Effect of Insulation on the Growth of Radish Plants- Cultivated Radish ( Raphanus sativus L.) Danielle Griggs, Meher Pandher, Avni Mehta, Meghan Royle Section 1 June 10th, 2013 Mr. Fusco 1
Abstract: Research has shown that when a plant is first germinating it is essential for the roots to be properly insulated, since they are not only the most important, but also the feeblest part of the plant. The research question being tested was: How effective are different types of insulation in promoting the growth of a radish plant? Radishes are vegetables that require a cool environment to grow. The purpose of the experiment was to use these various types of insulation and wrap them around the flowerpot to determine if the heat radiated by the insulation would have any effect on the length of the stem and root of the plant. This insulation can also cause some complications when substances get released into the soil and can potentially harm the plant. The types of insulation used in the experiment were: foam from a pool noodle, aluminum foil, cloth, and a towel. They were chosen because they are all harmless and easily accessible variants of common insulators that are in use today. It was predicted that the pool noodle would have the worst impact on the growth of the plant s stem and roots. Results showed that the pool noodle had the least growth compared to the rest of the insulators, but still grew higher than the control. It was concluded that the materials that surround the plant do have a positive impact on the growth of the radish plant. 2
Introduction: Many homes around the country keep outdoor plants and gardens, but face a problem during the cold winter months. Most plants will die out in the cold, however scientists acknowledge that insulation may prevent the plants from dying and allow the plants to continue to grow outside. When insulating plants, it is vital to protect the roots of the plants. Stems can easily become dormant during colder temperatures, but the roots cannot. Common insulators for plants include bubble wrap, styrofoam, and blankets. Although insulating plants will help plants flourish during the winter months, some complications come with the types of insulation being used. Plants need air circulation to survive, and if bubble wrap is used for insulation, then the bubbles could possibly restrict the amount of air being circulated. Also, if styrofoam is placed inside of the pot for insulation, then the chemicals in the styrofoam could leak into the soil and harm the plant. Thicker blankets have been shown to insulate plants better than thinner blankets. In our experiment, we will be using pool noodles in place of styrofoam, aluminum foil in place of bubble wrap to allow more air circulation, cloth, and towels for variants of blankets all wrapped outside of the pot to avoid chemicals being leaked into the soil. Pool noodles are made of a substance called polyethylene foam, a harmless type of plastic, so the pores within the noodle can also absorb high quantities of water. The type of plant chosen for this experiment was the radish. The scientific name of the radish is Raphanus sativus L. Radishes are vegetables that are usually grown during the cool season (spring or fall) and can grow very quickly depending on the species. The type of radishes we used could be harvested in 22 days, which was written on the bag of seeds. Sunlight and well-drained soil that is kept consistently moist are needed to keep radishes healthy and to guarantee a quick harvest. 3
A question we had while picking our experiment was how insulating would affect plants that thrive in cooler environments. Even though plants like radishes thrive during the cool months of spring and fall, the roots will still die in winter if the temperature is too cold. The purpose of this experiment is to test the ability of radishes to grow while being insulated and whether or not insulation will be harmful to the plants. The hypothesis being tested was: If insulating radishes harms the plant, then using the pool noodle will result in the shortest plants with the smallest roots. Materials: The materials used in this experiment were: aluminum foil, pool noodles, cloth, towel, 15 pots, potting soil, water, scissors, ruler, graduated cylinder, scoopula, labeling tape and duct tape. Procedure: Experiment Protocol The first step was to collect 15 round pots. Aluminum foil was wrapped around a pot (1 layer) and duct taped for security. The pool noodle was cut up to fit around a pot, and was duct taped for security. Cloth was cut, wrapped, and duct taped around the third pot (1 layer). The same protocol was followed for the towel. This procedure was repeated 3 times for each type of insulation. Three control pots were also prepared without insulation. For each trial, the group was careful not to cover the holes along the bottom of the pot. Each pot was filled with potting soil 2/3 of the way up. An indent was made into the soil and two seeds were placed in the middle of the pot. The soil was then filled up to 3/4 of the pot. Each plant was then labeled (1, 2, 3, and type of insulation). Since two seeds were planted, once both plants germinated after Day 1, the smaller seed was taken out, to allow the larger plant to have more space to grow. Each pot was 4
