Investigating the Comparison of Transpiration Rate between Aquatic Leaves and Terrestrial Leaves

Investigating the Comparison of Transpiration Rate between Aquatic Leaves and Terrestrial Leaves

RQ: What is the difference between the rate of transpiration of aquatic (Nelumbo Nucifera and Echinodorus Palaefolius) and terrestrial (Piper Betle and Anthurium Crystallinum) plants?

1. Introduction

In accordance with its geographical location, Indonesia is known for its hot temperature. However, for the last couple of years, Indonesia has been very inconsistent regarding the pattern climate. In general, when the sun is in the southern hemisphere from October to March, it will most likely to have an excessive amount of rain whereas the dry season will appear in April to September.

Both Nelumbo Nucifera and Echinodorus Palaefolius is an aquatic plants. Nelumbo Nucifera comes from a family of Nelumbonaceae whereas Echinodorus Palaefolius is from the family of Alismataceae. It has been a matter of common belief that water plants transpire large amounts of water, although there seems to be little evidence in support of such belief. According to Woods, he points out that “transpiration is not something which protoplasm does but something which it resists. It is not a physiological function or activity of protoplasm, although it may have a physiological relation to the normal development of certain plants parts of plants. Transpiration is nothing more than evaporation”.

On the other hand, both Piper Betle and Anthurium Crystallinum is a terrestrial plants. Plants in hot or dry environments may be adapted to reduce transpiration in order to survive in hot or dry conditions, for instance, preventing water loss. In other words, it can lose large amounts of water from their leaves because of transpiration. One of the thing that they could do is to open their stomata at night and close during the daylight. Unlike terrestrial plants that are located in hot or dry environment, theoretically, when there is plenty of water in the soil, transpiration is not a problem. This concept leads me to my research question for this investigation: What is the difference between the rate of transpiration of aquatic (Nelumbo Nucifera and Echinodorus Palaefolius) and terrestrial (Piper Betle and Anthurium Crystallinum) plants?

2. Investigation

2.1 Hypothesis

H1: There is a significant difference between the transpiration rate of terrestrial and aquatic leaves

H0: There is no significant difference between the groups; any observed differences may be due to chance and sampling error

2.2 Background Knowledge

Transpiration is a process that involves loss of water vapour through the stomata of plants. The transpiration pull draws water from the roots to the leaves because of the effects of capillary action. The primary forces that create the capillary action are adhesion and cohesion. Adhesion is the attraction that occurs between water and the surface of the xylem, and cohesion is the attraction between water molecules. The rate at which transpiration occurs refers to the amount of water lost by plants over a given time period. Plants regulate the rate of transpiration by opening and closing of stomata. However, a number of external factors that affect the rate of transpiration, namely: temperature, light intensity, humidity, and wind.

In this investigation, I will be using 4 different plants; 2 terrestrial plants and 2 aquatic plants. The first aquatic plant is Nelumbo Nucifera (also known as Sacred Water Lotus) in which is a subtropical plant where it grows best in areas with the annual daytime temperatures of 25 – 30°c but can tolerate 10 – 40°c. Most species of water lotus have rounded, variously notched and waxy leaves on long stalks. Those stalks arise from thick and fleshy underwater stems that are buried in the mud. Furthermore, Nelumbo Nucifera prefers a pH in the range 6 – 6.5, tolerating 5.5 – 7.3. Once established, plants can become invasive when growing in suitable conditions. In the swampy area, however, lived Echinodorus Palaefolius in which has a round with a horizontal leaf structure ranging from 20-40 cm, and rosettes as wide as 20-40 cm. The leaves shape of this plant is quite stiff and has rough hair on the top and bottom surfaces. Its leaf margins are often dry out if the air humidity is low.

Moving on to the terrestrial area, I will be using Piper Betle and Anthurium Crystallinum. Piper Betle is tropical plant that is usually at elevations below 900 meters. It prefers growing in areas where the mean annual temperature falls within the range 22-27 ° c, but can tolerate 17 – 31 ° c. It thrives under per-humid forest conditions with high relative humidity and sample supply of soil moisture. It flourishes in areas with a mean annual rainfall in the range 2,250 – 4,750mm. They usually have larger and less pungent leaves. Anthurium Crystallinum, on the other hand, has a distinctive feature. It has large leaves, heart-shaped, dark green, velvety with clear white veins. The leaves can measure up to 2 ‘and small crystals in veins cause the leaves to sparkle. It usually grows in warm temperatures (60-85 ° F), high humidity, indirect light and provide stable humidity.

I will then compared both transpiration rates between different categories of plants in this investigation. To collect the data, I will be using gas pressure sensor. This sensor enables to calculate the amount of pressure when water molecules are pulled up from the tube to the atmosphere by transpiration. As the plant transpires, pressure within the tube would go through a slow decrease as water evaporates through the leaf’s stomata. This equipment is effective only when used in freshly-cut branches.

