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Transpiration and Leaf Resistance Essay

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Transpiration and Leaf Resistance
By: Bernina Berber

Introduction Transpiration is a part of the water cycle process, and it is the loss of water vapor from parts of the plants. It is a process similar to evaporation. Evaporation and diffusion cause the plant tissue to have negative water potential. If you were to compare transpiration it would be like saying it is close to sweating (but in plants), especially in leaves but also in stems, flowers and roots. Stomata are dots with openings on top of the leaves surfaces, which in many plants have numerous on the undersides of the foliage. The stomas are boarded by guard cells that open and close the pore. Leaf transpiration happens through stomata, it is considered as a necessary need …show more content…

We determined the relative humidity of the air with a psychrometer.
Materials and Methods Citrus leaves come from a very mature orange tree that is located on our campus; of course they were chosen from a branch so not much damage was done to the tree. Once taken from the branch it was wrapped with parafilm, where it remained throughout the entire experiment. The segment was placed in a plastic bag with a moist paper towel and returned to lab rapidly. We measured the first weights when we returned to the lab. The weights were recorded every 30 seconds for 10 minutes and every 5 minutes for 35 minutes after that. During this time one of the other lab partners (we were in groups of four) measured the relative humidity of the air with a psychrometer. Measured temperature was 25° C and a vapor pressure of 3.165 kPa for the dry bulb. A temperature of 13° C (55.4° F) and a vapor pressure of depression of 0.682 kPa was found for the wet bulb. We were able to do this by a data table that was already provided for us. The equation RH = [ kPa (depress) / kPa (dry)] was used to determine the relative humidity of 21.5 %. The area of the leaves was found by cutting out paper tracings of all four leaves after the 45-minute weight measurement period. The tracings were then weighed and the total weight was compared to values on standard curve, which was also provided

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