continuously watered until the soil was damp to touch, every biology class. The first day of planting the amount of water added to each replicate was 30mL. After that point, the amount of water added each class was about 20 ml. Statistical Analysis The length of each plant was measured in millimeters. At the end of the project, the root was carefully removed from the soil and the length was measured in millimeters. The number of lateral roots attached to the primary root was also noted. For statistical analysis, the mean and high and low points of the growth of the radish for the insulations were collected. A graph showing the growth of the average lengths of the trials was also made along with a bar graph showing the correlation between the length of the root and number of lateral roots. A t-test was performed between each variable and the control to see if the insulation had any impact on the growth of the plant. Miscellaneous The independent variable was the type of insulation used to cover the pot (aluminum foil, towel, cloth, pool noodle). The dependent variable was the height of the seedlings and the length of their roots. The controls were the three pots without any insulation. The constants included the amount of potting soil, same type of potting soil in all pots, type of pots, amount of water, and the person who did the measuring. There were 3 replicates per type of insulation and control. Results: Table 1.1: Length of Radish Plant Covered by Pool Insulation Table 1.1 shown below organizes all the raw data obtained from the replicates surrounded by pool insulation from all 7 days of data collection. Data was first obtained after the plants germinated, and was successively taken every biology class regardless of the weekend; so each 5
Day refers to every other day once growth started. The length of the plants was calculated with a millimeter ruler. Between Day 1 and Day 2 there was a significant increase in the height of the plants, which leveled out in the next few days. After Day 6, the plants were shorter and more limp since the leaves started falling out. After Day 1, the 2nd seed was also taken out soil, which allowed the roots to grow better. The average growth and standard deviation of the three trials was calculated as well per day to show the variation of the different trials. Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Trial 1 15mm 92mm 97mm 109mm 111mm 110mm 108mm Trial 2 16mm 89mm 92mm 94mm 97mm 111mm 106mm Trial 3 20mm 96mm 98mm 103mm 104mm 108mm 108mm Average 17 ± 2.65 92.33 ± 95.67 ± 102 ± 104 ± 7 109.67 ± 107.33 ± (mm) 3.51 3.21 7.55 1.53 1.15 Table 1.2: Length of Roots of Radish Plant and Number of Lateral Roots With Pool Insulation Table 1.2 shows the length of the roots and the number of roots including the primary root after experimentation was completed. On the last day, after taking all the results, the individual plants were removed from the soil and laid on a paper towel to measure the length of the primary root. There were also a few lateral roots attached to the primary root, so those were taken into account as well. Length of roots Amount of roots Trial 1 25mm 6 Trial 2 34mm 9 Trial 3 39mm 10 6
Average 32.67mm 8.33 Table 2.1: Length of Radish Plant Covered by Towel Insulation Table 2.1 shown below organizes all the raw data obtained from the replicates surrounded by towel insulation from all 7 days of data collection. Data was first obtained after the plants germinated, and was successively taken every biology class regardless of the weekend, so each Day refers to every other day once growth started. The length of the plants was calculated with a millimeter ruler. The radish plant in trial 2 grew considerably larger than the other 2 trials. Trial 3 may have grown longer but after Day 4 the stem broke which reduced the length of the plant over the following three days. As seen with the pool insulation the height increased considerable between days 1 and 2. The average growth and standard deviation of the three trials was calculated as well per day to show the variation of the different trials. Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Trial 1 21mm 78mm 87mm 91mm 93mm 96mm 102mm Trial 2 33mm 122mm 130mm 126mm 119mm 127mm 137mm Trial 3 22mm 112mm 115mm 128mm 127mm (broken stem) 119mm (broken stem) 112mm (broken stem) Average 25.33 ± 104 ± 110.67 ± 115 ± 113 ± 114 ± 117 ± (mm) 6.66 23.07 21.83 20.81 17.78 16.09 18.03 Table 2.2: Length of Roots of Radish Plant and Number of Lateral Roots With Towel Insulation 7
