Blog Post #2

Introduction

Overview

My project still aims to study the effects of microplastics on Lactuca sativa plants. There have been a few changes and specifications to my project, but the purpose of my project remains the same. I have three hydroponic tanks set up, one control group, one with 0.166 um microplastics and the last with 1.54 um microplastics. Given recent setbacks with the lettuce growing too slow, I have now started growing wheatgrass from seed to study the impacts these particles have on their water uptake, health and biomass.

Progress

Setup

Starting 01.06.2026 I set up the hydroponic tanks and started growing the seeds. Below, I included multiple photos of that process. The first presents the specific type of seeds that I used, which is Bibb Lettuce. These aren't the fastest growing type of lettuce, but the leaves are often larger than other types which is why I chose it. I will be able to focus more on the health of the leaves and there will likely be mor measurable results. The second photo shows the growing sponges soaking up moisture, which I put the seeds into in the third picture. I used this method to sprout and grow the seeds because it helps maintain moisture and humidity. In the third photo, the plastic caps next to the sponge are also meant to increase humidity for the seeds. Combined, I put the sponges into the plastic holders and placed them into the hydroponic tanks. Notably, I used two seeds for each sponge to increase the chance of sprouting and there were eight sponges for each tank.

Hydroponic Tanks

Information on Tanks

The stickers were provided by the company with the purpose to reduce direct light exposure to the plants. This is meant to reduce any mold growth or algae.
The purple tweezers were provided by the company to move the seeds around, and I stir the solution every night because the microplastics do settle on the bottom occasionally.
The bottles in the front are the nutrients that I will add to the water when leaves start forming.
I have each tank labeled with the signs.
I ended up moving the lights lower recently to increase growth.
The light lamps are automatically made to provide 16 hours of sunlight and 8 hours of dark each day.
There are water pumps inside the tanks that provide oxygen to the plants and help mix around the particles.

Challenges

At this moment, my main issue is the fact that my lettuce plants are not growing fast enough. At this point I have been growing for around three-four weeks. There are plants in each tank that have started sprouting, but they are growing slower than I planned. The main element that I need right now is leaves to start forming so that I can track plant health over time in each tank. This is an important variable to study because it indicates more general trends rather than just looking at the specific water uptake.

Solution

To solve this concern, I have moved the sunlight lamps closer to the plants. I believe that the lights may have been too far away from the plants in the beginning, so I tried moved them so they are around 3 inches away from the plants. However, after waiting around 1.5 weeks, this still did not work as intended. I made the decision to purchase a new type of seed. Unfortunately, in Colorado, this is not the right growing time for Lettuce making it challenging to buy pre-grown lettuce plants, which was my original solution. I was going to purchase the plants from Home Depot, but the delivery time would take a couple weeks which wouldn't work with my timeline. To make it easier to simulate my methodology, I bought Wheatgrass seeds. These seeds only take around 2-3 weeks to fully grow from seed. They are still a food-plant as well and they grow extensive root systems and long shoots, which would give me the ability to study their overall health. However, I will need to alter my plant health scale slightly from what it was before. I originally was going to study the health and coloration of the leaves and growth primarily. Now, I will study the growth of the roots and shoots, the coloration of the shoots and the appearance of each plant.

Data Collection Highlights

Up to this point, I haven't had the chance to collect too much data considering the limited plant growth. Still, on day one I started measuring water uptake. Each day I measure the volume of the tank, which is given on the side. However, the marks for these tanks aren't very detailed, so I also measure the height of the water in cm so that I can calculate more specific volumes later. I am putting all of this data in a chart, as seen on the right. On the bottom of the spreadsheet, there is another tab for "Health". I marked the date when I switched to wheatgrass. I will continue to record water uptake every day. Then, once the wheatgrass begin to grow roots and shoots, I will record the plant health.

Reflection

So far, I have run into a few issues with my research, but I believe it is going in the right direction now. I was prepared for the lettuce seeds to not grow fast enough, given the estimated 60 day growth period. Though, I had planned to resolve that using pre-grown lettuce plants. Unfortunately, I was not able to purchase any in a timely manner, so I decided to replace the lettuce with wheatgrass. I think this was a feasible decision because wheatgrass is still a food plant and fits into the gap of my research, which was studying the effects of microplastics on terrestrial plants without the indirect effects of soil. Overall, once the wheatgrass begins growing, I will have data on the plant health and I will begin data analysis using statistical models to determine significance.

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