To calculate the data, I will be using ANOVA to analyze the differences of transpiration rate among each sample. In order to do that, I will be using Kolmogorov Smirnov normality test in Excel (alternative of SPSS). Basically, Kolmogorov Smirnov normality test is to compare the data distribution (which will be tested for normality) with the standard normal distribution. The standard normal distribution is data that has been transformed into Z-scores and assumed to be normal. In other word, Kolmogorov Smirnov test is a test of the difference between the data that is tested for normality and the standard normal data. If the significance is below 0.05, there is a significant difference, whereas if the significance is above 0.05, there will be no significant difference occurs.

2.3: Variables

Independent Variable

Different Types of Plants:

• Terrestrial (Piper Betle and Anthurium Crystallinu)
• Aquatic (Nelumbo Nucifera and Echinodorus Paleafolius)

Dependent Variable

Rate of Transpiration (kPa)

Controlled Variables

3. Procedure

3.1: Materials and Apparatus

3.2: Methodology

Leaf Sampling

1. Pick a branch that is wide enough to fit into the pipe (The branch needs to be approximately around 3cm)
2. Make a freshly new cut of the branch using a razor blade at a 45°angle instead of straight line because it could damage the inner vascular system of plants which may then affect the result of the experiment
3. Place the branch into the open side of the tubing
4. Secure the branch by tightening the clicking the hose clamp once

Setting up Gas Pressure Sensor

1. Position the ring stand, utility clamps and Vernier Gas Pressure Sensor. Attach it with the Lab Quest as well
2. Fill in the tubing with water by placing the syringe into the other end of the tubing and make sure to place the hose clamp on the opposite side of the tubing (Do not forget to open the hose clamp)
3. Make sure there are no air bubbles in it
4. Close the lock of the hose clamp and gently disconnect the syringe
5. Connect the plant to the tubing by carefully pushing the stem of the plant down into the end of the tubing where the water is running out. Be careful not to allow any air bubbles to form between the cut portion of the stem and the water in the tube. An excessive amount of force can damage the plant and can affect the results of the experiment
6. Secure it with the hose clamp
7. Attach the tubing into the gas pressure sensor. Make sure to unlock the hose clamp
8. Monitor the Lab Quest for 2 minute

Collecting Transpiration Data

1. Open the tap of the tubing to let water flow
2. Press the play button to record the data
3. Let the plant settle for 20 seconds as the pressure drops on the LabQuest
4. “Auto scale Once” the graph by clicking “Graph”
5. Wait for 2 minutes for data taking
6. Press the stop button to stop the timer
7. Click “Analyze” → “Curve Fit” → “Linear” to see the equation of the line
8. Collect the required data
9. Repeat the process for each trial

3.3: Risk Assessment

In the course of cutting the leaves from the plant, make sure to be cautious and to not use an excessive amount of force to cut the plant. It could damage the other parts of the plants. However, I should also consider;

• Ethical issues: Since I’m going to use plants for my experiment, I should also consider their lives as well. We might not know whether or not they do feel pain but they are still living beings. I should minimize damaging the plants to improve its quality of life.
• Environmental issues: There are no environmental issues. When disposing the plant, there is no additional treatment or alteration to the leaves therefore disposing it might not harm the environment.
• Safety Issue: There is no harmful impact toward the environment and the user however I need to be careful considering that I am bringing the school’s apparatus home.

4. Data

Quantitative Data

Raw data showing the transpiration rate of:

Aquatic Plants;

• Nelumbo Nucifera

• Echinodorus Paleafolius

Terrestrial Plants:

• Piper Betle

• Anthurium Crystallinum

Processed Data

Uncertainty calculation for rate using Gas Pressure Sensor

Processed data table of both terrestrial plant’s normal distribution with uncertainty

Processed data table of both aquatic plant’s normal distribution with uncertainty

Qualitative Data

5. Data Analysis

As can be seen from the data, the general trend shows that as the rate of transpiration in both plants is decreased. However there isnt any significant differences between the two types of plants. From the analyzed data using Kolmogorov Smirnov Normality Test, mean, standard deviation, Dn and Ks Table is obtained. With the basic understanding of if | 0,1440 | < | 0,2540| H0 will be accepted and H1 will be rejected, both of the variables are categorized as Normal.  According to the data, both of the combined terrestrial and aquatic plants have smaller variance of Dn compared to their variance of Ks Table. Terrestrial with the Dn of 0,304 and the Ks Table of 0,430 and Aquatic with higher variance of Dn (0,307) and Ks Table (0,430).

Since the rate of transpiration is measured through the amount of water loss, the rate of transpiration is directly related to the surface area because water evaporates through the stomata on the leaf surface. Based on my observation, terrestrial plants have wider and thinner leaves compared to the aquatic leaves. Aquatic leaves have a smaller portion compared to terrestrial leaves. Despite having smaller size than the terrestrial leaves, it has a thicker branch as well as leaves. Several structural features lessen the rate of transpiration. These include thick cuticles, thick cell walls and sunken stomata. However, on a general note, among the green leaves of the plants were some yellow and dried-looking leaves. This state of being could affect the rate of transpiration.

