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At what time of day does a plant grow most?

8-8034

Eighth Grade

Nativity Catholic School

Archdiocese of San Francisco

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2024 San Mateo County Office of Education STEM Fair

Abstract

The purpose of my project is to discover whether a plant grows more during the daytime or at nighttime. I also tested if a plant grows more outside or inside during wintertime. I believe that a plant grows more during the daytime because sunlight, carbon dioxide, and water are necessary for a plant to grow. The afternoon and morning provide this. Not to mention, temperatures are warm during the day so the plant will not die. In contrast to the day, the nighttime is very cold because temperatures drop to 60 degrees and below. There is also a high chance of wind and rain. Critters scavenging for food can also destroy the soil while trying to get the seeds. Variables in my experiments are control variables which are water and location. Variables that are changing are the independent variables: sunlight, moonlight, and weather. These variables then effect the dependent variables: plant growth. I measured and observed the control variables by having specific times in the week when I would water the plants. I also located the plants in areas where it would get enough nutrients from the sun and easy to access so I can water them. After waiting a week of measuring and observing my experiment the results ended with the plants growing more during the night. The outdoor peas only grew 2cm while the indoor peas grew to 6.5cm. On day 4 it started to rain so that is why the outdoor peas could not continue growing. In conclusion, my hypothesis was incorrect because the data in my chart shows that the peas grew mostly overnight than in the daytime.

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Purpose Statement

The purpose of my project is to discover whether a plant grows more during the night or day. I will also discover if a plant has a higher chance of growing if it is placed outside or inside during wintertime. I want to do this project because I think it will be very interesting and educational to discover when and where a plant grows more. The results can help me answer questions in the future about plant growth. I think this information will help others discover more about plants and the process of photosynthesis, and how this leads to the plant growing.

Hypothesis

I think a plant grows more in the daytime because research shows that a plant needs sunlight and water to grow, and the daytime provides exactly that. In the morning the sunlight is soft, and the morning dew sprinkles on the plant, while the afternoon also provides plant growth because the sun will shine brightly at the plants. These elements play an important part in growing a plant since nutrients in the sunlight and water help with photosynthesis. A plant would grow less at night because predators like rats, birds, and racoons can rampage through the dirt while trying to find seeds or other food. The temperatures also drop below 60 degrees during the wintertime, and there is high chance of rain and wind. These conditions would not be helpful towards plant growth.

Experimental Procedures and

Materials

• Distribute 2-4 Sweet Pea seeds into four potted plants about two inches deep.
• Put 2 pots outside, and two indoors(make sure pots are near area with some shade, but also a lot of sunlight).
• Every morning(5am to 9pm) put starting measurements at 5am then ending measurements at 9pm of plant growth into data chart.
• Every night(9pm to 5am) put starting measurements at 9pm then ending measurements at 5am of plant growth into data chart.
• Water plants every Sunday, Wednesday, and Friday.
• Measure plants by measuring stems and leaves with ruler.
• After measuring for a week, analyze which plants grew more and when.

Control Variables: Water, location

Independent Variables: Sunlight, Weather

Dependent Variable: Plant growth

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Experimental Results

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My results show that the Sweet Peas grow mostly at night. The chart shows that the indoor peas grew a day earlier than the outside peas. After a week the sweet peas inside grow up to 6.5cm, while the sweet peas outside grow up to 2cm. The outside peas stop growing after day 3 because of rain, while the indoor peas continue growing. Patterns of growth until nighttime appear, especially on day 4 and 6 for indoor peas. This data shows that my hypothesis was incorrect and plants grow more during the night.

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Experimental Results

Outside Sweet Peas Indoor Sweet Peas

Experimental Results

Growth of indoor Sweet Peas

Analysis of Experimental

Results

After collecting my data and observing the growth of my plants I learned that the plants mostly grew overnight. I noticed that the peas would absorb water and sunlight during the day but have little growth, until the next morning when I measured the plants and noticed that the peas grew overnight. I believe this is because the plants would go through photosynthesis during the day, and at night digest the nutrients and minerals which led to the growth. I also noticed that the indoor plants peas grew a day earlier than the outdoor peas. These results show that my hypothesis is incorrect since the plants grew more overnight.

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Conclusions

In conclusion, my hypothesis was incorrect. Plants grow more overnight than during the daytime. My results show that the outdoor peas grew only 2cm, this is because it started to rain and less sunlight appeared. However, the peas inside were sheltered from the rain and temperatures were 70-80 degrees because of my heater. When I watered my plants on days 1, 4, and 6(Sunday, Wednesday, and Friday) I noticed that they wouldn’t grow during the day until night. Questions I have now is whether my results would be different if I used other types of seeds rather than Sweet Peas? I also wonder if my results would have come out differently if I tried this experiment in other seasons? If I wanted to explore my questions by redoing the experiment I would change the seeds to vegetables. I would also try doing the experiment during Spring to see if plant growth would be quicker.

Acknowledgements

Thank you to my mom who helped me measure my plants and brainstorm questions for the science fair. Thank you to my friend, Louise, who walked with me to buy supplies at Ace Hardware and review my slides. Thank you Ace Hardware for supplying me with Sweet Pea seeds, pots, and soil.

Bibliography and

Sources

https://sciencing.com/do-plants-grow-faster-in-light-or-dark-12380615.html

Adrianne Jerrett

Leaf Group Ltd

October 20, 2021

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https://www.trees.com/gardening-and-landscaping/how-light-affects-plant-growth

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Trees.com Staff

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Trees.com

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August 5, 2023

https://www.longfield-gardens.com/article/how-sunlight-affects-plants#:~:text=Too%20many%20hours%20of%20sun,is%20trying%20to%20conserve%20moisture.

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Longfield Gardens

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Longfield-gardens.com

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n.d

https://aggie-horticulture.tamu.edu/ornamental/a-reference-guide-to-plant-care-handling-and-merchandising/light-temperature-and-humidity/

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Aggie Horticulture

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Texas A&M University System

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n.d