Hydrangea: Exterior vs Interior Sum 2017


Maximizing chlorophyll content and overall photosynthetic efficiency has been the highlight of many farming and reforestation efforts. There is no viable relationship between chlorophyll content and photosynthetic efficiency (Emerson, 1929). This is most likely due to the lack of comparison between the leaves tested in this experiment. Our group hopes that by measuring and comparing the interior and exterior leaves of Hydrangea paniculata, some relationship between the two variables will be shown. We spent the last several weeks studying several Hydrangea plants to answer our research question: in the summer of 2017, how are photosynthetic efficiency, LEF, phiNPQt, and chlorophyll content effected by comparing the differences between the interior and exterior of Hydrangea paniculata. Photosynthetic efficiency would be higher on the interior region compared to the exterior region  due to decreased light intensities (Boardman, 1977). However, LEF would be higher in the exterior because there was more exposure to light and SPAD would be higher in the interior region. Those plants exposed to higher light intensities were less efficient in transporting Hydrogen ions throughout the Thylakoid (Brand, 1997).

Methods: The organisms studied were Hydrangea paniculata in the Benefactor’s Plaza in North Campus of Michigan State University. Four of these organisms were measured by the MultispeQ Beta for photosynthetic efficiency, LEF, and chlorophyll content between 12:00 p.m. and 2:00 p.m. seven different times, each time taking 160 samples. Each organism was sectioned off into 8 sections: Northwest interior, Northwest exterior, Northeast interior, Northeast exterior, Southeast interior, Southeast exterior, Southwest interior, and Southwest exterior. The interior of the plant was defined as at least one foot from the edge of the organism toward the trunk. The exterior was defined as the leaves on the surface of the organism. Five leaves were measured in dry conditions using the device from each section in the order listed above for each organism. Organisms were measured in the following order: Hydrangea 3, Hydrangea 4, Hydrangea 5, then Hydrangea 6. To collect each sample, the device was clamped onto the leaf and ‘measure’ was immediately selected on a portable device set up with PhotoSynQ to collect the data (Kuhlgert, 2016). After the data was collected, the trace was analysed for photosynthetic activity. If the trace was valid, the measurement was accepted. On each day, we began measuring at plant number three. Starting on the interior region of the Northwest quadrant, moving clockwise around each plant, we sampled five leaves on the interior followed by the exterior, and moved on to the Northeast, Southeast, and Southwest Quadrants. The same protocol was followed on plants four, five, and six. Total sample size at the end would consist of 160 leaves each day (n=120).


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


  1. Which Hydrangea paniculata Bush is Being Measured? (Multiple Choice)
  2. Which Quadrant was Sample Taken From? (Multiple Choice)
  3. Sample is Taken From Interior/Exterior of Hydrangea Bush (Multiple Choice)
  4. This Measurement is Sample Number: (Multiple Choice)



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