Effect of fruit and flower proximity on photosynthesis



The goal of this project is to determine if the proximity of a leaf to a flower, or a fruit, impacts photosynthesis. See references for past work, but it seems that this should be the case. However, the effect is nuanced - photosynthesis (linear electron flow) has been seen to drop when near flowers, but seen to increase when near fruit, especially later stage fruit.

I'm attempting to replicate this work using, initially, tomatoes and then expand to other plants throughout the fall of 2016. I'd like to know both if branches with and without fruits see differences, but also if there is a difference 'upstream' and 'downstream' of the fruit itself. This may tell us something about how photosynthate (sugars) moves away from the leaf.


  1. Choose a plant which has branches with and without fruit or flowers. Branches of both types should be relatively health and free to many dead leaves.
  2. Mark the top-most branch you can reach as branch 1, and count backwards towards the bottom along the main stem.
  3. Then, on each branch, starting with the top-most leaf, mark that as one and measure each leaf moving towards the main trunk.
  4. Leaves which are on the tip side of the fruit should be marked as 'tip side' leaves, while those on the trunk side should be marked 'trunk side'.
  5. Make sure to randomly choose from among health branches, and rotate between fruited, flowered, and no-flower branches throughout the day.

Measure at least 6 branches in a day (2 of each branch type) for a meaningful collection of data, but ideally 10 branches of each type and 20 measurements per branch (600 measurements total) if possible.

Here is an image to help explain the directions and measurement process:



Support for higher photosynthesis in leaves nearby fruit, and higher photosynthesis as fruit matured: http://link.springer.com/article/10.1007/BF00380612

http://treephys.oxfordjournals.org/content/23/5/289.short “Leaves close to developing fruits exhibited a higher photosynthetic capacity than other leaves, but similar Ta.”

http://treephys.oxfordjournals.org/content/24/4/387.short Flowering, however, seems to decrease electron flow in Photosystem II, also lower stomatal conductance. “It is concluded that low Anet in leaves close to inflorescences was probably due neither to changes in Na nor to a decrease in Rubisco activity induced by low gs, but rather to a decrease in electron flow in photosystem II.“


Leaf Photosynthesis MultispeQ V1.0


Measures many photosynthesis-related parameters in <15 seconds, including:

  • Chlorophll Fluorescence: Phi2, PhiNPQ, PhiNO, NPQt, qL, LEF
  • Relative Chlorophyll: SPAD
  • Proton Motive Force: ECSt, vH+, gH+
  • Absorbance at: 450, 535, 605, 650, 730, 850, 880, and 940nm.
  • Leaf Thickness (in mm), angle, and cardinal direct...


  1. Branch Number (Multiple Choice)
  2. Branch Type (Multiple Choice)
  3. Leaf Location (Multiple Choice)
  4. Leaf Number (Multiple Choice)
  5. Fruit Development (Multiple Choice)
  6. Fruit Size (Multiple Choice)



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