Abstract
This experiment is meant to investigate how environmental factors such as wind, light, and heat affect the rate of transpiration in Zebra plants, Coleus, and Geranium. Among the environmental factors studied were: wind, light and temperature conducted. The study showed that the rate of transpiration was highest in coleus plant. Geranium plant showed the second highest rate of transpiration. The rate of transpiration is different from one plant species to another depending on the different morphologies and features. The rate of transpiration increased under wind and heat for all the plants tested. On the other hand, Zebra plant, recorded lower rates of transpiration when light was applied. However, windy condition exhibited the highest rate of transpiration of all the other environmental factors. The condition that showed the second highest rate of transpiration was heat.
Introduction
Transpiration is the process by which water moves through the plant. Besides, it refers to the evaporation of water from the internal leaf tissues to the atmosphere. Water evaporates into the atmosphere through the stems, leaves, and even flowers. There are three types of transpiration: lenticular transpiration, stomatal transpiration, and cuticular transpiration. Stomatal transpiration occurs through the stomata found on the leaf surface. It accounts for the highest plant water loss. In this case, 80-95%, of the total water loss is attributed to stomatal transpiration. Lenticular transpiration occurs from the plant surfaces such as the aerial portion. In cuticular transpiration, water moves into the atmosphere through the cuticles. Cuticles are found on the surfaces of the leaves. It accounts for the lowest water loss by plants.
During transpiration, coordination between the three plant organs: the root, the stem and the leaf is important for the smooth water movement. The roots provide large surface area for water absorption through some fine extensions called root hairs. The amount of water absorbed by plants is based on the number of roots hairs found on the roots. In this case, the larger the number, the more water is absorbed and the vice versa. The root, the stem, and the leaf are connected by a tube-like structure called the xylem through which water moves up the plant. The water movement up the plant stem from the root is driven by capillary action.
In this experiment, the rates of transpiration were compared among three plant species and under different environmental conditions.
Procedure
The experiment was conducted as follows:
Zebra plant sprig was picked from the shelf by clicking it. The sprig was then dragged and dropped near the photometer on the table. The plant sprig snapped into the potometer prompting the name of the plant to appear on a note near the potometer. The name of the plant species was recorded in table 1.
Next, the transpiration process was started by clicking the clock. It was allowed to proceed for one hour after which the amount of the water transpired by the plant was appeared in the digital readout near the potometer. The data was then recorded in the table 1.
Heater was then clicked and drugged from the lab bench to the table and dropped next to the porometer. The clock was started again and the setup allowed to run for one hour. At the end of the one hour, the amount of water transpired was displayed on the digital readout near the potometer. The data was then recorded. The steps were repeated for all the remaining two plant species and the other remaining appliances.
Results
The results obtained are as shown in table 1 below.
Under normal conditions, Zebra plant recorded the highest rate of transpiration. Indeed, the rate of transpiration was highest for Zebra in all the conditions. On the other hand, it was lowest for Coleus under normal, heat, and windy conditions. However, when light was applied the rate became higher than in Geranium. In general, the rate of transpiration was also found to be highest when heater was applied. The rate was lowest when light was applied.
Discussion
Water moves through higher plants due to various forces. They include the capillary action and the shoot tension. The latter is caused by the negative pressure caused by the evaporation of water from the stomata (Ahmadi and Baker, 260). Shoot tension is influenced by cohesive forces between water molecules and the adhesive forces between the molecules of water and molecules of different materials such as those of xylem walls. As a result of the adhesive and cohesive forces, transpiration is possible.
Heat speeds up the rate of transpiration because it causes an increase in the kinetic energy of water molecules. The wind speeds up the rate of water loss by driving away water vapour surrounding the leaf surface. Consequently, the diffusion gradient between the air in the surrounding environment and the internal air spaces of the leaf increases thereby leading to high rates of transpiration in windy environment.
Out of the three tested plants, Zebra plant recorded the highest rate of transpiration under all the conditions. Therefore, it has the lowest ability to withstand conditions of low humidity (Brodrib, Field, and Sack, 492).
Conclusion
The experiment finds that heat, wind, and light affect the rate of transpiration. Heat and wind increase the rate pf transpiration. However, light has little effect on the rate of transpiration. The experiment was successful except for some sources of errors.
Works cited
Ahmadi, A.and Baker, D. A. ‘The effect of water stress on grain filling processes in wheat.’Journal of Agric Science, 136, 2001Pp 257–269.
Brodrib, T. J, Field, T. S, Sack, L. ‘Viewing leaf structure and evolution from a hydraulic perspective.’Functional Plant Biology 37, 2010. Pp 488–498.
