Clear Nail Polish Lab Report

Abstract Stomata is important to plants because of their role in gas exchange and photosynthesis. Clear nail polish and clear plastic tape were used to make leaf impressions of A. floridanum. Once impressions were completed, compound microscopes were used to count the total number of stomata per slide. The counts of stomata were used to find stomatal densities, along with the open/closed ratios of stomata. Stomatal density and open/close ratio of stomata did not differ between the two locations. This may be due to the fact the locations being relatively close and that they likely experience the same amount of gaseous pollutants exposure.
Introduction
Leaves are important to plants because that is where photosynthesis and gas exchange
occurs, as well as other cellular/physiological processes (Lawson, 2009; Lin, Jach, & Cuelemans, 2001). Leaves contain several components including chloroplasts, guard cells, and stomata (Lawson, 2009). Guard cells are vital for osmoregulation, which are used in order to control what comes in and out of the cells of leaves (Lawson, 2009; Talbott & Zeiger, 1996). Stomata are made up of guard cells and can be found on either the lower or upper side of leaves (Lawson, 2009; as cited in Ticha, 1982). Stomata is important in plants for gas exchange, photosynthesis, and transpiration, which are important to the functioning of plants (Lin et al., 2001; Jarvis, Mansfield, & Davies, 1999). Stomatal counts are used to study how rising carbon dioxide levels affect plants and their processes, such as photosynthesis (Jarvis et al., 1999). Stomatal density and index are common ways to measure stomata in relation to pollutants, such as carbon dioxide levels (Jarvis et al., 1999; Lin, et al., 2001; Tricker et al., 2005). Another way stomata can be useful is for studying effects of air pollution, which affect how plants grow, as well as other processes in a plant (Pourkhabbaz et al., 2010; as cited in Viskari, 2000). We hypothesized that leaves in the Ecological Preserve would have higher stomatal densities than the leaves in the Corriher-Linn Library Parking Lot due to different levels of exposure to pollutants based on location. Also, we hypothesized that the open to close ratio of stomata of the leaves would differ between the two locations as well. Materials and Methods Samples of A.
floridanum were taken from one of two sites, the Corriher-Linn Library parking lot and the Stanback Ecological Preserve. We collected 12 leaves from the same tree species in both locations, as well as some extra leaves. For the leaf impressions we applied clear nail polish on the underside of the leaf in three different areas and allowed for the polish to dry. After the nail polish dried, clear, plastic tape was placed over it and then peeled off. After getting the impression, we placed the tape with the impressions on individual slides and cut off any excess tape.
After the leaf impressions were completed, we calibrated the compound microscopes. When the microscope was calibrated, area of view was calculated for each objective; 40X, 100X, and 400X. For this experiment, we used 400X magnification once the microscopes were calibrated. After the impressions were created, the microscopes were used to count the total number of stomata. After counting stomata, the stomatal density was calculated (the total number of stomata/area of view), as well as the ratio of open and closed stomata of each slide.
Results
An unpaired t-test was used to look for any differences in stomatal density in the library parking lot and the Stanback Ecological Preserve. The t-test revealed that stomatal density in the library parking lot was the same as the stomatal density in the Stanback Ecological Preserve (Figure 1).
Another unpaired t-test was used to look at differences in the open/close ratio of stomata in both locations.
The t-test revealed that there was not a difference in the open/close ratio of stomata between the two locations (Figure 2).
Discussion & Conclusion The stomatal densities and open/closed ratio were not influenced by location in respect to proximity to pollutants, meaning we had to reject both of our hypotheses. These results may be due to these two locations being relatively close to one another, rather than further away. A study done by Pourkhabbaz et al (2010) took samples from both an urban and a rural site, which further apart in distance. Results revealed differences between the rural and urban locations for stomatal density. Some studies have shown that stomatal density can be influenced by pollution, while others don’t have changes in stomatal density in regards to pollution (Lin et al., 2001; Pourkhabbaz et al., 2010; Riikonen et al., 2009). Some of the studies, such as the study done by Lin et al (2009), manipulated levels of CO2, along with other gaseous pollutants, in chambers used to control levels of CO2. The study conducted by Pourkhabbaz et al, (2010) used the leaves from their environment, as we did with this
study.
In conclusion, stomata can be useful as indicator to see how pollution may affect a plant. Stomata’s purpose in the plant is gas exchange, which plays a role in photosynthesis (Lin et al., 2001; Jarvis et al., 1999). Distance between locations may influence stomatal density if their proximity to pollutants is truly different.