Table 2.2 shows the length of the roots and the number of roots including the primary root after experimentation was completed. On the last day, after taking all the results, the individual plants were removed from the soil and laid on a paper towel to measure the length of the primary root. There were also a few lateral roots attached to the primary root, so those were taken into account as well. Trial 2 had the longest stem, and it has the longest roots as well. However the number of lateral roots was highest in Trial 1. Length of roots Amount of roots Trial 1 61mm 9 Trial 2 143mm 8 Trial 3 72mm 7 Average 92mm 8 Table 3.1: Length of Radish Plant Covered by Aluminum Foil Insulation Table 3.1 shown below organizes all the raw data obtained from the replicates surrounded by aluminum foil from all 7 days of data collection. Data was first obtained after the plants germinated, and was successively taken every biology class regardless of the weekend; so each Day refers to every other day once growth started. The length of the plants was calculated with a millimeter ruler. Trial 1 demonstrated the most growth, and there were no broken plants surrounded by aluminum foil. On Day 5, the Trial 3 sample was much higher than on Day 6 because the leaf may have come off, but then on Day 7 it grew again. The average growth and standard deviation of the three trials was calculated as well per day to show the variation of the different trials. Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Trial 1 19mm 105mm 108mm 108mm 106mm 115mm 120mm 8
Trial 2 20mm 89mm 114mm 103mm 105mm 105mm 109mm Trial 3 16mm 82mm 94mm 92mm 106mm 99mm 105mm Average 12 ± 2.08 92 ± 105.33 ± 101 ± 105.67 106.33 ± 115.33 ± (mm) 11.79 10.26 8.19 ±.58 8.08 7.77 Table 3.2: Length of Roots of Radish Plant and Number of Lateral Roots With Foil Insulation Table 3.2 shows the length of the roots and the number of roots including the primary root after experimentation was completed with the aluminum foil. On the last day, after taking all the results, the individual plants were removed from the soil and laid on a paper towel to measure the length of the primary root. There were also a few lateral roots attached to the primary root, so those were taken into account as well. Trial 1 had the longest stem and the longest as well as a considerably higher number of lateral roots attached to the primary root. Length of roots Amount of roots Trial 1 82mm 19 Trial 2 42mm 12 Trial 3 39mm 7 Average 54.33mm 12.67 Table 4.1: Length of Radish Plant Covered by Cloth Insulation Table 4.1 shown below organizes all the raw data obtained from the replicates surrounded by cloth from all 7 days of data collection. Data was first obtained after the plants germinated, and was successively taken every biology class regardless of the weekend; so each Day refers to every other day once growth started. The length of the plants was calculated with a millimeter 9
ruler. After Day 6 the plant in Trial 3 was a little smaller, but otherwise all 3 trials showed continuous growth through the 7 days. The average growth and standard deviation of the three trials was calculated as well per day to show the variation of the different trials. Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Trial 1 29mm 96mm 105mm 111mm 112mm 115mm 115mm Trial 2 20mm 93mm 108mm 111mm 121mm 119mm 122mm Trial 3 31mm 111mm 121mm 124mm 127mm 130mm 129mm Average 26.67 ± 100 ± 111.33 ± 115.33 ± 120 ± 121.33 ± 122 ± 7 (mm) 5.86 9.46 8.50 7.51 7.55 7.77 Table 4.2: Length of Roots of Radish Plant and Number of Lateral Roots With Cloth Insulation Table 4.2 shows the length of the roots and the number of roots including the primary root after experimentation was completed with the cloth. On the last day, after taking all the results, the individual plants were removed from the soil and laid on a paper towel to measure the length of the primary root. There were also a few lateral roots attached to the primary root, so those were taken into account as well. In this case Trial 1 had the least growth, but much longer roots and many more lateral roots. Length of roots Amount of roots Trial 1 82mm 16 Trial 2 31mm 11 Trial 3 48mm 8 Average 29.07mm 35 Table 5.1: Length of Radish Plant With No Insulation (Control) 10
