Quercus Alb Lab Report

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Impact of Light on Phenotypic Plasticity in Quercus Alba Leaves Katherina Raghunandan 100519036 CRN: 72027 TA: Erin Ussery Monday, March 23, 2015 Abstract This experiment was carried out in order to study the effect on leaf morphology for sun and shade exposed Quercus alba (white oak) leaves. When collecting leaves, the order was kept at random, but healthy leaves were collected. The purpose of this experiment was to determine whether or not an increased amount of light play a role in the phenotypic plasticity of Quercus alba leaves. The temperature, and amount of time left in light were kept constant. The only variable that changed was the amount of light that the leaves were exposed to. Through a data analysis (t-test)…show more content…
Some were placed in full sun for part of the day, while some we not exposed to full sun at any point during the day. The leaves were then placed in labeled zip-lock bags, and placed in a textbook to be pressed for a day. Digital images were then taken of each of the leaves. In the laboratory, a versatile image analysis software, ImageJ, was downloaded. Using ImageJ the digital images of the sun and shade exposed leaves were converted to grayscale, 8-bit black-and-white images. To set the scale, an image of a ruler was given and using ImageJ a line, of approximately 1 centimeter, was drawn. This line was set at a fixed distance, and was applied to all measurements. Then, each image of sun exposed leaves was opened, and the perimeter and area of each image was analyzed by following the given instructions. To acquire the Mean, Standard Deviation, and Minimum and Maximum for all of the sun exposed leaves, the summary of the perimeter and area were taken. This process was repeated for the shade exposed leaves. This data was then placed into an excel document, and using this date the ratio of perimeter to area of sun and shade exposed were calculated. Based on all the data collected (the area, perimeter, and ratio) a data analysis was conducted to find the P-value, t-value, and degrees of…show more content…
In one particular study, light was also considered a major factor. With respect to shade exposed leaves, it is shown that sun exposed leaves have a greater photosynthetic rate when it comes to the surface area (Gratani, L. et al. 2014). It is said that this is linked to a greater chlorophyll a:b ratio, and an increased amount of nitrogen per leaf area (Gratani, L et al. 2014). More nitrogen is allotted to carboxylation is sun exposed leaves and to light conservation is shade exposed leaves with variations in how much photosynthesis can occur (Gratani, L et al. 2014). The photosynthesis capacity is mainly higher in the leaves that are exposed to the greater amount of light. Intracanopy plasticity also plays an important role in the morphology of leaves. Typically shade exposed leaves are much larger, and have a lower leaf mass per area (Sack, Melcher, Liu, Middleton, & Pardee, et al. 2006). Shade exposed leaves also have a decreased stomatal density (Sack, Melcher, Liu, Middleton, & Pardee, et al. 2006). These morphological variances are believed to augment the total amount of carbon that is gained. Intracanopy in leaves is also linked to other various factors. Such as, temperature, and vapour pressure (Sack, Melcher, Liu, Middleton, & Pardee, et al.

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