Influence of Various Environmental Conditions on Transpiration Rate and Differences in Stomata Size and Distribution Across Plants Introduction We analyzed the effects of various environmental conditions on the Heteromeles arbutifolia plant, specifically rate of water loss from plant leaves by evaporation and diffusion out of stomates. These conditions were cool wind, hot wind, and high relative humidity. Understanding rates of transpiration is important because it can provide information on how temperature and other climate conditions affect a plant’s ability to absorb and maintain ideal water levels (Wullschleger, 2000). Such observations can be useful for understanding the trajectory of a plant’s adaptive evolutionary history within the context of its environment. I hypothesized that simulating high temperature environments (hot setting on blow dryer) will yield highest transpiration rates, based on my knowledge of the thermodynamics of heat molecules and their increased rate of collision as temperature rises. In our second experiment, stomata size, distribution, and frequency were measured in one monocot, dicot, gymnosperm, and fern species. Stomata are important in transpiration, as they open when surrounding conditions are ideal and allow the plant to take in carbon dioxide, a reactant of photosynthesis; however, open stomata exposes the plant’s interior to the external environment, increasing transpiration rates and thus water loss in plants. In this way, it is important to note differential stomatal size and distribution on the leaf exterior. Comparing these differences can reveal plants’ evolved stratagems to increase its chances for survival unique to its environment (Mitton, 1998). I hypothesized that the frequency of stomata would be highest in monocots, but the size of the stomata would be smallest. I predict this based on the idea that if there is such a high density of stomata, the stomata do not need to be very big (Mitton, 1998). I predict stomata size is largest in dicots but frequency is lowest because each stomata has a larger area and not as many need to be clustered on the leaf. Monocots may need such a large number of stomata and have them both on the top and bottom leaf surfaces because producing flowers requires lots of energy, which the plant obtains through taking in carbon dioxide from the environment. Methods For the second experiment, leaves of Strelitzia reginae or Bird of Paradise (monocot), Raphiolepis indica (dicot), Ginkgo biloba (gymnosperm), and Adiantum (fern) were collected Results The average transpiration rate for the stem under control was 0.067ml/min. For cool wind conditions, the average rate was 0.1190 ml/min, for hot wind condition 0.1436 ml/min, and for
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- Fall '09