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dioxide have been shown to be one factor that triggers the closing of stomates, which in turn would also decrease, or stop transpiration (Cahan, 2015). The Stomata is triggered to open in the light so that carbon dioxide is available for the light-dependent process of photosynthesis while they are closed in the dark in most plants. Very low levels of light at dawn can cause the stomata to open so they can access carbon dioxide for photosynthesis as soon as the sun hits their leaves.Wind can alter rates of transpiration by removing the boundary layer (that still layer of water vapour hugging the surface of leaves). Wind increases the movement of water from the leaf surface when it reduces the boundary layer, because the path for water to reach the atmosphere isshorter and thus increases transpiration (Namuth, 2015).ObjectivesThe objective of this lab is to determine the several environmental factors which affects the rate of transpiration. Also, to determine the stomatal distribution of the Hibiscus leaves. Materials and Method:Environmental Factors that Influence the Rate of Transpiration1.Two hibiscus leaves with petioles attached were weighed together on an analytical balance. The time was recorded and the leaves were placed outside in the shade.2.Another set of leaves were weighed and left in the lab. The temperature at both location was recorded.3.Each set of leaves were reweighed at half an hour intervals for one hour.Stomatal Distribution 1.Two hibiscus leaves were smeared on the upper surface with Vaseline. Vaseline was also smeared thinly on the lower surface of another set of hibiscus leaves. Both sets were weighed separately and the time was recorded.2.Each set of leaves were reweighed at half an hour intervals for one hour.3.The percentage change in mass for each treatment was calculated.
Results and Discussion:Leaf SetEnvironmentalFactor(oC)InitialWeight(g)Weight at 30Minutes(g)PercentChange inMassWeight at1 Hour(g)PercentChange inMassOutside Lab~27oC0.750.71-5.33%0.66-12.00%Inside Lab~24oC0.940.88-6.38%0.86-8.51%Table 1_ Experiment 1: Environmental Factors that Influence the Rate of Transpiration Sample Calculation:Percent Change in Mass =Final Mass(g) - Initial Mass(g)Initial Mass(g)×100Leaf Set 1: Outside LabPercent Change in Mass (30 Min utes) =0.71 - 0.750.75×100 = -5.33%Percent Change in Mass (1 Hour) =0.66 - 0.750.75×100 = -12.00%Leaf Set 2: Inside LabPercent Change in Mass (30 Minutes) =0.88 - 0.940.94×100 = -6.38%Percent Change in Mass (1 Hour) =0.86 - 0.940.94×100 = -8.51%______________________________________________________________________________Vaseline Present On:InitialWeight(g)Weight at 30Minutes(g)PercentChange inMassWeight at 1Hour(g)PercentChange inMassUpper Surface0.650.64-1.58%0.62-4.62%Lower Surface0.690.65-5.78%0.65-5.78%Table 2_Experiment 2: Stomatal DistributionSample Calculation:Vaseline Present on Upper Surface of Leaf
Percent Change in Mass (30 Minutes) =0.64 - 0.650.65×100 = -1.58%Percent Change in Mass (1 Hour) =0.62 - 0.650.65×100 = -4.62%Vaseline Present on Lower Surface of LeafPercent Change in Mass (30 Minutes) =0.65 - 0.690.69×100 = -5.78%Percent Change in Mass (1 Hour) =0.65 - 0.690.69×100 = -5.78%Water is transported in plants, from the roots to the leaves, following a decreasing water potentialgradient. Transpiration, or loss of water from the leaves, helps to create a lower osmotic potential