Effect of Canopy Location on Photosynthesis in Q. imbricaria

Overview

Q. imbricaria was assessed to determine whether or not there was a significant difference between the photosynthetic efficiency of the leaves on the outside of the canopy versus leaves on the inside of the canopy. This project can be replicated or contributed to by others in different areas, so long as the data collection and means of comparison remain similar. Data measured the linear electron flux (LEF), the photosynthetic efficiency of photosystem II (ΦII), and the chlorophyll content (PQSPAD) values for inner versus outer, as these were indicative of the photosynthetic activity of the trees by recording the amount of chlorophyll the leaves produced, the amount of light energy that is used for photosynthesis, and the flow of electrons. This study hypothesized that measuring three trees’ linear electron flux (LEF), chlorophyll content (PQ SPAD), and efficiency of photosystem II (ΦII) would show a significant difference in photosynthetic activity between the leaves on the outside versus the leaves on the inside due to their position on the canopy. The study predicted significantly greater photosynthetic activity (high LEF, high chlorophyll content, low ΦII) in leaves on the outer edges of the canopy compared to those on the inside. This added to previous research in determining whether leaf position in the canopy altered the photosynthetic abilities of the leaves.

It was important to record the quadrant being measured (inner/outer and the intermediate direction), and only trees of similar species, age, leaf quality, and light exposure were measured. Time for collecting data ranged from 1-2 consecutive hours during daylight, and only 120 measurements were taken per day to assure that differences in sun exposure did not affect the data.

Measurements were taken between the Q. imbricaria samples, each 8 years of age and located on MSU campus, west of Kedzie Hall and off of Auditorium Road. Forty measurements per tree (technical replicates) were taken on three trees (biological replicates) for a total of 1,440 measurements. In order to keep sampling random, each tree was divided into four quadrants (northeast, southeast, southwest, and northwest). A MultispeQ device was used for each of these measurements on a portion of the leaf that was free of holes and other deformities for an accurate measurement. ANOVA testing was used to verify that there were no significant differences in the data collected from the trees, and the means of all collected data for verified similar outside leaves were compared to the means of all collected data for the verified similar inside leaves using a T-Test to see if there was a statistical difference between their photosynthetic capabilities.

Protocols

Leaf Photosynthesis - MultispeQ Beta ONLY

Measures photosynthesis-related parameters in <15 seconds, including: Phi2, PhiNPQ, PhiNO, NPQt, qL, LEF, and SPAD. In addition, measures PAR (photosynthetically active radiation), ambient temperature and relative humidity.

Works with the MultispeQ Beta device only

Questions

  1. Inside or Outside (Multiple Choice)
  2. Quadrant (Multiple Choice)
  3. Tree Code (Multiple Choice)
  4. Sample Number (per quadrant) (Multiple Choice)

Locations

Discussions

Team

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