in Microgravity? Retrieved on November 17, 2009 from: http://www.jaxa.jp/article/special/kibo/takahashi_e.html
Tibbitts, T.W. Guidelines for Lighting of Plants in Controlled Environments. Retrieved on September 24, 2009 from: http://ncr101.montana.edu/light1994conf/8_1_Guidelines/Guidelines%0text.htm
Trinklein, David. Lighting Indoor Houseplants. Retrieved September 23, 2009 from: http://extension.missouri.edu/publications/DisplayPub.aspx?P=G6515
Tropisms. Retrieved on October 9, 2009 from: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Tropisms.html
Uri, John. Fundamental Biology. Retrieved September 10, 2009 from: http://research.lifeboat.com/mir_files/sc-fb-main.html
Van Patten, George F.; Bust, Alyssa F. Gardening Indoors with H.I.D. Lights. Van Patten Publishing, 1997: Vancouver.
