The effect of dirt accumulation on light absorption in the Banana leaf (Musa sp.)
Authors:Roxanne Barker, Alexis Carrington, Angela French, Lorelle Knight
Mentor:Stephen Davis, Distinguished Professor of Biology , Pepperdine University
Dust can be transported by wind, human activity, and many other factors. It was hypothesized that dust particles collected on leaves will block sunlight and decrease light absorbance, thus reducing the light energy reaching leaf pigments and making the leaf less healthy. To test this hypothesis, eight leaf samples with varying amounts of dust naturally coating them were collected from the leaves of the plant, Musa sp. The dust was then rinsed off the leaves, and the runoff was collected, evaporated, and weighed. A spectroradiometer was used to measure reflectance of the leaves both before and after dust removal. From these data the Normalized Difference Vegetation Index (NDVI), an index that uses spatial and temporal scales to estimate plant carbon gain, was found. Additionally, from the NDVI we derived a Dust Index (DI), a second index based on spectral reflectance pattern as a second form of measuring the reflectance by a leaf. A Leaf Area Meter was used to measure the area of each sample to calculate the amount of dust per leaf area. The data supported the proposed hypothesis; the dust index and NDVI showed significant differences between clean and dusty leaves. A regression analysis accounted for 77% of NDVI and 52% DI.