In our brainstorming session, we devised a plan to integrate physics and biology by investigating the correlation between plants and electricity. Our objective was to examine whether electrically powered lights could serve as a viable substitute for natural sunlight. To conduct this experiment, we opted for two artificial lights of contrasting colors, while also including sunlight as a control variable.
The need for a plant that is both easy to grow and fast-growing was initially considered. However, genetically modified seeds were unavailable due to a lack of contacts. Nevertheless, lentils were chosen as an alternative since they are the fastest growing plant accessible to us. Furthermore, careful consideration was given to the soil type used for planting. As a result, three different soil types were utilized: organic, moist organic, and woody soil
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The main concern was how to set up the equipment in order to establish a sealed environment that fully eliminates external light. Our primary goal is to exclusively supply the plants with artificial light, so it is essential to prevent any other undesired light from entering. We decided to utilize cardboard boxes as containers, which were equipped with openings for oxygenation. Opting for cardboard facilitated the process of shaping and customizing the boxes according to our requirements. The dimensions of both boxes were 36cmx27cmx14cm, which closely resembled an ideal size.
Our measurements would have been at least twice as much as the best ones. Our next strategy involves placing lamps inside the boxes in a way that provides an equal amount of light to each group of plants. To accomplish this, we made a hole on the top of the box so that the lam
can shine onto the plants. Inside each box, there are three pots with dimensions of 8x8x8, each containing different types of soil. However, our current challenge is maintaining proper hydration for the plants while also ensuring that the lights are not left on continuously for 24 hours. This could result in inaccurate sunlight simulation and potentially damage the cardboard material. It is particularly challenging because we conducted the experiment during a period when we were unable to be present.
The minimal effort control group involved placing it in a sunny window and regularly watering it, similar to an ordinary plant. To solve the problem of leaving the light on for too long, we created a programmable timer that could turn the lights on and off based on our preferences. After careful consideration, we set the timer to have 40-minute breaks between each 20-minute "shining" period. There are several reasons why we chose this longer interval duration.
Initially, our concern was that leaving the light on for an extended period could potentially ignite the cardboard because the filament's high temperature might be sufficient to start a fire. This posed a risk to the entire establishment. Another reason for the interval was the worry that the intense heat generated inside the box could harm the plants. To address this, we arranged for a supervisor to water the plants twice a day - once when they arrived at work and again before they left. Each pot contained 18 germinated seeds to maximize growth opportunities since we were unsure of the ideal planting depth for the seeds.
The seeds took 24 hours to germinate. The temperature inside the boxes rose to approximately
44 degrees, unless it remained at room temperature. We had three sets of three pots containing different soils. One pot had a yellow light, another had a purple light, and another remained in its natural state, serving as the control.
The natural set was bathed in sunlight, with the color selection determined using an intensity meter. The measured intensities were 4.0 lux for purple light and 3.76 lux for yellow light. We had expected a larger intensity difference, but this was the most we could achieve.
The experiment lasted for 12 days and involved recording the temperature indoors at various times to ensure it remained at a suitable level. The aim was to determine which set of plants would grow the most successfully, with the tallest lentil being measured using a ruler. Daily changes were measured using a ruler as well. The pots were distinguished by markers, with red representing woody soil, white representing organic soil, and green representing moist organic soil. My hypothesis was that plant growth would be poorest in the woody soil set and potentially highest in the most organic set.
The purple light produced better results due to its higher intensity compared to the control. For a diagram of the apparatus used, please refer to the final page. In summary, the tools utilized in our experiment included scissors for cutting cardboard, two lamps of different colors (purple and yellow) to vary the intensity, two cardboard boxes with dimensions of 36cmx27cmx14cm, a timer for controlling electricity, woody soil, organic soil, moist organic soil, lentil seeds, nine pots measuring 8cmx8cmx8cm, water, sunlight, a thermometer, and a ruler for measuring change. Markers were also used
to differentiate the soil types in the pots. Interestingly, the yellow light demonstrated no growth despite its lower intensity when compared to other lights.
Due to high temperatures and lack of water, it is probable that the seeds perished. Moreover, the plant cannot effectively utilize yellow light for growth as it resembles green light on the light spectrum. The reason behind the plant's green appearance to us is its absence in other colors; yellow and green are comparable in the light spectrum. If a green light was directed towards the plant, outcomes would likely be further compromised. As we could not continuously oversee the experiment, results exhibited inconsistency.