Table 5.1 shown below organizes all the raw data obtained from the replicates with no insulation for 7 days of data collection. Data was first obtained after the plants germinated, and was successively taken every biology class regardless of the weekend; so each Day refers to every other day once growth started. The length of the plants was calculated with a millimeter ruler. The plant in Trial 2 remained the same height for 3 consecutive days until Day 7. This was similar with Trial 3 except on Day 5 the height was 1mm lower. The average growth and standard deviation of the three trials were calculated as well per day to show the variation of the different trials. Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Trial 1 48mm 113mm 121mm 125mm 122mm 124mm 124mm Trial 2 15mm 86mm 95mm 101mm 101mm 101mm 111mm Trial 3 17mm 87mm 93mm 96mm 95mm 96mm 110mm Average 26.67 ± 95.33 ± 103 ± 107.33 ± 106 ± 107 ± 115 ± (mm) 18.50 15.31 15.62 15.50 14.18 14.93 7.81 Table 5.2: Length of Roots of Radish Plant and Number of Lateral Roots With No Insulation Table 5.2 shows the length of the roots and the number of roots including the primary root after experimentation was completed with no insulation. On the last day, after taking all the results, the individual plants were removed from the soil and laid on a paper towel to measure the length of the primary root. There were also a few lateral roots attached to the primary root, so those were taken into account as well. The length of the root in Trial 1 was much longer than the rest, and the stem was longer for that one too, but it didn t have as many lateral roots. Length of roots Number of roots Trial 1 96mm 5 11
Trial 2 23mm 9 Trial 3 20mm 3 Average 46.33mm 5.67 Table 1.1 Average Growth of Radish Plant Each Day (in mm) Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Pool 17 ± 2.65 92.33 ± 95.67 ± 102 ± 262 ± 7 109.67 ± 322 ± Towel 25.33 ± 3.51 104 ± 3.21 110.67 ± 7.55 115 ± 113 ± 1.53 114 ± 1.15 117 ± 6.66 23.07 Foil 12 ± 2.08 92 ± 21.83 105.33 ± 20.81 101 ± 17.78 105.67 16.09 106.33 ± 18.03 115.33 ± Cloth 26.67 ± 11.79 100 ± 10.26 111.33 ± 8.19 115.33 ± ±.58 120 ± 8.08 121.33 ± 7.77 122 ± 7 5.86 Control 26.67 ± 9.46 95.33 ± 8.50 103 ± 7.51 107.33 ± 7.55 106 ± 7.77 107 ± 115 ± 18.50 15.31 15.62 15.50 14.18 14.93 7.81 Graph 1.1: Effect of Time on the Length of Insulated Radish Plants Graph 1.1 provides a visual representation of Data Table 6.1 because it shows the difference between the lengths of each type of insulation per day. According to the graph, all the plants had a sharp increase between Days 1 and 2. After Day 2 the growth of the plants leveled out at a little bit over 100mm. The highest plant growth was in the cloth sample, while the lowest was in the control. However, all the lengths are quite close to each other and there seems to be no significant difference between any of the samples. 12
Graph 1.1: Effect of Time on the Length of Insulated Radish Plants Pool Towel Foil Cloth Control Table 6.2: Average Length of Roots and Number of Roots of Insulated Radish Plants Data Table 6.2 shows the average lengths of roots and the average number of roots of each type of insulation. The length of root was highest for the foil and the number of roots was highest for the cloth. In the cloth, the number of lateral roots attached to the primary roots was higher than the length of the root. Length of Roots Number of Roots Pool 32.67 mm 8.33 Towel 92 mm 8 Foil 54.33 mm 12.67 Cloth 29.07 mm 35 Control 46.33 mm 5.67 Graph 1.2: The Effect of Insulation on Height and Number of Roots 13
Graph 1.2 provides a visual representation of Data Table 6.2 because it shows the correlation between the height of the roots and the number of lateral roots attached to the primary root. According to the graph, the length of the root was generally much higher than the number of roots. The cloth was the only exception, because the length of the root was lower than the number of lateral roots. The longest root was measured in the plant insulated with the towel. The control had the least number of lateral roots. The cloth had the most number of lateral roots and smallest primary root. Graph 1.2: Effect of Insulation on Height and Number of Roots Length of Roots Number of Roots Table 7.1: Average Weekly and Total Growth of All Radish Plant Replicates Table 7.1 shows all of the processed data from the raw data we collected. The average weekly growth was calculated by adding up all of the lengths of the plants and dividing by the 7 days that we took results. The total growth was calculated by averaging the change in lengths of the plants. The highest point was the tallest the plant ever was. This data was mainly taken from Day 14
