Transpiration is the evaporation of water from plants. It’s not simply a hazard of plant life but it’s the engine that pulls water from the roots to cool the leaf and supply photosynthesis. The concentration of water vapor in the atmosphere is lower than that in the leaf. Because of this difference, water vapor diffuses from the spaces of the leaf, through the stomata in the epidermis. Stomata are in the lower epidermis; the lower surface receives less radiation from the sun that’s why it reduces water loss (Sadava 2010).
Each stoma allows carbon dioxide to enter for photosynthesis white water evaporates through each one in transpiration. The plant uses transpiration to pull the water up against gravity. Water can be pulled upward through tiny tubes because of the remarkable cohesion of water so that they form a continuous stream extending from leaves to root. The integrity of the column is also maintained by the adhesion of water to the xylem walls (Pidwirny, 2006).
These are important facts because when water is sticking together it means more water is pulled up the stem to replace the water loss.
Evaporation is the process of water changing from a liquid into a gas (Pidwirny, 2006). Transpiration is the evaporation of water from a plant’s flowers, stem or leaves back into the atmosphere. That’s how they are linked together. The question is what factors affect transpiration? The environmental factors that affect the rate of transpiration are light, temperature, humidity, wind and soil water (Sadava, 2010). In lab 3b, all of the plants in this experiment will lose a lot of water through transpiration, but those affected by the light and the fan will lose a larger amount of water.
Then the hypothesis can be factors that increase evaporation will increase transpiration. Plants transpire actively in the light than in the dark, lights also speeds up transpiration by warming the leaf. When there’s no wind the air surrounding the leaf will become increasingly humid, causing the rate of transpiration to reduce. So the prediction will be light and wind combined will result in the highest rate of transpiration. Methods I used the lab protocol 3b Plant Transport in the Lab manual to complete this experiment in order to collect all the data. Our group followed exactly very step in the manual.
There weren’t any changes in protocol. Leady, B. (2012). Fundamentals of Life Science Lab Manual. Plymouth, MI: Hayden-McNeil Pubishing. Results This is the data measuring the water loss in different conditions. These are the results of how the water level changed under the control, wind, light and the combination of light and wind in 0-20 minutes. The graph below is based on the numbers on the data chart. Discussion/ Conclusion What factors affect transpiration? The factors that affect transpiration are light, temperature, humidity, wind and soil water.
In lab 3b, all of the plants should lose a lot of water through transpiration, but those affected by the light and the fan will lose a larger amount of water. Therefore the hypothesis can be the factors that increase evaporation will increase transpiration. So the prediction will be light and wind combined will result in the highest rate of transpiration. In this experiment, the factors didn’t affect the plant much so the water level turned out to be the same. The reason the class had to do a control so everyone can compare the collected data to others.
When there is wind and light involved; the results will change. In this experiment the average transpiration rate for the control 0. 03 ml in 20 minutes is 0. 0015 ml/minute. That average transpiration rate is 0. 0015 for the entire time range of the graph. Plants transpire more actively in the light than in the dark. Light also speeds up the transpiration by warming the leaf. This also increases the rate of transpiration, as gasses move faster when heated. In this experiment the rate of transpiration for light would be 0. 0025 ml/minute.
The results didn’t reflect an increase much maybe the bulb wasn’t hot enough that’s why the plant didn’t absorb enough the heat. Wind can modify the rate of transpiration by removing the boundary layer of water. Windier conditions increase transpiration because the leaf’s boundary layer is smaller. When there’s no wind, the air surrounding the leaf will become increasingly humid, causing the rate of transpiration to reduce. The rate of transpiration for wind would be 0. 002 ml/minute. The results are only 0. 02 ml difference from the control; this happened because the wind wasn’t strong enough.
On the other hand, if the wind was heavy, it would alter the results by increasing the movement of water to reach the atmosphere. The rate of transpiration for the combination of wind and light in 20 minutes is 0. 003. These results did reflect an increase but not much either because there weren’t enough sources including wind and light. This is expected to be the highest rate of transpiration because of these two important factors wind and light combined. In the experiment this rate is not the highest due to the results of wind itself and the result of light alone.
The three other factors that could be investigated using this same technique are temperature, humidity and soil water (Sadava,2010). In this experimental design, the weaknesses can be the light was too small. The class would get better results if they provided a stronger and bigger light source. The problems this group didn’t get the results like others can be the aged tap water didn’t age enough and there were bubbles in the water that’s why the experiment didn’t work at all. Or it can be the plant was dying.