Optimally, a daily measurement would have been ideal. To determine the precise growth rate, I resorted to dividing the plant's final length by the number of days. Since the yellow light yielded no results, the only viable option was to compare the outcomes of the purple and natural lights, with the former having a lower intensity. This outcome was predictable. Notably, the seeds planted in moist organic soil thrived under natural light exposure.
The plants died around the 8th day, most likely due to lack of watering. On the 7th day, we measured the plants from the batch and found them to be 5.5 cm. However, when we returned on the 11th day, we noticed no change in the plant's height, confirming its death.
The difference in growth within the first seven days of the two plants is of interest. It is noteworthy that the naturally lit plant exhibits a much steeper line compared to the artificially lit plant. There is a geometric distinction between the two, evident as the gap
between the lines widens over time, indicating that the naturally lit plant grows at a faster rate than the artificially lit one. Despite the artificially lit plant perishing early on in the experiment, I included an additional line parallel to the original trajectory to estimate its potential growth. By the conclusion of the experiment, there would have been a 7.5 cm disparity in favor of the naturally lit plant, nearly doubling the size of the artificially lit one.
Comparing the soil VS light data reveals that natural light is optimal for seeds in moist organic soil. However, the results for woody type soil were discouraging due to the presence of obstacles that hindered seed growth. The only plant that successfully grew was the one exposed to natural light, although its maximum length reached only 7 cm. In contrast, plants exposed to bright light achieved much longer lengths, with the longest reaching 18 cm. This disparity highlights the plant's unsuitability for growth in woody type soil.
The soil's lack of density suggests a scarcity of nutrients for the plant. The sunlit plant, benefiting from the sunlight, obtained more nutrients and achieved the best result. However, due to the increasing nutrient demands as the plant grows, it would have eventually perished as the soil lacked sufficient nutrients. Notably, the organic soil displayed great potential for growth in the sunlit plant, yet it did not yield the optimal outcome for the purple lit plant.
In this case, I extended the purple lit plant graph because the plants died around the 8th day. The sunlit graph was steeper than the purple lit plant, so the line extension indicated that the plant
would have only been 4 cm long. This was worse than its performance in the moist organic soil. The reason behind this difference is unclear. However, it was observed that purple light produced better results than yellow light, although not for the anticipated reasons. Determining the best soil for growth was more challenging as it varied depending on the light conditions. This variability may have been influenced by various environmental factors.
It is necessary to conduct runoff experiments multiple times in order to address specific questions. These experiments should focus on determining the relative importance of soil and light. The need for repetition arises from several errors in the implementation of a previous experiment. One such error was the selection of artificial lights without considering that the yellow spectrum is similar to green, rendering it unusable for plants. Furthermore, the intensity of these lights was not properly taken into account, as it was considerably lower than sunlight. Consequently, future experiments should investigate how different intensities and colors impact plant growth.
The experiment suffered from a lack of control and inadequate observation. The data collected was imprecise and the absence of monitoring led to the death of many plants. To ensure a successful experiment, it is essential to enable plant monitoring, such as reducing the workload for the scientists involved.
The temperature varied between the different apparatuses, with the naturally lit plant experiencing ambient temperature while the other two sets had changing temperatures. This difference in temperature could potentially affect our results. To ensure consistency, it would be beneficial to acquire high intensity color lamps that remain cool and provide the plants with the same temperature.
The temperature
inside the boxes peaked at 42 degrees but returned to ambient temperature after cooling for 40 minutes. The amount of soil was not measured, and there may have been insufficient seeds planted in the small box, which could have led to incomplete germination. This data is essential for determining optimal methods of growing larger plants. Ultimately, this understanding can help increase food production and feed more people globally. Nevertheless, it remains uncertain whether various plants have unique growth needs.
When looking at the color preferences of a tomato, it may have different preferences when compared to lentils. Overall, this experiment was not conducted properly as the results were not precise or consistent enough. For example, the sunlit lamp yielded better outcomes when combined with organic soil, whereas the purple light worked best with moist organic soil.
Based on this experiment, it can be concluded that yellow light does not promote plant growth. However, additional testing is necessary to validate this observation. It is advised to examine the effects of different colors of light on diverse plant species and various types of soil. Moreover, it should be noted that these findings might only apply to lentils. So far, natural lighting seems to be the most effective in stimulating plant growth.
