Table of Contents
Abstract
As the population continues to grow and climate changes cause the temperatures to rise, agriculture grows weaker. This study examines if variegated leaves can produce higher rates of photosynthetic rates, compared to non-variegated leaves. Both types of leaves were placed under a UV lamp for observation. The leaves C02 levels were monitored with a bio chamber and a LabQuest2. The data collected from these trails were used to calculate the net primary productivity, gross primary productivity, and photosynthetic rates.
The variegated and non-variegated leaves presented that there was really no relationship shared between both leaves net primary productivity with p-value of 0.376033161066448, for the gross primary productivity of both leaves, and , 0.117135912456685, for both leaves placed in the dark (p > 0.5). The C02 rates did not have a significant difference between the two leaves. The research points out that variegated leaves could not produce faster or a larger amount of produce for agricultural purposes. The reason behind this is because leaves cannot physically produce an excessive amount of energy all at once; but rather they can store it and use it for later (Buttery, B.R. and Buzzel R.I. 1977). Therefore, leaves neither variegated or non-variegated can produce a significantly larger amount of photosynthesis.
Introduction
The purpose of this test is to determine if leaves of darker variegation produce a higher rate of photosynthetic rates; rather than non-variegated leaves of the Japanese Pittosporum plant. As the population rises and climate changes, the question on all scientists’ minds are; is our world capable of yielding enough food to keep it sustained? Leaves that can yield a higher photosynthetic rate could increase food produce for consumption and would be able to survive in much harsher temperatures. This could be the answer for food producing rates and the inevitable population problem.
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Photosynthesis is a process that uses sunlight energy for food. These mostly occur in green plants. Plants can do this because they are autotrophs, which means they can use energy from light to make their own food. Through this process there are many factors that go into the final product of glucose. Plants use sunlight and gases in the air such as C02 and water. Sunlight is known to be absorbed more abundantly in darker colors; such as a black asphalt making a city hotter than a city with white asphalt. Could the difference in leaf pigments make a difference in the photosynthetic rates they produce? Plants with darker colored features could be the key to producing more food with higher photosynthetic rates.
In tropical regions, it is possible to obtain more than one harvest per year and one focus has been on shortening crop duration to allow rapid harvest (Peng et al, 2000). An increase in photosynthetic rates will be able to produce a much larger crop. Utilizing the characteristics of certain leaves could be to the advantage of agriculture. In temperate regions, high temperatures can reduce the grain‐filling duration, reducing the biomass production rate during this period. There has been interest in manipulating the timing of senescence to obtain higher crop yields (E.H. Murchie, M. Pinto, P. Horton et al, 2008). So, the reason behind this study is to test the hypothesis that variegated leaves will absorb more sunlight and produce a higher rate of photosynthesis rather than the non-variegated leaves. If correct, this could increase the agricultural efficiency, in order to keep up with the growing population and rising temperatures. Giving farmers more mass produce for our world.
Methods
In the interest of testing the hypothesis, we compared the “leafy green” leaves photosynthetic productivity rate to the variegated leaves. This experiment consisted of eight, five-minute trials for the leaves collected from the College of Charleston campus. We collected our samples, outside of Randoff Hall, from the Japanese Pittosporum. We collected the samples from there because this was one of the few plants on Campus that had both variegated and non-variegated leaves growing from the same species.
First, we collected five grams of each variation of leaves from the species. We started by placing one of the variations of leaves in the bio chamber with the UV lamp directly on the leaves. Then, we let the leaf sit for five minutes under the lamp while we monitored them with the LabQuest2. We recorded this data in an excel spreadsheet. Next, we repeated this procedure twice with the variegated leaves. Then, we took the variegated leaves and placed them in the bio chamber without the UV lamp. These leaves sat under the lamp for five minutes as we monitored their CO2 levels with the LabQuest2. These consisted of two trails. Finally, we took the non-variegated leaves and placed them in the bio chamber for five minutes in the dark as well.
This procedure repeated once. After each trail we aired out each bio chamber before placing new leaves inside. The data from these trials will be recorded in the excel sheet. The experimental group will be the two variations of leaves from the plant species we are using. The controlled treatments are the amount of time the leaves are under the UV lamp or in the dark. Also, we will sanitize the bio chamber prior to placing each leaf inside. Our independent variable is the variation of the leaves being measured. Our dependent variable is the CO2 rates of the leaves. We will perform a t-test to analyze our data, to compare the productivity rate of photosynthesis both in variegated and non-variegated leaves together; and both leaves in the dark.