7, but in some cases where the height was smaller in Day 7, the data was taken from another Day when it was higher. The Data Table has 5 bolded rows that show the average of the values of the three rows underneath it. The three rows below the bolded row represent the data from the three trials with the corresponding bolded insulation. The average weekly growth was highest in the towel plant, followed by the cloth. Average (weekly) growth Total Growth Highest Point Pool 12.90mm 90.33mm 110mm Trial 1 13.29mm 93mm 111mm Trial 2 12.86mm 90mm 111mm Trial 3 12.57mm 88mm 108mm Towel 13.76mm 91.67mm 122.33mm 1 11.57mm 81mm 102mm 2 14.86mm 104mm 137mm 3 14.86mm 90mm 128mm Foil 12.86mm 93mm 113.33mm 1 14.43mm 101mm 120mm 2 11.43mm 89mm 114mm 3 12.71mm 89mm 106mm Cloth 13.62mm 95.33mm 122.33mm 1 12.29mm 86mm 115mm 2 14.57mm 102mm 122mm 3 14mm 98mm 130mm Control 12.14mm 88.33mm 115.33mm 1 10.86mm 76mm 125mm 15
2 13.7mm 96mm 111mm 3 11.86mm 93mm 110mm Table 8.1: Variation of Radish Stem Growth between Samples and the Control A t-test was performed to determine if the insulation had any impact on the growth of the plant. The three unbolded values of each insulation from the total growth column from Table 7.1 was compared with the three unbolded values of the control. If the p-value was above.05, it meant that the insulation had no impact on the growth of the plant and the null hypothesis would be accepted. All of the p-values were above.05, which meant that the growth of all the samples were statistically similar to the control. T-test Results: p-values Pool 0.781457517 Towel 0.733915039 Foil 0.568097118 Cloth 0.426847407 Discussion: After completing the experiments, the towel had the highest average weekly increase of growth, followed by the cloth, pool noodle, aluminum foil, and control respectively. To find this data, the previous week s data was subtracted from the current week. This, however, did not seem to be the most effective means of measuring our results, due to the fact that the first week of growth had an extremely high change in height, whereas the weeks following grew a very minimal amount. In addition, some weeks experience a period where the height was less than it was the week before, and then grew passed both heights, or got shorter and continued to get shorter. This could be plausible if the plant was beginning to die or wilt. The data was processed in other ways as well. The plant that had the highest growth at the end of the growing period was 16
determined. From this, it was found that the cloth had the highest total growth, followed by the aluminum foil, towel, pool noodle, and control. Due to the fact that some plants had experienced a reduction in growth, the highest point that the plant grew to within the growing period that was allowed was recorded. The towel and the cloth both shared the highest average height, followed, respectively, by the control, foil, and pool noodle. Once the processed data was compiled, it was determined that, typically the cloth or the towel improved the growth of the plant, whereas the control and pool noodle were not as effective at growing the radish plants. As previously stated, a common insulator in use is a thick blanket, and both the towel and cloth were used to represent the thick blanket, so it makes sense that these two showed the highest growth. This supported the hypothesis in the sense that the pool noodle did not produce the plants with the most growth. The noodle was used to represent the styrofoam, which could introduce harmful chemicals into the plant, so it s performance worse than the towel and cloth is justified. But the noodle did not necessarily deter from the growth of the plant, as in most categories, the pool noodle still resulted in more growth than the control plants in almost every category, the pool noodle was at the bottom half of the list in terms of growth, indicating that the pool noodle was not a very effective insulator. The foil was never at the top of the list, nor was it at the bottom. The root lengths and number of roots of each of the plants were also taken into consideration. The towel had the highest average length of roots, followed by the foil, control, pool noodle and cloth. This reflects the trend that was seen with the growth patterns of the stems of the plants. The towel usually had the most growth upward and shows to have the most growth downward as well. The roots of the control were longer than that of the pool noodle or the cloth. The control also has relatively high numbers in the highest point as well. The conclusion was made that the material that surrounds a 17
