Transpiration Report

Topics: Temperature, Cold, Transpiration Pages: 6 (2063 words) Published: November 18, 2010
The object of this experiment was to study how different environmental conditions affected the rate of transpiration of a plant. The environmental factors we looked at were the affects of various temperatures and different light amounts in the different temperatures. We found that as the temperature warmed up, the rate of transpiration was higher. When the temperature was at five degrees Celsius, the rate of transpiration was very low. When we took out half of the light source and measured the rate of transpiration in the three temperatures we found the same variability of results as earlier where the cold temperature transpired less than the hot temperature but, with less light the overall transpiration rate was less all together. Introduction:

In this experiment we demonstrated how transpiration works. We took branches from the same plant and measured the transpiration rate of each branch in different environmental conditions. The conditions that we looked at included different temperatures and the amount of light. When we started the experiment we believed that the hot environment would have a higher transpiration rate than the rest of the environments because the heat would speed up the evaporation of water vapor. We also believed that by taking out half of the light it would decrease the rate of transpiration but not much because the temperature plays a vital role in transpiration rates. We also thought that when the temperature was at a moderate temperature, the plant would still transpire just not as much as the hot environment. Also, when the plant was at a cold temperature we thought that it would transpire very little. We thought the same results for the decreased light but, we thought that the overall transpiration rate would decrease all together but still keep the low and high variability with the different temperatures.

The loss of water through evaporation from the plant surface is called transpiration (Brooker, 2008). Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere by a passive mechanism. This mechanism is described by the cohesion-tension theory. This theory explains that the loss of water by evaporation reduces the pressure of the water inside the leaf which is relative to atmospheric pressure. The reduced pressure pulls water out of the soil, in our case we only had water in jars, and up the xylem to maintain hydration (Wheeler, 2008). Transpiration is also important because it is used as a cooling mechanism for the leaves and it would prevent the leaves from drying up in the sunlight (Clum, 1925). Transpiration is a continuous process which keeps plants alive and healthy. Materials and Methods

First we had to set aside six days between my partner and I where we could spend four hours a day conducting the experiment. Then we had to reserve the controlled environment chamber for the days which we would be using it. Once the chamber was reserved we had to examine the chamber to make sure all aspects about it were working and order anything needed for the experiment ahead of time. Then the day prior to the day we would conduct the experiment we had to set the temperature to the correct temperature that we would be working with that next day. Each day we obtained a potometer and four azalea branches then made sure each branch had 25 leaves on it. We then filled a 16oz jar to the rim of water. In order to fit the branch in the hole of the potometer we had to cut the end of the branch with clippers at an angle. Once the branch was the right size, we put the end we cut through the hole of the potometer and into the water. We then put the bent glass tubing into the other hole of the potometer. With a little bit of force, we pushed the stopper into the glass jar. As we pushed the stopper into the jar, the water filled part of the tubing. Once the...
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