6. Evaluation

6.1: Conclusion

From the result of my experiment, I am able to accept my null hypothesis in which is that there is no significant difference between the groups. By combining both plants accordingly to its habitat, each variance of every statistics has an insignificant amount of difference. Using the ANOVA method on analyzing its effectiveness would come to no avail as its variance for N Sample (10) and Ks Table (0,430) remains the same to each other. There is a pretty huge gap between its variance for mean and standard deviation considering there are 0,234 differences for its mean and 0,257 differences for its standard. Supported by the data it can be said that the thicker and wider the area of the leaves is, the more the distance travelled by the air bubble and hence the greater the rate of transpiration. From both qualitative and quantitative data we see that the results where, in a span of 2 minute, thicker leaves were much larger than those leaves which have wider but thinner and drier leaves showing that area of the leaves is one of the major factors that effects transpiration. These results do partially prove my hypothesis to be right. However, external factors did occur which could be leads to an error in my experiment.

6.2: Strength

The experiment had relevant information. The ANOVA using Kolmogorov Smirnov Normality tests provide a means of comparing distributions, whether two sample distributions or a sample distribution with a theoretical distribution. The distributions are compared in their cumulative form as empirical distribution functions. It adequately explains the conditions that the variable is going through. The gas pressure sensor has provided an insight of data and thus, allowing me to understand what I was observing. Despite having its own error, the data collected by the labquest and gas pressure had helped me to further minimize human errors.

6.3: Weakness

There are a lot of errors within my investigation. I wasn’t considering the size of its branch, therefore the first 5 trials does not perfectly fit with the tube. An imperfect fit would allow water from the pipe to evaporate directly to the atmosphere without the process of transpiration, leading to random linear curve fit. It did not show any proper trends which would be a consistent downward movement. It turns out that the humidity of the room as well as the time of the experiment can affect the result. I have also discovered near the end of the experiment that the position of the leaves can affect the trend of the transpiration. Based on my observation during my numerous trials, I noticed that samples that are positioned a bit lower collected a better downward trend of transpiration.

Another thing is that plants can vary in sizes, health and maturity. It is a known fact that there would be no consistent data as different organisms would have different rates of physiological processes. When me and my parents first bought the plants, even the gardener couldn’t be able to estimate its age. Immature leaves can affect the rate of transpiration since only more mature leaves are able to effectively transpire. Therefore, there is a high probability that the samples that I have collected had impacted a significant errors that have led to my current result. In addition to that, each sample had different sizes of leaves and that all of them vary in width and maturity. Since maturity of leaves and its area can affect the transpiration rate of its leaves, it may be the other reason why errors occur in my data.

Lastly, Indonesia lately has been very inconsistent regarding the pattern climate. They are currently beyond what the government can predict. Therefore, since I am unable to fully control the weather conditions of the plant’s environment, I conducted my experiment inside my living room where I can monitor the exact temperature, humidity, and etc.

6.4: Extensions

A potential extension to this investigation is to have further study on to what extent other external factors affects the transpiration rate of both plants. This investigation would provide more further and more accurate information on those external factors could internally affects both plants, thus also affecting transpiration rate.

7. Appendices

Raw Data showing the transpiration rate of both terrestrial plants

Raw data showing transpiration rate of both aquatic plants

Processed data showing the terrestrial plant’s Normal Distribution;

Anthurium Crystallinum

Piper Betle

Processed data showing the aquatic plant’s Normal Distribution;

Nelumbo Nucifera

Echinodorus Paleafolius

8. Bibliography

Kumar Srinibas, (Unknown), Factors that Affect the Rate of Transpiration: External and Internal Factors, from http://www.biologydiscussion.com/transpiration/factors/factors-that-affect-the-rate-of-transpiration-external-and-internal-factors/14922

Bareeja G. Ben, (June 2013), Review: Plant Factors Influencing The Rate of Transpiration, from https://www.cropsreview.com/rate-of-transpiration.html

Csanyi Carolyn, (28 December 2018), How Plants Have Adapted to Prevent Water Loss, retrieved from https://homeguides.sfgate.com/plants-adapted-prevent-water-loss-104586.html

Siyavula.com, (Unknown), 5.3 Transpiration, retrieved from https://www.siyavula.com/read/science/grade-10-lifesciences/support-and-transport-systems-in-plants/05-support-and-transport-systems-in-plants-03

ICTinternational.com, (Unknown), Physiology of Water Absorption and Transpiration, retrieved from http://www.ictinternational.com/casestudies/physiology-of-water-absorption-and-transpiration/

Woods, A. F., Some recent investigations on the evaporation of water from plants. Botanical Gazette.