plant does make a difference on the growth pattern of the plant. For the most part, the towel and cloth seemed to have the greatest effect on the amount the plant grew. The plants that were surrounded in those materials grew the most. The control did very poorly in almost all categories (the control plants grew a fair amount in two categories) so the conclusion was made that radish plants will grow better when they have been insulated. A t-test was preformed to accurately determine if there was a statistically significant difference between the control and the various types of insulation that were used. The null hypothesis was: there is no significant difference between the insulation and the control. All the p-values were above.05, which meant that we had to accept our null hypothesis. However, to perform an accurate t-test 10 replicates are necessary, while this experiment only used 3. Therefore, if any of these replicates were even slightly inaccurate, the results could have been skewed. The growth in the control was also very varied since Trial 1 grew 76mm, while the other two Trials grew 96mm and 93mm. So, the research still indicates that the towel or the cloth wrapped around the pot will result in the greatest amount of growth. Some errors that may have occurred throughout the experiment were inconsistencies in measurements. Because a millimeter ruler was used, it was sometimes difficult to measure the plant exactly right and determine which was the closest mark. Other errors may have included the fact that our plants were not left under the light; they were left on a shelf under the sun. If the shades were drawn one day, our plants did not receive the maximum amount of light. Another error that could have occurred was in the measurement of the roots. The roots could not have been pulled to the longest length without them springing back or breaking. Also, the plants grew really high and because the pots were very small, it constricted the growth, which caused some of the stems to break. A larger pot may have resulted in better results to determine the impact of 18
the Before the initial experimentation began, a pipe insulator was going to be used. Because it was not known whether the material was fiberglass and could potentially be harmful, the group decided against using it in the experiment. This meant that a variable had to be deleted from the original procedure. From this experiment, it can be determined that certain plants are affected by the amount of heat that is trapped in their growing source. The radish plant, based on the results, is most likely a day neutral plant and relies on the temperature in which it is surrounded. The towel and the cloth seemed to trap in the right amount of heat for the radish plants to grow to their full potential. The control, which had no material covering it, did not seem to provide that much insulation. The labs in our school are typically left at a fairly cool temperature, showing that the room temperature may not have been optimal for the radish plant. by insulating them in the towel/loth, the group was able to trap in the right amount of heat. These findings can have a major impact on the agricultural industry. Companies that grow and sell radish plants would really benefit from this experiment. If they grew their radishes in pots, they could insulate them with a towel or cloth material to produce a greater yield in crop production. The next step from this could be to determine the optimal growing temperature for radish plants. This could be figured out by having pots of radish plant in different rooms and given the same amount of sunlight and water, but kept at different temperature. Whichever plants grow better would indicate which temperature was the most effective. Another experiment the group could do involves insulating different types of plants, specifically corn or soy. These plants in particular because they are a major agricultural crop that humans depend on for almost all food products and livestock. By determining the most optimal temperature for these crops to grow in, a company could increase their yields even more than they already have. 19
Literature Cited: Bostick, K. (n.d.). Insulation for Plants in Pots. Retrieved from http://www.gardenguides.com/130499-insulation-plants-pots.html. Morgan, S. (n.d.) The Cold, Hard Facts on Protecting Potted Plants. Retrieved from http://www.hgtv.com/landscaping/the-cold-hard-facts/index.html Stillman, J., & Hale, J. & Jarvela, M., & Burnett, J., Stonehill, H., & Perreault, S., & Boeckmann, C. (n.d.). Radishes. Retrieved from http://www.almanac.com/plant/radishes. Plants profile raphanus sativus l. cultivated radish. (2013, May 28). Retrieved from http://plants.usda.gov/java/profile?symbol=rasa2 (From the United States Department of Agriculture - Natural Resources Conservation Services) 20