Results
This test required the statistical t test for two-sample assuming unequal variances admits that the net primary productivity, was incomparably lower when both non-variegated and variegated leaves were considered (p=.117; df=1; p > 0.5). For the leaves placed in the dark, their photosynthetic rate seems to surpass the previously tested leaves (p=.376; df=2; p > 0.5).
Therefore, for the variegated leaves the test accepted the null; meaning there was no difference or relationship; and for the non-variegated leaves the test accepted the null as well. Furthermore, the variegated leaves did not produce a higher photosynthetic rate than the non-variegated leaves. The statistical results present that the darker leaves did not absorb more sunlight and it may have absorbed less than the non-variegated leaves.
Discussion
The outcome of our experiment disproves the hypothesis that variegated leaves will absorb more sunlight and produce a higher rate of photosynthesis rather than the non-variegated leaves. Furthermore, the experiment reveals that there is no relationship between Japanese Pittosporum leaves photosynthetic rates. With a (p>0.5) it shows that the difference between the C02 numbers the two leaves produced did not reveal a winner. Neither leaves produce more photosynthesis than the other. Properly measuring the photosynthetic rates with the plants uptake of C02 can show the amount each leaf produced.
The development of our experiment disproved the hypothesis that variegated leaves would ultimately absorb more sunlight; therefore, increasing its photosynthetic rates in Japanese Pittosporum. Furthermore, the net primary productivity was affected by receding photosynthetic rates in the darker colored leaves compared to lighter colored. In 1976, there was research conducted that focused on comparing the relationship between chlorophyll and rate of photosynthesis in soybeans. The results of the experiment revealed that there was no difference in between, “the two-leaf basis, PA” (Buttery, B.R. and Buzzel, R.I. 1977).
The soybeans with higher amounts of chlorophyll in their PA do not photosynthesis faster or have higher photosynthetic rates. Leaves with higher amounts of chlorophyll in them cannot use the products of light reactions because they have an insufficiency of enzymes/coenzymes. Hesketh (1963) showed that species can vary greatly in rate of photosynthesis and that this variation is not related to chlorophyll content (Buttery, B.R. and Buzzel, R.I. 1977).
Leaves containing very low levels of chlorophyll can absorb sunlight to satisfy them; but leaves containing high levels of chlorophyll can absorb extra light at low light levels (Buttery, B.R. and Buzzel, R.I. 1977). The experiment proves there is a “causative relationship between quantity of chlorophyll and rate of CO2 assimilation” (Buttery, B.R. and Buzzel, R.I. 1977). The relationship is dependent on the enzymes of the leaves plant.
Literature Cited
- Murchie, E. H., Pinto, M., & Horton, P. (2008). Agriculture and the new challenges for photosynthesis research. New Phytologist, 181(3), 532-552. doi:10.1111/j.1469-8137.2008.02705.x
- Buttery, B R., Buzzel, R I., & Research Station, Agricuhure Canada, Harrow, Ontario. (1977, January). The Relationship Between Chlorophyll Content and Rate of Photosynthesis in Soybeans. Retrieved from http://www.nrcresearchpress.com/doi/pdfplus/10.4141/cjps77-001
- Composition of photosynthetic pigments and photosynthetic characteristics in green and yellow sectors of the variegated Aucuba japonica ‘Variegata’ leaves. (2017, December 24). Retrieved April 03, 2018, from https://www.sciencedirect.com/science/article/pii/S0367253017334096
- Balino, K. T. (2018, August 28). Scientific Paper on Photosynthesis. Retrieved April 03, 2018, from https://www.scribd.com/doc/108457397/Scientific-Paper-on-Photosynthesis
- Saupe, S. G. (2009, January 7). Photosynthesis in Variegated Plant Tissues. Retrieved April 03, 2018, from https://employees.csbsju.edu/ssaupe/biol327/Lab/photosyn/gilson-lab.htm
- Murchie, E. H., Pinto, M., & Horton, P. (2008) and Buttery, B.R. and Buzzel, R.I. (1977).
